Meta AnalysisHumann = 21 comparison-level records from 18 reports2026Chile
Vitamin D Supplementation, Total Testosterone, and Androgen Bioavailability Markers in Adult Men: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Plain-language summary
This systematic review and meta-analysis set out to see whether vitamin D supplements raise testosterone or related markers in men. It pooled randomized trials measuring total testosterone, SHBG (sex hormone-binding globulin, a protein that binds testosterone and sets how much is free and usable), the free androgen index (a rough estimate of usable testosterone where higher means more available), and calculated free and bioactive testosterone. It found no clear effect of vitamin D on any of these. The certainty of the evidence was low for most measures.
Key findings
- No clear effect of vitamin D supplementation on total testosterone in adult men.
- No clear effect on sex hormone-binding globulin (SHBG) or free androgen index (FAI).
- Low certainty for most outcomes, very low for calculated free testosterone and bioactive testosterone.
How to analyze the study yourself
- Study type
- Meta-analyses pool data from multiple studies for greater statistical power, but they depend on the quality and consistency of the included trials.
- Population
- Adult men from randomized controlled trials.
- Funding
- Not reported
- Watch for
- This study found no clear evidence that vitamin D supplements raise testosterone or free-testosterone markers in men. Vitamin D is still worth keeping in a healthy range for other reasons, but if raising testosterone is your only goal, it is unlikely to move the needle.