RCTHumann = 982017
Vitamin D and Testosterone in Healthy Men: A Randomized Controlled Trial.
Plain-language summary
This study set out to test whether vitamin D supplements raise testosterone in healthy men. It randomly assigned 98 men with normal testosterone but low vitamin D to a high weekly dose or a dummy pill for 12 weeks, then compared hormones and metabolic markers. Vitamin D did not raise total testosterone. One measure of insulin sensitivity fell slightly and a second did not show a significant change. This trial is one of those pooled in the review already in this library that reached the same conclusion, so it is supporting evidence rather than a new finding. A second study here, on vitamin D and low testosterone, comes from the same Graz research group using a different group of men and a different design.
Key findings
- Vitamin D did not raise total testosterone in healthy men who started with normal levels.
- One measure of insulin sensitivity fell slightly on vitamin D, which is the opposite of the hoped-for direction.
- A second measure of insulin sensitivity moved the same way but did not show a significant change.
How to analyze the study yourself
- Study type
- Randomized trials assign people to groups by chance, so differences between groups are unlikely to come from who chose what, but this study was small and short-term, so it may miss subtler or longer-term effects.
- Population
- Healthy men with normal testosterone levels and low vitamin D.
- Funding
- Not reported
- Takeaway
- This study found that high-dose vitamin D did not raise testosterone in healthy men who started with normal levels. Vitamin D is still worth keeping in a healthy range for other reasons, but if raising testosterone is your only goal, this is unlikely to move the needle.