NEW YORK (Reuters Health) - Eating plenty of whole grains can help keep your arteries healthy, potentially warding off heart disease and stroke, a new study shows.
In a diverse group of men and women participating in the Insulin Resistance Atherosclerosis Study, those with diets containing the largest amounts of whole grains had the thinnest carotid artery walls and showed the slowest progression in artery wall thickness over a five-year period, lead author Dr. Philip B. Mellen of Wake Forest University School of Medicine in Winston-Salem, North Carolina and colleagues found.
"An increased consumption of whole grains represents a wholesome and palatable opportunity to reduce the risk of atherosclerosis and heart disease," Drs. Vasanti S. Malik and Frank B. Hu of the Harvard School of Public Health in Boston write in an editorial accompanying the study.
Thickening of the lining of the carotid arteries, which deliver blood to the brain, signals atherosclerosis, the buildup of fatty substances and other material that increases the risk of heart attack and stroke. While high levels of whole grain in the diet has been tied to a lower risk of type 2 diabetes and heart disease, the relationship between whole grains and atherosclerosis is not as well understood, Mellen and his team report in the American Journal of Clinical Nutrition.
To investigate, he and his colleagues looked at a multiethnic group of 1,178 men and women, estimating their whole grain consumption based on how much dark bread, cooked cereal and high-fiber cereal they ate. The researchers measured the study participants' carotid artery intimal medial thickness, the width of the two innermost layers of the blood vessel, at the study's outset and again five years later.
The higher a person's whole grain intake, the thinner his or her intimal medial thickness, the researchers found, and the less intimal medial thickness progressed during the course of the study. The association remained strong even after the researchers adjusted for other factors such as healthiness of overall diet and intake of certain nutrients, making it fairly clear that it was the whole grains themselves -- not some individual component -- that were responsible for their atherosclerosis-preventing effects.
"They're really nutritionally very complex," Mellen told Reuters Health. "We're learning more and more about all of the different constituents. It's not just the fiber, it's not just the B vitamins or the vitamin E or whatever. There's a lot going on there...the whole is greater than the sum of the parts."
Most Americans don't get much whole grain, he added; fewer than 10 percent meet the United States Department of Agriculture recommendation to consume three servings a day, while half don't eat any whole grains in a given day. In Mellen's study, the average intake of whole grain was less than one serving a day. "We have a long way to go," he said.
Mellen suggests adding a serving of whole grain -- for example, a slice of whole-wheat bread or a cup of whole-grain cereal -- to every meal. "It's a pretty approachable way to try to make a dietary improvement."
SOURCE: American Journal of Clinical Nutrition, 2007.
