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Flaxseed supplementation on glucose control and insulin sensitivity: A systematic review and meta-analysis of 25 randomized, placebo-controlled trials
Abstract
Context:
The results of human clinical trials investigating the effects of flaxseed on glucose control and insulin sensitivity are inconsistent.
Objective:
The present study aimed to systematically review and analyze randomized controlled trials assessing the effects of flaxseed consumption on glycemic control.
Data sources:
PubMed, Medline via Ovid, SCOPUS, EMBASE, and ISI Web of Sciences databases were searched up to November 2016.
Study selection:
Clinical trials in which flaxseed or its products were administered as an intervention were included.
Data extraction:
The outcomes were fasting blood glucose, insulin concentration, insulin resistance (HOMA-IR), insulin sensitivity (QUIKI), and hemoglobin A1c (HbA1c).
Results:
A total of 25 randomized clinical trials (30 treatment arms) were included. Meta-analysis suggested a significant association between flaxseed supplementation and a reduction in blood glucose (weighted mean difference [WMD], -2.94 mg/dL; 95%CI, -5.31 to - 0.56; P = 0.015), insulin levels (WMD, -7.32 pmol/L; 95%CI, -11.66 to -2.97; P = 0.001), and HOMA-IR index (WMD, -0.49; 95%CI,: -0.78 to - 0.20; P = 0.001) and an increase in QUIKI index (WMD, 0.019; 95%CI, 0.008-0.031; P = 0.001). No significant effect on HbA1c (WMD, -0.045%; 95%CI, -0.16 to - 0.07; P = 0.468) was found. In subgroup analysis, a significant reduction in blood glucose, insulin, and HOMA-IR and a significant increase in QUIKI were found only in studies using whole flaxseed but not flaxseed oil and lignan extract. Furthermore, a significant reduction was observed in insulin levels and insulin sensitivity indexes only in the subset of trials lasting ≥12 weeks.
Conclusions:
Whole flaxseed, but not flaxseed oil and lignan extract, has significant effects on improving glycemic control. Further studies are needed to determine the benefits of flaxseed on glycemic parameters.
... Some studies show the benefits of flaxseed supplementation on lipid profiles, anthropometric measures, and inflammatory cytokines such as C-reactive protein and interleukin-6 (IL-6) [12][13][14] . In fact, a meta-analysis demonstrated that whole flaxseed was the most efficient form to improve glycemic control and insulin resistance; nevertheless, this effect was not evaluated exclusively in patients with T2DM and prediabetes 15 . Furthermore, to the best of our knowledge, there are no meta-analyses conducted on patients with prediabetes and T2DM. ...
... or ground flaxseed) were compared in glycemic control among different pathologies and healthy individuals. This analysis found that supplementation with ground flaxseed was the most effective way to supplement flaxseed 15 . However, the effects of supplementation, specifically in patients with prediabetes and T2DM, had not been explored. ...
Background
Prediabetes and type 2 Diabetes Mellitus (T2DM) are characterized by increased blood sugar concentration and insulin resistance. Although there are only a few reports of potential benefits of flaxseed’s consumption on different metabolic parameters, there is no evidence of its effect among people with these conditions.
Objectives
The present systematic review and meta-analysis aimed to assess the effect of flaxseed supplementation on glycemic control variables and insulin resistance in prediabetes and T2DM.
Methods
A literature search was conducted through PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science, to identify Randomized Control Trials (RCTs) that evaluated the effect of milled or ground flaxseed supplementation on fasting blood glucose, HbA1c, insulin concentrations, or HOMA-IR. The data were analyzed using Comprehensive Meta-Analysis (CMA) software version 3.3 in a fixed-effect model.
Results
Seven studies were included in the systematic review and the meta-analysis, the results showed a significant reduction on fasting blood sugar (SMD: −0.392, 95% CI: −0.596, −0.187, p = <0.001, I² = 64.81%) insulin concentrations, (SMD: −0.287, 95% CI: −0.534, −0.041, p = 0.022, I² = 32.53%), HbA1c (SMD: −0.442, 95% CI: −0.770, −0.114, p = 0.008, I² = 11.058%), and HOMA-IR (SMD: −0.284, 95% CI: −0.530, −0.038, p = 0.024, I² = 0.00%) after flaxseed supplementation.
Conclusions
Flaxseed supplementation seems to improve glycemic control variables and insulin resistance in prediabetes and T2DM; however, more RCTs are needed to have more decisive evidence about doses, method of supplementation, and the possible effect of synergy with the dietetic treatment.
... Various therapeutic practices have been used for patients with NAFLD (Arab et al., 2014;Farhangi et al., 2022). Some herbs and medicinal plants are commonly used for preventing or treating diseases (Mohammadi-Sartang et al., 2018). However, the long-term safety and efficacy of these therapies have not yet been fully established (Arab et al., 2014). ...
Curcumin, as an antioxidant agent, has been proposed as a potential treatment for nonalcoholic fatty liver disease (NAFLD). The aim of the current systematic review and meta‐analysis was to summarize earlier findings regarding the effect of curcumin supplementation on liver enzymes and ALP in NAFLD patients. All studies published up to November 18, 2022, were searched through the PubMed, SCOPUS, and Web of Science databases to collect all randomized clinical trials (RCTs) on NAFLD patients in which curcumin was used as a treatment. A random‐effects model was used to measure pooled effect sizes. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to report pooled effect sizes. Subgroup analysis was utilized to investigate heterogeneity. A total of 14 studies were included in this systematic review and meta‐analysis. Our pooled meta‐analysis indicated a significant decrease in alanine aminotransferase (ALT) following curcumin therapy by pooling 12 effect sizes (WMD: –8.72; 95% CI: –15.16, –2.27, I² = 94.1%) and in aspartate aminotransferase (AST) based on 13 effect sizes (WMD: –6.35; 95% CI: –9.81, –2.88, I² = 94.4%). However, the pooled analysis of five trials indicated that there was no significant association between curcumin therapy and alkaline phosphatase (ALP) in NAFLD patients (WMD: −4.71; 95% CI: −13.01, 3.58, I² = 64.2%). Nevertheless, subgroup analyses showed significant effects of curcumin on ALP with a longer duration of supplementation. The findings of this systematic review and meta‐analysis support the potential effect of curcumin on the management of NAFLD. Further randomized controlled trials should be conducted in light of our findings.
... Consumption of flaxseed improves insulin sensitivity in individuals with prediabetes (Javidi et al., 2016) and obesity-related issues (Bongartz et al., 2022). Several studies indicate that the consumption of flaxseed improves glycemic control (Mohammadi-Sartang et al., 2018;Hajiahmadi et al., 2020;Villarreal-Renteria et al., 2022). The acute effects of flaxseed on postprandial hyperglycemia in individuals with T2DM have not been investigated until now (Moreira et al., 2022). ...
Pharmacological drugs targeting specific pathways involved in various diseases have seen recent advancement with newer and more efficient emerging drug targets, but these drugs are limited in terms of their side effects and patient adherence. The potential of plant-based diets in the form of functional foods is increasingly being realized as an option to treat and/or prevent several diseases. In this work, we have selected flaxseed (Linum usitatissimum), also known as linseed, to study its pharmacological efficacy and proposed mechanisms of action for medicinal purposes. The target genes of linseed with Disease Specificity Index (DSI >0.6) are compared to the associated genes of diabetes mellitus, decrease in appetite, addictive behavior, cardiovascular diseases (CVDs), inflammatory bowel diseases (IBDs), and Polycystic Ovary Syndrome (PCOS), and the selected genes are further evaluated using in silico methods. The binding affinity of flaxseed to three common target proteins (CCDC28b, PDCD6IP, and USP34) is assessed by docking and molecular dynamics (MD) simulations. The results show that linseed is safe to use for mutagenic toxicity and other cardiotoxicity measures, but linseed is unsafe for embryotoxicity, hERG toxicity, and cardiac failure. The analysis of the protein–protein interaction (PPI) network, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways indicates that flaxseed can be used as a medicinal herb for treatment of diabetes mellitus, cardiovascular diseases, IBDs, and PCOS.
... Additionally, the protein content of these seeds has been shown to stimulate insulin secretion, while the ALA content can contribute to increased insulin sensitivity [36,37,47]. A recent meta-analysis demonstrated that flaxseed significantly decreased insulin secretion in interventions lasting 12 weeks or more but not in shorter interventions [48]. These findings were further supported by another study that investigated the effects of flaxseed supplementation on blood glucose and insulin resistance in individuals with obesity and insulin resistance over a 12-week intervention period [49]. ...
Background/Aim: In recent years, there has been an increase in the prevalence of obesity and its complications, along with a growing awareness of healthy nutrition. As a result, consumers are seeking to incorporate more functional foods into their diets. Chia and flax seeds have gained popularity due to their soluble fiber and antioxidant capacity. This study aims to compare the effects of consuming cakes made with the addition of chia and flax seeds on blood glucose and insulin levels, as well as evaluate their impact on post-consumption satiety response in individuals. Methods: This randomized, double-blind, self-controlled experimental study involved 12 volunteers (19–64 years old) who were free from acute or chronic diseases. The participants had a body mass index (BMI) value between 18.5 and 24.9 kg/m2 and a Beck Depression Inventory score of 8 or below. The study investigated the effects of standard and test cakes containing 50 g of digestible carbohydrates, including chia-added cake, flaxseed-added cake, and chia+flaxseed-added cake. Postprandial blood sugar, insulin, and subjective satiety responses were assessed. A standard nutrition program (diet: 60% carbohydrates, 20% protein, 30% fat) was implemented at least one week before the study, and participants were asked to maintain 24-h food consumption records the day before the test days. Throughout the study period, individuals were instructed to avoid caffeine, medication, nutritional supplements, and heavy physical activity. Cake consumption sessions were conducted at the research center, with participants visiting four times in total, with at least 1-week intervals. Fasting for 10–12 h prior to each visit, saturation responses were measured using a visual analog scale at 0, 15, 30, 60, 90, 120, and 180 min. Blood samples were also collected to assess blood glucose and insulin levels. Results: The study revealed that cakes containing chia and flaxseeds, compared to the standard cake, as well as flaxseed-added cake compared to chia-added cake, resulted in higher plasma glucose under-curve values and saturation responses and lower hunger responses (P=0.038, P=0.016, P=0.004, respectively). Conclusion: The findings indicate that both chia and flax seeds impact glycemic control and the sensation of satiety, with flaxseed exhibiting greater effectiveness than chia.
... Com o crescente no mercado de produtos naturais, atrelado com a facilidade ao acesso às informações providenciado pelo acesso a internet, novos hábitos alimentares relacionados à medicina preventiva direcionou a pesquisa da indústria alimentícia em busca de produtos mais saudáveis. Assim, a linhaça vem sendo utilizada com fins medicinais e nutracêuticos na alimentação humana (Kajla et al., 2015), sendo considerada uma alimento funcional e seu uso em dietas alimentares proporciona equilíbrio entre os ácidos graxos no organismo, principalmente por sua alta taxa de ácidos poliinsaturados essenciais, tais como ácido alfa-linolênico e rico de fibra dietética solúvel (Cupersmid et al., 2012;Mohammadi-Sartang et al., 2018). ...
Este trabalho objetivou avaliar o padrão de expansão foliar de duas cultivares de linho (Linum usitatissimum, L.) semeadas na região litorânea de Santa Catarina utilizando o modelo Logístico. Para isso, duas cultivares de linho (marrom e dourada) foram avaliadas utilizando um delineamento de blocos completos casualizados com três repetições. Entre 28 e 107 dias após a semeadura, doze avaliações da área de folha foram realizadas utilizando análise de imagens, resultando na mensuração da área de 10.730 folhas. O modelo logístico foi ajustado para área média de folha em função do tempo e seus pontos críticos foram calculados para compreender o padrão de evolução deste caractere. Um teste de razão de verossimilhança indicou que os três parâmetros do modelo diferiram entre as cultivares, sugerindo que tanto a assíntota, quanto a forma da curva de expansão foliar são diferentes para cada cultivar. A cultivar marrom apresenta maior área de folha (se comparada com a dourada (β 1 = 1, 23). A máxima expansão foliar para a cultivar dourada foi de 0,01 cm 2 folha-1 dia-1 β 1 = 0, 79) observada aos 56 dias após a semeadura, diferindo da marrom, que apresentou uma taxa de expansão de de 0,014 cm 2 folha-1 dia-1 aos 72 dias após a semeadura. O ponto de desaceleração para a cultivar marrom foi atingido muito próximo do último dia de avaliação sugerindo que a expansão foliar desta cultivar ainda não atingiu seu máximo, sugerindo que mais avaliações deveriam ter sido realizadas para identificar a tendência de estabilização. Nossos resultados descrevendo a expansão foliar de cultivares de linho semeadas em regiões litorâneas do sul do Brasil poderão ser utilizados como referência para outros estudos avaliando a área de folha de linho.
... Several studies have shown that flaxseed consumption improves glycemic control [13,15,16,19]. However, to date, there are no studies that have investigated the acute effects of flaxseed on postprandial hyperglycemia in individuals with T2DM. ...
Background:
Postprandial glycemic excursions are associated with impairment control of diabetes mellitus. Long-term consumption of flaxseed can lower blood glucose levels; however, its effects on the postprandial glycemic response remain unknown. Therefore, this study aimed to evaluate the acute effects of raw flaxseed consumption on the 2 h postprandial glycemic curve in men with type 2 diabetes mellitus (T2DM).
Methods:
This was a randomized crossover clinical trial. Nineteen men with T2DM were randomly assigned a standardized breakfast without (control) or with a previous intake of 15 g of ground raw golden flaxseed (flax). Glycemia was measured at fasting and postprandial at 15, 30, 45, 60, 90, and 120 min. Palatability markers (visual appeal, smell, and pleasantness of taste) and taste intensity (sweetness, saltiness, bitterness, sourness, and creaminess) were evaluated.
Results:
The peak glucose rise and the 2 h AUC glycemic response reduced in the flax group by 17% (p = 0.001) and 24% (p < 0.001), respectively. The glucose peak time, palatability, and taste parameters did not differ between the two groups.
Conclusions:
Ingestion of 15 g of ground raw golden flaxseed before breakfast decreases the 2 h postprandial glycemic response in men with T2DM.
... Results from reviews and metanalyses show that flaxseed consumption has beneficial effects on blood pressure [274], lipid profile [275] and glucose metabolism [276]. Evidence regarding its effect on body composition indices, however, is controversial [277]. ...
The use of food supplements for weight loss purposes has rapidly gained popularity as the prevalence of obesity increases. Navigating through the vast, often low quality, literature available is challenging, as is providing informed advice to those asking for it. Herein, we provide a comprehensive literature revision focusing on most currently marketed dietary supplements claimed to favor weight loss, classifying them by their purported mechanism of action. We conclude by proposing a combination of supplements most supported by current evidence, that leverages all mechanisms of action possibly leading to a synergistic effect and greater weight loss in the foreseen absence of adverse events. Further studies will be needed to confirm the weight loss and metabolic improvement that may be obtained through the use of the proposed combination.
... In addition, ALA content of flaxseed [54,55] and its antioxidant substances [51] have positive effects on glycemic control and insulin sensitivity. Accordingly, whole flaxseed consumption is preferable to its oil or lignan supplements [56,57]. Our results regarding the beneficial effects of flaxseed on glycemic control [25,49,58], insulin level and insulin resistance [49] confirm the conclusions made by previous studies. ...
PurposeThe aim of the present study was to compare the clinical effect of flaxseed and hesperidin alone and with combination in patients with metabolic syndrome. Number of participants with treated metabolic syndrome was assessed as a primary end point.Methods
In this 12-week randomized controlled trial, ninety-eight patients with metabolic syndrome randomly assigned to receive either whole flaxseed powder (30 g/day), or hesperidin (1 g/day), or combination of 30 g flaxseed and 1 g hesperidin or no supplement while adhering a lifestyle modification program.ResultsIn comparison to control group, systolic blood pressure (− 5.68 vs. − 2.91 mmHg, P = 0.041) and serum concentrations of triglyceride (− 50.06 vs. 3.87 mg/dL, P = 0.033) in hesperidin group showed a significant reduction over 12 weeks of intervention. Comparison of the results of flaxseed group with the control group showed a significant improvement in serum concentrations of triglyceride (− 66 vs. 3.87 mg/dL, P = 0.028), insulin (− 4.27 vs. − 2.51 mU/L, P = 0.003) and accordingly insulin resistance (− 1.19 vs. − 0.76, P = 0.005) and sensitivity (0.03 vs. 0.01, P = 0.022) indices in flaxseed group. Combination of flaxseed and hesperidin improved three of five metabolic syndrome components including serum concentrations of triglyceride, glucose and systolic blood pressure as compared to placebo. Interestingly, co-administration of flaxseed and hesperidin with 77.3% reduction in the prevalence of defined metabolic syndrome was revealed to be most effective in controlling the metabolic syndrome, after which the group of flaxseed with 76% reduction and hesperidin group with 54.5% reduction were ranked second and third, respectively.Conclusions
It can be concluded that co-administration of flaxseed and hesperidin appears to be superior to either supplementation alone on metabolic syndrome treatment, while the effects of flaxseed are stronger than hesperidin supplementation.
... The results indicate that flaxseed supplementation may improve glycemic control. The changes may be more pronounced with whole flaxseed consumption, in subjects with higher baseline glucose levels, and in interventions longer than twelve weeks [71]. Adiponectin, which is produced by adipocytes and acts as a modulator of insulin sensitivity, has been shown to be low in insulin-resistant states. ...
Polycystic ovary syndrome (PCOS) is a complex disorder associated with ovarian dysfunction, infertility, menstrual irregularity, and hormonal impairments. Over the last decade, several studies have shown that some PCOS women have insulin resistance (InsR) and hyperinsulinemia, apart from being overweight or obese. Therefore, a crucial clinical aspect is that PCOS patients might develop glucose intolerance and type 2 diabetes. Insulin-sensitizing drugs have been used as first-line treatment to improve hyperinsulinemia in women with PCOS. Although reducing PCOS symptoms and signs, several used insulin-sensitizer drugs may induce side effects, which reduces compliance. D-chiro-inositol (DCI), which is a naturally occurring stereoisomer of inositol, has been classified as an insulin-sensitizer and seems to mitigate multiple InsR-related metabolic alterations in PCOS with a safe profile. However, according to a multi-targeted design, the supplementation with DCI can be synergistically integrated by combining other potential insulin-sensitizing drugs and/or nutraceuticals. The literature provides the initial support for using several unexplored nutraceutical interventions that may target relevant metabolic abnormalities associated with InsR in PCOS. With a need to promote interest in clinical research, this review aims to discuss the efficacy of DCI and the role of emerging nutraceuticals for managing InsR in PCOS.
... L. usitatissimum (Lu) Flax seed is the richest source of omega-3 fatty acids (4:1 proportion of omega 3 to omega 6) which has many beneficial effects some of them are to help to reduce anxiety and depression and decrease cardiovascular problems as it reduces triglycerides and increases HDL 17 . In the following research diabetes was induced in the rats by intraperitoneal injection of Streptozotocin (STZ) which destroys β cells, present in the islets of Langerhans of pancreas, therefore, causing experimental diabetes 18 .Though, many previously conducted studies were directed towards the positive effects of flax seeds such as hypolipidemic and hypoglycemic 19,20 including our prior study that was conducted to evaluate its combined effects with Glycyrrhiza glabra (GG) 21 , but none of the previous studies evaluated the anti dyslipidemic effects of different doses of Lu on diabetic rats 22 . ...
... There are limited studies evaluating the effects of flaxseed oil on FBS. 10,24,47 Our results are in line with previous studies. In one study, consumption of milled flaxseed or flaxseed oil (13.2 g/day) for 12 weeks in adults with type 2 diabetes did not influence glycemic control, or FBS. 10 Meropi et al indicated that ALA failed to lower FBS in healthy adults supplied with 15 mL/day of flaxseed oil. ...
Introduction:
It has been established that omega 3 fatty acids have cardio-protective effects through modulation of cardiometabolic risk factors via multiple mechanisms. The aim of this study was to investigate the effects of flaxseed oil on anthropometric indices and lipid profile in patients with coronary artery disease (CAD).
Methods:
A randomized, double-blind, placebo-controlled trial was performed in 44 patients with CAD. The subjects were randomly assigned to receive either 200 ml of 1.5% fat milk supplemented by 5 g of flaxseed oil (containing 2.5 g α-Linolenic acid) as intervention or 200 ml of 1.5% fat milk as placebo group for 10 consecutive weeks. Anthropometric indices and lipid profile were assessed at baseline and post-intervention.
Results:
The results indicated that supplementation with flaxseed oil had no impact on anthropometric indices. Weight, body mass index, waist circumference and hip circumference decreased statistically significant within groups, but not between groups. At the end of the intervention, diastolic blood pressure (DBP) decreased significantly (P = 0.022) in the intervention group. Moreover, the triglyceride (TG) level decreased significantly in the intervention group from 173.45 (49.09) to 139.33 (34.26) (P < 0.001). Other lipid profile indices including total cholesterol, low density lipoprotein and high density lipoprotein did not differ significantly within and between groups.
Conclusion:
We observed that supplementation of flaxseed oil improved TG and DBP but had no effect on other lipid profiles and anthropometric indices in patients with CAD.
Nuts possess a high concentration of essential nutrients and serve as a very effective source of bioactive chemicals that promote health. Therefore, they function as significant and nutritious snacks, while also being incorporated into numerous conventional and contemporary culinary preparations over the globe. It is strongly advised to regularly consume nuts in order to fully capitalize on the nutritional, bioactive, and antioxidant properties they possess, as well as to experience their desired taste and flavor. Robust scientific data indicate that individuals who consistently consume significant quantities of nuts (15 to 30 g of nuts) exhibit reduced prevalence of chronic non-communicable diseases. Nuts have been found to have positive health impacts, such as the potential to manage obesity and decrease the occurrence of cardiovascular disease (CVD), type 2 diabetes, several types of cancer, and other chronic diseases associated with food. The most robust and persistent positive impact of nut consumption is its correlation with decreased incidence of cardiovascular disease (CVD). Nuts find application in several food products within the food industry, encompassing oil, spreads, as well as in other sectors such as cosmetics and medicine, and as a viable source of biodiesel. The objective of this chapter is to provide a comprehensive overview of the characteristics, advantages, and uses of nuts.
Importance
Lignans are phytoestrogens abundant in Western diets and may be associated with type 2 diabetes (T2D) risk.
Objective
To prospectively investigate associations between lignan intake and T2D incidence.
Design, Setting, and Participants
Population-based cohort study of US men and women enrolled in the Nurses’ Health Study (NHS, 1984-2018), NHSII (1991-2019), and Health Professionals Follow-Up Study (HPFS, 1986-2020), as well as 496 participants from the Men’s Lifestyle Validation Study (MLVS). Participants were free of T2D, cardiovascular disease, and cancer at baseline. Data were analyzed from November 2022 to July 2023.
Exposures
Total and individual lignans were assessed using a validated food frequency questionnaire, which was updated every 2 to 4 years. In the MLVS, lignan intake was measured using 2 sets of 7-day diet records (7DDRs).
Main Outcomes and Measures
Incident T2D cases were confirmed using American Diabetes Association diagnostic criteria. Cox proportional hazards models were used to assess multivariable-adjusted associations.
Results
The current study included 201 111 participants (mean [SD] age, 44.7 [10.1] years; 161 169 female participants [80.2%]; 2614 African American participants [1.3%], 1609 Asian participants [0.8%], 2414 Hispanic and other race or ethnicity participants [1.2%], and 194 474 White participants [96.7%]) from the HPFS, NHS, and NHSII studies. The median (IQR) total lignan intake of the highest quintile ranged from 355.1 (330.2-396.9) μg/d in NHS to 459.9 (422.2-519.5) μg/d in HPFS at the median follow-up time. Over 5 068 689 person-years, 20 291 incident cases of T2D were identified. Higher lignan intake was inversely associated with T2D incidence, except for lariciresinol. The multivariable-adjusted pooled hazard ratios (HRs) for the highest vs lowest quintiles were 0.87 (95% CI, 0.83-0.91) for total lignans, 0.72 (95% CI, 0.69-0.76) for secoisolariciresinol, 0.92 (95% CI, 0.87-0.96) for pinoresinol, 0.93 (95% CI, 0.89-0.98) for matairesinol, and 0.99 (95% CI, 0.94-1.04) for lariciresinol. Secoisolariciresinol intake exhibited a significant inverse association with T2D risk among individuals with obesity (HR, 0.75 for body mass index [BMI] ≥30; 95% CI, 0.71-0.79 vs HR, 0.82 for BMI <25; 95% CI, 0.81-0.83; P < .001 for interaction) and premenopausal women (HR, 0.67 for premenopausal women; 95% CI, 0.65-0.69 vs HR, 0.82 for the past use of hormones; 95% CI, 0.76-0.88; P = .003 for interaction). Dietary lignan assessed with 7DDRs was associated with lower HbA 1c levels (percentage change range from −0.92% to 1.50%), as well as lower C-reactive protein levels and better lipid profiles.
Conclusions and Relevance
This cohort study found that long-term lignan consumption was associated with a lower T2D risk, particularly among individuals with obesity and premenopausal women.
Background: Nuts and seeds have been part of diets in most of the world for millenniums, and they have also been consumed in the Nordic and Baltic countries for centuries. Consumption of nuts and seeds is linked with various health outcomes. Therefore, when updating the Nordic Nutrition Recommendations (NNR), summarizing the best evidence on key health outcomes from the consumption of nuts and seeds is essential. Objectives: This study aims to evaluate the updated evidence on the consumption of nuts and seeds and health outcomes regarded relevant for the Nordic and Baltic countries, as well as their dose-response relationship presented in updated systematic reviews and meta-analyses. Method: The scoping review is built on a de novo systematic review and an umbrella review published in 2022 on the consumption of nuts and seeds and its various health outcomes, including cardiovascular disease and diabetes. Results: Intake of nuts and seeds is associated with a lower risk of cardiovascular diseases, with evidence assessed as probable. This conclusion is mirrored by evidence from trials on biomarkers for chronic diseases. An intake of a serving of nuts of 28–30 g/day compared to not eating nuts is estimated to translate into approximately 20% relative reduction in the risks of cardiovascular disease and premature deaths. For cancers, consumption of a serving of nuts is inversely associated with cancer mortality. However, for type 2 diabetes, there are mixed and inconclusive results. Additionally, there are inverse associations between nut consumption and respiratory and infectious disease mortality. Allergies for nuts are seen among 1–2% of the population. Conclusion: Overall, the current evidence supports dietary recommendations to increase nut consumption to a serving of nuts and seeds per day for people without allergies to these foods.
Objectives: Curcumin has antioxidant properties and has been proposed as a potential treatment for NAFLD. The aim of current systematic review and meta-analysis was to evaluate previous findings for the effect of curcumin supplementation on glycaemic indices, lipid profile, blood pressure, inflammatory markers, and anthropometric measurements of NAFLD patients. Methods: Relevant studies published up to January 2024 were searched systematically using the following databases: PubMed, SCOPUS, WOS, Science Direct, Ovid and Cochrane. The systematic review and meta-analysis were conducted according to the 2020 PRISMA guidelines. The quality of the papers was assessed the using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist. Pooled effect sizes were calculated using a random-effects model and reported as the WMD and 95% CI. Also, subgroup analyses were done to find probable sources of heterogeneity among studies. Results: Out of 21010 records initially identified, 21 eligible RCTs were selected for inclusion in a meta-analysis. Overall, 1191 participants of both genders, 600 in the intervention and 591 in the control group with NAFLD were included. There are several limitations in the studies that were included, for instance, the results are weakened substantially by potential bias or failure to account for potential adulteration (with pharmaceuticals) or contamination (with other herbs) of the curcumin supplements that were tested. However, previous studies have reported curcumin to be a safe complementary therapy for several conditions. Our study indicated that curcumin supplementation in doses of 50− 3000 mg/day was associated with significant change in FBG [WMD: − 2.83; 95% CI: − 4.61, − 1.06), I 2 = 51.3%], HOMA-IR [WMD: − 0.52; 95% CI: − 0.84, − 0.20), I 2 = 82.8%], TG
This meta‐analysis aimed to evaluate the effects of flaxseed supplementation on weight loss, lipid profiles, high‐sensitivity C‐reactive protein (hs‐CRP), and glucose levels in patients with coronary artery disease (CAD). A systematic search was performed using various online databases, including Scopus, PubMed, Web of Science, EMBASE, and Cochrane Library, to identify relevant randomized controlled trials (RCTs) until June 2023. To evaluate heterogeneity among the selected studies, the Q ‐test and I ² statistics were employed. Data were combined using either a fixed‐ or random‐effects model and presented as a weighted mean difference (WMD) with a 95% confidence interval (CI). Of the 428 citations, six RCTs were included. The pooled results did not show significant changes in the WMD of lipid factors (high‐density lipoprotein cholesterol, triglycerides (TG), low‐density lipoprotein cholesterol, and total cholesterol) following flaxseed intake. However, after performing a sensitivity analysis to determine the source of heterogeneity, flaxseed supplementation resulted in a significant decrease in TG levels (WMD = −18.39 mg/dL; 95% CI: −35.02, −1.75). Moreover, no significant differences were observed in either weight or BMI following flaxseed intake. However, the circulating levels of fasting blood glucose (WMD = −8.35 mg/dL; 95% CI: −15.01, −1.69, p = .01) and hs‐CRP (WMD = −1.35 mg/L; 95% CI: −1.93, −0.77, p < .01) significantly decreased after the intervention. Flaxseed supplementation was associated with lowering FBS, hs‐CRP, and TG levels but did not affect weight loss parameters and other lipid markers in CAD.
Flaxseed ( Linum usitatissimum L.) is derived from the flax plant, an annual herb. The primary relevance of flaxseed is in the human nutrition sector, where it is emerging as a significant functional food component due to its high level of active chemicals, which have been linked to health benefits. Flaxseed may be consumed in numerous forms, including milled, oil, and bakery items. The phytochemicals that are present in flaxseed have greatly drawn interest as bioactive molecules beneficial for health. It is naturally enriched with alpha‐linolenic acid, omega‐3 fatty acid, lignin, secoisolariciresinol diglucoside, and fiber which are physiologically active in the protection of some chronic illnesses such as cancer, diabetes, cardiovascular disease, and cerebrovascular stroke. Furthermore, the benefits of flaxseed eating have been demonstrated in the animal nutrition industry, resulting in healthier food from animal origin. In reality, the fatty acid profile of meat and fat in swine and poultry is directly impacted by the source of fat in the diet. Feeding omega‐3‐enriched diets with flaxseed will improve the omega‐3 content in eggs and meat, enriching the products. The current study focuses on the latest evidence on the chemical makeup of flaxseed and its positive benefits.
This article illustrates how dietary flaxseed can be used to reduce cancer risk, specifically by attenuating obesity, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD). We utilize a targeted metabolomics dataset in combination with a reanalysis of past work to investigate the “metabo-bioenergetic” adaptations that occur in White Leghorn laying hens while consuming dietary flaxseed. Recently, we revealed how the anti-vitamin B6 effects of flaxseed augment one-carbon metabolism in a manner that accelerates S-adenosylmethionine (SAM) biosynthesis. Researchers recently showed that accelerated SAM biosynthesis activates the cell’s master energy sensor, AMP-activated protein kinase (AMPK). Our paper provides evidence that flaxseed upregulates mitochondrial fatty acid oxidation and glycolysis in liver, concomitant with the attenuation of lipogenesis and polyamine biosynthesis. Defatted flaxseed likely functions as a metformin homologue by upregulating hepatic glucose uptake and pyruvate flux through the pyruvate dehydrogenase complex (PDC) in laying hens. In contrast, whole flaxseed appears to attenuate liver steatosis and body mass by modifying mitochondrial fatty acid oxidation and lipogenesis. Several acylcarnitine moieties indicate Randle cycle adaptations that protect mitochondria from metabolic overload when hens consume flaxseed. We also discuss a paradoxical finding whereby flaxseed induces the highest glycated hemoglobin percentage (HbA1c%) ever recorded in birds, and we suspect that hyperglycemia is not the cause. In conclusion, flaxseed modifies bioenergetic pathways to attenuate the risk of obesity, type 2 diabetes, and NAFLD, possibly downstream of SAM biosynthesis. These findings, if reproducible in humans, can be used to lower cancer risk within the general population.
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.
Flaxseed is a functional food because of its high content of alpha-linolenic acid, lignans, and dietary fiber. We hypothesized that flaxseed supplementation would improve cardiometabolic parameters in patients with type 2 diabetes mellitus (T2DM); however, clinical trials have shown conflicting results. Therefore, this systematic review and meta-analysis was conducted to determine the impact of flaxseed supplementation in patients with T2DM. Randomized controlled trials were systematically searched in PubMed, Web of Science, Scopus, Cochrane Library, and Embase until 25 March 2022. A total of 13 studies were included, and the results showed that flaxseed supplementation significantly reduced hemoglobin A1c (HbA1c) in participants with T2DM compared with the control group. In contrast, it had no effects on body weight, body mass index, blood pressure, fasting blood glucose (FBG), homeostatic model assessment for insulin resistance, quantitative insulin sensitivity check index, and lipid parameters. In the subgroup analyses, FBG was significantly reduced with supplementation of flaxseed in participants with baseline FBG ≥8.0 mmol/L or baseline HbA1c ≥7.0%. And a significant decrease in HbA1c in participants with baseline HbA1c ≥7.0% after flaxseed supplementation. In addition, subgroup analyses indicated that whole flaxseed supplementation significantly increased high-density lipoprotein cholesterol and reduced total cholesterol or low-density lipoprotein cholesterol in participants with T2DM. In conclusion, flaxseed supplementation significantly reduced HbA1c in participants with T2DM, especially those with poorly controlled blood sugar levels. However, larger scale studies with better designs are needed to confirm insignificant and/or ambiguous findings.
Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders around the world that can endanger reproductive, metabolic and psychological health in women. Flaxseed is considered as a functional food which provides remarkable amounts of α-linolenic acid (ALA), phytosterogenic lignans, and dietary fibers. This study was aimed to investigate the effectiveness of flaxseed or its oil supplementation on PCOS patients. We systematically searched all published randomized clinical trials indexed in PubMed, Scopus, and Google Scholar databases from inception up to May 2022. Intended exposure and outcome were flaxseed or its oil and metabolic, anthropometric, and hormonal status of women with PCOS, respectively. Initial search via related keywords revealed 69 articles. After excluding duplicates, title and abstract of 55 remaining papers were screened. Fourteen papers were obtained for full text screening. Finally, nine clinical trials published between 2011 and 2021 were included in qualitative synthesis. Based on the results of the present systematic review, we suggest that flaxseed supplementation has the potential to improve metabolic, hormonal, and anthropometric parameters in women with PCOS. However, we also deduce that due to the scarcity of high-quality studies, additional studies need to be conducted in order to derive a solid conclusion.
Consumption of nuts and seeds is associated with a range of health outcomes. Summarizing the best evidence on essential health outcomes from the consumption of nuts is essential to provide optimal recommendations. Our objective is to comprehensively assess health outcomes associations related to the consumption of nuts and seeds, using a culinary definition including tree nuts and peanuts (registered in PROSPERO: CRD42021258300). Health outcomes of interest include cardiovascular disease, cancer, diabetes, obesity, respiratory disease, mortality, and their biomarker for disease. We present associations for high versus low consumption, per serving, and dose-response relationships. Medline, Embase, Cochrane, and Epistemonikos were searched and screened for systematic reviews and meta-analyses. Evidence was extracted from 89 articles on the consumption of nuts and relevant health outcomes, including 23 articles with meta-analysis on disease and mortality, 66 articles on biomarkers for disease, and 9 articles on allergy/adverse outcomes. Intake of nuts was associated with reduced risk of cardiovascular diseases and related risk factors, with moderate quality of evidence. An intake of 28 grams of nuts per day compared to not eating nuts was associated with a 21% relative risk reduction of cardiovascular disease (including coronary heart disease incidence and mortality, atrial fibrillation, and stroke mortality), 11% risk reduction of cancer deaths, and 22% reduction in all-cause mortality. Nut consumption was also inversely associated with mortality from respiratory diseases, infectious diseases, and diabetes: however, associations between nut consumption and diabetes incidence were mixed. Meta-analyses of trials on biomarkers for disease generally mirrored meta-analyses from observational studies on cardiovascular disease, cancers, and diabetes. Allergy and related adverse reactions to nuts were observed among 1–2% of adult populations, with substantial heterogeneity between studies. Overall, the current evidence supports dietary recommendations to consume a handful of nuts and seeds per day for people without allergies to these foods.
We systematically reviewed randomized clinical trials (RCTs) to elucidate the overall effects of flaxseed oil consumption on blood pressure (BP) in patients with metabolic syndrome and related disorders. PubMed, Scopus, Cochrane Library, and ISI Web of Science databases were systematically searched until March 31, 2020, to find RCTs that examined the effect of flaxseed oil consumption on BP. Weighed mean difference (WMD) was pooled using a random-effects model. Standard methods were used for the assessment of heterogeneity, sensitivity analysis, and publication bias. Meta-analysis of five trials (6 arms) showed significant reductions in systolic (WMD: À3.86 mmHg, 95% CI: À7.59 to À0.13, p = .04) BP (SBP) after flaxseed oil consumption. However, the overall effect illustrated no significant change in diastolic (WMD:
Noncommunicable chronic diseases have been on the rise for decades. Almost 10% of the world adult population lives with type 2 diabetes mellitus (T2DM)—a leading cause of severe complications associated with disability and premature mortality. Worldwide, nearly 500 million adults are living with T2DM and 4.2 million deaths were caused directly by the disease. Dietary quality is a major component influencing the development of T2DM, due to diet-related inflammatory processes, linked to metabolically unhealthy obesity (MUO) and metabolic syndrome (MetS).
In addition to systemic and tissue-specific low-grade chronic inflammation, characterized by mediators such as various cytokines, T2DM is characterized by a disturbed homeostasis of oxidative stress, as well as a dysregulated glucose and lipid metabolism. Poor inflammatory and antioxidant status have been related to an enhanced risk of developing MUO, MetS, and T2DM. However, diet also is an important source of antioxidants, which are antiinflammatory and may reduce disease risk and improve symptomology. This includes dietary patterns rich in fruits/vegetables, which are good sources of fiber, vitamins, minerals, and phytochemicals such as polyphenols, and low in animal products, ultraprocessed foods, sugar, saturated fats, total calories, and salt. Mechanistic studies have highlighted that antiinflammatory and antioxidant diets might positively influence several cellular processes. These include direct effects on the homeostasis of reactive oxygen species (ROS) such as quenching effects by antioxidants, but also the interaction of dietary constituents with transcription factors, especially with nuclear factor kappa-B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf-2), important for regulating inflammation and oxidative stress, respectively. In this chapter, we evaluate the association between dietary patterns and T2DM, as well as the role played by MUO and oxidative stress in influencing inflammation and increasing the risk of MetS and, eventually, T2DM.
Seeds as culinary ingredients have become increasingly popular in recent years primarily due to their nutrient density and potential health benefits. Although their classification as a superfood is a relatively new phenomena, the culinary and medicinal use of seeds dates back to ancient civilizations. Specifically, this chapter will examine three popular seeds: chia, flax, and hemp.KeywordsFlax (or flaxseed)Chia (or chia seed)Hemp (or hempseed)Omega-3Fatty acidsFiber
Functional clinical nutrition is an integrative science; it uses dietary strategies, functional foods and medicinal plants, as well as combinations thereof. Both functional foods and medicinal plants, whether associated or not, form nutraceuticals, which can bring benefits to health, in addition to being included in the prevention and treatment of diseases. Some functional food effects from Avena sativa L (oats), Linum usitatissimum L. (brown flaxseed), Glycine max L. (soya) and Moringa oleifera have been proposed for nutritional disorders through in vitro and in vivo tests. A formulation called a bioactive food compound (BFC) showed efficiency in the association of oats, flaxseed and soy for dyslipidemia and obesity. In this review, we discuss the effects of BFCs in other nutritional disorders, as well as the beneficial effects of M. oleifera in obesity, cardiovascular disease, diabetes mellitus type 2, metabolic syndrome, intestinal inflammatory diseases/colorectal carcinogenesis and malnutrition. In addition, we hypothesized that a BFC enriched with M. oleifera could present a synergistic effect and play a potential benefit in nutritional disorders. The traditional consumption of M. oleifera preparations can allow associations with other formulations, such as BFCs. These nutraceutical formulations can be easily accepted and can be used in sweet preparations (fruit and/or vegetable juices, fruit and/or vegetable vitamins, porridges, yogurt, cream, mousses or fruit salads, cakes and cookies) or savory (vegetable purees, soups, broths and various sauces), cooked or not. These formulations can be low-cost and easy-to-use. The association of bioactive food substances in dietary formulations can facilitate adherence to consumption and, thus, contribute to the planning of future nutritional interventions for the prevention and adjuvant treatment of the clinical conditions presented in this study. This can be extended to the general population. However, an investigation through clinical studies is needed to prove applicability in humans.
PurposeDiabetes mellitus (DM) is a chronic non-communicable endocrine and metabolic disease that is thought to be the fastest emerging health challenge of the twenty-first century. Presently, 90% of diabetic population is handicapped with T2-DM, and the majority of pre-diabetes on the way to T2-DM progression. By keeping in view, a review article has been compiled to highlight the significance of value aided effective, low-cost, safe, and useful remedies that could easily be accessible to the global community in order to moderate the possibility of DM and related complications.Methods
Literature search for this review was carried out using scientific databases including PubMed, EBSCO, Scopus, Web of science, and google scholar. Whilst, value aided articles were selected on the basis of their therapeutic potential, safety profile and outreach.ResultsEscalating research data validated that herbal remedies and physical activities significantly prevents hyperglycemia, hyperlipidemia, and other complications in people with T2-DM.Conclusion
Globally, nearly half-billion individuals are living with diabetes. Therefore, it is urged to embrace herbal remedies and physical mediation in our daily routine in order to tackle such devastating disorder.
Xylene is a common pollutant in the environment that enters the body of animals and humans in various ways, but most often through the respiratory tract and adversely affects their overall health. However, xylene effects after oral exposure have not been sufficiently studied. This study aimed to investigate the effects of xylene exposure on the mouse organism and to identify possible beneficial effects of flaxseed on such exposure. Eighty mice were divided into four groups: control group C (basal diet + no xylene exposure), group X (oral exposure by 400 mg/kg/day xylene), group F (10% flaxseed supplementation of basal diet), and group XF (10% dietary flaxseed + oral exposure by xylene). Experimental trial took 14 days. Clinical examination, spectroscopic analysis of tissue aminotransferases, total lactate dehydrogenase (TLDH), and acetylcholinesterase (AchE) activities, electrophoretic analysis of LDH isoenzymes, western blot and immunohistochemical analysis of apoptosis as well as routine histology of the kidneys and jejunum, and transmission electron microscopy of the liver were performed. Marked restlessness in group X and high weight losses in mice of all groups were recorded during the experiment. Xylene promoted apoptosis (caspase-3 expression) without causing marked structural changes in the liver and jejunum, although renal cortex structure was affected adversely. In the brain, liver, and kidney of mice, xylene increased levels of liver transaminases, LDH, and decreased AchE activities, reflecting cell membrane damage. Flaxseed feeding improved animal behaviour, leakage of enzymes and prevented selected tissue toxic damage induced by xylene by protecting cell membrane integrity and fluidity and by suppressing apoptosis. These results point at the protective effect of flaxseed consumption on mice.
Seeds play important roles in human nutrition and health since ancient time. The term “specialty” has recently been applied to seeds to describe high‐value and/or uncommon food products. Since then, numerous studies have been conducted to identify various classes of bioactive compounds, including polyphenols in specialty seeds. This review discusses nutrients, fat‐soluble bioactives, polyphenols/bioactives, antioxidant activity, bioavailability, health benefits, and safety/toxicology of commonly consumed eight specialty seeds, namely, black cumin, chia, hemp, flax, perilla, pumpkin, quinoa, and sesame. Scientific results from the existing literature published over the last decade have been compiled and discussed. These specialty seeds, having numerous fat‐soluble bioactives and polyphenols, together with their corresponding antioxidant activities, have increasingly been consumed. Hence, these specialty seeds can be considered as a valuable source of dietary supplements and functional foods due to their health‐promoting bioactive components, polyphenols, and corresponding antioxidant activities. The phytochemicals from these specialty seeds demonstrate bioavailability in humans with promising health benefits. Additional long‐term and well‐design human intervention trials are required to ascertain the health‐promoting properties of these specialty seeds.
To evaluate responses to different sourdough breads, six groups of rats were fed a conventional refined wheat bread with no sourdough content (C_WhB); a leavened spelt bread baked with Rebola sourdough (Re_SpB); a durum wheat bread with Rebola sourdough (Re_DuB); or a multigrain bread leavened with Rebola (Re_MGB), Carla (Ca_MGB), or San Francisco sourdough (SF_MGB). Compared to C_WhB-fed rats, Re_SpB-, Re_DuB-, and Re_MGB-fed animals showed lower postprandial blood glucose levels, whereas SF_MGB-fed rats displayed a decreased postprandial blood insulin response and glucose and insulin products. The 3 week intake of Ca_MGB decreased blood triacylglycerols and the relative apparent absorption (RAA) of Fe2+, Cu2+, and Zn2+, whereas Re_MGB-fed animals showed lower serum levels of the MCP-1 inflammatory marker and decreased the Fe RAA. The 3 week consumption of the multigrain bread produced sourdough-specific effects. Thus, Re_MGB-fed animals displayed higher insulin concentrations than Ca_MGB- and SF_MGB-fed rats and decreased blood MCP-1 levels compared to those of Ca_MGB-fed animals. In addition, Ca_MGB-fed rats showed lower serum triacylglycerol concentrations than those of Re_MGB- and SF_MGB-fed animals, whereas SF_MGB-fed rats displayed higher RAA values of Ca2+, Cu2+, Fe2+, Mg2+, and Zn2+ than their Re_MGB and Ca_MGB counterparts. These sourdough-specific effects could be related to changes in the contents of sugars and organic acids, acidity, microbial composition, and proteolytic activity among sourdoughs. Hence, the consumption of sourdough breads improved postprandial blood glucose and insulin responses and produced sourdough-specific effects on RAA and serum insulin and triacylglycerol and MCP-1 levels in rats, showing that SF_MGB has the most promising beneficial effects.
Regarding the increasing prevalence of cardiometabolic abnormalities, and its association with non-communicable chronic diseases, providing preventive and therapeutic strategies is a priority. A randomized placebo-controlled study was conducted to assess the effects of combination therapy of milled brown flaxseed and hesperidin during lifestyle intervention on controlling cardiovascular risk in prediabetes. A total of forty-eight subjects were randomly assigned to receive lifestyle intervention plus combination therapy of brown flaxseed (30 g milled) and hesperidin (two 500 mg capsules) or lifestyle modification alone for 12 weeks. Changes from baseline in anthropometric measures, lipid profile and atherogenic indices, glucose homeostasis parameters, and inflammatory biomarkers was assessed as a primary end point. Anthropometric data comparison between the two groups showed a significant reduction in weight (p = 0.048). Waist circumference reduction was about twice that of the control group (− 6.75 cm vs − 3.57 cm), but this difference was not statistically significant. Comparison of blood pressure changes throughout the study indicated a greater reduction in blood pressure in the intervention group rather than control group (− 5.66 vs. − 1.56 mmHg, P = 0.049). Improvements of lipid profile and atherogenic indices, glucose homeostasis parameters, and inflammatory biomarkers in flaxseed-hesperidin group was significantly more than the control group after 12 weeks of intervention (p < 0.05). Our results indicate that co-administration of flaxseed and hesperidin as an adjunct to lifestyle modification program is more effective than lifestyle modification alone in the metabolic abnormalities remission of prediabetic patients. Trial registration: The trial was registered with ClinicalTrials.gov, number NCT03737422. Registered 11 November 2018. Retrospectively registered, https://clinicaltrials.gov/ct2/results?cond=&term=NCT03737422&cntry=&state=&city=&dist=.
PurposeFlaxseed can be effective at lowering and stabilising blood glucose responses. The aim of this study was to determine whether flaxseed could lower blood glucose response more effectively when consumed as a single portion of 30 g, or a split portion consumed three times per day (10 g flaxseed per portion).
Methods
The study was a randomised, repeated measures, cross-over design. Fifteen healthy participants consumed either (1) three flaxseed muffins containing a total of 30 g of flaxseed once in the morning, (2) three flaxseed muffins consumed at three different timepoints across the day (10 g flaxseed per muffin) or (3) three control muffins consumed at three different timepoints across the day (0 g flaxseed). The 24-h blood glucose response was measured using a continuous glucose monitor.
ResultsThe results of this study demonstrated that flaxseed muffins given three times a day were effective at lowering and maintaining blood glucose levels over 24 h, compared to the control muffins and that both flaxseed treatments resulting in a lower blood glucose iAUC during the night.Conclusion
The results of this study indicated that adding flaxseed to a daily diet produced a lower glucose profile over 24 h in a free-living context compared to the control muffins.
A wide variety of plant species provide edible seeds. Seeds are the dominant source of human calories and protein. The most important and popular seed food sources are cereals, followed by legumes and nuts. Their nutritional content of fiber, protein, and monounsaturated/polyunsaturated fats make them extremely nutritious. They are important additions to our daily food consumption. When consumed as part of a healthy diet, seeds can help reduce blood sugar, cholesterol, and blood pressure.
Phytoestrogens (PE) are compounds found in plants such as soy (isoflavones), flax seeds and cereals (lignans) and pomegranates (ellagitannins). PE have shown estrogenic/antiestrogenic, antioxidant, anti-inflammatory, antineoplastic and apoptotic activities. The human studies are showing promising although inconsistent results about the beneficial effects of PE on ameliorating the menopausal symptoms or reducing the risk of certain cancers, cardiovascular disease or diabetes. The effects of PE on the organism are mediated by the intestinal microbiota, which transforms them into bioactive PE such as genistein, equol, enterolignans and certain urolithins. In this work, we review the most recent findings about the bacteria able to metabolize PE, together with the latest studies on the effects of PE on health. In addition, we describe the possible factors hindering the demonstration of the beneficial effect of PE on health, evincing the importance of measuring the actual circulating PE in order to encompass the variability of PE metabolism due to the intestinal microbiota. With this in mind, we also explore an approach to ensure the access to bioactive PE.
Cancer causes considerable morbidity and mortality across the world. Socioeconomic, environmental, and lifestyle factors contribute to the increasing cancer prevalence, bespeaking a need for effective prevention and treatment strategies. Phytochemicals like plant polyphenols are generally considered to have anticancer, anti-inflammatory, antiviral, antimicrobial, and immunomodulatory effects, which explain their promotion for human health. The past several decades have contributed to a growing evidence base in the literature that demonstrate ability of polyphenols to modulate multiple targets of carcinogenesis linking models of cancer characteristics (i.e., hallmarks and nutraceutical-based targeting of cancer) via direct or indirect interaction or modulation of cellular and molecular targets. This evidence is particularly relevant for the lignans, an ubiquitous, important class of dietary polyphenols present in high levels in food sources such as flaxseed. Literature evidence on lignans suggests potential benefit in cancer prevention and treatment. This review summarizes the relevant chemical and pharmacokinetic properties of dietary polyphenols and specifically focuses on the biological targets of flaxseed lignans. The consolidation of the considerable body of data on the diverse targets of the lignans will aid continued research into their potential for use in combination with other cancer chemotherapies, utilizing flaxseed lignan-enriched natural products.
The aim of this study was to evaluate the efficacy of flaxseed supplementation plus lifestyle modification in comparison with lifestyle modification alone in the management of metabolic syndrome (MetS). A randomized controlled clinical trial was conducted on 44 patients with MetS. Participants were assigned to receive either the lifestyle advice and 30-g brown milled flaxseed daily or only the lifestyle advice as the control group. The percentage of individuals with MetS decreased from baseline by 50% and 82% in the control and intervention group, respectively. The reversion rate of central obesity was higher in the flaxseed group (36%) than control group (13%). Moreover, greater reduction in insulin resistance was observed in flaxseed group in comparison with control group (p < 0.001). Body weight, waist circumference, and body mass index decreased significantly in both groups with a significantly greater reduction in flaxseed group in comparison with controls (p < 0.05). There were no significant changes in blood pressure in any groups. Our results indicate that co-administration of flaxseed with lifestyle modification is more effective than lifestyle modification alone in management of MetS; whether these effects will be sustained with longer treatment durations remains to be determined. Copyright © 2016 John Wiley & Sons, Ltd.
Promising experimental studies suggest that quercetin has potential anti-inflammatory effects. However, the results of current clinical trials on quercetin's effects on the C-reactive protein (CRP), a sensitive inflammatory biomarker, are ambiguous. We conducted a meta-analysis of available randomized controlled trials (RCTs) to resolve this inconsistency and quantify the net effect of quercetin on circulating CRP concentrations. A systematic search was performed in several databases including SCOPUS, PubMed-Medline and Google Scholar until 16 June 2016. We used a random-effects model in combination with weight mean difference (WMD) and 95% confidence intervals (CI) for data analysis. Standard methods were used for the assessment of heterogeneity, meta-regression, sensitivity analysis and publication bias. The meta-analysis of seven RCTs (10 treatment arms) showed a significant reduction of circulating CRP levels (WMD: -0.33 mg/l; 95% CI: -0.50 to -0.15; P<0.001) following quercetin supplementation. In the subgroup analysis, a significant reducing effect was observed in trials with ⩾500 mg/day dosage (WMD: -0.34 mg/l; 95% CI: -0.52, -0.16; P⩽0.001) and in those with CRP <3 mg/l (WMD: -0.34 mg/l; 95% CI: -0.51, -0.18; P⩽0.001). In meta-regression, there was no association between changes in CRP concentrations, dose of supplementation and CRP baseline values. Our findings showed a significant effect of quercetin supplementation on the C-reactive protein-especially at doses above 500 mg/day and in patients with CRP <3 mg/l.European Journal of Clinical Nutrition advance online publication, 24 May 2017; doi:10.1038/ejcn.2017.55.
Background:
This study sought to investigate the effects of omega (ω)-3 polyunsaturated fatty acid (PUFA) supplementation on the lipid profiles and glucose (GLU) levels of overweight (OW) schoolchildren with metabolic syndrome (MS).
Methods:
Thirty-nine OW schoolchildren with MS, including 19 girls and 20 boys, received 1-month of dietary supplementation with gel capsules containing ω-3 fatty acids. Fasting lipid profiles and GLU levels were measured before and after supplementation.
Results:
Both sexes of OW schoolchildren with MS who received daily supplementation with 2.4 g of ω-3 fatty acids for 1 month displayed improved lipid profiles, reduced fasting GLU levels and reduced blood pressure (BP).
Conclusions:
These findings support the addition of omega-3 fatty acid supplementation to programs aiming to improve the metabolic status of OW children with MS, although additional research on the longer-term safety and efficacy of this treatment in this population is required.
Background
Designing the effective and early interventions can prevent progression of prediabetes to diabetes. Few studies have shown the effect of flaxseed on glycemic control. This study aimed to assess the effect of flaxseed powder on insulin resistance (IR) indices and blood pressure in prediabetic individuals.
Materials and Methods
In a randomized clinical trial, 99 prediabetic individuals were randomly divided into three groups: two groups received 40 g (FG40) and 20 g (FG20) flaxseed powder daily for 12 weeks and the third group was the control (CG). Before and after the intervention, anthropometric measurements, blood pressure, fasting serum glucose (FSG), insulin, homeostasis model assessment IR index (HOMA-IR), beta-cell function, and insulin sensitivity were measured.
Results
FSG significantly declined overall in all groups compared to the baseline (P = 0.002 in CG and FG20 groups and P = 0.001 in FG40). In contrast, mean of the changes in FSG was not significantly different between groups. Insulin concentration did not change significantly within and between the investigated groups. Although HOMA-IR reduced in FG20 (P = 0.033), the mean of changes was not significant between the three groups. Mean of beta-cell function increased in CG and FG40 groups compared to the baseline (P = 0.044 and P = 0.018, respectively), but mean of its changes did not show any difference between the three groups. The mean of changes in IR indices was not significant between the three groups. FG40 group had significantly lowered systolic blood pressure after the intervention (P = 0.005).
Conclusion
Daily intake of flaxseed powder lowered blood pressure in prediabetes but did not improve glycemic and IR indices.
Scope:
To investigate the effects of n-3 fatty acid supplements, both marine and plant-based, on glycemic traits in Chinese type 2 diabetes (T2D) patients.
Method and results:
In a double-blind randomized controlled trial, 185 recruited Chinese T2D patients were randomized to either fish oil (FO, n = 63), flaxseed oil (FSO, n = 61) or corn oil group (CO, served as control group, n = 61) for 180 days. The patients were asked to take corresponding oil capsules (4 capsules/day), which totally provided 2 g/day of eicosapentaenoic acid + docosahexaenoic acid in FO group and 2.5 g/day of alpha-linolenic acid in FSO group. No group×time interaction was observed for HOMA-insulin resistance, fasting insulin or glucose. Significant group×time interaction (P = 0.035) was observed for glycated haemoglobin (HbA1c), with HbA1c decreased in FO group compared with CO group (P = 0.037). We also found significant group×time interactions for lipid traits, including low-density lipoprotein cholesterol (P = 0.043), total cholesterol (TC) (P = 0.021), total cholesterol/ high-density lipoprotein cholesterol (TC/HDL-C) (P = 0.009) and triacylglycerol (TG) (P = 0.003), with the lipid profiles improved in FO group. No significant effects of FSO on glycemic traits or blood lipids were observed.
Conclusions:
Marine n-3 PUFA supplements may improve glycemic control and lipid profiles among Chinese type 2 diabetic patients. This article is protected by copyright. All rights reserved.
Background:
Both fish (FO) and flaxseed oils (FLX) are n-3 polyunsaturated fatty acids (PUFA). Fish oil contains long chain while FLX contains essential n-3 PUFA. We demonstrated that FO altered insulin secretion and resistance in polycystic ovary syndrome (PCOS) women but FLX did not. Surprisingly, the effects of FO were similar to those of the n-6 PUFA-rich soybean oil (SBO). Since increased branched chain (BCAA) and aromatic amino acids (AA) affect insulin secretion and resistance, we investigated whether FO, FLX and /or SBO affect plasma metabolites, especially AA.
Methods and findings:
In this six-week, randomized, 3-parallel arm, double-blinded study, 54 women received 3.5 g/day FO, FLX or SBO. In 51 completers (17 from each arm), fasting plasma metabolites were measured at the beginning and at the end. As compared to FLX, FO and SBO increased insulin response and resistance as well as several BCAA and aromatic AA. Pathway analysis indicated that FO exerted the largest biochemical impact, affecting AA degradation and biosynthesis, amine, polyamine degradation and alanine, glycine, l-carnitine biosynthesis and TCA cycle, while FLX had minimal impact affecting only alanine biosynthesis and l-cysteine degradation.
Conclusion:
Effects of FO and SBO on plasma AA were similar and differed significantly from those of the FLX. The primary target of dietary PUFA is not known. Dietary PUFA may influence insulin secretion and resistance directly and alter plasma AA indirectly. Alternatively, as a novel concept, dietary PUFA may directly affect AA metabolism and the changes in insulin secretion and resistance may be secondary.
A two-arm randomized open labeled controlled clinical trial was conducted on 50 patients with non-alcoholic fatty liver disease (NAFLD). Participants were assigned to take either a lifestyle modification (LM), or LM +30 g/day brown milled flaxseed for 12 weeks. At the end of the study, body weight, liver enzymes, insulin resistance and hepatic fibrosis and steatosis decreased significantly in both groups (p< 0.05); however, this reduction was significantly greater in those who took flaxseed supplementation (p < 0.05). The significant mean differences were reached in hepatic markers between flaxseed and control group, respectively: ALT [-11.12 compared with -3.7 U/L; P< 0.001], AST [-8.29 compared with -4 U/L; p < 0.001], GGT [-15.7 compared with -2.62 U/L; p < 0.001], fibrosis score [-1.26 compared with -0.77 kPa; p = 0.013] and steatosis score [-47 compared with -15.45 dB/m; p = 0.022]. In conclusion, flaxseed supplementation plus lifestyle modification is more effective than lifestyle modification alone for NAFLD management.
Functional food-flaxseed and its derivatives (flaxseed oil or lignans) are beneficial for human health, possibly because of their anti-inflammatory effects. C-reactive protein (CRP), a sensitive marker of inflammation was chosen to evaluate the anti-inflammatory effects of flaxseed. We searched randomized controlled trials from PubMed and the Cochrane Library in October 2015 and conducted a meta-analysis to evaluate the effectiveness of flaxseed and its derivatives on CRP. The mean differences (net change) in CRP (mg/L) concentrations were pooled with a random- or a fixed-effects model depending on the results of heterogeneity tests. Overall, flaxseed interventions had no effects on reduction of CRP (p = 0.428). The null effects were consistent in the subgroup analysis with multiple studies and population characteristics. Significant heterogeneity was observed in most of the analyses. Meta-regression identified baseline body mass index (BMI) as a significant source of heterogeneity (P-interaction = 0.032), with a significant reduction in CRP of 0.83 mg/L (95% confidence interval -1.34 to -0.31; p = 0.002) among subjects with a BMI of ≥30 kg/m². In conclusion, our meta-analysis did not find sufficient evidence that flaxseed and its derivatives have a beneficial effect on reducing circulating CRP. However, they may significantly reduce CRP in obese populations.
The gut microbiota has been implicated in obesity and its progression towards metabolic disease. Dietary interventions that target the gut microbiota have been suggested to improve metabolic health. The aim of the present study was to investigate the effect of interventions with Lactobacillus paracasei F19 or flaxseed mucilage on the gut microbiota and metabolic risk markers in obesity. A total of fifty-eight obese postmenopausal women were randomised to a single-blinded, parallel-group intervention of 6-week duration, with a daily intake of either L. paracasei F19 (9·4 × 1010 colony-forming units), flaxseed mucilage (10 g) or placebo. Quantitative metagenomic analysis of faecal DNA was performed to identify the changes in the gut microbiota. Diet-induced changes in metabolic markers were explored using adjusted linear regression models. The intake of flaxseed mucilage over 6 weeks led to a reduction in serum C-peptide and insulin release during an oral glucose tolerance test (P< 0·05) and improved insulin sensitivity measured by Matsuda index (P< 0·05). Comparison of gut microbiota composition at baseline and after 6 weeks of intervention with flaxseed mucilage showed alterations in abundance of thirty-three metagenomic species (P< 0·01), including decreased relative abundance of eight Faecalibacterium species. These changes in the microbiota could not explain the effect of flaxseed mucilage on insulin sensitivity. The intake of L. paracasei F19 did not modulate metabolic markers compared with placebo. In conclusion, flaxseed mucilage improves insulin sensitivity and alters the gut microbiota; however, the improvement in insulin sensitivity was not mediated by the observed changes in relative abundance of bacterial species.
Flaxseed has received attention for its anti-inflammatory and antioxidant role. The present study hypothesizes if flaxseed added to a weight loss diet could improve the lipid and metabolic profiles and decrease risk factors related to cardiovascular disease.
In a prospective, single blinded 42 days protocol, subjects were allocated into two groups with low carbohydrates intake: GriceLC (35% of carbohydrate and 60g of raw rice powder per day) and GflaxLC (32% of carbohydrate and 60g of flaxseed powder per day). Blood pressure, anthropometric measures and serum levels of isoprostane, C-reactive protein, Tumor Necrosis Factor-alpha, glucose, lipidic profile, uric acid, adiponectin, leptin and insulin were measured at baseline and at the end of interventions. Serum and urinary enterodiol and enterolactione were also measured.
A total of 27 men with cardiovascular risk factors were evaluated, with mean age of 33 +/- 10 years to GriceLC and 40 +/- 9 years to GflaxLC. Both groups experienced weight loss and systolic blood pressure reduction. A decrease in inflammatory markers (CRP and TNF-alpha) was observed after flaxseed intake (mean decrease of 25% and 46% for GflaxLC respectively). All groups also showed improvement in levels of total cholesterol, LDL-c, uric acid and adiponectin. Only GflaxLC group showed a decrease in triglyceride levels.
This study suggests that flaxseed added to a weight loss diet could be an important nutritional strategy to reduce inflammation markers such as CRP and TNF-alpha.Trial registration: ClinicalTrials.gov NCT02132728.
We assessed whether omega-3 index (red blood cell concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) was associated with insulin sensitivity and other metabolic outcomes in 47 overweight men aged 46.5 +/- 5.1 years. Participants were assessed twice, 16 weeks apart. Insulin sensitivity was assessed by the Matsuda method from an oral glucose tolerance test. Linear associations were examined; stratified analyses were carried out with participants separated according to the omega-3 index: lower tertiles (LOI; n=31) and highest tertile (HOI; n = 16). Increasing omega-3 index was correlated with higher insulin sensitivity (r = 0.23; p = 0.025), higher disposition index (r = 0.20; p = 0.054), and lower CRP concentrations (r = -0.39; p < 0.0001). Insulin sensitivity was 43% higher in HOI than in LOI men (Matsuda index 6.83 vs 4.78; p = 0.009). Similarly, HOI men had disposition index that was 70% higher (p = 0.013) and fasting insulin concentrations 25% lower (p = 0.038). HOI men displayed lower nocturnal systolic blood pressure (26.0 mmHg; p = 0.025) and greater systolic blood pressure dip (14.7 vs 10.8%; p = 0.039). Men in the HOI group also had lower concentrations of CRP (41% lower; p = 0.033) and free fatty acids (21% lower, p = 0.024). In conclusion, higher omega-3 index is associated with increased insulin sensitivity and a more favourable metabolic profile in middle-aged overweight men.
Omega-3 fatty acids (ω-3 FAs) have potential anti-inflammatory activity in a variety of inflammatory human diseases, but the mechanisms remain poorly understood. Here we show that stimulation of macrophages with ω-3 FAs, including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and other family members, abolished NLRP3 inflammasome activation and inhibited subsequent caspase-1 activation and IL-1β secretion. In addition, G protein-coupled receptor 120 (GPR120) and GPR40 and their downstream scaffold protein β-arrestin-2 were shown to be involved in inflammasome inhibition induced by ω-3 FAs. Importantly, ω-3 FAs also prevented NLRP3 inflammasome-dependent inflammation and metabolic disorder in a high-fat-diet-induced type 2 diabetes model. Our results reveal a mechanism through which ω-3 FAs repress inflammation and prevent inflammation-driven diseases and suggest the potential clinical use of ω-3 FAs in gout, autoinflammatory syndromes, or other NLRP3 inflammasome-driven inflammatory diseases.
Fiber intake is critical for optimal health. This review covers the anti-inflammatory roles of fibers using results from human epidemiological observations, clinical trials, and animal studies. Fiber has body weight-related anti-inflammatory activity. With its lower energy density, a diet high in fiber has been linked to lower body weight, alleviating obesity-induced chronic inflammation evidenced by reduced amounts of inflammatory markers in human and animal studies. Body weight-unrelated anti-inflammatory activity of fiber has also been extensively studied in animal models in which the type and amount of fiber intake can be closely monitored. Fermentable fructose-, glucose-, and galactose-based fibers as well as mixed fibers have shown systemic and local intestinal anti-inflammatory activities when plasma inflammatory markers and tissue inflammation were examined. Similar anti-inflammatory activities have also been demonstrated in some human studies that controlled total fiber intake. The anti-inflammatory activities of synbiotics (probiotics plus fiber) were reviewed as well, but there was no convincing evidence indicating higher efficacy of synbiotics compared with that of fiber alone. Adverse effects have not been observed with the amount of fiber intake or supplementation used in studies, although patients with Crohn's disease may be more sensitive to inulin intake. Several possible mechanisms that may mediate the body weight-unrelated anti-inflammatory activity of fibers are discussed based on the in vitro and in vivo evidence. Fermentable fibers are known to affect the intestinal microbiome. The immunomodulatory role of the intestinal microbiome and/or microbial metabolites could contribute to the systemic and local anti-inflammatory activities of fibers.
Aim. Animal and human study evidence supports the hypothesis that flaxseed lignan complex (FLC) at a dose of 600 mg secoisolariciresinol diglucoside (SDG)/day for three months would combat hyperglycaemia, dyslipidemia, blood pressure, central obesity, prothrombotic state, inflammation, and low density lipoprotein (LDL) oxidation. Methods. Sixteen type 2 diabetic patients completed this double-blind, randomised crossover placebo-controlled study. A univariate repeated measures analysis of covariance (significance P < 0.05) was followed by a mixed linear model effects analysis corrected for multiple comparisons (MCC). Results. Prior to MCC, FLC caused decreased fasting plasma glucose, A1c, inflammation (c-reactive protein (CRP) and interleukin-6 (IL-6)), and increased bleeding time. After correction for multiple comparisons, FLC induced a statistically significant increase in bleeding time and smaller waist circumference gain. No treatment effect occurred in the other variables before or after adjustment. Conclusions. It is concluded that FLC significantly increased bleeding time thus reducing the prothrombotic state, reduced central obesity gain as measured by waist circumference, and did not affect significantly the other dependent variables measured after adjustment for multiple comparisons. These findings, not yet published in human type 2 diabetes, suggest that this FLC dose over at least three months, may, subject to further investigation, reduce polypharmacy.
Obesity leads to an increase in inflammation and insulin resistance. This study determined antioxidant activity of flaxseed and its role in inflammation and insulin resistance in obese glucose intolerant people.
Using a randomized crossover design, nine obese glucose intolerant people consumed 40 g ground flaxseed or 40 g wheat bran daily for 12 weeks with a 4-week washout period. Plasma inflammation biomarkers (CRP, TNF-α, and IL-6), glucose, insulin, and thiobaribituric acid reactive substance (TBARS) were measured before and after of each supplementation.
Flaxseed supplementation decreased TBARS (p = 0.0215) and HOMA-IR (p = 0.0382). Flaxseed or wheat bran supplementation did not change plasma inflammatory biomarkers. A positive relationship was found between TBARS and HOMA-IR (r = 0.62, p = 0.0003).
The results of the study weakly support that decreased insulin resistance might have been secondary to antioxidant activity of flaxseed. However, the mechanism(s) of decreased insulin resistance by flaxseed should be further determined using flaxseed lignan.
This study evaluated the possible effects of flaxseed oil on renal damage associated with hyperlipidaemic rats. Wistar albino male rats were divided into three groups. Group I was fed with a pellet chow. Group II was fed with a high cholesterol diet (HCD) consisting of 5% cholesterol and 0.35% cholic acid added to the pellet chow. Group III was fed with the same HCD, but were orally treated with a dose of 15 mg/kg body wt/day flaxseed oil. Flaxseed oil treatment started 1 week before and continued throughout the 22 weeks of the HCD. At the end of the experiment, renal tissue and blood samples were collected. The biochemical and histopathological findings confirmed renal damage in hypercholesterolaemia conditions. Flaxseed oil reduced the hypercholesterolaemia-induced increase in the serum levels of total cholesterol, LDL and urea. Oil red O stain revealed that lowered serum lipid was accompanied by a decreased deposition of neutral lipid. Flaxseed oil effectively reversed these abnormalities, verifying the protective effects of flaxseed oil in ameliorating renal injuries associated with hypercholesterolaemia.
A healthy lifestyle may ameliorate metabolic syndrome (MetS); however, it remains unclear if incorporating nuts or seeds into lifestyle counseling (LC) has additional benefit. A 3-arm, randomized, controlled trial was conducted among 283 participants screened for MetS using the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian Americans. Participants were assigned to a LC on the AHA guidelines, LC + flaxseed (30 g/d) (LCF), or LC + walnuts (30 g/d) (LCW) group. After the 12-wk intervention, the prevalence of MetS decreased significantly in all groups: -16.9% (LC), -20.2% (LCF), and -16.0% (LCW). The reversion rate of MetS, i.e. those no longer meeting the MetS criteria at 12 wk, was not significantly different among groups (LC group, 21.1%; LCF group, 26.6%; and LCW group, 25.5%). However, the reversion rate of central obesity was higher in the LCF (19.2%; P = 0.008) and LCW (16.0%; P = 0.04) groups than in the LC group (6.3%). Most of the metabolic variables (weight, waist circumference, serum glucose, total cholesterol, LDL cholesterol, apolipoprotein (Apo) B, ApoE, and blood pressure) were significantly reduced from baseline in all 3 groups. However, the severity of MetS, presented as the mean count of MetS components, was significantly reduced in the LCW group compared with the LC group among participants with confirmed MetS at baseline (P = 0.045). Our results suggest that a low-intensity lifestyle education program is effective in MetS management. Flaxseed and walnut supplementation may ameliorate central obesity. Further studies with larger sample sizes and of longer duration are needed to examine the role of these foods in the prevention and management of MetS.
The n-6/n-3 fatty acid (FA) ratio has increased in the Western-style diet to approximately 10-15:1 during the last century, which may have contributed to the rise in cardiovascular disease (CVD). Prior studies have evaluated the effects on CVD risk factors of manipulating the levels of n-6 and n-3 FA using food and supplements or investigated the metabolic fate of linoleic acid (LNA) and alpha-linolenic acid (ALA) by varying the n-6/n-3 ratios. However, no previous studies have investigated the potential interaction between diet ratios and supplementation with eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). We used a factorial design approach with adults (n = 24) in a controlled feeding trial to compare the accretion of EPA and DHA into red blood cell membranes (RBC) by adding a direct source (algal oil supplement) of EPA and DHA in a diet with a 10:1 versus 2:1 ratio of n-6/n-3 FA. Subjects were randomized into 8-week crossover diet sequences and each subject consumed three of four diets [10:1, 10:1 plus supplement (10:1 + S), 2:1 and 2:1 + S]. LNA and ALA intakes were 9.4 and 7.7%, and 1.0 and 3.0% during the low and high ALA diets, respectively. Compared to the Western-style 10:1 diet, the 2:1 diet increased EPA by 60% (P < 0.0001) in RBC membranes without the direct EPA source and a 34% increase (P = 0.027) was observed with the 10:1 + S diet; however, DHA levels increased in both diet ratios only with a direct DHA source. Shifting towards a 2:1 diet is a valid alternative to taking EPA-containing supplements.
There has been a growing interest in lignans, a class of phyto-oestrogens, because of their potentially favourable effects on human health. The aim of the present study was to compare the metabolic profile of post-menopausal women consuming various amounts of dietary lignans. Phyto-oestrogen intake was assessed using a 3-d dietary record analysed with a Canadian food phyto-oestrogen content data table in 115 post-menopausal women (age 56.8 (SD 4.4) years and BMI 28.5 (SD 5.9) kg/m(2)). Plasma enterolactone (ENL), the major biologically active metabolite of dietary lignans, was determined by time-resolved fluoroimmunoassay. Anthropometrics, abdominal adipose tissue areas (computed tomography), body composition (hydrostatic weighing) and insulin sensitivity (hyperinsulinaemic-euglycaemic clamp) were measured in all women. Women in the high dietary lignan intake subgroup (n 29) had a significantly lower BMI and total body fat mass, as well as a better glucose disposal rate (GDR; P < 0.05), compared with women in the low lignan intake subgroup (n 28). The majority of women with the highest dietary lignan intake were also in the highest quartile of plasma ENL (59 %). Women in the highest ENL quartile had a significantly lower BMI (26.1 (SD 4.4) v. 30.4 (SD 6.9) kg/m(2), P < 0.05), total body fat mass (24.8 (SD 9.8) v. 33.3 (SD 13.3) kg, P < 0.05), 2 h postload glycaemia (5.5 (SD 0.9) v. 5.7 (sd 0.8) nmol/l, P < 0.05) and a higher GDR (8.3 (SD 2.7) v. 5.5 (SD 2.8), P < 0.01) compared with women in the lowest ENL quartile. In conclusion, women with the highest ENL concentrations had a better metabolic profile including higher insulin sensitivity and lower adiposity measures.
The effects of ingestion of flaxseed gum on blood glucose and cholesterol, particularly low-density lipoprotein cholesterol, in type 2 diabetes were evaluated. Flaxseed gum was incorporated in wheat flour chapattis. Sixty patients of type 2 diabetes were fed a daily diet for 3 months, along with six wheat flour chapattis containing flaxseed gum (5 g), as per the recommendations of the American Diabetic Association. The control group (60 individuals) consumed an identical diet but the chapattis were without gum. The blood biochemistry profiles monitored before starting the study and at monthly intervals showed fasting blood sugar in the experimental group decreased from 154+/-8 mg/dl to 136+/-7 mg/dl (P=0.03) while the total cholesterol reduced from 182+/-11 mg/dl to 163+/-9 mg/dl (P=0.03). Results showed a decrease in low-density lipoprotein cholesterol from 110+/-8 mg/dl to 92+/-9 mg/dl (P=0.02). The study demonstrated the efficacy of flax gum in the blood biochemistry profiles of type 2 diabetes.
Several clinical trials have investigated the effects of flaxseed and flaxseed-derived products (flaxseed oil or lignans) on blood lipids; however, the findings have been inconsistent.
We aimed to identify and quantify the effectiveness of flaxseed and its derivatives on blood lipid profiles.
A comprehensive literature search was performed on the basis of English reports of randomized controlled trials of flaxseed or its derivatives on lipid profiles in adults, which were published from January 1990 to October 2008. Attempts also were made to access unpublished data. Study quality was assessed by using the Jadad score, and a meta-analysis was conducted.
Twenty-eight studies were included. Flaxseed interventions reduced total and LDL cholesterol by 0.10 mmol/L (95% CI: -0.20, 0.00 mmol/L) and 0.08 mmol/L (95% CI: -0.16, 0.00 mmol/L), respectively; significant reductions were observed with whole flaxseed (-0.21 and -0.16 mmol/L, respectively) and lignan (-0.28 and -0.16 mmol/L, respectively) supplements but not with flaxseed oil. The cholesterol-lowering effects were more apparent in females (particularly postmenopausal women), individuals with high initial cholesterol concentrations, and studies with higher Jadad scores. No significant changes were found in the concentrations of HDL cholesterol and triglycerides.
Flaxseed significantly reduced circulating total and LDL-cholesterol concentrations, but the changes were dependent on the type of intervention, sex, and initial lipid profiles of the subjects. Further studies are needed to determine the efficiency of flaxseed on lipid profiles in men and premenopausal women and to explore its potential benefits on other cardiometabolic risk factors and prevention of cardiovascular disease.
A randomized double-blind placebo controlled study design was used to assess the effects of flaxseed lignan complex supplementation during exercise training on a metabolic syndrome composite score and osteoporosis risk in older adults. A total of 100 subjects (50 years) were randomized to receive flaxseed lignan (543mgday¹ in a 4050mg complex) or placebo while completing a 6 month walking program (3060minday¹, 56daysweek¹). Fasting serum glucose, triacylglycerol (TAG), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, total cholesterol, interleukin-6, and tumor necrosis factor- were measured every 2 months, while body composition, bone mineral density, and resting blood pressure were assessed at baseline and at 6months. A composite Z score of 6 risk factors for metabolic syndrome (fasting glucose, HDL cholesterol, TAG, abdominal adiposity, blood pressure, and inflammatory cytokines) was calculated at baseline and at 6months. Men taking placebo increased metabolic syndrome composite Z score (p< 0.05), but there were no changes in the other groups. A significant group sex time interaction was noted for TAG (p = 0.017) and diastolic blood pressure (p = 0.046), with men taking flaxseed lignan decreasing diastolic blood pressure relative to men taking placebo, and men taking placebo increasing TAG relative to men taking flax lignan. There were no differences between groups for change in bone measures, body composition, lipoproteins, or cytokines. Males taking the flaxseed lignan complex reduced metabolic syndrome score relative to men taking placebo, but a similar trend was not seen in females. Flaxseed lignan had no effect on bone mineral density or content, body composition, lipoproteins, glucose, or inflammation.
Flaxseed (FS) has high contents of omega-3 fatty acids and lignans with antioxidant properties. Its use in preventing thoracic X-ray radiation therapy (XRT)-induced pneumonopathy has never been evaluated. We evaluated FS supplementation given to mice given before and post-XRT. FS-derived lignans, known for their direct antioxidant properties, were evaluated in abrogating ROS generation in cultured endothelial cells following gamma radiation exposure. Mice were fed 10% FS or isocaloric control diet for three weeks and given 13.5 Gy thoracic XRT. Lungs were evaluated at 24 hours for markers of radiation-induced injury, three weeks for acute lung damage (lipid peroxidation, lung edema and inflammation), and at four months for late lung damage (inflammation and fibrosis). FS-Lignans blunted ROS generation in vitro, resulting from radiation in a dose-dependent manner. FS-fed mice had reduced expression of lung injury biomarkers (Bax, p21 and TGF-beta1) at 24 hours following XRT and reduced oxidative lung damage as measured by malondialdehyde (MDA) levels at 3 weeks following XRT. In addition, FS-fed mice had decreased lung fibrosis as determined by hydroxyproline content and decreased inflammatory cell influx into lungs at 4 months post XRT. Importantly, when Lewis lung carcinoma cells were injected systemically in mice, FS dietary supplementation did not appear to protect lung tumors from responding to thoracic XRT. Dietary FS is protective against pulmonary fibrosis, inflammation and oxidative lung damage in a murine model. Moreover, in this model, tumor radioprotection was not observed. FS lignans exhibited potent radiation-induced ROS scavenging action. Taken together, these data suggest that dietary flaxseed may be clinically useful as an agent to increase the therapeutic index of thoracic XRT by increasing the radiation tolerance of lung tissues.
Type II diabetic subjects were given 50 g protein, 50 g glucose, or 50 g glucose with 50 g protein as a single meal in random sequence. The plasma glucose and insulin response was determined over the subsequent 5 h. The plasma glucose area above the baseline following a glucose meal was reduced 34% when protein was given with the glucose. When protein was given alone, the glucose concentration remained stable for 2 h and then declined. The insulin area following glucose was only modestly greater than with a protein meal (97 +/- 35, 83 +/- 19 microU X h/ml, respectively). When glucose was given with protein, the mean insulin area was considerably greater than when glucose or protein was given alone (247 +/- 33 microU X h/ml). When various amounts of protein were given with 50 g glucose, the insulin area response was essentially first order. Subsequently, subjects were given 50 g glucose or 50 g glucose with 50 g protein as two meals 4 h apart in random sequence. The insulin areas were not significantly different for each meal but were higher when protein + glucose was given. After the second glucose meal the plasma glucose area was 33% less than after the first meal. Following the second glucose + protein meal the plasma glucose area was markedly reduced, being only 7% as large as after the first meal. These data indicate that protein given with glucose will increase insulin secretion and reduce the plasma glucose rise in at least some type II diabetic persons.
Many factors influence carbohydrate absorption. Slower rates of absorption may have advantages in reducing postprandial glycemia and insulinemia and, in time, reduce serum low-density-lipoprotein (LDL) cholesterol and apolipoprotein B concentrations. Foods high in viscous fiber or antinutrients, or foods that are resistant to gelatinization, show slower rates of digestion and absorption and may be called low glycemic index or lente carbohydrate foods. Specific enzyme inhibitors may also cause lente effects. Certain small-intestinal effects of lente carbohydrate may be mimicked by altering feeding frequency (eg, nibbling vs gorging). Increased meal frequency reduces post-prandial insulin and glucose responses in people with non-insulin-dependent diabetes and in nondiabetic volunteers and lowers serum concentrations of LDL cholesterol and apolipoprotein B. Reduced hepatic cholesterol synthesis has been reported. Increased meal frequency may also slow small-intestinal absorption in the treatment of conditions such as diabetes, hyperlipidemia, and possibly obesity.
Supplementation of type II diabetic diets with n-3 fatty acids (FAs) from fish oil (FO) has been associated with lowered triglyceride and VLDL levels, although reports of impaired glycemic control have limited their use. Effects of n-3FAs from nonmarine sources are less well documented. Therefore, an investigation comparing the effects of linseed oil (LO) with FO supplementation was undertaken in subjects with type II diabetes.
Eleven subjects with type II diabetes were given supplements with LO and FO for 3 months each in a randomized double-blind crossover fashion after 3 months of olive oil placebo. Oils were given as 35 mg FA.kg body wt-1.day-1. After each 3-month period, fasting glucose and insulin levels, HbA1c, lipid profiles, insulin sensitivity (SI), glucose effectiveness (SG), and acute insulin response to glucose (AIRG) were evaluated.
HbA1c and lipid values were within the normal range at randomization. Repeated measures analysis of variance testing found no significant differences in weight; fasting glucose and insulin levels; HbA1c; total, LDL, and HDL cholesterol levels; SI; SG; or AIRG with either active oil. FO was associated with significant reductions in triglycerides and a trend toward decreased SI.
In a population with well-controlled type II diabetes, 3 months of FO but not LO resulted in lowered triglyceride levels. Neither LO nor FO significantly affected glycemic control, cholesterol values, SG, or insulin secretion, while a nonsignificant trend toward decreased insulin sensitivity was found with FO.
The results of human clinical trials have revealed that the effects of resveratrol on adipokines are inconsistent. Our objective was to elucidate the role of resveratrol supplementation on adipokines through a systematic review and a meta-analysis of available randomized placebo-controlled trials (RCTs).(1) The search included PubMed-MEDLINE, SCOPUS and ISI web of sciences database till up to 6th November 2016. Weight mean differences (WMD)(2) were calculated for net changes in adipokines using fixed-effects or random-effects models; meta-regression analysis and publication bias were conducted in accordance with standard methods. Nine RCTs with 11 treatment arms were eligible for inclusion in this systematic review and meta-analysis. Meta-analysis of data from 10 treatment arms showed a significant change in plasma adiponectin concentrations following resveratrol supplementation (WMD: 1.10μg/ml, 95%CI: 0.88, 1.33, p <0.001); Q=11.43, I(2)=21.29%, p=0.247). There was a significant greater adiponectin-reducing effect in trials with higher than or equal to 100mg/day (WMD: 1.11 ug/ml, 95%CI: 0.88, 1.34, p <0.001), versus those with less than 100 mg/day dosage (WMD: 0.84 ug/ml, 95%CI: -0.62, 2.31, p=0.260). Meta-analysis of data from 5 treatment arms did not find any significant change in plasma leptin concentrations following resveratrol supplementation (WMD: 3.77ng/ml, 95% CI: -2.28, 9.83, p=0.222; Q=8.00, I(2)=50.01%). Resveratrol significantly improves adiponectin but does not affect leptin concentrations. Additional studies are required to further evaluate the potential benefits of resveratrol on adipokines in humans.
Background:
Limited data are available that evaluated the effects of combined omega-3 fatty acids and vitamin E supplementation on glucose homeostasis parameters and lipid concentrations in gestational diabetes (GDM).
Objectives:
The present study was designed to determine the effects of omega-3 fatty acids and vitamin E co-supplementation on glucose homeostasis parameters and lipid concentrations among women with GDM who were not on oral hypoglycemic agents.
Methods:
This prospective randomized, double-blind, placebo-controlled clinical trial was carried out among 60 patients with GDM. Patients were randomly allocated to take either 1000-mg omega-3 fatty acids from flaxseed oil plus 400-IU vitamin E supplements (n = 30) or placebo (n = 30) for 6 weeks. Fasting blood samples were obtained from at the beginning of the study and after 6-week intervention to quantify related variables.
Results:
After 6 weeks of intervention, changes in fasting plasma glucose (-11.8 ± 11.0 vs +1.5 ± 11.9 mg/dL, P < .001), serum insulin concentrations (-1.8 ± 6.9 vs +5.8 ± 12.1 μIU/mL, P = .004), homeostasis model of assessment-estimated insulin resistance (-0.8 ± 1.6 vs +1.4 ± 2.8, P = .001), homeostasis model of assessment-estimated beta cell function (-0.2 ± 27.7 vs +22.8 ± 48.2, P = .02), and quantitative insulin sensitivity check index (+0.01 ± 0.02 vs -0.01 ± 0.02, P = .01) in the omega-3 fatty acids plus vitamin E group were significantly different from the changes in these indicators in the placebo group. Changes in serum triglycerides (+10.8 ± 41.5 vs +34.2 ± 35.5 mg/dL, P = .02), VLDL-cholesterol (+2.1 ± 8.3 vs +6.8 ± 7.1 mg/dL, P = .02), low-density lipoprotein (LDL)-cholesterol (+11.6 ± 18.8 vs +1.7 ± 15.9 mg/dL, P = .03) and HDL-cholesterol concentrations (+1.9 ± 8.7 vs -2.4 ± 7.7 mg/dL, P = .04) were significantly different between the supplemented women and placebo group. However, after controlling for baseline total cholesterol levels, maternal age, and BMI at baseline, the changes in serum LDL-cholesterol concentrations were not significantly different between the 2 groups. We did not find any significant effect of joint omega-3 fatty acids and vitamin E supplementation on total cholesterol concentrations.
Conclusions:
Overall, we demonstrated that omega-3 fatty acids and vitamin E co-supplementation in GDM women had beneficial effects on glucose homeostasis parameters, serum triglycerides, VLDL-cholesterol, and HDL-cholesterol concentrations, but it did not influence total-cholesterol and LDL-cholesterol levels.
Background & aims:
This study was carried out to evaluate the effects of omega-3 fatty acid administration on markers of insulin resistance, lipid concentrations, biomarkers of inflammation and oxidative stress in patients with diabetic nephropathy (DN).
Methods:
This parallel randomized double-blind placebo-controlled clinical trial was performed among 60 patients with DN. Patients were randomly allocated into two groups to receive either 1000 mg/day omega-3 fatty acid from flaxseed oil (n = 30) or placebo (n = 30) for 12 weeks. Fasting blood samples were taken at the onset of the study and 12 weeks after supplementation to assess glycaemic status, lipid concentrations, biomarkers of inflammation and oxidative stress.
Results:
After 12 weeks of treatment, patients who consumed omega-3 fatty acid supplements compared with the placebo had significantly decreased serum insulin levels (-39.6 ± 10.8 vs. -7.2 ± 8.4 pmol/L, P = 0.001), homeostasis model of assessment-estimated b cell function (HOMA-B) (-30.2 ± 11.2 vs. -1.5 ± 6.8, P = 0.03) and improved quantitative insulin sensitivity check index (QUICKI) (+0.01 ± 0.004 vs. +0.002 ± 0.004, P = 0.03). Additionally, compared with the placebo, omega-3 fatty acid administration led to a significant reduction in serum triglycerides (-19.8 ± 8.8 vs. +12.6 ± 10.2 mg/dL, P = 0.01) and VLDL-cholesterol concentrations (-4.0 ± 1.8 vs. +2.5 ± 2.0 mg/dL, P = 0.01). Supplementation with omega-3 fatty acid had no significant effects on other lipid subfractions, biomarkers of inflammation and oxidative stress compared with the placebo. In addition, within-group differences revealed significant reductions in serum insulin (P = 0.001), HOMA-IR (P = 0.004), HOMA-B (P = 0.01), serum triglycerides (P = 0.03), VLDL- (P = 0.03), total- (P < 0.001), LDL- (P = 0.002), total-/HDL-cholesterol ratio (P = 0.001), blood urea nitrogen (P = 0.04), and significant increases in QUICKI (P = 0.001) and nitric oxide (P = 0.005) and total antioxidant capacity concentrations (P = 0.02) in the omega-3 fatty acid group.
Conclusions:
Our findings indicated that omega-3 fatty acid administration for 12 weeks among DN patients had favorable effects on insulin levels, HOMA-B, QUICKI, serum triglycerides and VLDL-cholesterol; however, it did not influence biomarkers of inflammation and oxidative stress.
Background & Aims: Many experimental and clinical trials suggested that flaxseed might be a potent antihypertensive, but the evidences concerning the effects of flaxseed supplements on blood pressure (BP) has not been fully conclusive. We aimed to assess the impact of the effects of flaxseed supplements on blood pressure through systematic review of literature and meta-analysis of available randomized controlled trials (RCTs).
Methods: The literature search included PUBMED, Cochrane Library, Scopus, and EMBASE up to February 2015 to identify RCTs investigating the effect of flaxseed supplements on plasma blood pressure. Effect size was expressed as weighed mean difference (WMD) and 95% confidence interval (CI).
Results: 15 trials (comprising 19 treatment arms) with 1302 participants were included in this meta-analysis. Random-effects meta-analysis suggested significant reductions in both systolic BP (SBP) (WMD: -2.85 mmHg, 95%CI: -5.37 to -0.33, p=0.027) and diastolic BP (DBP) (WMD: -2.39 mmHg, 95%CI: -3.78 to -0.99, p=0.001) following supplementation with flaxseed products. When the studies were stratified according to their duration, there was a greater effect on both SBP and DBP in the subset of trials with ≥12 weeks of duration (WMD: -3.10 mmHg, 95%CI: -6.46 to 0.27, p=0.072 and -2.62 mmHg, 95%CI: -4.39 to -0.86, p=0.003, respectively) vs the subset lasting <12 weeks (WMD: -1.60 mmHg, 95%CI: -5.44 to 2.24, p=0.413, and -1.74 mmHg, 95%CI: -4.41 to 0.93, p=0.202, respectively). Another subgroup analysis was performed to assess the impact of flaxseed supplement type on BP. Reduction of SBP was significant with flaxseed powder (WMD: -1.81 mmHg, 95% CI: -2.03 to -1.59, p < 0.001) but not oil (WMD: -4.62 mmHg, 95%CI: -11.86 to 2.62, p=0.211) and lignan extract (WMD: 0.28 mmHg, 95% CI: -3.49 to 4.04, p = 0.885). However, DBP was significantly reduced with powder and oil preparations (WMD: -1.28 mmHg, 95% CI: -2.44 to -0.11, p = 0.031, and -4.10 mmHg, 95%CI: -6.81 to -1.39, p=0.003, respectively), but not with lignan extract (WMD: -1.78 mmHg, 95% CI: -4.28 to 0.72, p = 0.162).
Conclusions: This meta-analysis of RCTs showed significant reductions in both SBP and DBP following supplementation with various flaxseed products.
The objective of this study was to determine the effect of alpha-linolenic acid (ALA) supplementation on blood lipids and inflammatory markers, in relation to apolipoprotein (apo) E genotype. The diets of 50 dyslipidemic male patients were supplemented with 15 mL of flaxseed oil per day for 12 weeks. Retrospectively, 3 apo E genotype variants were found (ε2/ε3, n=7; ε3/ε3, n=33; ε3/ε4, n=10). No significant differences were found among apo E genotypes in any variables at baseline. ALA supplementation produced a small but significant decrease in high-density lipoprotein cholesterol (from 1.12 to 1.08 mmol/L, 43 to 42 mg/dL; p=0.008) and apo A-I levels (from 1.28 to 1.24 g/L, p=0.036) in the ε3/ε3 homozygotes. In addition, ALA supplementation resulted in a significant decrease in the serum concentration of serum amyloid A (SAA) (p=0.014), C-reactive protein (CRP) (p=0.013), macrophage colony-stimulating factor (MCSF) (p<0.001), and interleukin (IL)-6 (p=0.028). Serum SAA and MCSF were also significantly decreased in the ε3/ε4 group (p=0.005 and p=0.017, respectively). In contrast, ALA produced no effects on any of the inflammatory markers in the ε2/ε3 group. ALA may have beneficial effects on inflammation in dyslipidemic carriers of the apo ε3/ε3 and ε3/ε4 genotypes, but not in carriers of the ε2 allele.
High blood pressure is a major health burden positively associated with the risk of cardiovascular disease and other chronic diseases. Flaxseed is a rich dietary source of α-linolenic acid, lignans, and fiber, with a number of positive health benefits on blood pressure.
The purpose of this study was to clarify the effect of flaxseed consumption on blood pressure. Further, the influence of different baseline blood pressure, type of flaxseed supplementation, and duration of flaxseed supplementation on blood pressure was explored.
PubMed (MEDLINE), Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library (Central) were searched through July 2014 for studies in which humans supplemented their habitual diet with flaxseed or its extracts (i.e., oil, lignans, fiber) for ≥2 wk.
A total of 11 studies (14 trials) were included in the analysis. Random-effects meta-analyses were conducted for the mean difference in blood pressure. Results indicated that flaxseed supplementation reduced systolic blood pressure (-1.77 mm Hg; 95% CI: -3.45, -0.09; P = 0.04) and diastolic blood pressure (-1.58 mm Hg; 95% CI: -2.64, -0.52 mm Hg; P = 0.003). These results were not influenced by categorization of participants into higher baseline blood pressure (≥130 mm Hg). An improvement in diastolic blood pressure was observed in subgroup analysis for consuming whole flaxseed (-1.93 mm Hg; 95% CI: -3.65, -0.21 mm Hg; P < 0.05) and duration of consumption ≥12 wk (-2.17 mm Hg; 95% CI: -3.44, -0.89 mm Hg; P < 0.05).
The present meta-analysis suggests that consumption of flaxseed may lower blood pressure slightly. The beneficial potential of flaxseed to reduce blood pressure (especially diastolic blood pressure) may be greater when it is consumed as a whole seed and for a duration of >12 wk.
© 2015 American Society for Nutrition.
Background:
Flaxseed is a promising alternative to reduce the risk of diseases associated with body weight excess because it is rich in a-linolenic acid, lignans, and dietary fiber. Flaxseed (Linum usitatissimum) can be found in brown and golden varieties; however, questions have arisen as to whether the variety may influence the health effects.
Objective:
The objective of this study was to compare the effects of brown and golden flaxseeds on lipid profile, glycemia, blood pressure, inflammatory status,body weight, and body composition in overweight adolescents.
Methods:
Seventy-five overweight adolescents (33 boys, 42 girls; age 13.7 ! 2.1 y), from Alegre-ES, Brazil, were randomized to one of the three groups (n ¼ 25) on a parallel, single-blind clinical trial. They received 28 g/d of brown flaxseed (BF), golden flaxseed (GF), or the equivalent amount of wheat bran (Control, CG) in different preparations at school from Monday to Friday for 11 wk. Blood pressure, anthropometric evaluation, and the analyses of blood total cholesterol, lipoproteins, glucose, and inflammatory markers were performed at the beginning and at the end of the intervention. The data were analyzed by ANCOVA at 5% significance.
Results:
The groups who consumed brown and golden flaxseed showed significant reduction in diastolic blood pressure. Brown and golden flaxseed did not differentially affect plasma lipid responses, plasma glucose and inflammatory profile, although all groups (BF, GF, and CG) showed increased levels of TNF-a.
Conclusions:
The adolescents consumed about half the daily amount provided, which may not have been sufficient to exert the health benefits of flaxseed reported in the literature, concerning the lipid profile, inflammation biomarkers and body composition.
Objective:
Soy-soluble polysaccharides and flaxseed gum are underutilized dietary fibers of interest to the food industry. However, because the ability of soluble fibers to modulate postprandial glucose and insulin metabolism has been related to their viscous effects, the utility of these and other low-viscosity soluble fibers remains unproven. The objective of this study was to examine the associations between soy-soluble polysaccharides and flaxseed gum concentration, product viscosity, and the postprandial glycemic and insulinemic responses in the context of glucose solutions as well as fluid and gelled dairy products.
Methods:
Twelve healthy males participated in a randomized crossover postprandial study in which they visited the laboratory following overnight fasts on 11 occasions to consume one of 11 study treatments, each consisting of 50 g available carbohydrates. The study treatments included a glucose reference (in duplicate), glucose solutions containing soy-soluble polysaccharides (6%), flaxseed gum (0.7%), or guar gum (0.23%), all matched for an apparent viscosity of 61 mPa·s at 50 s⁻¹, as well as dairy-based beverages and puddings with 0% or 1% soluble fiber added. Blood samples were collected at fasting and up to 2 hours postprandially for determination of glucose and insulin concentrations. Area under the curve (AUC), peak concentration, and time-to-peak values as well as glycemic index (GI) and insulinemic index (II) were calculated.
Results:
Fiber fortification of a 50 g glucose solution had no effect on postprandial blood glucose or insulin levels, even at a high concentration (i.e., 6% soy-soluble polysaccharides). Glucose AUC and GI values for the dairy-based beverage (p < 0.05) and pudding (p < 0.01) controls were significantly lower than the glucose reference. Glucose AUC and GI values for the soy-soluble polysaccharide-fortified dairy products (p < 0.01) and flaxseed gum-fortified dairy products (p < 0.001) were significantly lower than the glucose reference. No significant differences were observed between the fiber-fortified fluid and gelled dairy-based study treatments and no significant differences were observed in terms of the insulin AUC, II, and peak insulin concentration between any of the dairy products.
Conclusions:
All dairy products had lower glycemic responses relative to the reference, with no effect of beverage versus pudding matrix observed and minimal impact of 1% flaxseed gum or soy-soluble polysaccharides. Product apparent viscosity, but not fiber concentration, was significantly and inversely correlated with glucose AUC and GI.
Objective:
The omega-3 polyunsaturated fatty acid (n-3 PUFA) as well as lignan components of flaxseed (FLX) can have beneficial effects. In this 6-week-long, randomized, double-blinded, placebo-controlled study, we investigated the effects of FLX lignans on cardiovascular risk factors.
Methods:
Thirty-seven subjects (13 men and 24 women, age: 54±7 years, body mass index [BMI]: 29.7±1 kg/m2) consumed nutrition bars with similar macronutrient contents. The fatty acid composition and the lignan contents of the bars differed significantly. Two FLX bars both contained 3.0 g of alpha linolenic acid (ALA: 18:3 n-3) but different amount of lignans (0.15 g vs. 0.41 g).
Results:
High-lignan FLX decreased total cholesterol (C) by 12% (p=0.044), LDL-C by 15% (p=0.022), and oxidized (Ox)-LDL by 25% (p=0.035). Regular FLX tended to increase Ox-LDL by 13% (p=0.051). The difference between the effects of high-lignan vs. regular lignan FLX on Ox-LDL was highly significant (p=0.004).
Conclusion:
High-lignan FLX has the unique property of decreasing Ox-LDL, which is an independent risk factor for cardiovascular disease.
The first quantitative method for the determination of both lignans and isoflavonoid phytoestrogens in plasma is presented. Using ion-exchange chromatography the diphenols are separated into two fractions 1) the biologically “active” fraction containing the free compounds + mono- and disulfates and 2) the biologically “inactive” fraction containing the mono- and diglucuronides and the sulfoglucuronides. After hydrolysis the fractions are further purified by solid phase extraction and ion exchange chromatography. Losses during the complete procedure are corrected for using radioactive estrogen conjugates during the first steps and later by adding deuterated internal standards of all compounds measured (matairesinol, enterodiol, enterolactone, daidzein, O-desmethylangolensin, equol, and genistein). The final determination is carried out by isotope dilution gas chromatographγ-mass spectrometry in the selected ion monitoring mode (GC/MS/SIM). The diphenols may be measured at concentrations as low as 0.2 to 1.0 nmol/1. Results of plasma analyses of all compounds in 27 pre- and postmenopausal omnivorous and vegetarian women are presented for the first time. The most important findings are that the free+sulfate fraction is low for genistein (3.8% of total), but as much as 21-25% of enterolactone and enterodiol occurs in mis fraction. A good correlation between plasma and urine values was found. Total concentrations of individual compounds vary greatly between the subjects (from pmol/1 to μmol/l), the vegetarians having higher values, particularly one vegan subject. The highest total enterolactone concentration value exceeded 1 ümol/1. It is concluded that a highly specific method for the assay of 3 lignans and 4 isoflavonoids in plasma has been developed. This method will be useful in future studies of lignan and isoflavonoid metabolism.
Type 2 diabetes (T2D) is a result of complex gene-environment interactions, and several risk factors have been identified, including age, family history, diet, sedentary lifestyle and obesity. Statistical models that combine known risk factors for T2D can partly identify individuals at high risk of developing the disease. However, these studies have so far indicated that human genetics contributes little to the models, whereas socio-demographic and environmental factors have greater influence. Recent evidence suggests the importance of the gut microbiota as an environmental factor, and an altered gut microbiota has been linked to metabolic diseases including obesity, diabetes and cardiovascular disease. Here we use shotgun sequencing to characterize the faecal metagenome of 145 European women with normal, impaired or diabetic glucose control. We observe compositional and functional alterations in the metagenomes of women with T2D, and develop a mathematical model based on metagenomic profiles that identified T2D with high accuracy. We applied this model to women with impaired glucose tolerance, and show that it can identify women who have a diabetes-like metabolism. Furthermore, glucose control and medication were unlikely to have major confounding effects. We also applied our model to a recently described Chinese cohort and show that the discriminant metagenomic markers for T2D differ between the European and Chinese cohorts. Therefore, metagenomic predictive tools for T2D should be specific for the age and geographical location of the populations studied.
Context:
The natural health product, BeneFlax, is a standardized flaxseed [Linum usitatissimum L. (Linaceae)] lignan enriched product with evidence of product quality and known quantity of the bioactive component, lignan. The acceptance of this natural health product for its various health benefits requires greater evidence of its safety in the general population.
Objective:
We determined whether flaxseed lignan causes clinical hypoglycemia or hypotension in healthy older adults as an important aspect of safety.
Materials and methods:
Participants aged 49-87 years were randomized in a double-blind trial to receive flaxseed lignan (543 mg/day in BeneFlax) or placebo while completing a 6-month walking program. The 94 participants who completed the study were stratified by age (<65 years versus ≥65 years) and treatment category to determine whether older adults were more susceptible to adverse effects.
Results:
After 6 months of treatment, average plasma glucose level (5.4 ± 0.6 mmol/L), systolic blood pressure (127 ± 14 mm Hg), and diastolic blood pressure (80 ± 9 mm Hg) were within normal clinical range. Controlling for sex and body mass index covariates resulted in no observed differences between plasma glucose or blood pressure measurements between treatment or age groups (p > 0.05). No incidents of hypoglycemia or hypotension were observed during BeneFlax treatment, suggesting that 543 mg falls at or below the no observable adverse effect level (NOAEL).
Discussion and conclusion:
These data suggest the flaxseed lignan product BeneFlax does not pose a risk of hypoglycemia or hypotension in healthy adults aged 49-87 years.
Objective:
Olive oil (OO) is a rich source of monounsaturated fat and bioactive components that exert strong anti-oxidant and anti-inflammatory properties. Flaxseed oil (FO) is rich in α-linolenic n-3 fatty acid (ALA), which also exhibits anti-inflammatory effects. This randomized, cross-over study aimed at exploring whether diet's enrichment with FO could beneficially alter inflammatory markers and lipid profile, compared to OO, in a sample of normal weight, apparently healthy young adults.
Materials and methods:
Participants were supplied with 15 mL/day of either FO or OO. Each intervention and the wash-out period lasted 6 weeks. Dietary, anthropometric and physical activity variables were recorded at the beginning and the end of each intervention. Serum biochemical and inflammatory markers were measured. Compliance to the intervention was evaluated by fatty acid analysis in erythrocytes. Repeated Measures ANOVA was used to assess the effect of the treatment.
Results:
Thirty seven participants completed the study. No difference between the two interventions was observed in adiponectin, TNF-α, high sensitivity-CRP or glucose levels and lipid profile. At the end of the FO period, participants exhibited significant reductions in total (-5.0%) and LDL-cholesterol (-6.7%) levels (all P<0.01). During the FO and the OO period serum adiponectin changes were significantly correlated with changes in erythrocyte %ALA (rs=0.34, P=0.007) and in erythrocyte %EPA (r(s)=0.47, P=0.01), respectively.
Conclusions:
Daily consumption of FO did not confer any benefit in inflammatory or biochemical markers in normal weight young adults, who traditionally use olive oil as the main edible oil.
The Cochrane Handbook for Systematic Reviews of Interventions (the Handbook) has undergone a substantial update, and Version 5 of the Handbook is now available online at www.cochrane-handbook.org and in RevMan 5. In addition, for the first time, the Handbook will soon be available as a printed volume, published by Wiley-Blackwell. We are anticipating release of this at the Colloquium in Freiburg. Version 5 of the Handbook describes the new methods available in RevMan 5, as well as containing extensive guidance on all aspects of Cochrane review methodology. It has a new structure, with 22 chapters divided into three parts. Part 1, relevant to all reviews, introduces Cochrane reviews, covering their planning and preparation, and their maintenance and updating, and ends with a guide to the contents of a Cochrane protocol and review. Part 2, relevant to all reviews, provides general methodological guidance on preparing reviews, covering question development, eligibility criteria, searching, collecting data, within-study bias (including completion of the Risk of Bias table), analysing data, reporting bias, presenting and interpreting results (including Summary of Findings tables). Part 3 addresses special topics that will be relevant to some, but not all, reviews, including particular considerations in addressing adverse effects, meta-analysis with non-standard study designs and using individual participant data. This part has new chapters on incorporating economic evaluations, non-randomized studies, qualitative research, patient-reported outcomes in reviews, prospective meta-analysis, reviews in health promotion and public health, and the new review type of overviews of reviews.
Diabetes mellitus is characterized by hyperglycemia and associated with aberrations in the metabolism of carbohydrate, protein, and lipid that result in development of secondary complications. Extensive studies have indicated that nutritional therapy plays a pivotal role in the controlling or postponing of development of these secondary complications. Several functional foods have been shown to possess hypoglycemic and hypolipidemic properties. Flax seed (FS) is a functional food that is rich in omega 3 fatty acids and antioxidants and is low in carbohydrates. In exploratory studies, FS was incorporated in recipes, which resulted in a reduction in the glycemic index of the food items. These observations prompted us to investigate the efficacy of FS supplementation in type 2 diabetics (n = 29). Subjects were assigned to the experimental (n = 18) or the control group (n = 11) on the basis of their desire to participate in the study. The experimental group's diet was supplemented daily with 10 g of FS powder for a period of 1 month. The control group received no supplementation or placebo. During the study, diet and drug intake of the subjects remained unaltered. The efficacy of supplementation with FS was evaluated through a battery of clinico-biochemical parameters. Supplementation with FS reduced fasting blood glucose by 19.7% and glycated hemoglobin by 15.6%. A favorable reduction in total cholesterol (14.3%), triglycerides (17.5%), low-density lipoprotein cholesterol (21.8%), and apolipoprotein B and an increase in high-density lipoprotein cholesterol (11.9%) were also noticed. These observations suggest the therapeutic potential of FS in the management of diabetes mellitus.
The objective of the study was to compare the effects of essential vs long-chain omega (n)-3 polyunsaturated fatty acids (PUFAs) in polycystic ovary syndrome. In this 6-week, prospective, double-blinded, placebo (soybean oil)-controlled study, 51 completers received 3.5 g n-3 PUFA per day (essential PUFA from flaxseed oil or long-chain PUFA from fish oil). Anthropometric variables, cardiovascular risk factors, and androgens were measured; oral glucose tolerance test (OGTT) and frequently sampled intravenous GTT (IVGTT) were conducted at baseline and 6 weeks. Between-group comparisons showed significant differences in serum triglyceride response (P = .0368), whereas the changes in disposition index also tended to differ (P = .0621). When within-group changes (after vs before intervention) were considered, fish oil and flaxseed oil lowered serum triglyceride (P = .0154 and P = .0176, respectively). Fish oil increased glucose at 120 minutes of OGTT (P = .0355), decreased the Matsuda index (P = .0378), and tended to decrease acute insulin response during IVGTT (P = .0871). Soybean oil increased glucose at 30 (P = .0030) and 60 minutes (P = .0121) and AUC for glucose (P = .0122) during OGTT, tended to decrease acute insulin response during IVGTT (P = .0848), reduced testosterone (P = .0216), and tended to reduce sex hormone-binding globulin (P = .0858). Fasting glucose, insulin, adiponectin, leptin, or high-sensitivity C-reactive protein did not change with any intervention. Long-chain vs essential n-3 PUFA-rich oils have distinct metabolic and endocrine effects in polycystic ovary syndrome; and therefore, they should not be used interchangeably.