Whenever the ARC WM Director sees the title of a randomised trial, he tries to predict the findings. When he sees a trial of vitamin and mineral supplementation in otherwise healthy people, he predicts a null result. This is exactly what happened when he came across a trial of zinc and folic acid supplementation to promote male fertility, recently published in JAMA.[1] Sure enough, the supplements had no effect on either fertility rates or semen quality.

Why were these two agents selected for evaluation? Apparently seminal fluid is very rich in zinc, while folic acid and zinc often act synergistically. However, discerning News Blog readers will immediately spot that this is a very facile argument. It is akin to the risible conclusion that because bones contain calcium, calcium can prevent osteoporosis in people who are not calcium deficient. However, vitamin and mineral supplementation is a large industry and human beings have been beguiled by simplistic remedies throughout our evolution. Expect many more boring trials of vitamin and mineral substitution. If I had more time on my hands, I would carry out a multiple indication review across all vitamin and mineral substitution types to establish, once and for all, that vitamins and minerals should not be given to people who are not vitamin or mineral deficient. A possible exception is iron, because humans have no method to excrete iron and therefore absorb iron badly.

Richard Lilford, ARC WM Director

Reference:

1. Schisterman EF, Sjaarda LA, Clemons T, et al. Effect of Folic Acid and Zinc Supplementation in Men on Semen Quality and Live Birth Among Couples Undergoing Infertility Treatment. A Randomized Controlled Trial. JAMA. 2020; 323(1): 35-48.