title: Supplementation with vitamin D does not increase serum testosterone levels in healthy males.
abstract: Cross-sectional studies indicate a positive relation between serum 25-hydroxyvitamin D [25(OH)D] and testosterone. It is not known if this relation is causal, which in theory could be in both directions. A cross-sectional population based study was designed with pooled data from 3 vitamin D randomized clinical trials (RCTs) performed in Tromsø with weight reduction, insulin sensitivity, and depression scores as endpoints, and one testosterone RCT in subjects with low serum testosterone (<11.0 nmol/l) and with body composition as endpoint. Serum 25(OH)D and androgens were measured in 893 males in the cross-sectional part, at baseline and after 6-12 months of supplementation with vitamin D 20 000 IU-40 000 IU per week vs. placebo in the vitamin D RCTs (n=282), and at baseline and after one year treatment with testosterone undecanoate 1 000 mg or placebo injections (at baseline and after 6, 16, 28, and 40 weeks) in the testosterone RCT (n=37). In the cross-sectional study, serum 25(OH)D was found to be a significant and positive predictor of serum testosterone. In the vitamin D RCTs, no significant effect on serum total or free testosterone levels was seen, and in the testosterone RCT no significant effect on serum 25(OH)D was seen. This was unchanged in sub-analyses in subjects with low serum 25(OH)D (or testosterone) levels. In conclusion, in subjects without significant vitamin D deficiency, there is no increase in serum testosterone after high dose vitamin D supplementation. Similarly, in subjects with moderately low serum testosterone levels, substitution with testosterone does not increase serum 25(OH)D.
authors.affiliation: Department of Clinical Medicine, Tromsø Endocrine Research Group, University of Tromsø, Norway. rolf.jorde@unn.no
authors.forename: R
authors.initials: R
authors.lastname: Jorde
authors.forename: G
authors.initials: G
authors.lastname: Grimnes
authors.forename: M S
authors.initials: MS
authors.lastname: Hutchinson
authors.forename: M
authors.initials: M
authors.lastname: Kjærgaard
authors.forename: E
authors.initials: E
authors.lastname: Kamycheva
authors.forename: J
authors.initials: J
authors.lastname: Svartberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D006262:Health; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D010919:Placebos; D013739:Testosterone / Q000097:blood*; D014807:Vitamin D / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D010919:Placebos; D014807:Vitamin D; D013739:Testosterone; C104450:25-hydroxyvitamin D