I can confirm this to be true. I get my testosterone checked regularly along with my TSH numbers. For some reason my TSH is never a consistent number and my testosterone levels have been in the crapper for a long time. Even with testosterone supplements my levels didn’t improve much, if at all. Last July my doctor said my PSA numbers were a bit high so he told me to stop taking the Andriol, the testosterone supplement. Fast forward to December when I started taking 2000 IU of vitamin D per day. I had my blood tested again a few weeks ago at the end of February and my doctor said my testosterone levels were higher than they’ve been over the last few years while taking supplements.
The male reproductive tract has been identified as a target tissue for vitamin D, and previous data suggest an association of 25-hydroxyvitamin D [25(OH)D] with testosterone levels in men. We therefore aimed to evaluate whether vitamin D supplementation influences testosterone levels in men. Healthy overweight men undergoing a weight reduction program who participated in a randomized controlled trial were analyzed for testosterone levels. The entire study included 200 nondiabetic subjects, of whom 165 participants (54 men) completed the trial. Participants received either 83 μg (3,332 IU) vitamin D daily for 1 year (n = 31) or placebo (n =2 3). Initial 25(OH)D concentrations were in the deficiency range (< 50 nmol/l) and testosterone values were at the lower end of the reference range (- nmol/l for males aged 20-49 years) in both groups. Mean circulating 25(OH)D concentrations increased significantly by nmol/l in the vitamin D group, but remained almost constant in the placebo group. Compared to baseline values, a significant increase in total testosterone levels (from ± nmol/l to ± nmol/l; p < ), bioactive testosterone (from ± nmol/l to ± nmol/l; p = ), and free testosterone levels (from ± nmol/l to ± nmol/l; p = ) were observed in the vitamin D supplemented group. By contrast, there was no significant change in any testosterone measure in the placebo group. Our results suggest that vitamin D supplementation might increase testosterone levels. Further randomized controlled trials are warranted to confirm this hypothesis.