A systematic review of randomized controlled trials related to the effects of garlic supplementation on platelet aggregation.

The increment of platelet aggregation factors has been considered a key phenomenon in atherosclerosis. Studies have shown that garlic (Allium sativum) is associated with a reduction in platelet aggregation and thrombosis. Hence, the present systematic review was conducted to evaluate the effect of garlic on platelet aggregation. All randomized controlled trials (RCTs) with keywords related to garlic and platelet aggregation were thoroughly searched in electronic databases including PubMed, Scopus, ISI Web of Science, and Google Scholar up to January 2021. Moreover, the references of all related articles were screened to discover more relevant studies. The quality of each study was reported based on Cochrane Collaboration's tool. In total, 12 studies met the inclusion criteria from 18,235 identified articles (including 595 participants). Most of the studies assessed platelet aggregation in response to different inducers. Of the 12 clinical trials, six studies depicted the beneficial effect of garlic on reducing platelet aggregation. The summary of the quality assessment indicated that most of the studies had high-quality scores. Regarding the small number of RCTs and heterogeneity between studies, it is impossible to make a proper conclusion about the impacts of garlic on platelet aggregation. Therefore, further precise trials with a standard design are necessary to validate the anti-thrombotic effect of garlic.

Effects of garlic supplementation on serum inflammatory markers: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND AIMS: Previous studies have indicated that garlic consumption may be beneficial in improving inflammation. This systematic review and meta-analysis aimed to examine the effect of garlic supplementation on inflammatory biomarkers. METHODS: PubMed/Medline, Scopus and ISI web of science were searched up to February 2019. Random effects model was used to calculate the overall effects on C-reactive protein (CRP), Interleukin-6 (IL-6), and Tumor necrosis factor- α (TNF-α). RESULTS: 17 randomized controlled trials (RCTs) were included in the meta-analyses. Garlic supplementation significantly reduced the level of circulating CRP (P < 0.05), whereas it did not have any significant effect on IL-6 level (p > 0.05). Sub-group analysis showed that aged garlic extract (AGE) was able to reduce CRP and TNF-α significantly (P < 0.05). CONCLUSIONS: This meta-analysis showed that supplementation with garlic could reduce the level of circulating CRP and AGE could reduce the level of TNF-α and CRP, whereas it had no significant effect on the IL-6 level.

Effects of garlic supplementation on liver enzymes: A systematic review and meta-analysis of randomized controlled trials.

Current evidence on the beneficial effects of garlic on liver enzymes is contradictory. Therefore, the aim of this systematic review and meta-analysis is to evaluate the effect of garlic supplementation on human liver enzymes, such as Alanine Transaminase (ALT/SGPT) and Aspartate Transaminase (AST/SGOT). To collect the required data, PubMed, Scopus, ISI Web of Science, and Google scholar databases were systematically searched from inception to June 2019. A meta-analysis was conducted using the random-effects model to evaluate the effects of garlic supplementation on ALT and AST levels. The Cochran's Q-test and inconsistency index were also used to evaluate heterogeneity among the studies. Among a total of 15,514 identified articles, six studies (containing 301 participants) met the inclusion criteria. Results of the meta-analysis showed that garlic supplementation significantly decreased AST level (Hedges' g = -0.36, 95% confidence interval [CI]: -0.72, -0.004, p = .047); whereas, it had no significant effect on ALT level (Hedges' g = -0.22, 95% CI: -0.64, 0.20, p = .310). Results showed that garlic supplementation reduced AST levels significantly; however, had no significant effect on ALT levels. Further studies are still needed to confirm the results.

The effect of vitamin D supplementation on the androgenic profile in men: A systematic review and meta-analysis of clinical trials.

The aim of this systematic review and meta-analysis was to evaluate the effect of vitamin D supplementation on total testosterone (TT) and sex hormone-binding globulin (SHBG) in men. We searched PubMed, Scopus and Web of Science for randomized, controlled trials of vitamin D supplementation in men ≥18 years old up to September 2018, without language restrictions. Meta-analysis was based on a random effects model. The systematic review was registered as CRD42018094498. We identified 3,402 articles, of which eight studies with 10 effect sizes met the inclusion criteria. Vitamin D daily dose equivalents ranged from 600 to 4,000 per day to 60,000 IU per week; duration was 6 weeks to 36 months. In general, vitamin D supplementation had no significant effect on TT (MD = 0.20, 95% CI: -0.20, 0.60, p = 0.336) and SHBG (MD = 1.56, 95% CI: -0.85, 3.97, p = 0.204). Subgroup analysis conducted with duration of prescription, type (daily or weekly), dosing frequency and baseline vitamin D and TT concentration showed that vitamin D did not significantly affect TT. The present study did not find any evidence to support beneficial effect of vitamin D supplementation on TT and SHBG in men. Thus, further large-scale randomised controlled trials are required to evaluate the effects of vitamin D supplementation on androgen in men.

Branched-chain amino acid supplementation and exercise-induced muscle damage in exercise recovery: A meta-analysis of randomized clinical trials.

OBJECTIVE: Accumulating evidence suggests positive effects of branched-chain amino acids (BCAAs) on moderate muscle damage. However, findings vary substantially across studies. The aim of this review was to examine the effect of BCAAs on recovery following exercise-induced muscle damage. METHODS: Controlled trials were identified through a computerized literature search and tracking of citations performed up to November 2015. To pool data, either a fixed-effects or a random-effects model was used; for assessing heterogeneity, Cochran's Q and I2 tests were used. RESULTS: Eight trials met the inclusion criteria. Pooled data from the eight studies showed that BCAAs significantly reduced creatine kinase at two follow-up times (<24 and 24 h) in comparison with placebo recovery (<24 h: mean difference, -71.55 U/L, 95% confidence interval, -93.49 to -49.60, P < 0.000, n = 5 trials; 24 h: mean difference, -145.04 U/L, 95% confidence interval, -253.66 to -36.43, P = 0.009, n = 8 trials). In contrast, effects were not significant in any of the follow-up times for muscle soreness or lactate dehydrogenase. CONCLUSION: The current evidence-based information indicates that use of BCAAs is better than passive recovery or rest after various forms of exhaustive and damaging exercise. The advantages relate to a reduction in muscle soreness and ameliorated muscle function because of an attenuation of muscle strength and muscle power loss after exercise.