Vitamin D: The “sunshine” vitamin gets another look.
Vitamin D is known to promote bone and heart health. It may provide benefit in boosting the immune system and lowering risks of certain cancers. Until recently, there have been few studies examining the effects of Vitamin D on reproductive health. Most of what is known regarding its precise activity has been studied primarily in laboratory mice and its potential role in human fertility has been inferred from these animal studies which show that Vitamin D-deficient animals demonstrate altered mating behaviors, decreased fertility rates and a lower litter size. These data suggest that although not critical for successful reproduction, Vitamin D levels and most importantly, its deficiency may affect reproductive efficiency. Furthermore, when these Vitamin D-deficient rodents are fed Vitamin D-rich diets, their reproductive capacity can be restored.
It is only natural to take the next step and to begin to question whether Vitamin D would have similar effects in human reproduction; could the lessons from mice and rats be applied to humans? Only recently, has science begun to explore associations between Vitamin D levels and reproductive capacity. In fact there have been associations between Vitamin-D deficiency and women who have irregular menstrual cycles due to Polycystic Ovarian Syndrome (PCOS). When supplemented with Vitamin D, some of these women experience a return of monthly menstrual cycles and can demonstrate fertility rates comparable to women who have regular menstrual cycles.
Most recently, the effects of Vitamin D have been associated with reproductive outcomes in IVF. In a one study, women who demonstrated adequate Vitamin D levels faired better during IVF cycles and were more likely to become pregnant than their Vitamin D-insufficient counterparts. Although these initial studies are small, the results are promising.
Vitamin D is not the smoking gun; low levels will not inhibit pregnancy and adequate supplementation will not insure a resultant pregnancy. Currently neither of our governing bodies, the American College of Gynecologists (ACOG) nor the American Society of Reproductive Medicine (ASRM), formally recommends Vitamin D supplementation; they call for adequate folic acid intake and promote a healthful and well-balanced diet. However, if these initial studies are confirmed and the adequate presence of Vitamin D promotes a favorable IVF cycle outcome, it behooves us to take note. The measurement of Vitamin D blood-levels prior to beginning an IVF cycle is not the standard of care. Thus, women must supplement these levels empirically. Daily intake of 2000 IU of Vitamin D may provide sufficient stores to promote reproductive capacity. In the absence of kidney disease, Vitamin D supplementation is safe and hopefully will continue to demonstrate a favorable outcome in larger clinical studies. It would not be surprising to find that Vitamin D supplementation will become a welcome addition to current treatment courses that promote fertility and bring a little sunshine into our lives.