Low Vitamin D Levels Related to an Increased Risk of PAD

Low levels of vitamin D may be associated with an increased risk for peripheral arterial disease (PAD), according to a new study.

Researchers at the Albert Einstein College of Medicine (New York; NY, USA) analyzed data from a national survey measuring vitamin D levels in 4,839 U.S. adults, and correlated the results with PAD prevalence. The researchers also measured risk factors for PAD such as cholesterol levels, diabetes, blood pressure (BP), and inflammatory markers such as C-reactive protein, as well as ankle-brachial index, a PAD screening tool that measures blood flow to the legs.

The researchers found that higher levels of vitamin D correlated with a lower incidence of PAD. In the participants with the highest vitamin D levels--more than 29.2 nanograms per milliliter (ng/mL)--only 3.7% had PAD. Among those with the lowest levels--less than 17.8 ng/mL--8.1% had PAD. After adjusting for age, sex, race, and co-existing health problems, the researchers found that adults in the lowest vitamin D group had a 64% higher prevalence of PAD compared to those with the highest vitamin D levels; for each 10-ng/mL lower vitamin D level, there was a 29% higher risk of PAD. The researchers claimed that this does not mean that vitamin D is having a protective effect itself, although this is one hypothesis. It is also possible that higher vitamin D levels may be a marker of other health practices (such as eating a healthier diet or engaging in more physical activity) which could be related to sun exposure. The study was presented at the American Heart Association (AHA) Arteriosclerosis, Thrombosis, and Vascular Biology annual Conference, held during April 2008 in Chicago (IL, USA).

"In animals, vitamin D has anti-inflammatory activity,” said lead author Michal Melamed, M.D., M.H.S., an assistant professor of medicine and epidemiology. "In addition, in mice, vitamin D is a regulator of one of the hormone systems that affects blood pressure. The cells in the blood vessels in the body have receptors for vitamin D, so vitamin D may have direct effects on the vessels, although this has not been fully worked out.”

"Other vitamins have been thought to help prevent cardiovascular disease, such as vitamin E, which did not pan out after being tested in a randomized clinical trial,” added Dr. Melamed. "Therefore, we would not recommend people start taking vitamin D supplements without talking to their doctors. However, we recommend eating a balanced diet. People obtain vitamin D either through exposure to the sun or from foods, especially fish and fortified milk and other fortified foods.”

Vitamin D, or 25-hydroxyl vitamin D, is converted by the body to a hormone that strengthens bones. Severe vitamin D deficiency can cause diseases such as rickets in children. Scientists are only beginning to explore the relationship between 25-hydroxyl vitamin D and cardiovascular disease.


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