Vitamin D Supplementation, Total Testosterone, and Androgen Bioavailability Markers in Adult Men: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 42451097 · doi:10.3390/nu18132090
What was done
A systematic review and meta-analysis (PROSPERO CRD420261365005) evaluated randomized controlled trials investigating the effect of vitamin D supplementation on total testosterone (TT) and androgen bioavailability markers in adult men. Databases (PubMed, Web of Science, Scopus, ClinicalTrials.gov, WHO ICTRP) were searched from inception to April 2026. Meta-analyses applied random-effects REML models with Hartung-Knapp adjustments. Qualitative synthesis retained 27 studies, and quantitative synthesis included 18 reports operationalized into 21 comparison-level records.
What was found
Vitamin D supplementation showed no significant effect on total testosterone across 11 comparisons (mean difference [MD] 0.47 nmol/L, 95% CI -0.50 to 1.44; I² = 24.1%). No clear effects were found for sex hormone-binding globulin (MD 0.27 nmol/L, 95% CI -2.14 to 2.68), free androgen index (MD -0.37, 95% CI -4.28 to 3.55), calculated free testosterone (MD -0.0096 nmol/L, 95% CI -0.0525 to 0.0332), or bioactive testosterone (MD -0.47 nmol/L, 95% CI -1.77 to 0.83). GRADE certainty was low for TT, SHBG, and FAI, and very low for calculated free testosterone and bioactive testosterone.
Why it matters
Despite observational associations between vitamin D status and androgens, pooled randomized trial evidence indicates that vitamin D supplementation does not meaningfully alter testosterone or androgen bioavailability in adult men.
Limits
Embase was omitted due to institutional access limitations, and 27 full-text reports could not be retrieved for screening. Directly measured and calculated free testosterone could not be pooled together due to assay non-equivalence. Total participant sample size is not stated in the abstract, and certainty of evidence across all outcomes was graded as low or very low.
Cited by
- contradicts Deficiencies in zinc, magnesium, or vitamin D can cause a deterioration in testosterone levels of over 100 ng/dL depending on severity.