MONDAY, June 19, 2006 (HealthDay News) -- If you love your arteries, eat your vegetables.
So say researchers who found that mice fed a vegetable-rich diet cut their risk for atherosclerosis -- hardening of the arteries -- by 38 percent.
"There is some epidemiological evidence that people who eat a lot of fruits and vegetables, probably more than five servings a day, have a lower risk of coronary heart disease than people who don't," added lead researcher Michael Adams, a professor of pathology at Wake Forest University School of Medicine, Winston-Salem, N.C.
However, "there are a lot of problems with epidemiological [population-based] studies, a lot of factors that can't be controlled for," he said. For instance, "those who eat a lot of fruits and vegetables are healthier in other ways," such as exercising more, he added.
So, Adams and his team decided to look at the physiological level for how vegetable intake might affect blood vessel health.
Their study is published in the July issue of the Journal of Nutrition and is funded by food maker General Mills, whose brands include Green Giant vegetables.
Adams' team fed a control group of 53 mice a vegetable-free diet. Another group of 54 mice got the same base diet, but with vegetables added to make up 30 percent of the total diet. Vegetables included freeze-dried broccoli, peas, green beans, corn and carrots.
After 16 weeks, they assessed the animals' health and found those who ate the vegetable-rich diet had lower total cholesterol levels, lower levels of the so-called "bad" cholesterol or low-density lipoprotein (LDL) and a 7 percent lower average body weight.
"The mice who consumed 30 percent of their diet as vegetables developed atherosclerotic plaques that were 38 percent smaller than those of the mice who consumed no vegetables," he said.
They didn't track exercise as a variable, but the mice all lived in the same environment and so probably got about the same amount of activity, Adams said.
"We looked at the accumulation of a marker of inflammatory activity," he said. "Inflammation is known to be an integral part of the development of atherosclerotic plaque." The vegetables may work, he said, by their anti-inflammatory properties.
The study is "interesting and encouraging," said Alice Lichtenstein, chair of the nutrition committee for the American Heart Association.
"The observation has been made in humans that people who eat fruits and vegetables have less coronary artery disease and less heart disease," she said. But to her knowledge, no one knows the mechanism.
"It may be a direct effect, or people eating a lot of fruits and vegetables may have a diet [that is also] healthy in other ways," added Lichtenstein, who is director of the Cardiovascular Nutrition Lab at the U.S. Department of Agriculture's Human Nutrition Research Center on Aging.
As for advice, Adams said boosting vegetable and fruit intake is always wise. "The average consumption in this country of green and yellow vegetables and of fruits is two to three servings a day. If people just ate 2 or 3 more servings a day, odds are they would be much healthier for it."
To learn more about nutrition, visit the American Dietetic Association.