Vitamin D and Testosterone. Sunshine Vitamin Not So Manly, After all? Vitamin D Increases Aromatase Activity in Sertoli Cells

Vitamin D is all the rave. Even mainstream nutritionists are now jumping on the vitamin D bandwagon and the hype is spilling over from the Internet to newspapers and TV stations. "Take your Vitamin D!" is what children and adults, men and women, couch-potatoes and top-level athletes are told. Recently discovered problems related to the accurate measurement of actual vitamin D levels aside (e.g. Shah. 2011), a recent investigation into the immediate effects of vitamin D on aromatase activity in Sertoli cells of rat testes, suggests that we have to reevaluate whether this advice, which is hitherto largely based on epidemiological data, is not overgeneralizing, to say the least.

Image 1: Transverse section of a tubule of the testis of a rat. X 250. (Wikipedia)

After all, the results of the aforementioned study, which has been published in the Journal of Vertebrate Reproduktive Science & Technology (Zanatta. 2011), clearly indicate that, contrary to common believe, your testosterone levels will not benefit from high vitamin D levels. On the contrary, in their in-vitro study Zanatta et al. found that incubation of Sertoli cells with 100nm 1,25D "increased the amount of aromatase transcript [...] in [Sertoli cells of] 30-day-old rats". Additionally, the scientists were also able to show that the increased aromatase activity was not exclusively due to a genomic effect, but was mediated via a "non-genomic activation of the membrane-bound vitamin D receptor involving the PKA pathway". Whether this is a tissue-, rat- or even age-specific effect does yet still warrant further investigation.
The latter is especially true in view of conflicting data on the effects of vitamin D on aromatase activity in especially in view of previous studies such as Lundgvist 2011 et al. (Lundgvist. 2011) who found that

In breast cancer MCF-7 cells, aromatase gene expression and estradiol production were decreased, while production of androgens was markedly increased. In NCI-H295R cells, 1α,25-dihydroxyvitamin D(3) stimulated aromatase expression and decreased dihydrotestosterone production. In prostate cancer LNCaP cells, aromatase expression increased after the same treatment, as did production of testosterone and dihydrotestosterone. In summary, our data show that 1α,25-dihydroxyvitamin D(3) exerts tissue-specific effects on estrogen and androgen production and metabolism.

So, will taking supplemental Vitamin D3 (1,25D) transform you into a hermaphrodite? Will you get rid of gynecomastia (gyno), but develop testicular cancer? The answer to both questions is probably "NO" And I am by no means suggesting that you extrapolate the rat data from isolated sertoli cells to human beings, but In view of these findings, it is nevertheless becoming increasingly questionable whether the correlations between testosterone and vitamin D that have been observed in epidemiological studies have not been misinterpreted as causative, where in fact, both, higher testosterone, as well as vitamin D levels, are a mere results of confounding variables such as an overall healthier, more active lifestyle. After all, our previous understanding of the connection between vitamin D and testosterone could have been as misleading as the idea that firetrucks cause fire, because an "epidemiological" investigation of fires would show that they are present whenever ones breaks out.

Video 1: Clifford L. Johnson, MSPH (CDC):

"The Importance of Monitoring Vitamin D Status in the U.S.",

Thursday, August 19, 2010, at 9 a.m. (EDT)

A pros pos epidemiological studies: A recent report from the Centers for Disease Control and Prevention National Center for Health Statistics in Maryland (see video above) states that in the US...

[t]he risk of vitamin D deficiency increased between 1988-1994 and 2001-2002 in both sexes but did not change between 2001-2002 and 2005-2006.

With two-thirds of the population having, what the National Center for Disease Control and Prevention considers "sufficient vitamin D" levels, you probably better follow my previous advice and just get your level tested before starting on any kind of supplementation regime. If you want to do me a favor, you also check how taking additional D affects your testosterone levels. I promise to publish your results - anonymously, of course ;-)