Vitamin D and Testosterone in Healthy Men: A Randomized Controlled Trial
Abstract
CONTEXT: Available evidence shows an association of vitamin D with androgen levels in men. However, results from preliminary randomized controlled trials (RCTs) are conflicting.
OBJECTIVE: To evaluate whether vitamin D supplementation increases total testosterone (TT) levels in healthy men.
DESIGN: The Graz Vitamin D&TT-RCT is a single-center, double-blind, randomized, placebo-controlled trial conducted between December 2012 and January 2017.
SETTING: Endocrine outpatient clinic at the Medical University of Graz, Austria.
PARTICIPANTS: Ninety-eight healthy men with TT levels ≥10.4 nmol/L and 25-hydroxyvitamin D [25(OH)D] levels <75 nmol/L completed the study.
INTERVENTION: Subjects were randomly assigned to receive 20,000 IU/wk of vitamin D3 (n = 50) or placebo (n = 50) for 12 weeks.
MAIN OUTCOME MEASURES: Primary outcome was TT measured using mass spectrometry. Secondary outcomes were free testosterone, sex hormone-binding globulin, estradiol, follicle-stimulating hormone, and luteinizing hormone levels; free androgen index; metabolic characteristics; and body composition.
RESULTS: In healthy men [mean values ± standard deviation: age, 39 years (±13 years); 25(OH)D level, 53.3 nmol/L (±18.3 nmol/L); TT, 19.1 nmol/L (±5.6 nmol/l)], no significant treatment effect on TT was found; however, there were significant effects on quantitative insulin sensitivity check index (QUICKI) and a trend toward decreased Matsuda index. In the treatment group, median (interquartile range)…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 50 participants or records.
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