Vitamin D for Men
Men and women have identical vitamin D requirements at the population level, but several vitamin D-linked outcomes matter more (or exclusively) to men: testosterone, sperm quality, prostate health, and cardiovascular risk. Here's what the evidence supports.
Standard dosing
- 19–70 years: 600 IU/day RDA (IOM); Endocrine Society suggests 1,500–2,000 IU/day for adults at risk.
- 71+ years: 800 IU/day RDA.
- Correction if deficient: 2,000–4,000 IU/day for 8–12 weeks, then re-test.
Testosterone
Vitamin D receptors are expressed in testicular Leydig cells. Observational studies find a positive correlation between 25(OH)D and total testosterone. Supplementation trials are mixed — some report modest increases in deficient men, others show no effect. See our testosterone page for the full trial breakdown. If deficient, correcting deficiency is reasonable and may modestly help; if already sufficient, more won't raise T further.
Sperm quality and fertility
Vitamin D deficiency has been associated with reduced sperm motility, morphology, and count in observational studies. The 2018 Blomberg-Jensen RCT of 307 subfertile men showed cholecalciferol 1,400 IU/day + 500 mg calcium modestly improved sperm motility and DNA fragmentation vs placebo, though effect on live birth rate was not significant. Vitamin D is a low-cost adjunct in male-factor infertility workup.
Cardiovascular
Cardiovascular disease kills more men than any other single cause. Observational studies link low 25(OH)D with hypertension, atherosclerosis, and CV mortality. The 25,000-person VITAL trial (2019) tested 2,000 IU/day for 5.3 years and found NO reduction in major cardiovascular events overall — a dampener on the enthusiasm. Correcting deficiency remains reasonable; adding vitamin D on top of sufficiency does not reduce heart attacks.
Muscle mass and strength
Skeletal muscle has vitamin D receptors and deficiency causes proximal myopathy (leg weakness, difficulty standing from a chair). Vitamin D repletion improves grip strength and gait speed in deficient older men. In already-sufficient young men, additional vitamin D doesn't enhance resistance training gains.
Prostate health
Ecological and case-control data hinted at a protective role for vitamin D against prostate cancer. The SELECT trial (selenium and vitamin E) had a small vitamin D arm and did not show benefit. A 2018 randomised active-surveillance study (Marshall) suggested vitamin D 4,000 IU/day may reduce Gleason score progression in low-risk prostate cancer, but the trial was small and not definitive. This remains an unsettled research area — no current guideline recommends vitamin D supplementation specifically for prostate cancer prevention or treatment.