Marnani EH, et al. - Via a systematic review and meta-analysis, experts intended to assess the impact of vitamin D supplementation on total testosterone (TT) and sex hormone-binding globulin (SHBG) in men. For randomized, controlled trials of vitamin D supplementation in men ≥18 years old up to September 2018, without language restrictions, PubMed, Scopus, and Web of Science were explored. Eight studies out of 3,402 articles 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 and the span was 6 weeks to 36 months. No important impact of vitamin D supplementation on TT was observed. Subgroup analysis conducted with duration of prescription, type (daily or weekly), dosing frequency and baseline vitamin D and TT concentration demonstrated that vitamin D did not markedly influence TT. No evidence to support the useful impact of vitamin D supplementation on TT and SHBG in men was concluded. Therefore, additional large-scale randomized controlled trials were needed to assess the impacts of vitamin D supplementation on androgen in men.