No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Garlic supplementation and serum cholesterol: A meta-analysis
Journal of Clinical Pharmacy and Therapeutics
Abstract
Prevention of cardiovascular disease by modifying its major risk factors, including serum cholesterol levels, is an important strategy. Regular intake of garlic has been suggested, but its impact on cholesterol levels has been inconsistent.
A systematic review to critically summarize the evidence on the effect of garlic on serum cholesterol.
We carried out a comprehensive search of the Cochrane Library, MEDLINE, EMBASE, electronic publishing sites, reference lists of relevant papers and manual searches of relevant journals from inception to March 2008. We contacted experts and local manufacturers and distributors of garlic products to identify additional studies. To evaluate the effects of garlic on cholesterol levels in both healthy and hypercholesterolaemic subjects, randomized controlled trials of garlic ranging from 11 to 24 weeks in duration were included. Data were extracted and trial quality was assessed independently by two reviewers. The data were meta-analysed.
Thirteen trials including 1056 subjects were eligible for the meta-analysis. Overall, administration of garlic did not show any significant difference in effects on all outcome measures examined when compared with placebo. Garlic therapy did not produce any statistically significant reduction in serum total cholesterol level (mean difference, -0.04 mmol/L; 95% CI -0.15 to 0.07 mmol/L), LDL-cholesterol level (mean difference, 0.01 mmol/L; 95% CI -0.10 to 0.11 mmol/L), triglycerides level (mean difference, -0.05 mmol/L; 95% CI -0.17 to 0.06 mmol/L) or apolipoprotein B level (mean difference, -0.02 g/L; 95% CI -0.03 to 0.001 g/L). There was no difference between garlic and placebo on HDL-cholesterol level (mean difference, 0.01 mmol/L; 95% CI -0.03 to 0.05 mmol/L). As moderate to high heterogeneity exists among pooled studies, conclusive recommendations cannot be made at present on the actual effects of garlic therapy on serum cholesterol levels.
The available evidence from randomized controlled trial does not demonstrate any beneficial effects of garlic on serum cholesterol.
... Garlic supplements, mainly dried and pulverized whole clove supplements, have been used in a large number of controlled clinical trials since the mid-1980s, focusing primarily on serum cholesterol and blood pressure [1][2][3]. The effects on blood pressure have been moderately consistent for hypertensive subjects, while the effects on serum lipids have been inconsistent, even for persons with high baseline cholesterol levels [1,2,[4][5][6]. Of the 23 qualifying trials on serum cholesterol with a garlic powder product, 43% found no effect [1]. Due to the inconsistencies, the trials have been the subject of several meta-analyses (nine on serum lipids and eight on blood pressure), with the overall conclusions Figure 1. ...
... Product C2 simply stated to take 1-3 capsules per day. 4 For E2, no claim was made for the amount of garlic powder; it is estimated to be 0.40 g garlic powder per tablet, based on an average of 60% of tablet weight. 5 Kwai or Kwai Sapec or Kwai forte was originally made by Lichtwer Pharma, GmbH, Berlin, using 300 mg of LI 111 garlic powder that was standardized to contain 1.3% alliin and to yield 0.6% allicin. The tablets were used in numerous cardiovascular clinical trials from 1986 to 2005. ...
... 4 Tmin = the time (h) after consumption until AMS was first detected in the breath, with the limitation that the first breath was taken at about 1 h after consumption. 5 Allicin bioavailability = RRF = 100% × (RF product /RF control ). The RF control , determined with the low-protein meal (standard control, see Table 5), was used for all determinations, regardless of product meal type. ...
Allicin is considered responsible for most of the pharmacological activity of crushed raw garlic cloves. However, when garlic supplements and garlic foods are consumed, allicin bioavailability or bioequivalence (ABB) has been unknown and in question because allicin formation from alliin and garlic alliinase usually occurs after consumption, under enzyme-inhibiting gastrointestinal conditions. The ABB from 13 garlic supplements and 9 garlic foods was determined by bioassay for 13 subjects by comparing the area under the 32-h concentration curve of breath allyl methyl sulfide (AMS), the main breath metabolite of allicin, to the area found after consuming a control (100% ABB) of known allicin content: homogenized raw garlic. For enteric tablets, ABB varied from 36⁻104%, but it was reduced to 22⁻57% when consumed with a high-protein meal, due to slower gastric emptying. Independent of meal type, non-enteric tablets gave high ABB (80⁻111%), while garlic powder capsules gave 26⁻109%. Kwai garlic powder tablets, which have been used in a large number of clinical trials, gave 80% ABB, validating it as representing raw garlic in those trials. ABB did not vary with alliinase activity, indicating that only a minimum level of activity is required. Enteric tablets (high-protein meal) disintegrated slower in women than men. The ABB of supplements was compared to that predicted in vitro by the dissolution test in the United States Pharmacopeia (USP); only partial agreement was found. Cooked or acidified garlic foods, which have no alliinase activity, gave higher ABB than expected: boiled (16%), roasted (30%), pickled (19%), and acid-minced (66%). Black garlic gave 5%. The mechanism for the higher than expected ABB for alliinase-inhibited garlic was explored; the results for an alliin-free/allicin-free extract indicate a partial role for the enhanced metabolism of γ-glutamyl S-allylcysteine and S-allylcysteine to AMS. In conclusion, these largely unexpected results (lower ABB for enteric tablets and higher ABB for all other products) provide guidelines for the qualities of garlic products to be used in future clinical trials and new standards for manufacturers of garlic powder supplements. They also give the consumer an awareness of how garlic foods might compare to the garlic powder supplements used to establish any allicin-related health benefit of garlic.
... Sin embargo, los estudios en seres humanos han brindado resultados contradictorios. Mientras que dos revisiones sistemáticas de ensayos clínicos aleatorizados (13,14) han concluido que los efectos de los extractos de Allium sativum en dosis diarias entre 900 mg a 2 g, no presentan diferencias significativas en los niveles de HDL, LDL, triglicéridos y colesterol total; también admiten que no se puede extrapolar esta conclusión debido a la heterogeneidad de los estudios. ...
... En el grupo de estudio también se encontró un incremento del HDL-c de 4,1 mg/dL (IC95%: 2,9-5,3); sin embargo, la evidencia en este punto es contradictoria (21) ; por ejemplo: Khoo y Azis (14) , en un metanálisis de 12 ensayos clínicos aleatorizados, encontraron un incremento significativo de los valores de HDL-c de 2,32 mg/dL (IC95%: 0,15-4,64); a diferencia de los metanálisis de Reinhart et al. (22) ; y Stevinson et al. (15) quienes no hallaron diferencias significativas (diferencia de 0,97 mg/dL; IC 95%: 1,16-7,35). Esto puede deberse a metodologías diversas y con errores de aplicación, y se ve reflejado en resultados numéricos, pero que no reflejan una relevancia clínica. ...
... En el caso de los triglicéridos, se encontraron diferencias significativas en las cifras (21,5 mg/dL; IC 95%: 14,3-28,7 mg/dL), pero que no tuvieron influencia en el estado clínico de los pacientes. Los estudios antes mencionados (14,15,22,23) también son contradictorios sobre el tema, encontrando diferencias en los valores de triglicéridos entre 2,65-15,04 mg/dL. ...
Objetivo: Determinar el efecto del consumo de cápsulas de Allium sativum en una dosis diaria de 1 g por 12 semanas en pacientes con dislipidemia residentes en la ciudad de Huancayo (3200 msnm). Materiales y Métodos: Estudio experimental de un solo grupo de intervención con comparación pre-post. Se evaluaron a 33 sujetos (hombres y mujeres) con diagnóstico de dislipidemia de acuerdo a los criterios ATP III; quienes recibieron cápsulas con dosis de 1g diario por doce semanas. Se analizaron los valores de colesterol total, LDL-c, HDL-c y triglicéridos antes y después de la intervención. Resultados: Después de doce semanas, se encontraron reducciones estadísticamente significativas (p<0.001) de los valores de colesterol total (Δ 62.4 mg/dl; IC 95%: 59.1-65.7), LDL-c (Δ 63.7 mg/dl; IC 95%: 60.3-67.1) y Triglicéridos (Δ 21.5 mg/dl; IC 95%: 14.3-28.7) y aumento del HDL-c (Δ 4.1 mg/dl; IC 95%: 2.9-5.3). Conclusión: La intervención por doce semanas con cápsulas de Allium savitum en pacientes con dislipidemia mostró efectos estadísticamente significativos en los niveles de colesterol total, LDL-c, HDL-c y triglicéridos. Se recomienda realizar estudios clínicos aleatorizados para poder evaluar en real magnitud las tendencias observadas en estos resultados preliminares.
... Garlic contains high levels of organosulfur compounds and flavonoids as well as a variety of compounds that function synergistically to provide various health benefits [3]. The body of evidence on garlic continues to grow, and numerous clinical trials have been published [4][5][6][7]. Animal studies suggest that garlic has potential antilipidemic, antihypertensive, antiglycemic, antithrombotic and antiatherogenic properties [8][9][10]. However, clinical trials and reports from systematic reviews or metaanalyses present inconsistent results despite preclinical studies that suggest that garlic has potential preventive effects on CVD risk factors [4][5][6][7]. ...
... Animal studies suggest that garlic has potential antilipidemic, antihypertensive, antiglycemic, antithrombotic and antiatherogenic properties [8][9][10]. However, clinical trials and reports from systematic reviews or metaanalyses present inconsistent results despite preclinical studies that suggest that garlic has potential preventive effects on CVD risk factors [4][5][6][7]. The contradiction may be attributed to variations the manufacturing process that can markedly influence the composition of garlic products. ...
... Recently, meta-analyses investigating garlic consumption with respect to blood LDL-C or HDL-C levels reported conflicting findings. Ried et al. [4] demonstrated that garlic intake significantly improved these end points, whereas three meta-analyses questioned the robustness of such findings and the reported clinical effectiveness [6,7,37]. In contrast to the previous meta-analyses, our metaanalysis exclusively included garlic powder intake to avoid confounders. ...
Although preclinical studies suggest that garlic has potential preventive effects on cardiovascular disease (CVD) risk factors, clinical trials and reports from systematic reviews or meta-analyses present inconsistent results. The contradiction might be attributed to variations in the manufacturing process that can markedly influence the composition of garlic products. To investigate this issue further, we performed a meta-analysis of the effects of garlic powder on CVD risk factors.
We searched PubMed, Cochrane, Science Direct and EMBASE through May 2014. A random-effects meta-analysis was performed on 22 trials reporting total cholesterol (TC), 17 trials reporting LDL cholesterol (LDL-C), 18 trials reporting HDL cholesterol (HDL-C), 4 trials reporting fasting blood glucose (FBG), 9 trials reporting systolic blood pressure (SBP) and 10 trials reporting diastolic blood pressure (DBP).
The overall garlic powder intake significantly reduced blood TC and LDL-C by -0.41 mmol/L (95% confidence interval [CI], -0.69, -0.12) (-15.83 mg/dL [95% CI, -26.64, -4.63]) and -0.21 mmol/L (95% CI, -0.40, -0.03) (-8.11 mg/dL [95% CI, -15.44, -1.16]), respectively. The mean difference in the reduction of FBG levels was -0.96 mmol/L (95% CI, -1.91, -0.01) (-17.30 mg/dL [95% CI, -34.41, -0.18]). Evidence for SBP and DBP reduction in the garlic supplementation group was also demonstrated by decreases of -4.34 mmHg (95% CI, -8.38, -0.29) and -2.36 mmHg (95% CI, -4.56, -0.15), respectively.
This meta-analysis provides consistent evidence that garlic powder intake reduces the CVD risk factors of TC, LDL-C, FBG and BP.
... In a review study, Sobenin et al. [77]showed that garlic could improve the lipid profile. However, in a meta-analysis study, Khoo et al. [78] showed that garlic does not affect lipid profile. ese different results might be due to different types of garlic, different study designs, baseline lipid profiles, and study populations [34,75]. ...
... Besides, inhibiting adipogenesis and adipocyte differentiation through downregulation of PPARc, SREBP-1c, and fatty acid-binding protein (aP2) are other beneficial effects of garlic in obesity treatment [37,79]. Khoo and Aziz [78] indicated that garlic supplementation might reduce waist circumference without affecting body weight and BMI. ese different results may be due to different types of garlic, different duration of the study, and amount of dosage. ...
Nonalcoholic fatty liver disease (NAFLD) is globally the leading cause of hepatic dysfunction. Garlic has many physiological benefits, including anti-inflammatory, antioxidant, anticancer, lipid-lowering, and antidiabetes effects. The present study aimed to systematically review the effects of garlic (Allium sativum) and its mechanisms of function in managing NAFLD and its associated complications. The guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statements were applied to perform the study (CRD42021289348). The Scopus, Embase, Web of Science, Cochrane PubMed, and Google Scholar databases were searched until February 2022. According to the inclusion criteria, finally, 12 studies were entered into the study. The evidence provided in the study revealed that garlic could regulate the development of NAFLD via several mechanisms of action, such as lowering body weight, modulating lipid and glucose metabolism, and reducing inflammation and oxidative stress (OS). Overall, the beneficial effects of garlic in the treatment of NAFLD make it a potential therapeutic and efficient agent in managing NAFLD and its related risk factors. There is an insufficient number of clinical trials addressing the effects of garlic in humans; therefore, conducting more human research in the future is recommended.
... Then, 19,023 articles remained after removing the duplicates, and 18,992 articles were excluded after reviewing the titles and abstracts. Finally, 31 full-text articles (Chiavarini et al., 2016;Emami, Rouhani, & Azadbakht, 2017;Fleischauer, Poole, & Arab, 2000;Guercio, Turati, La Vecchia, Galeone, & Tavani, 2016;Hu et al., 2014;Khoo & Aziz, 2009;Kodali & Eslick, 2015;Kwak et al., 2014;Li, Ying, Shan, & Ji, 2018;Reinhart, Coleman, Teevan, Vachhani, & White, 2008;Reinhart, Talati, White, & Coleman, 2009;Ried, 2016;Ried, Frank, Stocks, Fakler, & Sullivan, 2008;Ried, Toben, & Fakler, 2013;Rohner, Ried, Sobenin, Bucher, & Nordmann, 2015;Sahebkar et al., 2016;Shabani et al., 2018;Silagy & Neil, 1994;Stevinson, Pittler, & Ernst, 2000;Sun, Wang, & Qin, 2018;Taghizadeh, Hamedifard, & Jafarnejad, 2018;Turati et al., 2014;Turati, Pelucchi, Guercio, La Vecchia, & Galeone, 2015;Wang, Yang, Qin, & Yang, 2015;Wang, Zhang, Lan, & Wang, 2017;Warshafsky, Kamer, & Sivak, 1993;Xiong et al., 2015;Zeng et al., 2012;Zhou, Ding, & Liu, 2013;Zhou et al., 2011;Zhu, Zou, Qi, Zhong, & Miao, 2014) were reviewed for further assessment. ...
... Among the 31 studies, 11 studies (Chiavarini et al., 2016;Fleischauer et al., 2000;Guercio et al., 2016;Hu et al., 2014;Kodali & Eslick, 2015;Li et al., 2018;Turati et al., 2014Turati et al., , 2015Zhou et al., 2013Zhou et al., , 2011Zhu et al., 2014) were about cancer and tumor outcomes (gastric cancer, colorectal cancer, upper aerodigestive tract cancer, prostate cancer, and colorectal adenomatous polyps), 13 studies (Emami et al., 2017;Khoo & Aziz, 2009;Kwak et al., 2014;Reinhart et al., 2009;Ried, 2016;Ried, Toben, et al., 2013;Sahebkar et al., 2016;Shabani et al., 2018;Stevinson et al., 2000;Sun et al., 2018;Wang et al., 2017;Warshafsky et al., 1993;Zeng et al., 2012) (Reinhart et al., 2008;Ried, 2016;Ried et al., 2008;Rohner et al., 2015;Silagy & Neil, 1994;Wang et al., 2015;Xiong et al., 2015) were about cardiovascular outcomes (systolic blood pressure and diastolic blood pressure), and only one systematic review and meta-analysis (Taghizadeh et al., 2018) was about serum C-reactive protein levels. Finally, 50 unique outcomes extracted from the 16 most recent meta-analyses were analyzed in this umbrella review, and the map of allium vegetable-related outcomes is reported in Figure 2. ...
Previously, our meta‐analysis and other studies have suggested that allium vegetable consumption is beneficial for health, but no umbrella review has been conducted to assess the evidence of the various health benefits of allium vegetable consumption. Therefore, we conducted this umbrella review on this topic. This umbrella review included a total of 16 meta‐analyses with 50 unique outcomes. The most beneficial cancer‐related outcome was shown for gastric cancer (risk ratio 0.78; 95% confidence interval [CI] 0.67–0.91). In addition, only 8 weeks of garlic consumption significantly decreased serum total cholesterol (weighted mean differences −17.20 mg/dl; 95% CI −23.10 to −11.30), and patients with dyslipidemia who consumed garlic experienced more benefits than the whole population. Diabetic patients with longer durations of garlic intake experienced more benefits in terms of fasting blood glucose (FBG), HbA1c, and serum fructosamine than healthy participants, and garlic intake was associated with blood pressure reduction in hypertensive patients but not in normotensive participants. Limited side effects of garlic, such as garlic odor and gastrointestinal complaints, were reported among the included meta‐analyses. Our results suggested that allium vegetables might be beneficial for cancer prevention. In particular, garlic was comparatively safe and is recommended as a long‐term dietary component for patients with dyslipidemia, diabetes, and hypertension. Allium vegetables as the common dietary vegetables around the world were suggested to be beneficial for cancer prevention in this umbrella review. Especially, the garlic seemed to be comparatively safe and recommended as long‐term diet for patients with dyslipidemia, diabetes, and hypertension.
... Algunos metaanálisis actuales confirman las propiedades del ajo mencionadas anteriormente [19]. Sin embargo, en otros muchos trabajos se concluye que el ajo no presenta dichas propiedades [20][21][22] y/o si las tuviese, que no son lo suficientemente significativas como para justificar su empleo con tales fines [23]. ...
... Tal y como se ha explicado en esta introducción, algunos estudios defienden que el ajo presenta numerosas propiedades beneficiosas para la salud y en concreto para prevenir y tratar las dislipemias [13][14][15][16][17][18][19]. Sin embargo, los resultados de estos estudios están más en concordancia con los obtenidos por otros autores, que no atribuyen al ajo poder suficiente como para ser empleado en dislipemias de manera individual [20][21][22][23]. De hecho, en dichos metaanálisis se obtienen reducciones de CT del 9-12% con respecto a placebo (mayores que en el presente estudio) y aun así consideran que el poder hipolipemiante de los preparados de ajo debe ser testado en revisiones más extensas. ...
Introducción: Las dislipemias son alteraciones de las lipoproteínas que transportan el colesterol y los triglicéridos, siendo consideradas factor de riesgo de enfermedades cardiovasculares. La eficacia de la utilización de productos vegetales cono el ajo (Allium sativum) para prevenir y tratar dislipemias es discutida. Hay pocos estudios publicados sobre el efecto de estos productos en el ámbito de la farmacia comunitaria.
Objetivos: Estudiar la variación de los valores de colesterol total en pacientes tratados con un complemento alimenticio a base de ajo en cápsulas. Relacionar dichos valores con factores demográficos y con la toma o no de medicamentos hipocolesterolemiantes de prescripción médica (MHPM). Comprobar si los resultados obtenidos concuerdan con los encontrados en la bibliografía.
Material y métodos: Estudio experimental y controlado realizado en una farmacia comunitaria. Los pacientes que aceptaron participar se dividieron aleatoriamente en dos grupos, grupo intervención (GI) que tomaba complemento alimenticio de ajo y grupo control (GC) que no lo tomaba.
Resultados: 59 sujetos, 29 pertenecientes al GC y 30 al GI. Mayor descenso del colesterol total en los que no tomaban MHPM, pero no puede atribuirse al efecto del complemento alimenticio administrado ya que el descenso se produce en los dos grupos. No se encontraron diferencias significativas entre los grupos. En los que ya tomaban MHP, el efecto del complemento alimenticio fue prácticamente inapreciable.
Conclusiones: En las condiciones del estudio realizado, el efecto del complemento alimenticio de ajo no parece ser lo suficientemente efectivo como para reducir los niveles de colesterol de forma significativa.
... 4 Various studies have shown the positive impact of garlic effects on lipid levels; however, some contradictory results are also reported. 5 Besides, extensive laboratory studies have demonstrated that garlic has a wide range of biological activities including antioxidant activity, lipid-lowering, and antiinflammatory activity by suppressing inflammatory mediators. [6][7][8] Data from human studies are, however, limited and inconsistent. ...
... Our results are consistent with previous observations in hypercholesterolemic or healthy participants that found no significant differences in lipid levels between those treated with garlic and placebo. 5 Baseline plasma values appear to be an important factor in demonstrating the lipid-lowering capacity of the treatment under investigation. In a German placebo-controlled study, those participants with baseline higher levels of cholesterol (250-300 mg/ dL) experienced a greater decrease in cholesterol levels with ingestion of 800 mg/d of dried garlic powder. ...
This study was designed to investigate whether garlic tablets possess anti-inflammatory and lipid-lowering effects in healthy adults. Twelve healthy adults participated in a randomized, cross-over design with a three-week treatment and a two-week washout period. Participants received either garlic powder tablets twice daily or two placebo tablets/day for three weeks. Plasma and peripheral blood mononuclear cells (PBMC) were isolated from fasting blood samples at baseline and after each three-week treatment with garlic or placebo. PBMC were cultured, stimulated with lipopolysaccharide (LPS), and changes in cell culture supernatants tumor necrosis factor-α (TNF-α) levels were determined. In addition, changes in plasma high-sensitivity C-reactive protein (hs-CRP), as well as plasma levels of lipids were determined. After three weeks of supplementation, LPS-stimulated TNF-α release in cell culture supernatant was lower after garlic than placebo (P <0.05) whereas no significant changes were observed in unstimulated TNF-α release or plasma TNF-α. There were no significant differences in plasma hs-CRP, cholesterol, triglyceride, LDL cholesterol, and HDL cholesterol levels between garlic and placebo. In healthy individuals, garlic supplementation did not change plasma levels of TNF-α and hs-CRP while it caused lower TNF-α release into cell culture supernatant after stimulation by LPS.
... 7 Prevention of cardiovascular disease by modifying its major risk factors, including serum cholesterol levels, is an important strategy. 8 Meta analysis of the controlled trial of garlic to reduce hypercholesterolemia showed a significant reduction in the total serum cholesterol levels. 9 However, a study reported that garlic powder preparation did not significantly affect plasma lipids levels. ...
... 10 Another study also not demonstrate any beneficial effects of garlic on serum cholesterol. 8 Our study was in accord to many studies. According to a study taking garlic supplement for 8−12 weeks can lower cholesterol by 17 mg of cholesterol/dl of blood, and reduction is statistically significant but it is unlikely that it will lessen risk of heart attack. ...
Background: Oral garlic supplementation may be effective in decreasing serum cholesterol levels as much as 15% to 20%. Garlic indirectly effect atherosclerosis by reduction of hyperlipidemia, hypertension and probably diabetes mellitus and prevents thrombus formation. This study was undertaken to test the hypothesis that garlic powder with a prolonged mode of action promises potent biological effects into hypocholesterolemia. Methods: Fifty albino rats were randomly divided into 5 equal groups (n=10). All rats were initially fed normal diet for at least 7 days. Then Group A was control and was fed a normal diet + 0.5% cholesterol, Group B was fed normal diet and 3 mg garlic per 10 g of feed and Group C was fed normal diet and 10 mg garlic per 10 g of feed. The experiment lasted for 12 weeks. Body weight and serum cholesterol were noted before and after giving garlic + cholesterol. Results: Effect of serum cholesterol level was significantly decreased after taking 3 and 10 mg of garlic. However it was observed that the body weight was increased after taking garlic. Conclusion: Garlic consumption although can decrease the level of serum cholesterol but it increases the body weight. Garlic consumption alone can decrease serum cholesterol level, but it cannot be used as the main therapeutic agent for hyperlipidaemia.
... In another study it was reported that long term use of garlic in reducing atheromatous lesions to almost 50%, particularly in the aorta 35 . However, numerous studies indicated no lipid lowering effects of garlic (36)(37)(38)(39)(40)(41)(42)(43)(44) and revealed negative effects on hypertension [45][46] . ...
Nature is serving as an abundant source of medicinal herbs and plants. Garlic is a medicinal herb with potential nutritional values. It has been used as a potential medicinal herb. Since time immemorial, garlic is a remedy for various physiological disorders. This review focuses on the medicinal uses of garlic in treatment and prevention of several chronic and acute diseases including infection of multidrug resistant Shigella infection. Bangladesh J. Nutr. Vol. 32, December 2019, P: 61-72
... of lipid in serum.42 Other studies focused to describe the effective dosage of garlic to have the optimum effect. ...
Garlic, a member of the Allium family, widely used as culinary and medicinal herbs since ancient histories, displays aptly described anti-inflammatory and antioxidant properties. Garlic’s therapeutic benefit is showed to be result of its constituent organosulfur compounds. Previous study reported garlic to possess several benefits on cardiovascular health including antihypertensive, anti-atherosclerotic, and antilipidemic activities. This review elaborates the phytochemical composition, pharmacological activities, mechanism of actions, and current clinical evidence of garlic in mitigating cardiovascular disease.
... 95 However, a metanalysis of 13 trials where garlic use was compared with placebo, no significant difference was found on all outcome measure. 96 A review of the studies carried out to investigate the effect of garlic on thrombosis has shown modest but statistically significant reduction in platelet aggregation with garlic when it was compared with placebo. 97 Garlic has also been studied for its effect on hypertension with no conclusive results or favourable outcomes have been found. ...
Cardiovascular disease (CVD) is the leading cause of death worldwide; responsible for 30% of all deaths globally. Food and nutrition are evidently an integral part of human health and play a crucial role in the cardiometabolic health of an individual. Poor diet quality is strongly associated with elevated risk of CVD morbidity and mortality. There is also strong evidence showing the effectiveness of "healthy" diet and other lifestyle patterns in the primary an d secondary prevention of cardiometabolic disease spectrum. There has been much emphasis on the preventive aspect of CVD and overall cardiometabolic health over the last three decades. Western societies and health systems have done quite a lot in improving and promoting healthy lifestyle choices. Unfortunately, developing countries, despite the worrisome rise in these preventable conditions, have contributed little to address this major issue with significant health and economic implications. The emphasis in these countries is mostly on the therapeutic, pharmacological, and more expensive tertiary management of the conditions that arise from poor cardiometabolic health, lifestyle, and dietary patterns. There is a lack of relevant and easy to understand authentic patient information or any effort to disseminate it to the public and patient population. Furthermore, there is not much effort at the governmental level to implement any meaningful measures concerning prevention of these conditions for the public at large. In this review about the nutritional needs and recommendations for cardiovascular health for Pakistani population, we have tried to encompass the relevant information into two papers. In the first, we cover the basic concepts, including mechanisms and other information relating to food and nutrition and their association with CVD and other cardiometabolic conditions (diabetes, dyslipidaemia, etc.). In the upcoming second issue, we will discuss more specific recommendations for the Pakistani population and dietary advice for CV health.
... Mechanism of action of garlic are (i) depressed activity of hepatic lipogenesis and cholesterolegenic enzyme such as malic enzyme, fatty acid synthetase, glucose 6-phosphate dehydrogenase and 3hydroxy,3-methyl glutaryl CoA (HMG-CoA) reductase [30] . (ii) Inhanced excreation of acidic and neutral steroid into bile after garlic feeding [31] and increased loss of bile salt in faeces and mobilization of tissue lipid into circulation as garlic has a profound effect in post-prandial hyperlipidemia [32] . (iii) Suppressed LDL oxidation by garlic preparation, especially by aged garlic extract (AGE) and aqueous garlic extract [33] , thus having anti-atherogenic effect [34][35] . ...
Garlic is an important universal dietary and medicinal plant which is being used as food and herbal medicine since ancient times. Hyperlipidemia is considered one of the major risk factors causing cardiovascular diseases (CVDs). CVDs accounts for one third of total deaths around the world, it is believed that CVDs will turn out to be the main cause of death and disability worldwide by the year 2020. The aim of the present literature review was to evaluate the effect of garlic on hyperlipidemia. The medicinal importance of garlic is attributed to its lipids lowering and antiatherogenic effects. Being important spice in human food, garlic can contribute its lipids lowering and anti-atherogenic effects. So it has been evaluated so far by several clinical trials in hyperlipidemia. Most of the studies on the effect of oral garlic on serum lipids have shown positive results within the low range of hyperlipidemia. The lipids lowering effect of garlic remains for a few months only. The conclusion of the literature review is need of further planned clinical trials to evaluate its qualitative and quantitative aspect of hypolipidemic effect in clinical practice.
... Effect of the GBSD in patients with high BP leads to recognition of the possibility that GSAC with its ACE-inhibitory and vasodilating activities may play a major role. Turner et al. (2004) and a meta-analysis by Khoo and Aziz (Khoo and Aziz et al., 2009). Long term trial is required for determining beneficial effects of GBSD on blood cholesterol. ...
Prevalence of hypertension is 26 % globally and expected to increase by 29 % till 2025, while in Pakistan its rate is 35 % due to genetic susceptibility, gender, urbanization and secondary life styles in middle ages, which causes heart diseases and stroke. It is the 1 st and 3 rd dominant cause of death worldwide. Non-pharmacological medication such as use of garlic in diet to reduce hypertension is the main goal in this study. As the bioactive sulfur compound source, garlic consists of S-Allylcysteine. Garlic-derived polysulfide triggers the production of vascular gasotransmitter hydrogen sulphide (H2S) and improves the regulation of endothelial nitric oxide (NO) which encourages smooth muscle relaxation, vasodilatation and blood pressure (BP) reduction. This randomized control study was planned to conclude the effect of garlic bread supplementary diet (GBSD) product on BP in patients with hypertension stage 1 and 2. In total, 2 patients with stage 1 hypertension and 2 with stage 2 hypertension were prescribed with a daily dose of GBSD (containing 600 mg garlic powder n=1 and n=1, respectively) or placebo (n=1 and n=1, respectively) for 12 weeks, were allocated to efficacy analyses. Systolic and diastolic blood pressure values were checked at weeks 4, 8 and 12. During the intervention an eloquent decline of systolic and diastolic BP within the range of 19.5-18.5 and 14.4-13.5 mmHg, respectively compared to placebo specifically during 8 and 12 week, obtained. GBSD was well tolerated, and had a clinically pertinent hypotensive effect in patients with stage 1 and 2 hypertension.
... One may ask that this additional effect could be due to garlic in this composition as studies have shown favorable effects of garlic in reduction of serum cholesterol levels and blood pressure control. Garlic is also known to have anti-oxidant and anti-platelet activities [23,24]. ...
Objectives: To assess the trend and effectiveness of Ajwa dates usage in management of coronary artery disease. Methods: In this, hospital based descriptive study, 150 cases of CAD were divided into 3 groups. Group One taking Ajwa alone, group Two on allopathic medicine and group Three taking both SCIREA Journal of Health Volume 3, Issue 1, February 2019 2 Ajwa and allopathic treatment. Data was collected through self-constructed questionnaire. Analysis done on SPSS version 20. Results: There were 50 subjects in each group. Mean age 52 ± 12 years. M: F ratio was 2: 1. 66% of entire study population was hypertensive, 41% diabetic and 43% hyperlipidemic. Study subjects were assessed for symptoms like chest pain, dyspnea, orthopnea or mixed symptoms. 38% in group One, and 50% in group Two and Three each, had chest pain, 24%, 8% and 22% had dyspnea, 2%, 6% and 12% had orthopnea, whereas 2% 14% and 12% had mixed symptoms in each respective group. Symptomatic relief for chest pain was 37% in group One, 60% in Two and 76% in group Three (P value < 0.05). Dyspnea and orthopnea results were not statistically significant. Overall symptomatic relief was 66% in group Three (P value < 0.05), Out of 2 preparations, Ajwa paste (pulp + seed) and Ajwa combination (Ajwa paste + Ginger garlic syrup), combination therapy was better i.e. 30% in group One and 75% in group Three had symptomatic improvement. Overall, results were highly significant with P value .000. Conclusion: The study suggests that Ajwa has some role in management of CAD, especially in symptomatic improvement.
... The possible mechanism of action of garlic are (i) depressed activity of hepatic lipogenesis and cholesterolegenic enzyme such as malic enzyme, fatty acid synthetase, glucose 6 -phosphate dehydrogenase and 3hydroxy,3-methyl glutaryl CoA (HMG-CoA) reductase [32] . (ii) Inhanced excreation of acidic and neutral steroid into bile after garlic feeding [16] and increased loss of bile salt in faeces and mobilization of tissue lipid into circulation as garlic has a profound effect in post-prandial hyperlipidemia [33] . (iii) Suppressed LDL oxidation by garlic preparation, especially by aged garlic extract (AGE) and aqueous garlic extract [34] , thus having anti-atherogenic effect. ...
... Summarizes a number of animal studies in the literature, from which we can include garlic preparations usually displayed positive effects. The mechanism of action of garlic that has been known to reduce lipid levels in experimental animals is by reducing cholesterol absorption in the intestine, inhibiting enzymes that play a role in cholesterol biosynthesis, and deactivating 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase), which also plays a role in cholesterol biosynthesis (Khoo and Aziz, 2009). The substance of garlic which is thought to play a role in reducing lipid levels is Allicin. ...
Dyslipidemia is one of the high-risk factors that cause cardiovascular disease and the prevalence is increasing all the time. Garlic (Alii sativi) has been suggested to reduce serum lipid level. Poly-herbal is herbal medicine that has been widely used in Indonesia, and it contains Alii sativi, Belericae fructus, Curcumae aeroginosae, and Amomi fructus extract. This study aimed to evaluate the effects of poly-herbal tablet on lipid levels in dylipidemia subjects. The study was conducted for 6 weeks on 58 dyslipidemic subjects. The subject was divided into 2 groups. Group 1 was given Poly-herbal with the dose 2x1200 mg, and group 2 was not given anti-dyslipidemic drugs (control group). Serum lipid level (total cholesterol, LDL, HDL, and triglycerides) were checked before the treatment (H0) and after the treatment (M6). There was a significant difference on the reduction of serum lipids level between the group that given Poly-herbal vs control group, respectively total cholesterol (-12.04±3.2 vs 8.38±4.3; p=.000), LDL (-4.42±2.8 vs 6.93±4.7; p=.049) and HDL (-2.62+1.0 vs 3.31+1.4; p=.005). Triglyceride level on Poly-herbal group is not significantly decreased. In Poly-herbal group there was also a decrease in HDL levels which was not statistically significant (-2.62±1, p=.015). This is probably due to the HDL baseline in the control group included in the normal HDL category (57.38 ± 14.9) so that the HDL levels after being given treatment did not increase. This study suggests that using Poly-herbal in dyslipidemia subjects can reduce the level of total cholesterol and LDL.
... La posible efi cacia de Allium sativum en el control de otros factores de riesgo cardiovascular (perfi les lipídicos) se presenta en siete revisiones sistemáticas y metanálisis, que presentan un gran solapamiento de estudios incluidos junto con dispares criterios de inclusión y valoración de riesgo de sesgos (Stevinson et al., 2000;Ackermann et al., 2001;Alder et al., 2003;Khoo & Aziz 2009;Reinhart et al., 2009;Zeng et al., 2012;Kwak et al., 2014). Por ello se recoge en formato narrativo la información más importante presentada en dichas revisiones. ...
Casi toda la historia que conocemos de nuestra Isla es aque-
lla que comenzó en 1492, con la llegada de Colón a la tierra
más hermosa que ojos humanos jamás han visto. En su
Diario de Navegación el Gran Almirante apuntó, con fecha 5
de noviembre de 1492, “Dizque dixo un indio por señas que
el almáciga era buena para cuando les dolía el estómago”.
Esta es, según apuntan muchos investigadores, la primera
referencia escrita al uso de las plantas medicinales por la
población aborigen cubana.
Desde ese entonces a esta fecha muchas cosas han cambiado.
Más de 500 años tejieron la cubanía, se tiñó de nuevas razas
nuestro archipiélago, con sangre se bañaron la manigua y
la sierra, pero resistiendo el paso tiempo todavía las plantas
medicinales siguen del lado de los cubanos. Si algo ha cam-
biado para semejante regalo de la Madre Naturaleza, es que
las infl uencias de la inmigración española, africana, china y
otras, enriquecieron la tradición de su uso.
Otro cambio ha sido, sin dudas, el aportado por la investiga-
ción científi ca. A este amplio campo de la Ciencia han dedicado
su vida, científi cos cubanos de la talla de Juan Tomás Roig
y Mesa, Víctor Fuentes Fiallo, Francisco Morón Rodríguez y
muchos otros. Más allá de la tradición, el uso etnológico de
las plantas medicinales transita hoy hacia su aplicación en el
campo de la Medicina sobre la base de evidencias. Muchísi-
mas especies vegetales han sido estudiadas a profundidad y
su empleo en el ámbito de la Fitoterapia está respaldado por
sufi cientes investigaciones farmacológicas y toxicológicas,
incluyéndose ensayos clínicos. También es necesario recor-
dar que el 30 % de los fármacos existentes son derivados de
plantas. A pesar de que estos clasifi can como medicamentos
sintéticos, tal hecho demuestra la importancia que han te-
nido las plantas medicinales en el desarrollo de la industria
farmacéutica moderna.
... wykazali, że spożywanie sproszkowanego czosnku wpływa na obniżenie cholesterolu całkowitego (o 15,83 mg/dl) i cholesterolu LDL (o 8,11 mg/dl) [40]. Jednak meta- analiza Khoo i Aziz, obejmująca 13 badań, wykazała, że podawanie czosnku nie wpłynęło na zmiany w stężeniach cholesterolu, trójglicerydów, a także apolipoproteiny B [34]. Dane pochodzące z wyników badań przeprowadzo- nych przez Lau, dostarczają dowodów wskazujących, że nawet krótkoterminowa suplementacja czosnkiem zwięk- sza odporność lipoprotein o małej gęstości na utlenianie [41]. ...
Cardiovascular diseases are the leading cause of death worldwide. Literature data indicate that, due to these diseases, approximately 17.5 million people died in 2012. Types of cardiovascular disease include ischemic heart disease, cerebrovascular disease, peripheral vascular disease, congenital heart disease, rheumatic heart disease, cardiomyopathy and arrhythmia. Proper nutrition is an important factor in reducing the risk of cardiovascular events. An interesting element of our diets is spices. For thousands of years, they have been used in the treatment of many diseases: bacterial infections, coughs, colds, and liver diseases. Many studies also demonstrate their antioxidant, chemopreventive, anti-inflammatory and immunomodulatory properties. This paper focuses on discussing the importance of selected spices (garlic, cinnamon, ginger, coriander and turmeric) in the prevention and treatment of cardiovascular diseases.
... In addition, Khoo and Aziz. 23 did not perform subgroup analyses by trial duration (short vs. long term efficacy); which proved effective (RCTs longer than 8 weeks) in SR by Ried. 25 Given the good safety profile of garlic preparations, the risk-benefit ratio seems to favour this treatment. For green tea, two SRs 26,27 concluded that significant reductions in serum TC and LDL-cholesterol concentrations, but no effect on HDL cholesterol. ...
Background:
The aim of this article is to summarize and critically evaluate the evidence from systematic reviews (SRs) of complementary and alternative medicine (CAM) for lowering blood lipid levels (BLL).
Methods:
Eight electronic databases were searched until March 2016. Additionally, all the retrieved references were inspected manually for further relevant papers. Systematic reviews were considered eligible, if they included patients of any age and/or gender with elevated blood lipid levels using any type of CAM. We used the Oxman and AMSTAR criteria to critically appraise the methodological quality of the included SRs.
Results:
Twenty-seven SRs were included in the analyses. The majority of the SRs were of high methodological quality (mean Oxman score=4.81, SD=4.88; and the mean AMSTAR score=7.22, SD=3.38). The majority of SRs (56%) arrived at equivocal conclusions (of these 8 were of high quality); 7 SRs (37%) arrived at positive conclusions (of these 6 were of high quality), and 2 (7%) arrived at negative conclusions (both were of high quality). There was conflicting evidence regarding the effectiveness of garlic; and promising evidence for yoga.
Conclusions:
To conclude, the evidence from SRs evaluating the effectiveness of CAM in lowering BLL is predominantly equivocal and confusing. Several limitations exist, such as variety of doses and preparations, confounding effects of diets and lifestyle factors, or heterogeneity of the primary trials among others.
... One of the most studied medicinal properties of garlic is lipid-lowering activity(78). However, findings of RCTs and several available meta-analyses on the lipid-modifying effects of garlic have been controversial(79)(80)(81)(82)(83)(84)(85). The latest and most comprehensive meta-analysis investigated the impactof different garlic preparations (including raw garlic, garlic powder, garlic oil and aged garlic extract) on lipid indices by reviewing 39 RCTs (86). ...
The review provides an up-to-date summary of the findings on the lipid-lowering effects of the most important nutraceuticals and functional foods. Based on the current knowledge, nutraceuticals might exert significant lipid-lowering, and their use has several advantages – they have natural origins and are mainly extracted from natural products, they are mostly safe and very well tolerated and their use is supported by the findings from randomizded controlled trials and meta-analyses, finally the lipid-lowering effect of most nutraceuticals is multimechanistic, what makes them potential candidates for improving the effects of current lipid-lowering drugs when used in combination. However, still a number of important questions need to be addressed, including whether longer durations of therapy would result in a better response, and what is the the safety profile of nutraceuticals, especially at doses higher than those consumed in an average diet. In addition, data regarding the impact of nutraceuticals supplementation on the incidence of cardiovascular outcomes are lacking, and it is not clear if additional lipid lowering by nutraceuticals can modify the residual cardiovascular risk that remains following statin therapy.
... mg/dL. The trial showing no effect (24) was published at the same time as that by Reinhart et al. (23), but it screened and included only half as many publications. This may perhaps indicate a bias. ...
Background:
Thousands of studies have been published based on animal and human studies evaluating garlic's effects and safety.
Objective:
We reviewed the available literature investigating the effects of garlic supplements on hypertension, hypercholesterolemia, C-reactive protein (CRP), pulse wave velocity (PWV), and coronary artery calcium (CAC), as well as available data on side effects.
Methods:
We searched PubMed for all human studies using medical subject heading words through 30 May 2013 and assessed relevant review articles and original studies. Only double-blind, randomized, controlled trials and meta-analyses of double-blind, randomized, controlled trials were included. The review of articles and data extraction were performed by 2 independent authors, with any disagreements resolved by consensus.
Results:
Garlic supplementation reduced blood pressure by 7-16 mm Hg (systolic) and 5-9 mm Hg (diastolic) (4 meta-analyses and 2 original studies). It reduced total cholesterol by 7.4-29.8 mg/dL (8 meta-analyses). The most consistent benefits were shown in studies that used aged garlic extract (AGE). A few small studies that used AGE also showed favorable effects on CAC, CRP, and PWV. Although garlic is generally safe, rare adverse reactions have been documented with limited causality established.
Conclusion:
We conclude that garlic supplementation has the potential for cardiovascular protection based on risk factor reduction (hypertension and total cholesterol) and surrogate markers (CRP, PWV, and CAC) of atherosclerosis. Larger studies are warranted to evaluate these effects further.
... There are natural compounds with medical value like garlic that over years have gained a unique place as a potential to control diabetes and its metabolic complications. There are many natural materials with anti-diabetic effects [12]. Garlic is one of the most popular spices in cooking and is the most selling plant supplementary all over the world. ...
... Conflicting results are reported concerning the effects of gar-132 lic on LDL-C. In 3 out of 6 meta-analyses, LDL-C was significantly de-133 creased following garlic administration (Ackermann et al. 2001; Kwak 134 et al. 2014; Ried et al. 2013), while in the remaining reviews, no effect 135 of garlic on this parameter could be observed (Khoo and Aziz 2009; 136 Reinhart et al. 2009; Zeng et al. 2012). Three (Silagy and Neil 1994a) 137 (Reinhart et al. 2009; Zeng et al. 2012) out of five studies reported a 138 significant decrease in triacylglycerol levels. ...
Purpose
To gain further insight into the strength of evidence and extent of possible biases in the scope of studies investigating the impact of garlic and garlic supplement intake on biomarkers of cardiovascular disease, we performed an umbrella review of all published meta-analyses synthesizing data from both observational studies and randomized controlled trials.
Methods
Electronic database PubMed (between 1966 and June 2015) was searched for systematic reviews and meta-analyses using following search terms: (“garlic” OR “allium sativum” OR “allicin” OR “organosulfur”) AND (“cardiovascular” OR “coronary” OR “cholesterol” OR “triglyceride” OR “atherosclerosis” OR “blood pressure” OR “hypertension” OR “blood glucose”) AND (“systematic review” OR “meta-analysis”), with no restriction to calendar data and language. Hand-search of reference lists and relevant clinical guidelines was performed as well.
Results
Nine systematic reviews investigated the effects of garlic on lipid parameters and eight systematic reviews analyzed the effects on blood pressure parameters were identified. Eight of nine meta-analyses synthesizing the effect of garlic on blood lipids reported significantly decreased total cholesterol levels. Inconsistent results could be detected for HDL-cholestrol, LDL-cholesterol, and triacylglycerols. The effect of garlic on systolic blood pressure showed consistent results across publications with 7 out of 8 meta-analyses demonstrating a substantial decrease in systolic blood pressure. Similar results could be reported regarding the effect of garlic on diastolic blood pressure, i.e. 6 out of 8 meta-analyses detected significant reductions in diastolic blood pressure levels following interventions with garlic.
Conclusion
According to the data summarized in the present umbrella review, garlic preparations as well as garlic exerted some positive effects on indicators and biomarkers of cardiovascular disease, typically without causing any serious side effects. However, with regard to the substantial heterogeneities between the different trials enrolled in the various meta-analyses of this review, a conservative interpretation of the outcome seems to be appropriate.
... Studies had also shown its significant lipid-lowering effects in the liver and anti-platelet activity [47,48]. Further study suggested that garlic has no effect on drug metabolism [49,50]. ...
Objectives: To evaluate the toxicity of lisinopril in liver of male rats and its reversal effect of garlic capsule (GAR) and selenium-vitamin A, vitamin B, vitamin C (SACE).
Methods: Thirty five adult male wistar rats were randomly assigned into 5 groups of 7 animals per group. Group I serves as the control, animals in Groups II, III, IV and V received 28 mg/kg body weight of lisinopril via oral route. Group III was co-treated with GAR at therapeutic dose of 250 mg/kg body weight per day. Group IV was co-treated with SACE at dose of 500 mg/kg body weight. Lastly, group V was co-treated with GAR and SACE at doses of 250 and 500 mg/kg body weight respectively, and the experiment last for 8 days.
Results: Administration of lisinopril caused systemic toxicity in liver as well as adverse histopathologic changes in the tested tissue. While GAR and SACE significantly (P
... Several meta-analyses on the impact of garlic on lipid levels reported inconsistent results [35][36][37][38][39][40][41], but none of them has addressed particularly the changes of Lp(a) concentrations. An explanation for the luck of beneficial effects on plasma Lp(a) concentrations could be the M A N U S C R I P T ...
... Results from animal studies suggest that garlic (or its preparations) exerts a hypocholesterolemic effect and reduces atherosclerotic plaque area (Gorinstein et al., 2006;Jastrzebski et al., 2007). In human studies, ingestion of garlic or garlic powder tablets has been variably reported to reduce (Sobenin et al., 2008;Kumar et al., 2013;Ashraf et al., 2005;Reinhart, 2009) or not affect plasma lipid values in subjects with mild to moderate hypercholesterolemia or diabetic patients (Simons et al., 1995;Superko, 2000;Gardner et al., 2001;Gardner et al., 2007;Khoo, 2009). Thickening of the intima-media of the arterial wall is the earliest detectable anatomic change in the development and progression of atherosclerosis. ...
This study was designed to investigate whether garlic powder tablets in adjunct to conventional medical treatment could have an effect on carotid intima-media thickness (CIMT) and plasma lipoproteins and lipids in patients with coronary artery disease (CAD).
A randomized, placebo-controlled, clinical trial was conducted on 56 patients with CAD between the ages of 25 and 75 years. The patients were randomly divided into two groups: garlic group (n = 27), receiving garlic powder tablet (1200 µg allicin/tab) twice daily and the placebo group (n = 29), receiving placebo for 3 months. The rate of atherosclerosis progression was measured by B-mode ultrasonography as the increase in CIMT.
After 3 months of taking garlic tablets, CIMT values had minor variations (0.009 ± 0.007 mm reduction from baseline), while in the placebo group, an increase in CIMT values was observed (0.04 ± 0.01 mm increase from baseline). After 3 months of treatment, mean CIMT difference from baseline was significantly differ between the two groups (p < 0.001). Plasma lipids and lipoproteins (total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, Apolipoprotein A1 and Apolipoprotein B) did not differ between the two groups.
The results suggest that dry garlic powder tablet is superior to placebo in prevention of CIMT progression in patients with CAD and may be considered as an adjunct treatment for atherosclerosis.
© The Author(s) 2015.
... For example, ingestion of heat-treated garlic may yield only minimal allicin compounds. 27,28 Thus, the different garlic preparation methods used in the trials may have contributed to the heterogeneous study findings and preclude an appropriate analysis of a dose relationship. Finally, the duration of intervention in all trials was relatively short, with a mean of 13.5 weeks. ...
Background:
Many patients prefer herbal medications to conventional drugs. Limited trial evidence suggests that garlic preparations reduce high blood pressure (BP).
Methods:
We searched electronic databases through March 2014 to identify all randomized controlled trials that compared a garlic preparation to placebo in hypertensive patients. Trials were required to report BP values at baseline and after a follow-up of at least 4 weeks.
Results:
Nine double-blind trials with 482 individuals fulfilled our inclusion criteria. Included trials were rather small, and the quality of the majority of included trials was moderate. Follow-up ranged from 8 to 26 weeks. All trials reported office BP measurements. Systolic BP and diastolic BP (SBP and DBP) were more effectively reduced in individuals treated with garlic preparations than in individuals treated with placebo. However, heterogeneity was high (weighted mean difference (WMD) for SBP was -9.1 mm Hg; 95% confidence interval (CI), -12.7 to -5.4; P for heterogeneity = 0.0006; and I2 = 71%; WMD for BP was -3.8 mm Hg; 95% CI, -6.7 to -1.0; P for heterogeneity = 0.00001; I2 = 80%). When analyses were restricted to higher-quality trials using intention-to-treat analysis or to trials with concealed treatment allocation and standardized and blinded BP measurement, effect sizes for SBP but not for DBP were lower and heterogeneity disappeared.
Conclusions:
Although evidence from this review suggests that garlic preparations may lower BP in hypertensive individuals, the evidence is not strong. A well-conducted and powered trial of longer duration is needed to confirm these findings.
Ethnopharmacological relevance:
Metabolic diseases are the major causes of macrovascular and microvascular complications which lead to morbidity and mortality. Traditionally, garlic has been used as food and medicine for more than 5000 years. However, efficacy studies have shown conflicting results regarding the garlic effect.
Aim of the study:
This study aims to evaluate the efficacy of garlic on the components of metabolic syndrome (MetS) in metabolic disease patients.
Materials and methods:
This study was a systematic review and meta-analysis of randomized controlled trials (RCTs). Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), and Google scholar were searched till 25th December 2021 for identifying the relevant studies that have shown the effects of garlic on components of metabolic syndrome in metabolic disease patients. The mean difference with 95% CI was calculated using fixed-effect or random-effect models.
Results:
The effect of garlic has shown significant changes on waist circumference (p-value= <0.0001), total cholesterol (p < 0.0001), low density lipoprotein (p = 0.01), high density lipoprotein (p < 0.00001), triglycerides (p < 0.00001), systolic blood pressure (p < 0.00001), diastolic blood pressure (p < 0.00001), glucose (p < 0.00001), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (p = 0.04), C-reactive protein (p < 0.00001), tumor necrosis factor (TNF)-α (p = 0.002), interleukin (IL)-6 (p = 0.0001). Subgroup analysis has shown the favorable effects of garlic in metabolic disease patients.
Conclusion:
Our meta-analysis results confirm the findings that garlic could be useful as an anti-hyperlipidemic, anti-hyperglycemic, anti-hypertensive and anti-inflammatory drug.
Der Wildapfel ist aus Kasachstan zu uns gekommen und fühlt sich so richtig wohl hier. Er ist kulinarisch ebenso vielseitig wie in der traditionellen Heilkunde (Abb. 5.1). Beliebte Kombinationen mit Äpfeln sind Orangen, Feigen, Chili, Gewürznelken, Wacholder, Rosinen, Vanille, Zimt, Zitronenmelisse und Zitronenverbene.
Cardiovascular diseases (CVDs) have become a common disease threat worldwide among men and women. CVDs include different pathologies, such as coronary heart disease, congenital heart disease, and cerebrovascular disease. There is historical evidence, which describes the beneficial and preventive effects of vegetables, fruits, and herbs in CVDs. There are several medicines obtained from plants that are being used in the treatment of heart diseases. In comparison to standard modern medicines, herbal preparations are being used due to their cost-effectiveness and a belief that they have comparatively less side effects. However, the safety-related beliefs about herbal medicines need to be tested through research. In the present book chapter, the medicinal plants and their application in the treatment of CVDs are summarized. The pharmacological potential of various medicinal herbs against CVD has been also discussed.
Garlic has long been known possessing many benefits for health and used as a pivotal spice for daily meals in many countries. Recent studies showed that black garlic has many advantages such as no strong odor and still remaining bioactivities of fresh ones, even better. Commercial black garlic products in Vietnam have not showed the physicochemical analysis as well as the original source. This study concentrated on Allium sativum L. garlic bulds collected at Ninh Thuan province, an area of which garlic is one of main agricultural products. The essential oil of the fresh garlic was analyzed by GC‐MS. From the fresh garlic bulds, two compounds, uracil (1) and butyl 4‐hydroxybenzoate (2) were isolated and structurally determined. Fresh garlic bulds were then prepared to black garlic. The physicochemical analysis methods showed that the S‐allyl cysteine, reducing sugar, total polyphenol and total protein content of 12‐day black garlic were much higher than those of fresh one. For instance, the S‐allyl cysteine content in fresh garlic and black one were 53.2 and 663.6 μg/g, the reducing sugar were 9.73 and 36.51 g/100g, respectively.
Garlic (Allium sativum) is a widely known medicinal plant, potential of which remains to be fully evaluated. Its wide-range beneficial effects appear to be relevant for treatment and prevention of atherosclerosis and related diseases. It is generally believed that garlic-based preparations are able to improve lipid profile in humans, inhibit cholesterol biosynthesis, suppress low density lipoprotein oxidation, modulate blood pressure, suppress platelet aggregation, lower plasma fibrinogen level and increase fibrinolytic activity, thus providing clinically relevant cardioprotective and anti-atherosclerotic effects. It is important to assess the level of evidence available for different protective effects of garlic and to understand the underlying mechanisms. This information will allow adequate integration of garlic-based preparations to clinical practice. In this review, we discuss the mechanisms of anti-atherosclerotic effects of garlic preparations, focusing on antihyperlipidemic, hypotensive, anti-platelet and direct anti-atherosclerotic activities of the medicinal plant. We also provide an overview of available meta-analyses and a number of clinical trials that assess the beneficial effects of garlic.
Hypercholesterolemia, as one of the major risk factors in development of cardiovascular diseases, is of mounting prevalence worldwide in recent years. Many nutraceuticals and phytochemical supplements serve as a promising complementary therapy in the management of hypercholesterolemia. Among them, spicy foods have attracted a special attention. Plasma lipid-lowering activity of garlic, ginger, and turmeric have been well studied in both humans and animals. Consumption of either 3 g/day of ginger or 2 g/day curcumin for over 4 weeks effectively reduced blood cholesterol in hypercholesterolemia subjects. However, effects of chili and black peppers on blood cholesterol are little studied clinically. The present review is to summarize the findings of recent studies on the efficacy and mechanism of spicy foods and their primary bioactive components in management of hypercholesterolemia from preclinical studies to clinical trials.
Dyslipidaemia is characterized by increased blood levels of total or LDL cholesterol and triglycerides, or decreased HDL cholesterol levels, and is a risk factor for cardiovascular disease. Dyslipidaemia has a high worldwide prevalence, and many patients are turning to alternatives to pharmacotherapy to manage their lipid levels. Lifestyle modification should be emphasized in all patients to reduce cardiovascular risk and can be initiated before pharmacotherapy in primary prevention of cardiovascular disease. Many functional foods and natural health products have been investigated for potential lipid-lowering properties. Those with good evidence for a biochemical effect on plasma lipid levels include soy protein, green tea, plant sterols, probiotic yogurt, marine-derived omega-3 fatty acids and red yeast rice. Other products such as seaweed, berberine, hawthorn and garlic might confer some limited benefit in certain patient groups. Although none of these products can reduce lipid levels to the same extent as statins, most are safe to use in addition to other lifestyle modifications and pharmacotherapy. Natural health products marketed at individuals with dyslipidaemia, such as policosanol, guggulsterone and resveratrol, have minimal definitive evidence of a biochemical benefit. Additional research is required in this field, which should include large, high-quality randomized controlled trials with long follow-up periods to investigate associations with cardiovascular end points.
Backgrounds and Objectives: Physical inactivity adversely affects the lipid profile. Based on the inconsistent and sometime contradictory results about the effects of endurance training and Garlic supplementation on lipid profile, this study was conducted to investigate the concurrent effect of endurance training and Garlic supplementation on body composition and lipid profile in sedentary young males. Materials and Methods: Thirty-six inactive healthy males were randomly divided into four groups, first group underwent endurance training and received garlic supplement (TG), second group only received garlic supplement (G) in third group endurance training plus placebo was implemented (TP), and fourth group only received placebo (P). Garlic capsule was prescribed two times per day (each capsule contains 500 mg allicin) over a period of 4 weeks. The training groups performed aerobic exercise including 30-45 minutes running at 60 to 75% of maximum heart rate. In addition to measuring the anthropometric variables, two blood samples were taken before and after the interventions and were analyzed for lipid profile. One-way ANOVA and Bonferroni post hoc test were applied to analyze the data. Results: We observed no significant difference among groups in body composition and triglyceride, cholesterol, low density lipoprotein (LDL-C) and high density lipoprotein (HDL-C) levels (p>0.05). Yet, HDL-C levels significantly decreased in TG group compared to pre-test levels (p>0.05). Conclusion: In the present study garlic supplementation along with endurance training had no significant effect on TG and LDL-C levels. Yet, HDL-C levels increased in TG group. Therefore, garlic supplementation along with endurance training might have favorable effect on lipid profile but further studies are needed.
Evidence for the safety and effectiveness of dietary supplements is mixed. The extent to which older people use dietary supplements concomitantly with conventional medications is often under-appreciated by physicians. We conducted a literature review on clinical considerations associated with dietary supplement use, focusing on benefits and harms, motivations for use and contribution to polypharmacy among older people. Vitamin D ≥ 800 IU has demonstrated benefits in fracture prevention. Vitamins A, E, and β-carotene have been associated with an increase in total mortality in several meta-analyses. A range of non-vitamin dietary supplements have been studied in randomized controlled trials but their efficacy remains largely unclear. Supplement use has been associated with a range of adverse events and drug interactions yet physicians rarely initiate discussions about their use with older patients. Older people may take dietary supplements to exercise control over their health. Given the contribution of supplements to polypharmacy, supplements may be targeted for “deprescribing” if the risk of harm is judged to outweigh benefits. This is best done as part of a comprehensive, patient-centered approach. A respectful and non-judgmental discussion may result in a shared decision to reduce polypharmacy through cessation of dietary supplements.
• KEY MESSAGES
• Herbal medications and other dietary supplements are highly prevalent among older people. Physicians are often unaware that their patients use herbal medications and other dietary supplements concomitantly with conventional medications.
• Herbal medications and other dietary supplements contribute to high rates of polypharmacy, particularly among older people with multimorbidity. Herbal medications and other dietary supplements can interact with conventional medications and be associated with a range of adverse events.
• Physicians need to be patient-centered and non-judgmental when initiating discussions about herbal medications and other dietary supplements. This is important to maintain and develop patient empowerment and self-management skills.
Nutraceuticals are increasingly recognized as effective modulators of lipid and lipoprotein metabolism and will likely have a prominent role in both the prevention and treatment of a wide range of dyslipidemic conditions in future health care systems. However, it is also recognized that the magnitude and direction of lipid responses to nutraceutical therapy is often not consistent on a patient-to-patient basis. These variable lipid responses are underscored by numerous metabolic, pathological, environmental, and genetic factors. The significance of nutraceuticals in future personalized lipid-lowering stratagems will depend greatly on our ability to apply advances in nutrigenomic technology to identify those subject-specific factors that influence how different individuals respond to specific nutraceutical therapies. This chapter will explore what is known regarding subject-specific lipid responses to nutraceuticals and discussadvances that have been made in identifying metabolic and genetic factors that may account for these variable responses.
The term complementary and alternative therapy (CAM) describes an array of treatments that serve as an adjunct to standard medicine practices but also serve as systems of intervention on their own. Many of these approaches promote a holistic view of medicine, positing that psychological or emotional experiences have an interactive relationship with physical experiences, and a growing body of research supports this link (see Astin, Shapiro, Eisenberg, & Forys, 2003; Cohen & Herbert, 1996; Pelletier, 1992). This is not limited to links between physical conditions and an individual's current mental state, as there is also mounting evidence to suggest that early traumatic experience and ongoing life stress can combine to affect the course of clinical disorders (Barreau et al., 2007). In this chapter we present a description of popular CAM approaches, their clinical applications, and a brief summary of supporting research. Our review includes approaches originating from Western and Eastern cultural traditions, as well as herbal remedies, lifestyle modifications, tactile therapies, movement therapies, and psychological (mind–body) therapies. Suggestions for future research are provided.Keywords:complementary and alternative medicine;mind-body;integrative medicine
A healthy dietary pattern is a cornerstone for the prevention and treatment of cardiovascular disease (CVD) and type 2 diabetes (T2DM). Compelling scientific evidence has shown many health effects of individual foods (including herbs and spices), beverages, and their constituent nutrients and bioactive components on risk of chronic disease and associated risk factors. The focus of functional foods research that is reviewed herein has been on assessing the health effects and underlying mechanisms of action of fruits and vegetables, whole grains, dairy products including fermented products, legumes, nuts, green tea, spices, olive oil, seafood, red wine, herbs, and spices. The unique health benefits of these functional foods have been the basis for recommending their inclusion in a healthy dietary pattern. A better understanding of strategies for optimally including functional foods in a healthy dietary pattern will confer greater benefits on the prevention and treatment of CVD and T2DM.
Introduction: Diabetes is a common serious metabolic disorder, and it may cause nephropathy. Garlic was experimentally documented to have an antidiabetic potential. Aim of the work: Investigate the possible protective role of garlic in the structural changes of the renal cortex in diabetic male albino rats. Materials and methods: Rats were divided into two main groups; group I included rats that were divided equally into a control group Ia (rats were administered distilled water) and a garlic group Ib (rats were administered 100▒mg/kg garlic powder). Group II (diabetic group) included rats in which diabetes was induced by a single intraperitoneal injection of 60▒mg/kg body weight streptozotocin; then, the rats were divided into two groups: an untreated diabetic group IIa (rats were administered distilled water) and a garlic-treated diabetic group IIb (rats were administered 100▒mg/kg garlic powder). Results: At the end of the experiment, the rats in the untreated diabetic group showed a nonsignificant change in their body weight and a significant increase in the mean fasting blood glucose by 40.6%. Microscopic examination of the renal cortex showed structural changes in both the proximal convoluted tubules and distal convoluted tubules in the form of a luminal cast, less basal infolding, and fewer basal mitochondria with loss of its cristae. Loss of microvilli of proximal convoluted tubules, extravasation of red blood cells, and a significant increase in the thickness of the glomerular basement membrane were also observed. However, at the end of the experiment, the garlic-treated diabetic group showed a significant increase in body weight by 21.7%, a significant decrease in the mean fasting blood glucose level by 29.6%, and absence of the most of the structural changes of the renal cortex. Conclusion: Garlic could protect against diabetes-induced structural changes in the renal cortex.
Cardiovascular disease (CVD) remains the leading cause of death and disability in developed countries and was predicted by the WHO to become the major cause of mortality in developing countries by 2010. Effective prevention needs a global strategy based on knowledge of the importance of risk factors, including diet. In recent years, many researches have been focused on the role of fiber, omega 3 fatty acids and phytochemicals in the prevention of CVD. The objective of this review is to present an updated overview of the potential effect of fiber, omega 3 fatty acids and phytochemicals in reducing the incidence of CVD through diet.
We evaluated the physiological effects of formulations added with black garlic extract on skin care. Black garlic was made by spontaneous fermentation for 40 days at 60~70°C and 85~95% RH without any additives. When black garlic extract was added to formulation, the tyrosinase activity was decreased significantly (p<0.05, p<0.01, p<0.001). Base formulation inhibited slightly elastase activity (<5%), while black garlic formulation had about 8-fold higher elastase inhibitory activity (p<0.01). It was observed that formulations, with or without black garlic extract, decreased thiobarbituric acid reactive substances (TBARS) and hydrogen peroxide which were increased by UVB irradiation, although there were no significant differences of these contents between black garlic formulation and base formulation. In conclusion, black garlic formulation had high inhibitory activities for tyrosinase and elastase, suggesting that black garlic may have beneficial properties as a material for cosmeceuticals.
One of the factors contributing to the increased risk of developing premature atherosclerosis is low plasma concentrations of high-density lipoprotein (HDL) cholesterol. Multiple potential mechanisms account for the cardioprotective effects of HDL and its main protein apolipoprotein A-I (apo A-I). Diet has an important role in modulating HDL cholesterol level. The widespread use of nutritional supplements may also alter the biology of HDL. In this review, we discuss the effect of select nutritional supplements on serum HDL cholesterol and apo A-I levels. Some nutritional supplements, such as phytosterols, soy proteins, and black seed extracts, may increase HDL cholesterol levels, while others such as cholic acid and high doses of commonly used antioxidant vitamins may downregulate HDL cholesterol levels and reduce its cardioprotection. Multiple mechanisms are involved in the regulation of HDL levels, so changes in production and clearance of HDL may have different clinical implications. The clinical relevance of the changes in HDL and apo A-I caused by nutrient supplementation needs to be tested in controlled clinical trials.
This is the third edition of European cardiovascular disease statistics. The first edition was published in 2000 when the European Union (EU) consisted of 15 Member States. After enlargement in 2004 and then again in 2007, there are now 27 Member States. Much has changed in the last seven years, but cardiovascular disease (CVD) remains the main cause of death in the EU. The European cardiovascular disease statistics was the first publication to bring together all the available sources of information about the burden of CVD in Europe, including data on death and illness, treatment, the prevalence of behavioural risk factors for CVD (smoking, diet, physical inactivity and alcohol consumption), and the prevalence of medical conditions associated with CVD (raised cholesterol, raised blood pressure, overweight and obesity, and diabetes). It
has become an indispensable resource for anybody working on reducing the burden of CVD in Europe or in public health generally.<br /
To identify studies measuring garlic powder tablets effects on systolic and diastolic blood pressure and to investigate if studies published prior to January 1994 would perform better than those published later.
Using MEDLINE (January 1966 through December 2004) studies involving human subjects that examined the effect of garlic (Allium sativum) on serum lipids and blood pressure were obtained. Studies that were conducted using garlic in the form of garlic powder tablets were included in the data extraction. Correlation coefficients were calculated for total serum cholesterol, systolic and diastolic blood pressure with respect to date of publication. Trials published prior to January 1994 were placed into an "earlier" group and compared to the "latter" group of studies published from January 1994 onward.
Eighteen trials were identified whereupon the inverse associations between total serum cholesterol, systolic and diastolic blood pressures with respect to time of publication were correlated (-0.614, -0.627, and -0.587 respectively, p < 0.05). No significant associations were observed between systolic and diastolic blood pressure with respect to total serum cholesterol (0.388 and 0.431 respectively). The following differences between the earlier and later groups were observed for total serum cholesterol (31.4 +/- 19.0 vs. 3.5 +/- 5.8 mg/dl, p = .004); systolic blood pressure (11.0 +/- 9.2 vs. 2.0 +/- 4.4 mmHg, p = .133) and diastolic blood pressure (5.8 +/- 3.4 vs. 0.9 +/- 2.4 mmHg, p = .018).
Publications published prior to January 1994 performed better than those published after January 1994, suggesting that allicin may be responsible for the antihypertensive effects of garlic powder tablets. However, a lack of correlation between changes in total serum cholesterol and blood pressure suggests that other organo-sulfur compounds may also play a role in the antihyper-tensive mechanisms of garlic.
Abstract
Garlic and its preparations have been widely recognized as agents for prevention and treatment of cardiovascular and other metabolic diseases, atherosclerosis, hyperlipidemia, thrombosis, hypertension and diabetes. Effectiveness of garlic in cardiovascular diseases was more encouraging in experimental studies, which prompted several clinical trials. Though many clinical trials showed a positive effect of garlic on almost all cardiovascular conditions mentioned above, however a number of negative studies have recently cast doubt on the efficary of garlic specially its cholesterol lowering effect of garlic. It is a great challenge for scientists all over the world to make a proper use of garlic and enjoy its maximum beneficial effect as it is the cheapest way to prevent cardiovascular disease. This review has attempted to make a bridge the gap between experimental and clinical study and to discuss the possible mechanisms of such therapeutic actions of garlic.
To assess the size and consistency of garlic's effect on total serum cholesterol in persons with cholesterol levels greater than 5.17 mmol/L (200 mg/dL).
Clinical trials were identified by a computerized literature search of MEDLINE and by an assessment of the bibliographies of published studies and reviews.
Trials were selected if they were randomized and placebo-controlled and if at least 75% of their patients had cholesterol levels greater than 5.17 mmol/L (200 mg/dL). Studies were excluded if they did not provide enough data to compute effect size. Five of 28 studies were selected for review.
Details of study design, patient characteristics, interventions, duration of therapy, and cholesterol measurements were extracted by one author and were verified by another.
Study quality was evaluated by multiple reviewers using a closed-ended questionnaire. Patients treated with garlic consistently showed a greater decrease in total cholesterol levels compared with those receiving placebo. Meta-analysis of homogeneous trials estimated a net cholesterol decrease attributable to garlic of 0.59 mmol/L (95% CI, 0.44 to 0.74) (23 mg/dL [CI, 17 to 29]) (P < 0.001).
Meta-analysis of the controlled trials of garlic to reduce hypercholesterolemia showed a significant reduction in total cholesterol levels. The best available evidence suggests that garlic, in an amount approximating one half to one clove per day, decreased total serum cholesterol levels by about 9% in the groups of patients studied.
It has been suggested that the quality of clinical trials should be assessed by blinded raters to limit the risk of introducing bias into meta-analyses and systematic reviews, and into the peer-review process. There is very little evidence in the literature to substantiate this. This study describes the development of an instrument to assess the quality of reports of randomized clinical trials (RCTs) in pain research and its use to determine the effect of rater blinding on the assessments of quality. A multidisciplinary panel of six judges produced an initial version of the instrument. Fourteen raters from three different backgrounds assessed the quality of 36 research reports in pain research, selected from three different samples. Seven were allocated randomly to perform the assessments under blind conditions. The final version of the instrument included three items. These items were scored consistently by all the raters regardless of background and could discriminate between reports from the different samples. Blind assessments produced significantly lower and more consistent scores than open assessments. The implications of this finding for systematic reviews, meta-analytic research and the peer-review process are discussed.
To determine the effect of 900 mg/day of dried garlic powder (standardised to 1.3% allicin) in reducing total cholesterol.
Double-blind, randomised six-month parallel trial.
115 individuals with a repeat total cholesterol concentration of 6.0-8.5 mmol/l and low-density lipoprotein (LDL) cholesterol of 3.5 mmol/l or above after six weeks of dietary advice.
The active treatment group received dried garlic tablets (standardised to 1.3% allicin) at a dosage of 300 mg three times daily. The control group received a matching placebo.
Primary end-point: total cholesterol concentration; secondary end-points: concentrations of LDL and high-density lipoprotein cholesterol, apolipoproteins (apo) A1 and B, and triglycerides.
There were no significant differences between the groups receiving garlic and placebo in the mean concentrations of serum lipids, lipoproteins or apo A1 or B, by analysis either on intention-to-treat or treatment received. In a meta-analysis which included the results from this trial, garlic was associated with a mean reduction in total cholesterol of -0.65 mmol/l (95% confidence intervals: -0.53 to -0.76).
In this trial, garlic was less effective in reducing total cholesterol than suggested by previous meta-analyses. Possible explanations are publication bias, overestimation of treatment effects in trials with inadequate concealment of treatment allocation, or a type 2 error. We conclude that meta-analyses should be interpreted critically and with particular caution if the constituent trials are small.
Meta-analysis should be as carefully planned as any other research project, with a detailed written protocol being prepared in advance.The a priori definition of eligibility criteria for studies to be included and a comprehensive search for such studies are central to high quality meta-analysis.The graphical display of results from individual studies on a common scale is an important intermediate step, which allows a visual examination of the degree of heterogeneity between studiesDifferent statistical methods exist for combining the data, but there is no single ''correct'' method.A thorough sensitivity analysis is essential to assess the robustness of combined estimates to different assumptions and inclusion criteria.
In this paper we consider the validity and power of some commonly used statistics for assessing the degree of homogeneity between trials in a meta-analysis. We show, using simulated individual patient data typical of that occurring in randomized controlled trials in pain, that the most commonly used statistics do not give the expected levels of statistical significance (i.e. the proportion of trials giving a significant result is not equal to the proportion expected due to random chance) when used with truly homogeneous data. In addition, all such statistics are shown to have extremely low power to detect true heterogeneity even when that heterogeneity is very large. Since, in most practical situations, failure to detect heterogeneity does not allow us to say with any helpful degree of certainty that the data is truly homogeneous, we advocate the quantitative combination of results only where the trials contained in a meta-analysis can be shown to be clinically homogeneous. We propose as a definition of clinical homogeneity that all trials have (i) fixed and clearly defined inclusion criteria and (ii) fixed and clearly defined outcomes or outcome measures. In pain relief, for example, the first of these would be satisfied by all patients having moderate or severe pain, whilst the second would be satisfied by using at least 50% pain relief as the successful outcome measure.
To investigate the effect of garlic on total cholesterol level in persons with elevated levels by conducting a meta-analysis of randomized, double-blind, placebo-controlled trials.
Systematic literature searches were conducted on the MEDLINE, EMBASE, BIOSIS, Cochrane Library, AMED, and CISCOM databases. Manufacturers of commercial garlic preparations and experts in the field were asked about published or unpublished trials.
Selected trials were required to state that they were randomized, double-blind, and placebo-controlled; use garlic monopreparations; include persons with mean total cholesterol levels of at least 5.17 mmol/L (200 mg/dL); and report total cholesterol level as an end point. There were no language restrictions.
Two reviewers, blinded to key identifiers of each paper, independently extracted data in a standardized manner and assessed methodologic quality by using the Jadad scale. Discrepancies were settled through discussion.
In the 13 trials included in the meta-analysis, garlic reduced total cholesterol level from baseline significantly more than placebo (P < 0.01); the weighted mean difference was -0.41 mmol/L (95% CI, -0.66 to -0.15 mmol/L) (-15.7 mg/dL [CI, -25.6 to -5. 7 mg/dL]). Six diet-controlled trials with the highest scores for methodologic quality revealed a nonsignificant difference between garlic and placebo groups; the weighted mean difference was -0.11 mmol/L (CI, -0.30 to 0.08 mmol/L) (-4.3 mg/dL [CI, -11.7 to 3.1 mg/dL]).
The available data suggest that garlic is superior to placebo in reducing total cholesterol levels. However, the size of the effect is modest, and the robustness of the effect is debatable. The use of garlic for hypercholesterolemia is therefore of questionable value.
The garlic (Allium sativa L.) bulb has been used as a food and condiment for centuries throughout the entire world and in Egypt for perhaps 5000 years. Since the passage of the Dietary Supplement Health and Education Act (DSHEA) of 1994 by the U.S. Congress, it has been claimed that garlic dietary supplements possess health benefits. Support for this claim is not the primary objective of this publication. The primary objective of this article is to demonstrate that the prediction of a potential health benefit(s) from garlic is largely dependent on the process used to produce a product.
Early trials of garlic preparations on blood lipids mainly supported a lipid-lowering effect, whereas later well-designed garlic tablet trials were mainly entirely null. However, enteric simulation tests suggest that this discordance may result from ineffective delivery of bioactive agents from the brands of garlic powder (GP) and cyclodextrin-bound garlic oil (GO) tablets tested in some recent negative trials. In contrast, enteric simulation tests show that the preformed bioactive agents present in "traditional" gelatin capsules of GO are efficiently released, although such capsules have rarely been investigated in lipid-lowering trials. It was hypothesized that gelatin capsules of GO given to normal subjects would improve specified coronary heart disease risk factors. Effects of a GP preparation were also investigated. Subjects (n = 51; men and women, mean age 27 y) were randomly assigned to receive either 8.2 mg/d of GO (allyl sulfides) or placebo for 11 wk. Another 27 subjects received garlic powder (GP) of similar biopotential (7.8 mg allicin/d). Outcome measures were 95% confidence intervals (CI) between GO and placebo groups for differences between baseline and subsequent sample times. Men and women combined showed no significant differences save for an improved total antioxidant capacity at 6 wk (P = 0.01). Hence, no benefit from GO after 11 wk is one plausible conclusion. However, there were significant differences in effect of GO between men and women for HDL cholesterol (HDL-C) (P = 0.004) and total cholesterol (TC)/HDL-C (P = 0.003). Women showed favorable effects in terms of CHD risk factors (i.e., increases in HDL-C and reductions in TC/HDL-C), whereas men had small adverse effects. There was a significant difference in the GO effect for glucose (P = 0.006), with a reduction seen for men and an increase for women. The gender effects were unexpected and such analyses were not planned in advance. Confirmation of these findings with larger numbers of subjects would have importance for the use of garlic against CHD and for the design of future garlic studies.
Previous studies using garlic have found alterations on a number of cardiovascular disease (CVD) risk factors including blood pressure, plasma viscosity, platelet activity, and serum lipid levels. The latest clinical research suggests that consumption of garlic powder does not play a significant role in lowering plasma lipid levels when in conjunction with a low-fat, low-cholesterol diet. Additional well-controlled, long-term studies that explore dosage and preparation type are necessary to confirm the efficacy of garlic in lowering cholesterol levels and to fully understand garlic's potential role in CVD.
Garlic and its preparations have been widely recognized as agents for prevention and treatment of cardiovascular and other metabolic diseases, atherosclerosis, hyperlipidemia, thrombosis, hypertension and diabetes. Effectiveness of garlic in cardiovascular diseases was more encouraging in experimental studies, which prompted several clinical trials. Though many clinical trials showed a positive effect of garlic on almost all cardiovascular conditions mentioned above, however a number of negative studies have recently cast doubt on the efficacy of garlic specially its cholesterol lowering effect of garlic. It is a great challenge for scientists all over the world to make a proper use of garlic and enjoy its maximum beneficial effect as it is the cheapest way to prevent cardiovascular disease. This review has attempted to make a bridge the gap between experimental and clinical study and to discuss the possible mechanisms of such therapeutic actions of garlic.
Cochrane Reviews have recently started including the quantity I 2 to help readers assess the consistency of the results of studies in meta-analyses. What does this new quantity mean, and why is assessment of heterogeneity so important to clinical practice?
Systematic reviews and meta-analyses can provide convincing and reliable evidence relevant to many aspects of medicine and health care.1 Their value is especially clear when the results of the studies they include show clinically important effects of similar magnitude. However, the conclusions are less clear when the included studies have differing results. In an attempt to establish whether studies are consistent, reports of meta-analyses commonly present a statistical test of heterogeneity. The test seeks to determine whether there are genuine differences underlying the results of the studies (heterogeneity), or whether the variation in findings is compatible with chance alone (homogeneity). However, the test is susceptible to the number of trials included in the meta-analysis. We have developed a new quantity, I 2, which we believe gives a better measure of the consistency between trials in a meta-analysis.
Assessment of the consistency of effects across studies is an essential part of meta-analysis. Unless we know how consistent the results of studies are, we cannot determine the generalisability of the findings of the meta-analysis. Indeed, several hierarchical systems for grading evidence state that the results of studies must be consistent or homogeneous to obtain the highest grading.2–4
Tests for heterogeneity are commonly used to decide on methods for combining studies and for concluding consistency or inconsistency of findings.5 6 But what does the test achieve in practice, and how should the resulting P values be interpreted?
A test for heterogeneity examines the null hypothesis that all studies are evaluating the same effect. The usual test statistic …
Recent studies have cast doubt on the proposed lipid-lowering and blood pressure-lowering effects of garlic. We tested the effect of dried garlic (Allium sativum) powder on blood lipids, blood pressure and arterial stiffness in a 12-week randomised, double-blind, placebo-controlled trial. Seventy-five healthy, normo-lipidaemic volunteers (men and women aged 40-60 years) were assigned to dried garlic powder tablets (10.8 mg alliin (3-(2-propenylsulfinyl)-L-alanine)/d, corresponding to about three garlic cloves) or placebo. Sixty-two subjects were eligible for the per-protocol analysis. The primary outcome measure was serum total cholesterol concentration. Secondary outcome measures were LDL-cholesterol, HDL-cholesterol and triacylglycerol concentrations, blood pressure and arterial stiffness (assessed by pulse wave velocity). No significant differences between the garlic and placebo groups were detected for any of the outcome measures. However, garlic powder was associated with a near-significant decrease (12 %) in triacylglycerol concentration (P=0.07). In conclusion, garlic powder tablets have no clinically relevant lipid-lowering and blood pressure-lowering effects in middle-aged, normo-lipidaemic individuals. The putative anti-atherosclerotic effect of garlic may be linked to risk markers other than blood lipids.
Epidemiologic studies show an inverse correlation between garlic consumption and progression of cardiovascular disease. Cardiovascular disease is associated with multiple factors such as raised serum total cholesterol, raised LDL and an increase in LDL oxidation, increased platelet aggregation, hypertension, and smoking. Numerous in vitro studies have confirmed the ability of garlic to reduce these parameters. Thus, garlic has been shown to inhibit enzymes involved in lipid synthesis, decrease platelet aggregation, prevent lipid peroxidation of oxidized erythrocytes and LDL, increase antioxidant status, and inhibit angiotension-converting enzyme. These findings have also been addressed in clinical trials. The studies point to the fact that garlic reduces cholesterol, inhibits platelet aggregation, reduces blood pressure, and increases antioxidant status. Since 1993, 44% of clinical trials have indicated a reduction in total cholesterol, and the most profound effect has been observed in garlic's ability to reduce the ability of platelets to aggregate. Mixed results have been obtained in the area of blood pressure and oxidative-stress reduction. The findings are limited because very few trials have addressed these issues. The negative results obtained in some clinical trials may also have resulted from usage of different garlic preparations, unknown active constituents and their bioavalability, inadequate randomization, selection of inappropriate subjects, and short duration of trials. This review analyzes in vitro and in vivo studies published since 1993 and concludes that although garlic appears to hold promise in reducing parameters associated with cardiovascular disease, more in-depth and appropriate studies are required.
Compounds in garlic work synergistically to produce various effects, but, because of garlic's chemical complexity, processing methods yield preparations with differing efficacy and safety. Although thiosulfinates such as allicin have been long misunderstood to be active compounds due to their characteristic odor, it is not necessary for garlic preparations to contain such odorous compounds to be effective, and they decompose and disappear during any processing. Garlic exhibits hypolipidemic, antiplatelet, and procirculatory effects. It prevents cold and flu symptoms through immune enhancement and demonstrates anticancer and chemopreventive activities. In addition, aged garlic extract possesses hepatoprotective, neuroprotective, antioxidative activities, whereas other preparations may stimulate oxidation. Additional effects may be caused by S-allylcysteine, S-allyl mercaptocysteine), saponins, N-alpha-fructosyl arginine, and other substances formed during a long-term extraction process. Although not all of active ingredients of garlic are known, and allicin-like transient components are not directly active, ample research suggests that an allicin-free garlic preparation that is standardized with a bioavailable component such as S-allylcysteine, is active and various effects of garlic may be attributed to it. Furthermore, various chemical constituents in garlic products, including nonsulfur compounds such as saponins, may contribute to the essential biological activities of garlic. Further studies are needed to confirm their bioavailability and associated activities.
In a double blind, placebo controlled randomised study the effects of a standardised garlic powder tablet (Kwai(*), Lichtwer Pharma) on blood lipids and blood pressure was investigated. A total of 52 out-patients with total cholesterol values over 6.5 mmol/l took part in the study. Patients were randomly allocated to take tablets containing a total of 900 mg garlic powder (standardised to 1.3% alliin) daily or the same number of placebo tablets for six months. All patients were advised to follow a low fat/cholesterol diet. Blood lipids were measured at baseline and after three and six months treatment. Blood pressure and well-being were assessed in monthly intervals. The baseline mean for serum total cholesterol of 6.92 mmol/l was reduced to 6.31 mmol/l after six months of garlic powder tablet treatment. Corresponding values for placebo were 7.05 mmol/l before and 6.74 mmol/l after placebo treatment. The difference between active treatment and placebo is statistically significant (p < 0.05). The mean values for low density lipoprotein cholesterol (LDL-C) was reduced by nearly 10% by garlic and by 6% by placebo. Mean systolic blood pressure (SBP) remained unchanged in the placebo group and was reduced in the active treated group by 17% from 145 to 120 mmHg (p < 0.001). Mean diastolic blood pressure (DBP) remained unchanged in the placebo group and was reduced in the active treated group from 90 mmHg to 80 mmHg (p < 0.01). The differences between active and placebo treatment were significant after two months of treatment for DBP and after four months for SBP. Well-being, as analysed by a five-point score system, remained unchanged in the placebo group and was improved in the active treated group by 20% (p < 0.001).
• This report of an expert panel of the National Cholesterol Education Program provides new guidelines for the treatment of high blood cholesterol in adults 20 years of age and over. Total cholesterol levels are classified as follows: <200 mg/dL —"desirable blood cholesterol"; 200 to 239 mg/dL—borderline—high blood cholesterol; ≥240 mg/dL—high blood cholesterol. The guidelines detail which patients should go on to have lipoprotein analysis, and which should receive cholesterol-lowering treatment on the basis of their low density lipoprotein (LDL)—cholesterol levels and status with respect to other coronary heart disease risk factors. Dietary therapy is the primary cholesterol-lowering treatment. The report specifies the LDL-cholesterol levels at which dietary therapy should be started and the goals of therapy, and provides detailed guidance on the nature of the recommended dietary changes. If, after six months of intensive dietary therapy, LDL-cholesterol exceeds specified levels, drug treatment should be considered.
(Arch Intern Med 1988;148:36-69)
To 1) conduct a thorough search of the literature for randomized controlled trials (RCTs) addressing the efficacy of garlic as an antihy-perlipidemic agent, 2) critically appraise those studies, and 3) make a recommendation for practicing health care professionals.
Two independent reviewers extracted data from the articles identified from several data bases, using the previously tested Boyack and Lookinland Methodological Quality Index (MQI) as the standard.
Six of ten studies found garlic to be effective. The average drop in total cholesterol was 24.8 mg/dL (9.9%), LDL 15.3 mg/dL (11.4%), and triglycerides 38 mg/dL (9.9%). The over-all average MQI score was 39.6% (18%-70%). Major shortcomings of many of the RCTs included short duration, lack of power analysis and intention to treat analysis, as well as lack of control of diet as a confoundingvariable.
The low methodological quality of the studies make it difficult to recommend garlic as an antihyperlipidemic agent. Until larger RCTs of longer duration, which correct the existing methodological flaws, are designed and carried out, it is best not to recommend garlic be used to treat mild to moderate hyperlipidemia.
For the first time, a weak clinical efficacy of a 12-week therapy with garlic powder (daily dose, 800 mg) is demonstrated in patients with peripheral arterial occlusive disease stage II. The increase in walking distance in the verum group by 46 m (from 161.0 ± 65.1 to 207.1 ± 85.0 m) was significantly higher (P<0.05) than in the placebo group (by 31 m, from 172.0 ± 60.9 to 203.1 ± 72.8). Both groups received physical therapy twice a week. The diastolic blood pressure, spontaneous thrombocyte aggregation, plasma viscosity, and cholesterol concentration also decreased significantly. Body weight was maintained. It is quite interesting that the garlic-specific increase in walking distance did not appear to occur until the 5th week of treatment, connected with a simultaneous decrease in spontaneous thrombocyte aggregation. Therefore, garlic may be an appropriate agent especially for the long-term treatment of an incipient intermittent claudication.
In a multicentric placebo-controlled randomised study the effect of standardized garlic-powder tablets (Kwai, Sapec) in the treatment of hyperlipidaemia was investigated. A total of 261 patients of 30 general practitioners in West Germany with total cholesterol and/or triglyceride values more than 200 mg/dl (mostly hyperlipoproteinaemia type II a/II b) took part in the study. Patients were randomly allocated to take tablets containing a total of 800 mg garlic powder (standardized to 1.3% of alliin content) daily or the same number of placebo tablets for 16 weeks (monthly controlled). 221 patients were used for statistical analysis of total cholesterol and 219 patients for the analysis of triglyceride values. Mean serum cholesterol levels dropped in the verum group from 266 to 235 mg/dl (i.e. 12%) during the 4 month treatment period, mean triglyceride values fell in the verum group from 226 to 188 mg/dl (i.e. 17%). The best cholesterol lowering effects were seen in the patients with initial total cholesterol values between 250-300 mg/dl. The difference between the verum and placebo group was highly significant (p less than 0.001). A mild garlic smell was observed in up to 21% of the verum group and up to 9% in the placebo group. Only one of the patients left the study for this reason. Standardized garlic tablets have been shown to be effective in the treatment of hyperlipidaemia by lowering total cholesterol values by an average of 12% and triglyceride values by an average of 17%.
The Expert Panel of the National Cholesterol Education Program has identified 10 risk factors for the occurrence of an atherosclerotic event. Each of these factors does not represent an independent risk. Male sex, family history of premature coronary events, cigarette smoking (> 10/day), systemic hypertension, diabetes mellitus and severe obesity (>30% overweight) should be viewed as cholesterol-dependent atherosclerotic risk factors and not in themselves as atherogenic. There is no doubt that atherosclerotic events are more common in people with these risk factors, but only in those populations with an average serum total cholesterol level above 3.9 mmol/l. Those most prone to having an atherosclerotic event are those who have already had such an event or who have pre-existing coronary heart disease. However, by including these as risk factors, no distinction is made between primary and secondary prevention. Atherosclerotic events of any kind, though predictive of future events are not, by definition, true risk factors and should not be viewed as such. The only absolute, unequivocal, independent atherosclerotic risk factor is an elevated serum total or, more specifically, low density lipoprotein (LDL)-cholesterol level. Whether a low level of high density lipoprotein cholesterol is an independent risk factor is not clear, but it should probably be regarded as an additive risk when the serum LDL-cholesterol is elevated.
To assess the effects of standardized garlic powder tablets on serum lipids and lipoproteins, glucose, and blood pressure.
Forty-two healthy adults (19 men, 23 women), mean age of 52 +/- 12 years, with a serum total cholesterol (TC) level of greater than or equal to 220 mg/dL received, in a randomized, double-blind fashion, either 300 mg three times a day of standardized garlic powder in tablet form or placebo. Diets and physical activity were unchanged. This study was conducted in an outpatient, clinical research unit.
The baseline serum TC level of 262 +/- 34 mg/dL was reduced to 247 +/- 40 mg/dL (p < 0.01) after 12 weeks of standard garlic treatment. Corresponding values for placebo were 276 +/- 34 mg/dL before and 274 +/- 29 mg/dL after placebo treatment. Low-density lipoprotein cholesterol (LDL-C) was reduced by 11% by garlic treatment and 3% by placebo (p < 0.05). There were no significant changes in high-density lipoprotein cholesterol, triglycerides, serum glucose, blood pressure, and other monitored parameters.
Treatment with standardized garlic 900 mg/d produced a significantly greater reduction in serum TC and LDL-C than placebo. The garlic formulation was well tolerated without any odor problems.
For the first time, a weak clinical efficacy of a 12-week therapy with garlic powder (daily dose, 800 mg) is demonstrated in patients with peripheral arterial occlusive disease stage II. The increase in walking distance in the verum group by 46 m (from 161.0 +/- 65.1 to 207.1 +/- 85.0 m) was significantly higher (P < 0.05) than in the placebo group (by 31 m, from 172.0 +/- 60.9 to 203.1 +/- 72.8). Both groups received physical therapy twice a week. The diastolic blood pressure, spontaneous thrombocyte aggregation, plasma viscosity, and cholesterol concentration also decreased significantly. Body weight was maintained. It is quite interesting that the garlic-specific increase in walking distance did not appear to occur until the 5th week of treatment, connected with a simultaneous decrease in spontaneous thrombocyte aggregation. Therefore, garlic may be an appropriate agent especially for the long-term treatment of an incipient intermittent claudication.
1. Studies of the effects of garlic on platelet aggregation have produced inconsistent results possibly related to variations in study design and in the garlic preparations used.
2. The present study examined the effects on platelet aggregation and serum thromboxane and lyso-platelet activating factor, of feeding garlic extract to healthy men using a placebo-controlled, double-blind design. The effects of the same garlic preparation on platelet aggregation in vitro were also investigated.
3. There were no significant differences in platelet aggregation with adenosine diphosphate, platelet activating factor (PAF) or collagen according to treatment group. Serum thromboxane and IysoPAF also showed no change related to garlic supplements.
4. In vitro aggregation with collagen decreased linearly with increasing amounts of garlic extract, but concentrations were higher than those attainable in vivo. Gastrointestinal side effects prevented the use of higher doses of garlic which must be considered to be pharmacological as they exceed changes achievable by dietary modification.
Garlic powder tablets have been reported to lower serum cholesterol levels. There is widespread belief among the general public that garlic powder tablets aid in controlling cholesterol levels. However, much of the prior data demonstrating the cholesterol-lowering effect of garlic tablets involved studies that were inadequately controlled.
To determine the lipid-lowering effect of garlic powder tablets in patients with hypercholesterolemia.
This was a randomized, double-blind, placebo-controlled, 12-week, parallel treatment study carried out in 2 outpatient lipid clinics. Entry into the study after 8 weeks of diet stabilization required a mean low-density lipoprotein cholesterol level on 2 visits of 4.1 mmol/L (160 mg/dL) or lower and a triglyceride level of 4.0 mmol/L (350 mg/dL) or lower. The active treatment arm received tablets containing 300 mg of garlic powder (Kwai) 3 times per day, given with meals (total, 900 mg/d). This is equivalent to approximately 2.7 g or approximately 1 clove of fresh garlic per day. The placebo arm received an identical-looking tablet, also given 3 times per day with meals. The main outcome measures included levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol after 12 weeks of treatment.
Twenty-eight patients (43% male; mean +/- SD age, 58 +/- 14 years) received garlic powder treatment and 22 (68% male; mean +/- SD age, 57 +/- 13 years) received placebo treatment. There were no significant lipid or lipoprotein changes in either the placebo- or garlic-treated groups and no significant difference between changes in the placebo-treated group compared with changes in the garlic-treated patients.
Garlic powder (900 mg/d) treatment for 12 weeks was ineffective in lowering cholesterol levels in patients with hypercholesterolemia.
Potential and documented interactions between alternative therapy agents and warfarin are discussed.
An estimated one third of adults in the United States use alternative therapies, including herbs. A major safety concern is potential interactions of alternative medicine products with prescription medications. This issue is especially important with respect to drugs with narrow therapeutic indexes, such as warfarin. Herbal products that may potentially increase the risk of bleeding or potentiate the effects of warfarin therapy include angelica root, arnica flower, anise, asafoetida, bogbean, borage seed oil, bromelain, capsicum, celery, chamomile, clove, fenugreek, feverfew, garlic, ginger ginkgo, horse chestnut, licorice root, lovage root, meadowsweet, onion, parsley, passionflower herb, poplar, quassia, red clover, rue, sweet clover, turmeric, and willow bark. Products that have been associated with documented reports of potential interactions with warfarin include coenzyme Q10, danshen, devil's claw, dong quai, ginseng, green tea, papain, and vitamin E. Interpretation of the available information on herb-warfarin interactions is difficult because nearly all of it is based on in vitro data, animal studies, or individual case reports. More study is needed to confirm and assess the clinical significance of these potential interactions.
There is evidence that a wide range of alternative therapy products have the potential to interact with warfarin. Pharmacists and other health care professionals should question all patients about use of alternative therapies and report documented interactions to FDA's MedWatch program.
Most trials of bulb garlic and garlic powder tablets indicate reduced coronary heart disease (CHD) risk in elevated-risk subjects. Most persons taking garlic supplements lack overt risk of CHD. However, no trials have tested steam-distilled garlic oil (GO) capsules with healthy subjects. The objectives of the present randomized, double-blind, placebo-controlled study were to determine whether GO capsules reduce CHD risk in trained male runners. Twenty-seven volunteers (mean age, 28.8 years) completed the study. Each took 12.3 mg/day GO (or placebo) capsules for 16 weeks. Main outcome measures were 95% confidence intervals (CIs) between GO and placebo groups for differences in changes of blood pressure (BP), plasma lipids, total antioxidant status (TAS), low-density lipoprotein (LDL) composition and blood clotting factors. Principal results as mean differences (95% CI) between GO and placebo are: pulse, 2.9 beats/min (-0.8 to 6.7), P = 0.12; systolic BP, -4.5 mmHg (-10.8 to 1.9), P = 0.16; plasma total cholesterol, 0.01 mmol/l (-0.34 to 0.37), P = 0.95; plasma triglycerides, -0.20 mmol/l (-0.43 to 0.03), P = 0.09; plasma TAS, 45 micromol Trolox equivalent/l (-35 to 124), P = 0.26; LDL density, 0.0019 g/ml (-0.0005 to 0.0043), P = 0.12; LDL triglycerides/protein, -0.078 mg/mg (-0.149 to -0.007), P = 0.03; LDL cholesterol/protein, -0.24 mg/mg (-0.69 to 0.22), P = 0.3; LDL TAS/triglycerides, 29 nmol/mg (11, 68), P = 0.15; prothrombin time, 0.99 s (-0.36 to 2.35), P = 0.14; partial thromboplastin time, 3.0 s (-1.0 to 7.1), P = 0.13. Results were null statistically. Trends with GO were mostly towards lower CHD risk, and a larger study (approximately 150 subjects) is required to test their validity.
Most chemical and biological studies about garlic have been conducted using organosulfur compounds. However, a variety of steroid saponins from garlic and related Allium species are being increasingly recognized for their importance in biological processes. This report demonstrates the isolation and structure determination of steroid saponins from garlic and aged garlic extract (AGE). In addition, the in vitro antifungal antitumor cytotoxicity and blood coagulability effects of steroid saponins from garlic and related Allium species are provided. Animal studies on the cholesterol-lowering effects of the saponin fractions from garlic are also summarized.
The medicinal use of garlic dates back thousands of years, but there was little scientific support of its therapeutic and pharmacologic properties until recently. In the past decade, the cancer-protective effects of garlic have been well established by epidemiologic studies and animal experiments. However, the cardiovascular-protective properties of garlic are less well understood. In particular, despite the reported hypocholesterolemic effect of garlic, the mechanism of the effect is unclear. In a recent randomized, double-blind, placebo-controlled intervention study, we showed that aged garlic extract (AGE) supplementation was effective in lowering plasma concentration of total cholesterol by 7% and LDL cholesterol by 10% in hypercholesterolemic men compared with subjects consuming a placebo. Supplementation of AGE in animal diets similarly reduced plasma concentrations of total cholesterol and triacylglycerol by 15 and 30%, respectively. In subsequent experiments using cultured rat hepatocytes, we found 44--87% inhibition of cholesterol synthesis by the water-extractable fraction (WEF), methanol-extractable fraction (MEF) and petroleum ether-extractable fraction (PEF) of fresh garlic, and Kyolic (liquid form of AGE). These observations suggested that hydrophilic and hydrophobic compounds of garlic are inhibitory to cholesterol synthesis. Because S-allylcysteine (SAC) alone was less potent than Kyolic, which contains SAC and other sulfur compounds, a maximal inhibition appears to require a concerted action of multiple compounds of garlic. In a series of experiments, we further characterized the inhibitory potency of individual water-soluble and lipid-soluble compounds of garlic. Among water-soluble compounds, SAC, S-ethylcysteine (SEC), and S-propylcysteine (SPC) inhibited cholesterol synthesis by 40--60% compared with 20--35% by gamma-glutamyl-S-allylcysteine (GSAC), gamma-glutamyl-S-methylcysteine (GSMC) and gamma-glutamyl-S-propylcysteine (GSPC). Lipid-soluble sulfur compounds (i.e., diallyl sulfide, diallyl disulfide, diallyl trisulfide, dipropyl sulfide and dipropyl trisulfide) at low concentrations (0.05--0.5 mol/L) slightly (10--15%) inhibited cholesterol synthesis but became highly cytotoxic at high concentrations (1.0--4.0 mol/L). All water-soluble compounds, except S-allylmercaptocysteine, were not cytotoxic, judging from the release of cellular lactate dehydrogenase into the culture medium. Taken together, the results of our studies indicate that the cholesterol-lowering effects of garlic extract, such as AGE, stem in part from inhibition of hepatic cholesterol synthesis by water-soluble sulfur compounds, especially SAC.
Cardiovascular disease is a complex and multifactorial disease characterized by such factors as high cholesterol, hypertension, reduced fibrinolysis, increase in blood-clotting time and increased platelet aggregation. Dietary therapy is the first step in the treatment of hyperlipidemia; garlic has been used medicinally for centuries and is still included in the traditional medicine of many cultures. Historically, there has been great interest in the role of garlic in reducing cardiovascular risk factors. Evidence from numerous studies points to the fact that garlic can bring about the normalization of plasma lipids, enhancement of fibrinolytic activity, inhibition of platelet aggregation and reduction of blood pressure and glucose. However, some contradictory results have also emerged as a result of methodological shortcomings, the use of different formulations/preparations of garlic and different time scales of the studies. Accordingly, further clinical studies are required in which standardized formulations of garlic with known compositions can be used. Such formulations (e.g., Aged Garlic Extract) are now available and are being investigated. Evidence obtained from these studies indicates that garlic has potential in the prevention and control of cardiovascular disorders and is beneficial when taken as a dietary supplement.
The health benefits of garlic likely arise from a wide variety of components, possibly working synergistically. The complex chemistry of garlic makes it plausible that variations in processing can yield quite different preparations. Highly unstable thiosulfinates, such as allicin, disappear during processing and are quickly transformed into a variety of organosulfur components. The efficacy and safety of these preparations in preparing dietary supplements based on garlic are also contingent on the processing methods employed. Although there are many garlic supplements commercially available, they fall into one of four categories, i.e., dehydrated garlic powder, garlic oil, garlic oil macerate and aged garlic extract (AGE). Garlic and garlic supplements are consumed in many cultures for their hypolipidemic, antiplatelet and procirculatory effects. In addition to these proclaimed beneficial effects, some garlic preparations also appear to possess hepatoprotective, immune-enhancing, anticancer and chemopreventive activities. Some preparations appear to be antioxidative, whereas others may stimulate oxidation. These additional biological effects attributed to AGE may be due to compounds, such as S-allylcysteine, S-allylmercaptocysteine, N(alpha)-fructosyl arginine and others, formed during the extraction process. Although not all of the active ingredients are known, ample research suggests that several bioavailable components likely contribute to the observed beneficial effects of garlic.
To summarize the effects of garlic on several cardiovascular-related factors and to note its adverse effects.
English and non-English citations were identified from 11 electronic databases, references, manufacturers, and experts from January 1966 through February 2000 (depending on the database searched). Reports of cardiovascular-related effects were limited to randomized controlled trials lasting at least 4 weeks. Reports of adverse effects were not limited by study design. From 1798 pertinent records, 45 randomized trials and 73 additional studies reporting adverse events were identified. Two physicians abstracted outcomes and assessed adequacy of randomization, blinding, and handling of dropouts. Standardized mean differences of lipid outcomes from placebo-controlled trials were adjusted for baseline differences and pooled using random effects methods.
Compared with placebo, garlic preparations may lead to small reductions in the total cholesterol level at 1 month (range of average pooled reductions, 0.03-0.45 mmol/L [1.2-17.3 mg/dL]) and at 3 months (range of average pooled reductions 0.32-0.66 mmol/L [12.4-25.4 mg/dL]), but not at 6 months. Changes in low-density lipoprotein levels and triglyceride levels paralleled total cholesterol level results; no statistically significant changes in high-density lipoprotein levels were observed. Trials also reported significant reductions in platelet aggregation and mixed effects on blood pressure outcomes. No effects on glycemic-related outcomes were found. Proven adverse effects included malodorous breath and body odor. Other unproven effects included flatulence, esophageal and abdominal pain, allergic reactions, and bleeding.
Trials suggest possible small short-term benefits of garlic on some lipid and antiplatelet factors, insignificant effects on blood pressure, and no effect on glucose levels. Conclusions regarding clinical significance are limited by the marginal quality and short duration of many trials and by the unpredictable release and inadequate definition of active constituents in study preparations.
To evaluate the hypocholesterolemic effect of an enteric-coated garlic supplement standardized for allicin-releasing potential in mild to moderate hypercholesterolemic patients.
A double-blind randomized, placebo-controlled intervention study was conducted in 46 hypercholesterolemic subjects who had failed or were not compliant with drug therapy. Each subject was given dietary counseling to lower fat intake and enteric-coated Australian garlic powder tablets with 9.6 mg allicin-releasing potential or matching placebo tablets.
After 12 weeks, the garlic supplement group (n=22) had a significant reduction in total cholesterol (TC, -0.36 mmol/L. -4.2%) and LDL-cholesterol (LDL-C, -0.44 mmol/L, -6.6%) while the placebo group (n=24) had a non-significant increase in TC (0.13 mmol/L, 2.0%) and LDL-C (0.18 mmol/L, 3.7%). HDL-cholesterol was significantly increased in the placebo group (0.09 mmol/L, 9.1%), compared to the garlic group (-0.02 mmol/L, -0.9%). and no significant difference in triglycerides or in LDL/HDL ratio was observed between groups.
The study demonstrates that enteric-coated garlic powder supplements with 9.6 mg allicin-releasing potential may have value in mild to moderate hypercholesterolemic patients when combined with a low fat diet. Taken with other evidence, the efficacy of garlic for lipoprotein metabolism might require allicin bioavailability to be enhanced through the use of, for example, an enteric-coated dose form. If this is the case, the possibility remains that greater hypocholesterolemic efficacy may be evident at a higher allicin dose. Also noteworthy in this study was a small reduction in energy intake with garlic compared with placebo, attributable to reduction in fat, carbohydrate and alcohol intakes. This may also have contributed to the effects on blood lipids. This study suggests that garlic supplementation has a cholesterol-lowering effect, which may be mediated by direct action of a biologically active compound or compounds and in part through the effect on food and nutrient intake.
Proper randomisation means little if investigators cannot include all randomised participants in the primary analysis. Participants might ignore follow-up, leave town, or take aspartame when instructed to take aspirin. Exclusions before randomisation do not bias the treatment comparison, but they can hurt generalisability. Eligibility criteria for a trial should be clear, specific, and applied before randomisation. Readers should assess whether any of the criteria make the trial sample atypical or unrepresentative of the people in which they are interested. In principle, assessment of exclusions after randomisation is simple: none are allowed. For the primary analysis, all participants enrolled should be included and analysed as part of the original group assigned (an intent-to-treat analysis). In reality, however, losses frequently occur. Investigators should, therefore, commit adequate resources to develop and implement procedures to maximise retention of participants. Moreover, researchers should provide clear, explicit information on the progress of all randomised participants through the trial by use of, for instance, a trial profile. Investigators can also do secondary analyses on, for instance, per-protocol or as-treated participants. Such analyses should be described as secondary and non-randomised comparisons. Mishandling of exclusions causes serious methodological difficulties. Unfortunately, some explanations for mishandling exclusions intuitively appeal to readers, disguising the seriousness of the issues. Creative mismanagement of exclusions can undermine trial validity.
There has been an impressive gain in individual life expectancy with parallel increases in age-related chronic diseases of the cardiovascular, brain and immune systems. These can cause loss of autonomy, dependence and high social costs for individuals and society. It is now accepted that aging and age-related diseases are in part caused by free radical reactions. The arrest of aging and stimulation of rejuvenation of the human body is also being sought. Over the last 20 years the use of herbs and natural products has gained popularity and these are being consumed backed by epidemiological evidence. One such herb is garlic, which has been used throughout the history of civilization for treating a wide variety of ailments associated with aging. The role of garlic in preventing age-related diseases has been investigated extensively over the last 10-15 years. Garlic has strong antioxidant properties and it has been suggested that garlic can prevent cardiovascular disease, inhibit platelet aggregation, thrombus formation, prevent cancer, diseases associated with cerebral aging, arthritis, cataract formation, and rejuvenate skin, improve blood circulation and energy levels. This review provides an insight in to garlic's antioxidant properties and presents evidence that it may either prevent or delay chronic diseases associated with aging.
Although garlic is believed to have health-promoting benefits, many of the claimed benefits are not supported by good scientific studies. This review critically examined current scientific literature concerning claims of cardiovascular benefits from regular consumption of garlic or garlic preparations. The vast majority of recent randomized, placebo-controlled studies do not support a role for garlic in lowering blood lipids. There also is insufficient evidence to support a role in reducing blood pressure. While there have been indications of antiatherosclerotic effects associated with garlic consumption, there are insufficient data in humans. Investigation of antithrombotic effects of garlic consumption appears to hold promise, but too few data exist to draw firm conclusions.
Homotoxicology is a form of therapy that uses homoeopathically diluted remedies with a view of eliminating toxins from the body. It is not a therapeutic method based on accepted scientific principles or biological plausibility. Yet numerous clinical studies have claimed efficacy. The aim of this systematic review is to summarise and critically evaluate the evidence from rigorous clinical trials of this form of therapy.
Seven electronic databases were searched for all studies of homotoxicological medicines for any human condition. To be included, trials had to be randomised and placebo-controlled. Data from such studies were validated and extracted according to pre-defined criteria. Their methodological quality was formally assessed using the Jadad score. Key data of all included trials were tabulated and summarised in narrative form.
Seven trials met our inclusion criteria. Their Jadad scores indicated mostly a high methodological standard. The trials tested the efficacy of seven different medicines for seven different indications. The results were positive in all but one study. Important flaws were found in all trials. These render the results of the primary studies less reliable than their high Jadad scores might suggest.
Despite mostly positive findings and high ratings on the Jadad score, the placebo-controlled, randomised clinical trials of homotoxicology fail to demonstrate the efficacy of this therapeutic approach.
The paper summarizes the knowledge on the antihyperlipidemic effect of garlic, formulations prepared from it, and the individual components, which were obtained prevalently in recent decade. It presents varying opinions based on experimental results concerning the mechanisms by means of which the effect takes place. In vitro experiments were carried out mainly on the cultures of rat hepatocytes and an inhibitory effect on important enzymic activities taking place in the biosynthesis of cholesterol and fatty acids was demonstrated. The most frequently employed in vivo models were rabbits. The antiatheraogenic effect was markedly manifested by a reduction of lipid plaques in the arteries in hypercholesterolemic animals, decreased accumulation of cholesterol in vascular walls, and other positive interventions.
Evidence that garlic inhibits platelet aggregation, increases fibrinolysis, reduces blood pressure, enhances anti-oxidant activity, and reduces serum lipids suggests that it may have cardio-protective properties. The lack of qualitative standardization of garlic preparations and the methodological weaknesses of earlier studies makes comparison between different studies complicated. Quantitative pooling of data in meta-analyses of the primary trials strongly suggests that garlic is an effective lipid-lowering agent.
Garlic has long been used medicinally, most recently for its cardiovascular, antineoplastic, and antimicrobial properties. Sulfur compounds, including allicin, appear to be the active components in the root bulb of the garlic plant. Studies show significant but modest lipid-lowering effects and antiplatelet activity. Significant blood pressure reduction is not consistently noted. There is some evidence for antineoplastic activity and insufficient evidence for clinical antimicrobial activity. Side effects generally are mild and uncommon. Garlic appears to have no effect on drug metabolism, but patients taking anticoagulants should be cautious. It seems prudent to stop taking high dosages of garlic seven to 10 days before surgery because garlic can prolong bleeding time.
Risk factors for cardiovascular disease, including high cholesterol, high homocysteine, hypertension and inflammation, increase the risk of dementia, including its most common form, Alzheimer's disease (AD). High cholesterol is also associated with elevated beta-amyloid (Abeta), the hallmark of AD. Oxidative damage is a major factor in cardiovascular disease and dementia, diseases whose risk increases with age. Garlic, extracted and aged to form antioxidant-rich aged garlic extract (AGE or Kyolic), may help reduce the risk of these diseases. AGE scavenges oxidants, increases superoxide dismutase, catalase, glutathione peroxidase, and glutathione levels, and inhibits lipid peroxidation and inflammatory prostaglandins. AGE reduces cholesterol synthesis by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase and is additive with statins in its action. Inhibition of cholesterol, LDL oxidation, and platelet aggregation by AGE, inhibits arterial plaque formation; AGE decreases homocysteine, lowers blood pressure, and increases microcirculation, which is important in diabetes, where microvascular changes increase heart disease and dementia risks. AGE also may help prevent cognitive decline by protecting neurons from Abeta neurotoxicity and apoptosis, thereby preventing ischemia- or reperfusion-related neuronal death and improving learning and memory retention. Although additional observations are warranted in humans, compelling evidence supports the beneficial health effects attributed to AGE in helping prevent cardiovascular and cerebrovascular diseases and lowering the risk of dementia and AD.
Epidemiologic studies show an inverse correlation between garlic consumption and progression of cardiovascular disease. Cardiovascular disease is associated with multiple factors such as raised serum total cholesterol, raised LDL and an increase in LDL oxidation, increased platelet aggregation, hypertension, and smoking. Numerous in vitro studies have confirmed the ability of garlic to reduce these parameters. Thus, garlic has been shown to inhibit enzymes involved in lipid synthesis, decrease platelet aggregation, prevent lipid peroxidation of oxidized erythrocytes and LDL, increase antioxidant status, and inhibit angiotension-converting enzyme. These findings have also been addressed in clinical trials. The studies point to the fact that garlic reduces cholesterol, inhibits platelet aggregation, reduces blood pressure, and increases antioxidant status. Since 1993, 44% of clinical trials have indicated a reduction in total cholesterol, and the most profound effect has been observed in garlic's ability to reduce the ability of platelets to aggregate. Mixed results have been obtained in the area of blood pressure and oxidative-stress reduction. The findings are limited because very few trials have addressed these issues. The negative results obtained in some clinical trials may also have resulted from usage of different garlic preparations, unknown active constituents and their bioavalability, inadequate randomization, selection of inappropriate subjects, and short duration of trials. This review analyzes in vitro and in vivo studies published since 1993 and concludes that although garlic appears to hold promise in reducing parameters associated with cardiovascular disease, more in-depth and appropriate studies are required.