Vitamin D and Testosterone in Healthy Men: A Randomized Controlled Trial.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 28938446 · doi:10.1210/jc.2017-01428
What was done
A single-center, double-blind, randomized, placebo-controlled trial evaluated whether vitamin D3 supplementation increases total testosterone in healthy men. One hundred healthy men with baseline total testosterone ≥10.4 nmol/L and 25-hydroxyvitamin D <75 nmol/L were randomized to receive 20,000 IU/week of vitamin D3 (n = 50) or placebo (n = 50) for 12 weeks; 98 completed the study. The primary outcome was total testosterone measured by mass spectrometry. Secondary outcomes included free testosterone, SHBG, estradiol, FSH, LH, free androgen index, metabolic characteristics, and body composition.
What was found
No significant treatment effect was found for total testosterone (median change in treatment group: 0.5 nmol/L, IQR -0.63 to 0.63 nmol/L; P = 0.497). For secondary outcomes, there was a significant decrease in the quantitative insulin sensitivity check index (QUICKI median change: -0.02, IQR -0.04 to 0.01; P = 0.034) and a trend toward a decreased Matsuda index (median change: -0.9, IQR -3.2 to 0.8; P = 0.051).
Why it matters
Despite observational associations between vitamin D status and androgens, this randomized trial demonstrates that vitamin D supplementation does not raise testosterone levels in healthy, eugonadal men.
Limits
The study was single-center with a modest sample size (n = 98 completers) and a 12-week duration. It was restricted to healthy men with normal baseline testosterone, precluding conclusions about hypogonadal men or those with severe vitamin D deficiency.
Cited by
- contradicts Correcting clinical deficiencies in vitamin D, zinc, and magnesium can result in an incremental increase of 100 to 150 ng/dL in total testosterone.