"While everyone knows that eating more vegetables is supposed to be good for you, no one had shown before that it can actually inhibit the development of atherosclerosis," said Michael Adams, D.V.M., lead researcher. "This suggests how a diet high in vegetables may help prevent heart attacks and strokes."
The study used specially bred mice that rapidly develop atherosclerosis, the formation on blood vessel walls of fatty plaques that eventually protrude into the vessel's opening and can reduce blood flow. The mice have elevated low-density lipoprotein ( LDL), or "bad" cholesterol, which is also a risk factor for atherosclerosis in humans.
Half of the mice in the study were fed a vegetable-free diet and half got 30 percent of their calories from a mixture of freeze-dried broccoli, green beans, corn, peas and carrots. These five vegetables are among the top-10 vegetables in the United States based on frequency of consumption.
After 16 weeks, the researchers measured two forms of cholesterol to estimate the extent of atherosclerosis. In mice that were fed the vegetable diet, researchers found that plaques in the vessel were 38 percent smaller than those in the mice fed vegetable-free diets. There were also modest improvements in body weight and cholesterol levels in the blood.
The estimates of atherosclerosis extent involved measuring free and ester cholesterol, two forms that accumulate in plaques as they develop. The rate of this accumulation has been found to be highly predictive of the actual amount of plaque present in the vessels.