Selenium levels impact risk of leg artery disease

New research suggests that the amount of selenium in a person's blood could impact their risk of developing peripheral artery disease, or PAD.

PAD occurs when arteries in the legs become narrowed or clogged with fatty deposits, reducing blood flow to the legs, leading to leg cramps and walking difficulty. PAD affects about 8 million Americans and is associated with significant disease and death.

In their study, Dr. Eliseo Guallar, of The Johns Hopkins School of Public Health in Baltimore and colleagues found that the likelihood of having PAD fell as people's blood levels of selenium increased, but that PAD risk then climbed slightly for people with the highest selenium levels.

PAD is an "important marker" of atherosclerosis (hardening of the arteries) throughout the body, Guallar and colleagues point out in a report in the American Journal of Epidemiology.

While there is some evidence that selenium levels are related to heart disease risk, it is questionable whether consuming more selenium would be beneficial in the US, where most people get more than enough of the nutrient, they add.

To investigate, they looked at 2,062 men and women age 40 and older, comparing their blood levels of selenium with their "ankle-brachial blood pressure index" - a widely used test for PAD.

When the researchers divided study participants into four groups based on selenium levels, they found those with the second-lowest levels were 25 percent less likely to have PAD than those with the lowest levels.

For people in the second-highest quartile, PAD risk was 42 percent lower than for those with the least selenium. Those with the highest levels of selenium had a 33 percent lower risk of PAD than those with the lowest levels.

Using a different analytical technique, the researchers found that the risk of PAD declined as selenium levels rose up to 150-160 ng/mL, and then began to increase in people with higher selenium levels.

While the relationship wasn't statistically significant, the findings do suggest that there's a "U-shaped" relationship between selenium levels and PAD risk, the researchers say.

More research is needed, they add, to identify the ideal selenium levels for reducing the risk of heart disease and other types of chronic illness in populations with different selenium intakes.

SOURCE: American Journal of Epidemiology, April 15, 2009