Too Little Vitamin D Puts Heart at Risk

Dec. 1, 2008 -- Getting too little vitamin D may be an underappreciated heart disease risk factor that's actually easy to fix.

Researchers say a growing body of evidence suggests that vitamin D deficiency increases the risk of heart disease and is linked to other, well-known heart disease risk factors such as high blood pressure, obesity, and diabetes.

For example, several large studies have shown that people with low vitamin D levels were twice as likely to have a heart attack, stroke, or other heart-related event during follow-up, compared with those with higher vitamin D levels.

"Vitamin D deficiency is an unrecognized, emerging cardiovascular risk factor, which should be screened for and treated," says researcher James H. O'Keefe, MD, director of preventive cardiology at the Mid America Heart Institute in Kansas City, Mo., in a news release. "Vitamin D is easy to assess, and supplementation is simple, safe and inexpensive."

Most of the body's vitamin D requirements are met by the skin in response to sun exposure. Other less potent sources of vitamin D include foods such as salmon, sardines, cod liver oil, and vitamin D-fortified foods like milk and some cereals. Vitamin D can also be obtained through supplements.

Vitamin D Deficiency on the Rise

Vitamin D deficiency is traditionally associated with bone and muscle weakness, but in recent years a number of studies have shown that low levels of the vitamin may predispose the body to high blood pressure, congestive heart failure, and chronic blood vessel inflammation (associated with hardening of the arteries). It also alters hormone levels to increase insulin resistance, which raises the risk of diabetes.

In a review article published in the Journal of the American College of Cardiology, researchers surveyed recent studies on the link between vitamin D deficiency and heart disease to come up with practical advice on screening and treatment.

They concluded that vitamin D deficiency is much more common than previously thought, affecting up to half of adults and apparently healthy children in the U.S.

Researchers say higher rates of vitamin D deficiency may be due in part to people spending more time indoors and efforts to minimize sun exposure through the use of sunscreens. Sunscreen with a sun protection factor (SPF) of 15 blocks approximately 99% of vitamin D synthesis by the skin.

"We are outside less than we used to be, and older adults and people who are overweight or obese are less efficient at making vitamin D in response to sunlight," says O'Keefe. "A little bit of sunshine is a good thing, but the use of sunscreen to guard against skin cancer is important if you plan to be outside for more than 15 to 30 minutes of intense sunlight exposure."