Vitamin D: Are You Getting Enough?

If women maintained high levels of vitamin D, they could reduce their risk of breast cancer as much as 50 percent; colorectal cancer up to 253 percent; and heart disease, stroke and peripheral artery disease more than 100 percent, says vitamin D expert Michael F. Holick, MD, PhD, of Boston University Medical Center. In one of the few studies to look at the direct benefits of vitamin D supplementation on disease, 18 people with hypertension exposed to ultraviolet B light three times a week for up to 10 minutes at a time for three months not only increased their vitamin D levels about 180 percent, but reduced their blood pressure to normal levels.

Unfortunately, D is not an easy vitamin to get these days. We've been trained to avoid the best source (the sun) by covering our body and using sunscreen. Even if you skip the sunscreen, it's nearly impossible to get enough D from sun exposure between October and April, no matter where you live, said Dr. Holick. The only good dietary source—wild-caught (not farmed) oily fish like salmon and mackerel—is expensive and often high in mercury.

That's why an estimated 50 percent or more of the world's population have a vitamin D deficiency. In the United States, 42 percent of African-American girls and women ages 15 to 49 and about 35 percent of all women ages 20 to 69 have low blood levels of vitamin D. Overall, women are more than twice as likely as men to have low levels of this important vitamin.

How to Get More Vitamin D