The American Heart Association says PAD occurs when arteries in the legs become narrowed or clogged with fatty deposits, which then reduces the blood flow to the legs; the condition affects millions of people and is significantly related to disease and death.

The body converts vitamin D into a hormone that makes bones stronger and a severe deficiency of the vitamin can cause diseases such as rickets in children; it is only recently that scientists have started to explore the relationship between vitamin D and cardiovascular disease.

Dr. Michael Melamed, an assistant professor of Medicine and Epidemiology and Population Health at Albert Einstein College of Medicine in New York City, says in mice, vitamin D has an anti-inflammatory action and is also a regulator of one of the hormone systems that affects blood pressure.

Dr. Melamed suggests that the cells in the blood vessels in the body have receptors for vitamin D which possibly has a direct effect on the vessels.

In order to examine a possible relationship between vitamin D and PAD, the researchers analyzed data from a national survey measuring vitamin D levels in 4,839 U.S. adults; the data also included the ankle-brachial index, a PAD screening tool that measures blood flow to the legs.

The researchers also measured other risk factors for peripheral arterial disease such as cholesterol levels, diabetes, blood pressure and inflammatory markers such as C-reactive protein.

They found that higher levels of vitamin D correlated with a lower prevalence of PAD and those with the highest vitamin D levels only 3.7 percent had PAD, while among those with the lowest levels 8.1 percent had PAD.

Adjustments for age, sex, race and co-existing health problems, were applied and it remained that those in the lowest vitamin D group had a 64 percent higher prevalence of PAD compared to those with the highest vitamin D levels.

The researchers say this does not suggest that vitamin D in itself has a protective effect but possibly that higher vitamin D levels may be a marker of other health practices such as a healthy diet and being physically active.

They say more research is called for in the form of a large randomized clinical trial of vitamin D supplementation from natural food sources.

Dr. Melamed does not recommend people start taking vitamin D supplements before talking to their doctors and advises a balanced diet where vitamin D is obtained from foods, especially fish and fortified milk and through exposure to the sun.

The American Heart Association too recommends that healthy people get adequate nutrients by eating a variety of foods in moderation, rather than by taking supplements which are not a substitute for a balanced, nutritious diet that limits excess calories, saturated fat, trans fat, sodium and dietary cholesterol.

Good sources of vitamin D include fortified milk, salmon, sardines, cod liver oil and some fortified cereals and eating such a diet has been shown to reduce coronary heart disease risk in healthy people and in those with coronary disease.

Experts say vitamin-D deficiency is highly prevalent worldwide and affects as many as one-third to one-half of otherwise healthy middle-aged to elderly adults.

The research was presented at the American Heart Association's Arteriosclerosis, Thrombosis and Vascular Biology Annual Conference and is published in Arteriosclerosis, Thrombosis, and Vascular Biology: Journal of the American Heart Association.