A meta-analysis of randomized, double-blind, placebo-controlled trials for the effects of garlic on serum lipid profiles

Institute of Toxicology, Shandong University, Shandong, Jinan 250012, PR China.
Journal of the Science of Food and Agriculture (Impact Factor: 1.88). 07/2012; 92(9):1892-902. DOI: 10.1002/jsfa.5557
Source: PubMed

ABSTRACT Inconsistent results were obtained for the lipid-regulating effects of garlic in clinical trials. With increasing interest in complementary medicine for hyperlipoidemia, it is important to explore the real effects of garlic. This meta- analysis was performed to investigate the influence of garlic on serum lipid parameters.
A total of 26 studies were included into meta-analysis. Overall, garlic was superior to placebo in reducing serum total cholesterol (TC) and triglyceride (TG) levels. Compared with the placebo groups, serum TC and TG levels in the garlic group were reduced by 0.28 (95% CI, -0.45, -0.11) mmol L⁻¹ (P = 0.001) and 0.13 (95% CI, -0.20, -0.06) mmol L⁻¹ (P < 0.001), respectively. The effects of garlic were more striking in subjects with long-term intervention and higher baseline TC levels. Garlic powder and aged garlic extract were more effective in reducing serum TC levels, while garlic oil was more effective in lowering serum TG levels. In contrast, garlic did not influence other lipid parameters, including low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), apolipoprotein B, and TC/HDL-C ratio.
Garlic could reduce serum TC and TG levels, and garlic therapy should benefit patients with risk of cardiovascular diseases.

1 Follower
  • [Show abstract] [Hide abstract]
    ABSTRACT: Abstract Objective: This study was performed to determine the favorable effects of garlic on metabolic status and pregnancy outcomes among pregnant women at risk for pre-eclampsia. Methods: This randomized, double-blind, placebo-controlled trial was conducted among 44 pregnant women, primigravida, aged 18-40 years old at 27 weeks' gestation with positive roll-over test. Participants were randomly assigned to receive either one garlic tablet (equal to 400 mg garlic and 1 mg allicin) (n=22) or placebo (n=22) once daily for 9 weeks. Fasting blood samples were taken at baseline and after 9 weeks' intervention to measure metabolic profiles and biomarkers of oxidative stress. Results: Administration of garlic compared with the placebo resulted in decreased levels of serum high sensitivity C-reactive protein (hs-CRP) (-1425.90 vs. 1360.50 ng/mL, P=0.01) and increased plasma glutathione (GSH) (+98.10 vs. -49.87 µmol/l, P=0.03). A trend toward a significant effect of garlic intake on reducing fasting plasma glucose (FPG) (P=0.07), insulin (P=0.09) and increasing quantitative insulin sensitivity check (QUICKI) (P=0.05) was also observed. Conclusion: Consumption of garlic for 9 weeks among pregnant women at risk for pre-eclampsia led to decreased hs-CRP and increased GSH, but did not affect lipid profiles, total antioxidant capacity (TAC) and pregnancy outcomes.
    Journal of Maternal-Fetal and Neonatal Medicine 10/2014; DOI:10.3109/14767058.2014.977248 · 1.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Allium sativum, Hibiscus sabdariffa and Zingiber officinale are medicinal plants with wide use in traditional medicine; however, the increasing use of crude extracts for traditional medicine applications raises safety concerns. We made a preliminary determination of the phytochemical constituents and antimicrobial and safety profiles of aqueous extracts of A. sativum, H. sabdariffa and Z. officinale. The extracts were administered orally to Wistar rats for 30 days: a control group received distilled water, three groups received the three extract, and a fifth group received a combination of the three extracts. All three extracts, either individually or in combination, had antimicrobial activity, and all extracts influenced the activities of marker enzymes. The evidence lends credence to use of these plants in traditional medicine but also suggests the probable toxic potential of crude plant extracts.
    06/2014; 8(4). DOI:10.1016/j.jtusci.2014.05.004
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although preclinical studies suggest that garlic has potential preventive effects on cardiovascular disease (CVD) risk factors, clinical trials and reports from systematic reviews or meta-analyses present inconsistent results. The contradiction might be attributed to variations in the manufacturing process that can markedly influence the composition of garlic products. To investigate this issue further, we performed a meta-analysis of the effects of garlic powder on CVD risk factors. We searched PubMed, Cochrane, Science Direct and EMBASE through May 2014. A random-effects meta-analysis was performed on 22 trials reporting total cholesterol (TC), 17 trials reporting LDL cholesterol (LDL-C), 18 trials reporting HDL cholesterol (HDL-C), 4 trials reporting fasting blood glucose (FBG), 9 trials reporting systolic blood pressure (SBP) and 10 trials reporting diastolic blood pressure (DBP). The overall garlic powder intake significantly reduced blood TC and LDL-C by -0.41 mmol/L (95% confidence interval [CI], -0.69, -0.12) (-15.83 mg/dL [95% CI, -26.64, -4.63]) and -0.21 mmol/L (95% CI, -0.40, -0.03) (-8.11 mg/dL [95% CI, -15.44, -1.16]), respectively. The mean difference in the reduction of FBG levels was -0.96 mmol/L (95% CI, -1.91, -0.01) (-17.30 mg/dL [95% CI, -34.41, -0.18]). Evidence for SBP and DBP reduction in the garlic supplementation group was also demonstrated by decreases of -4.34 mmHg (95% CI, -8.38, -0.29) and -2.36 mmHg (95% CI, -4.56, -0.15), respectively. This meta-analysis provides consistent evidence that garlic powder intake reduces the CVD risk factors of TC, LDL-C, FBG and BP.
    Nutrition research and practice 12/2014; 8(6):644-654. DOI:10.4162/nrp.2014.8.6.644 · 1.13 Impact Factor