Evidence growing for vitamin D-heart health link

NEW YORK (Reuters Health) - People with a deficiency in vitamin D may be at increased risk of heart and blood vessel disease, the authors of a new review of current research on vitamin D and cardiovascular health conclude.

While placebo-controlled, randomized trials are needed to confirm the relationship, in the meantime, "vitamin D supplementation is simple, safe and inexpensive," Dr. John H. Lee of the Mid America Heart Institute and the University of Missouri in Kansas City and colleagues say.

Doctors have long known that adequate vitamin D, obtained through diet and sunlight, is required for bone health, Lee and his team note in the current issue of the Journal of the American College of Cardiology. But more recent research is showing that vitamin D may also be important for other body functions, they add.

People can obtain vitamin D through supplements, fortified foods such as milk and orange juice, and fish oil, while skin exposed to ultraviolet radiation synthesizes vitamin D. Obese people appear to be at greater risk of vitamin D deficiency, possibly because it gets trapped in fat cells.

In the current report, Lee and his colleagues note that deficiency in vitamin D is more common than previously realized, with the Third National Health and Nutrition Examination Survey identifying it in up to 57 percent of adults in the United States.

Low levels of vitamin D have been linked to heart attack, heart failure, stroke, diabetes-related cardiovascular disease, and peripheral arterial disease, the researchers report, adding that studies have also linked inadequate amounts of vitamin D to high blood pressure and diabetes.

One study found people with low levels of vitamin D were more likely to have a stroke, heart attack, heart failure, or blockage of blood flow in the heart during five years of follow-up, with these risks being even higher among people with high blood pressure.

People with chronically low vitamin D levels secrete too much parathyroid hormone, and this condition, known as hyperparathyroidism, has also been tied to heart and blood vessel problems, the researchers add.

Current U.S. recommendations for vitamin D intake are 200 international units daily for people under 50 years old, 400 IU for people 50 to 70, and 600 IU for people over 70, Lee and his team point out, but there is evidence that people actually need much more. "Many experts in the field suggest the recommended daily intake of vitamin D be increased to at least 800 to 2,000 IU of vitamin D daily, doses that are difficult to achieve without supplementation, particularly in higher latitudes and in areas of extreme winter climate," they add.

While taking in up to 2,000 IU of vitamin D daily is regarded as safe by the Food and Drug Administration, the researchers note. The authors of a risk assessment reported last year concluded that up to 10,000 IU a day is safe.

SOURCE: Journal of the American College of Cardiology, December 9, 2008.