BOSTON, NOV. 7 -- New scientific research supports the idea that lowering the amount of fat in the diet can reverse the buildup of deadly fatty material in the arteries and reduce the number of subsequent heart attacks.

In a 2 1/2-year study of 120 men under the age of 63, all of whom had heart disease and high levels of "bad" cholesterol, a team led by cardiologist Greg Brown at the University of Washington found that a combination of two cholesterol-lowering drugs was more effective than one in controlling heart disease.

The results, published in Thursday's New England Journal of Medicine, "offer substantial evidence of the benefits of aggressive cholesterol-lowering for management of patients with established {heart} disease," the researchers said.

"Bad" cholesterol is low-density lipoprotein (LDL). Along with high-density lipoprotein (HDL), it makes up total body cholesterol. The ratio between LDL and HDL is considered important in projecting the risk of heart attack. The National Heart, Lung and Blood Institute recommends that LDL be lower than 130 milligrams per deciliter of blood. Levels of LDL above 160 indicate a high risk of heart disease, and the HDL should be above 35, the institute suggests.

Among volunteers who took a placebo or the drug colestipol if their blood had too much "bad" cholesterol, heart disease worsened in 46 percent of the patients. Ten of the 52 people died, had non-fatal heart attacks or required heart surgery.

In contrast, among the patients treated aggressively with a combination of drugs, only 21 percent saw a progression of their disease when they took colestipol and lovastatin and only 25 percent got worse when they received niacin and colestipol.

Five of the 94 people in those two groups died, had heart attacks or required heart surgery.

Colestipol, sold as Colestid, is made by Upjohn. Niacin is sold by Rorer as Nicolar. Lovastatin, a product of Merck Sharp & Dohme, is sold as Mevacor.

Nine of the patients initially included in the study had to withdraw because they could not tolerate the side effects of niacin or colestipol.

The Brown team said that "strictly interpreted, our results apply to a fraction of the roughly 6 million men in the American population who have angina" or who have had a heart attack, a family history of heart disease and "bad" cholesterol levels greater than 124. Only about 1 million of these men are under 63.

Further work, they said, will be needed to see whether the findings apply to women, heart disease patients with normal cholesterol levels or older men.