People with low vitamin D levels may face an increased risk for peripheral artery disease (PAD), a study suggests.

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 Americans and is associated with significant disease and death.

People obtain vitamin D by making it themselves (through skin exposure to sunlight), by eating foods like fish and fortified dairy products that contain vitamin D, or by taking dietary supplements. Adequate vitamin D levels are necessary for bone health, but researchers are only beginning to explore vitamin D’s connection to cardiovascular disease.

Dr. Michal L. Melamed from Albert Einstein College of Medicine, Bronx, New York and colleagues analyzed data from a national survey in which vitamin D levels were measured 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.

Average vitamin D levels were significantly lower in people with PAD than in people without PAD, Melamed and colleagues report.

In the participants with the highest vitamin D levels, only 3.7 percent had PAD. Among those with the lowest levels, 8.1 percent had PAD.

Participants with the lowest vitamin D levels were 2.18 times more likely to have PAD than were participants in the highest vitamin D levels after adjustment for age, gender, and race.

For each 10 nanogram per milliliter decrease blood vitamin D level, there was a 35 percent increase in the prevalence of PAD, the investigators say.

Melamed cautions, however, that “the evidence is not quite there yet to suggest patients with PAD would benefit from vitamin D supplementation.”

She added, “If there is a causal relationship between low vitamin D levels and PAD, it may be that long-standing vitamin D deficiency causes PAD and that intervening once PAD is already established may not change the course of the disease. Therefore, more studies are needed in this area.”

SOURCE: Arteriosclerosis, Thrombosis, and Vascular Biology, June 2008.