How vitamin D may benefit men's health

How can we get American men interested in vitamin D? Most men could care less. Say vitamin D did something men find really important, like improve athletic performance or induce hair growth? Or, say it improved sexual performance or increased virility? Nothing would get men treating their vitamin D deficiency like a study that showed vitamin D increased organ size!
Sixteen years ago, Professor Walter Stumpf (who taught me at UNC School of Medicine) first made the case that vitamin D is intimately involved with sex and reproduction. Male genital tissue contains lots of vitamin D receptors but their significance and function remain unknown. One researcher actually gave a vitamin D-like-drug to see if it improved sexual performance in patients with renal failure! To bad for the instant popularity of vitamin D, the results showed no improvement.
Am J Obstet Gynecol. 1989 Nov;161(5):1375-84 Clin Nephrol. 1980 May;13(5):208-14
Vitamin D does appear to improve virility. Conception peaks in the summer, when vitamin D levels are highest, and ebbs in the winter, when vitamin D stores are low. Vitamin D deficiency has profound effects on rat testicles, including dramatically reducing spermatogenesis. Vitamin D deficient male rats were 73% less likely to successfully father pups than vitamin D sufficient males. Vitamin D restored virility to vitamin D deficient male rats and should do the same for vitamin D deficient male humans. Hum Reprod. 1992 Jul;7(6):735-45 Ann Nutr Metab. 1992;36(4):203-8 Ann Nutr Metab. 1995;39(2):95-8 J Nutr. 1989 May;119(5):741-4
What else are men interested in besides sex? Hair growth! In fact, hair follicles have large numbers of vitamin D receptors but their function is unknown. Although there are no human studies showing vitamin D will grow men a new head of hair, vitamin D like drugs do grow hair in mice. (By the way, both my wife and my barber have told me my head has stopped balding and I've kept my 25(OH)-vitamin D level around 50 ng/ml for several years.) One relevant animal study should get the attention of men; the title contains two of their favorite words: "nude" and "hair growth."