Effect of vitamin D monotherapy on indices of sarcopenia in community-dwelling older adults: a systematic review and meta-analysis.

BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis. A significant decrease in SPPB scores was observed with vitamin D supplementation compared with placebo (MD: -0.23; 95% CI -0.40 to -0.06; I2  = 0%; P = 0.007). Vitamin D supplementation conferred no effect on HGS (MD: -0.07 kg; 95% CI -0.70 to 0.55; I2  = 51%, P = 0.82), TUG (MD: 0.07 s; 95% CI -0.08 to 0.22; I2  = 0%, P = 0.35), ALM (MD: 0.06 kg/m2 ; 95% CI: -0.32 to 0.44; I2  = 73%, P = 0.77), general muscle strength (SMD: -0.01; 95% CI -0.17 to 0.15; I2  = 42%, P = 0.90), or general physical performance (SMD: -0.02; 95% CI -0.23 to 0.18; I2  = 71%, P = 0.83). CONCLUSIONS: Vitamin D supplementation did not improve any sarcopenia indices in community-dwelling older adults and may compromise some aspects of physical performance. Future studies are warranted to investigate the impact of vitamin D supplementation on individual indices of SPPB, including mobility and balance, in older adults.

The Relation between Caffeine Consumption and Endometriosis: An Updated Systematic Review and Meta-Analysis.

While the contributing factors leading to endometriosis remain unclear, its clinical heterogeneity suggests a multifactorial causal background. Amongst others, caffeine has been studied extensively during the last decade as a putative contributing factor. In this systematic review and meta-analysis, we provide an overview/critical appraisal of studies that report on the association between caffeine consumption and the presence of endometriosis. In our search strategy, we screened PubMed and Scopus for human studies examining the above association. The main outcome was the relative risk of endometriosis in caffeine users versus women consuming little or no caffeine (<100 mg/day). Subgroup analyses were conducted for different levels of caffeine intake: high (>300 mg/day) or moderate (100-300 mg/day). Ten studies were included in the meta-analysis (five cohort and five case-control studies). No statistically significant association was observed between overall caffeine consumption and risk for endometriosis (RR 1.12, 95% confidence interval (CI) 0.97-1.28, I2 = 70%) when compared to little or no (<100 mg/day) caffeine intake. When stratified according to level of consumption, high intake was associated with increased risk of endometriosis (RR 1.30, 95%CI 1.04-1.63, I2 = 56%), whereas moderate intake did not reach nominal statistical significance (RR 1.18, 95%CI 0.99-1.40, I2 = 37%). In conclusion, caffeine consumption does not appear to be associated with increased risk for endometriosis. However, further research is needed to elucidate the potential dose-dependent link between caffeine and endometriosis or the probable role of caffeine intake as a measurement of other unidentified biases.