The effects of vitamin D supplementation on muscle strength and mobility in postmenopausal women: a systematic review and meta-analysis of randomised controlled trials.

BACKGROUND: The results obtained from previous trials regarding the effects of vitamin D supplementation on muscle strength and mobility in postmenopausal women have been inconsistent. This systematic review and meta-analysis of randomised controlled trials (RCTs) aimed to investigate the effect of vitamin D supplementation on muscle strength and mobility in postmenopausal women. METHODS: A comprehensive search on EMBASE, PubMed, MEDLINE and SCOPUS was performed to identify relevant articles published up to 28 March 2019. RCTs published in English measuring the effect of all forms and doses of vitamin D supplementation with or without calcium on muscle strength and mobility outcomes in postmenopausal women were included. RESULTS: In total, 29 eligible studies were included in the systematic review. The pooled findings using a random effects model showed that vitamin D supplementation insignificantly increased hand grip strength (HGS) as the measurement of muscle strength (MD = 0.656; 95% confidence interval = -0.037 to 1.350, P = 0.06). However, it did not affect timed-up-and-go (TUG) as the measurement of mobility (MD = 0.118; 95% confidence interval = -0.655 to 0.892, P = 0.76). The subgroup analyses showed that vitamin D supplementation improved HGS with respect to dosages >1000 IU day-1 (P = 0.016), a treatment duration of 3 months (P Ë‚ 0.001) and subjects with baseline vitamin D <30 ng mL-1 (P = 0.033). CONCLUSIONS: The present review demonstrates that vitamin D supplementation resulted in small but nonsignificant improvements in muscle strength compared to control in postmenopausal women. No significant effect was observed in mobility after vitamin D administration.

Effects of folic acid supplementation on C-reactive protein: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND AIM: Given the contradictory results of previous randomized controlled trials (RCTs), we performed a systematic review and meta-analysis to quantify and summarize the effects of folic acid supplementation on C-reactive protein (CRP). METHODS AND RESULTS: We performed a systematic search of all available RCTs conducted up to October 2018 in the following databases: PubMed, Scopus, and Cochrane. RCTs that investigated the effect of folate on CRP were included in the present study. Data were combined with the use of generic inverse-variance random-effects models. Statistical heterogeneity between studies was evaluated using Cochran's Q-test. Ten RCTs (1179 subjects) were included in the present meta-analysis. Pooled analysis results showed that folate supplementation significantly lowered the serum CRP level (weighted mean difference (WMD): -0.685 mg/l, 95% CI: -1.053, -0.318, p < 0.001). However, heterogeneity was significant (I2 = 96.7%, p = 0.000). Stratified analyses indicated that sex, intervention period, and type of study population were sources of heterogeneity. Following analysis, results revealed that the greatest impact was observed in women (WMD: -0.967 mg/l, 95% CI: -1.101, -0.833, p = 0.000), patients with type 2 diabetes mellitus (WMD: -1.764 mg/l, 95% CI: -2.002, -1.526, p = 0.000), and intervention period less than 12 weeks (WMD: -0.742 mg/l, 95% CI: -0.834, -0.650, p = 0.000). CONCLUSION: This meta-analysis suggested that folic acid supplementation could significantly lower the serum CRP level. Folic acid leads to greater CRP lowering effect in women, patients with T2DM, and those with less than 12-week intervention.

Resveratrol supplementation significantly influences obesity measures: a systematic review and dose-response meta-analysis of randomized controlled trials.

This study aimed to summarize earlier randomized controlled trials on the effects of resveratrol supplementation on body weight (BW), body mass index (BMI), waist circumference (WC) and fat mass (FM). We searched PubMed, SCOPUS, Cochrane Library and Google Scholar from inception to April 2018 using relevant keywords. All clinical trials investigating the effects of resveratrol supplementation on BW, BMI, WC and FM in adults were included. Overall, 28 trials were included. Pooled effect sizes suggested a significant effect of resveratrol administration on weight (weighted mean differences [WMD]: -0.51 kg, 95% confidence interval [CI]: -0.94 to -0.09; I2  = 50.3%, P = 0.02), BMI (WMD: -0.17 kg m-2 , 95% CI: -0.32, -0.03; I2  = 49.6%, P = 0.02) and WC (WMD: -0.79 cm, 95% CI: -1.39, -0.2; I2  = 13.4%, P = 0.009), respectively. However, no significant effect of resveratrol supplementation on FM was found (WMD: -0.36%, 95% CI: -0.88, 0.15; I2  = 0.0%, P = 0.16). Findings from subgroup analysis revealed a significant reduction in BW and BMI in trials using resveratrol at the dosage of <500 mg d-1 , those with long-term interventions (≥3 month), and performed on people with obesity. Taken together, the data suggest that resveratrol supplementation has beneficial effects to reduce BW, BMI and WC, but not FM.