ATVB: Low vitamin D levels associated with an increased risk of PAD

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Low levels of vitamin D may be associated with an increased risk for peripheral arterial disease (PAD), researchers reported at the American Heart Association’s (AHA) 2008 Arteriosclerosis, Thrombosis and Vascular Biology (ATVB) annual conference April 16-18.

PAD occurs when arteries in the legs become narrowed or clogged with fatty deposits, reducing blood flow to the legs. PAD affects about 8 million U.S. patients and is associated with significant disease and death, according to the AHA’s Heart Disease and Stroke Statistics 2008 Update.

“In animals, vitamin D has anti-inflammatory activity,” said Michal Melamed, MD, MHS, lead author of the study and assistant professor of medicine and epidemiology and population health at Albert Einstein College of Medicine in New York City.

“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,” Melamed said.

To study whether there is a relationship of vitamin D with PAD, Melamed and colleagues analyzed data from a national survey measuring vitamin D levels in 4,839 U.S. adults. Researchers in that survey had also documented ankle-brachial index, a PAD screening tool that measures blood flow to the legs.

“We also measured other risk factors for peripheral arterial disease such as cholesterol levels, diabetes, blood pressure and inflammatory markers such as C-reactive protein,” Melamed said.

The researchers found that higher levels of vitamin D correlated with a lower prevalence of PAD. In the participants with the highest vitamin D levels—more than 29.2 nanogram per milliliter (ng/mL)—only 3.7 percent had PAD. Among those with the lowest levels—less than 17.8 ng/mL—8.1 percent had PAD, the authors wrote.

“After adjusting for age, sex, race and co-existing health problems, we found adults in the lowest vitamin D group had a 64 percent higher prevalence of PAD compared to those with the highest vitamin D levels,” Melamed said. “For each 10 ng/mL lower vitamin D level, there was a 29 percent higher risk of PAD.”

However, the investigators noted that these findings do not mean that vitamin D is having a protective effect itself, despite a prior hypothesis.

The findings need to be addressed in a large randomized clinical trial of vitamin D supplementation, Melamed concluded.

The results of the study will also be published in Arteriosclerosis, Thrombosis, and Vascular Biology: Journal of the American Heart Association.