FATS LINKED TO WOMEN'S HEART RISKS.

Byline: Jane E. Brody The New York Times

The kinds of fats consumed, not the total amount of fat, determine a woman's risk of suffering a heart attack, according to the first major study of the effects of all dietary fats in women.

The 14-year study of more than 80,000 female nurses highlighted two types of fats as the bad actors in heart disease: saturated fats, found mainly in meat and dairy foods, and trans fats, found in most margarines, commercial baked goods and deep-fried foods prepared with hardened vegetable oils.

The research, which documented 939 heart attacks, fatal and nonfatal, among the participants, is the latest in a series of studies that have sought to define more carefully the effects of diet on heart disease. The earlier research focused mainly on saturated fat, cholesterol and total fat intake as the chief dietary factors. The new findings confirm and extend those from a report, published four years ago and based on the same study of nurses, about the risk of trans fats.

When the researchers took into account other influences on coronary risk, such as smoking, trans fats stood out as the most serious problem. Among the women who consumed the largest amounts of trans fats, the chance of suffering a heart attack was 53 percent higher than among those at the low end of trans fat consumption.

But women in the group with the largest consumption of total fat - 46 percent of calories - had no greater risk of heart attack than those in the group with the lowest consumption of total fat- 29 percent of calories.

The researchers, from the Harvard School of Public Health and Brigham and Women's Hospital in Boston, said this suggested that limiting consumption of trans fats would be more effective in avoiding heart attacks than reducing overall fat intake. The authors said they believe that their finding would apply to men as well as to women.

But other researchers pointed out that the study had not examined the effects of a diet any lower in fat than 29 percent of calories, and some health researchers said they would continue to recommended that people reduce total fat consumption.

About 5 percent to 10 percent of the fat in most Americans' food is trans fat, which is produced when vegetable oils are artificially hydrogenated to increase their firmness and resistance to rancidity. Liquid vegetable oils, including olive, canola, soybean and corn oils, are free of trans fat.

Trans fats are not listed on food labels - the Food and Drug Administration is considering a petition that would require such listing - but a product is likely to contain them if hydrogenated fat is listed among the ingredients. The softer the fat, the fewer trans fats it contains.

Confirming earlier research, the new study found that polyunsaturates, which are highest in safflower, soybean, corn and sunflower oils, could lower coronary risk even below normal levels, and that monounsaturates, most prominent in olive and canola oil, had a small benefit.

The study is being published today in The New England Journal of Medicine, but it already has generated extensive comment, especially from advocates of a low-fat diet to prevent heart disease and those who say a high-fat diet promotes obesity and some cancers.

``How can they say what happens on a low-fat diet when no group in the study consumed less than 29 percent of calories from fat?'' said Dr. Dean Ornish of Sausalito, Calif., who has demonstrated that a vegetarian diet, in which only 10 percent of calories are derived from fat, can reverse arterial clogging and reduce recurrent heart attacks by 50 percent in patients with advanced heart disease.

Two previous studies, in men, also linked the consumption of trans fats to an increase in coronary disease. And the earlier, less definitive report from the study on the nurses concluded that eating lots of trans fats raised a woman's risk of heart disease by as much as 50 percent.

That report prompted some manufacturers to produce margarines free of trans fats and also led to a popular belief that butter is better than margarine, a conclusion that the researchers of the latest study say is wrong.