As daylight hours begin to wane, it’s time to reconsider the vitamin D question. Just how much does a woman need? And, can vitamin D—also known as the "sunshine" vitamin because it’s produced in the skin in response to sun exposure—really protect us against a host of chronic diseases?
First, where do the experts stand on this question? Here are their recommendations for healthy, adult women:
Health Canada: 200 IU (International Units) per day, from exposure to sunlight and vitamin D-rich foods, such as fatty fish (salmon, mackerel, sardines and tuna), or fortified foods, such as milk, infant formula, margarine and plant-based beverages (e.g., soy beverages).
(Note: There are different recommendations for women who are pregnant or breastfeeding, women over age 50, and children.)
Clearly, there’s no consensus. On the one hand, we’ve got the Canadian Cancer Society advocating for vitamin D supplementation during the fall and winter, and, on the other hand, Health Canada saying don’t bother supplementing because most healthy adult women are getting enough. In fact, Health Canada is in the midst of a comprehensive review of vitamin D, in the face of mounting evidence about the potential benefits of vitamin D, including new research that suggests it might reduce the risk for cancer, heart disease and even diabetes. But the evidence is still far from conclusive and there’s still no consensus on how much vitamin D is required to prevent such chronic diseases.
If you’re into reading scientific literature (and have access to an institutional subscription), the American Journal of Clinical Nutrition just published a lengthy supplement entitled, "Vitamin D and Health in the 21st Century: An Update." It may help inform your decision about whether to supplement your diet with vitamin D. Better yet, talk to your doctor about how much vitamin D is right for you. There are some risks associated with taking too much of the vitamin.
And check back at the Best Health Blog. We’ll keep you up to date on the latest policy decisions relating to health and nutrition.