Testosterone is the most important male sexual hormone. In males it is mainly responsible for the development of the sex organs, the formation and maintenance of the typical male sexual characteristics, sperm production and the controlling of male desire.
Stimulated by UV radiation, 90% of vitamin D in the body is produced by the skin. An average vitamin D level of 30 nanograms per millilitre of blood (30 ng/ml) represents the scientific value from which vitamin D has a sufficiently positive effect. Optimal values are between 40 and 60 ng/ml.
The Sunlight Research Forum (SRF) is a non-profit organisation with its headquarters in the Netherlands. Its aim is to make the latest medical and scientific findings concerning the effects of moderate UV radiation on humans accessible to the general public.
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A summary of the "Wehr E, Pilz S, Boehm BO, März W, Obermayer-Pietsch B. (Department of Internal Medicine, Division of Endocrinology and Nuclear Medicine, Medical University Graz, Graz, Austria): Association of vitamin D status with serum androgen levels in men" study can be downloaded from the SRF website www.sunlightresearchforum.eu