Effect of Vitamin D Supplementation on Testosterone Levels in Men.

Horm Metab Res () (2010)
S Pilz, S Frisch, H Koertke, J Kuhn, J Dreier, B Obermayer-Pietsch, E Wehr and A Zittermann
Department of Internal Medicine, Division of Endocrinology and Metabolism, Medical University of Graz, Austria.

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??g (3?332?IU) vitamin D daily for 1 year (n=31) or placebo (n=23). 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 (9.09-55.28?nmol/l for males aged 20-49 years) in both groups.

Mean circulating 25(OH)D concentrations increased significantly by 53.5?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 10.7±3.9?nmol/l to 13.4±4.7?nmol/l; p<0.001), bioactive testosterone (from 5.21±1.87?nmol/l to 6.25±2.01?nmol/l; p=0.001), and free testosterone levels (from 0.222±0.080?nmol/l to 0.267±0.087?nmol/l; p=0.001) 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. © Georg Thieme Verlag KG Stuttgart · New York. DOI: 10.1055/s-0030-1269854 * PMID: 21154195
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