Flip-flop: Vegetable oil perils found Acids may cause heart disease

data called consumer 'nightmare'

October 07, 1992|By Marian Burros | Marian Burros,New York Times News Service

In response to harsh criticism in the last few years about the amount of saturated fat in the American diet, many food manufacturers have reluctantly switched from palm and coconut oils and lard to partially hydrogenated vegetable oils made from soybean and corn oils.

Now, in a stunning example of revisionist nutrition, new data show these oils -- found in margarine, vegetable shortening and a host of products ranging from doughnuts and pies to cookies and crackers -- may cause heart disease.

This latest nutritional flip-flop may boil the blood of angst-ridden consumers who, in the face of conflicting advice, want to throw up their hands and break out the butter. Wrong. The basic message remains the same: Eat less fat.

"It's a nightmare," said Dr. Edward Emken, a specialist in oils for the U.S. Department of Agriculture. "It's really a nasty thing when you try to explain it. There's total confusion for consumers."

The suspect ingredients are produced when food manufacturers convert vegetable oils to margarine or shortenings that are solid or semisolid at room temperature.

This process creates trans fatty acids. For years, studies about those acids were conflicting: Evidence showed they both raised and lowered cholesterol levels. But studies in the last two years have pointed to the harmful effects of these fatty acids.

A study by two Dutch scientists, reported in the New England Journal of Medicine in 1990, was the first to cause widespread concern. It showed that trans fatty acids raise the harmful elements in cholesterol while lowering protective elements.

The Agriculture Department has now confirmed the Dutch study. While the Agriculture Department study, conducted for the Institute of Shortening and Edible Oils, an industry group, has not yet been published, those who have seen it say it supports the earlier Dutch work.

"Evidence is growing that trans fatty acids raise cholesterol levels just like saturated fatty acids," said Dr. Scott M. Grundy, director of the center for human nutrition at the University of Texas Southwestern Medical Center and an expert on coronary risks of dietary fats, who has seen the study. "We should try to reduce the amount of trans fatty acids in foods."

Further evidence has been found by a 1987 study that followed the dietary habits of 85,000 nurses for eight years. The study, led by Dr. Walter Willett, a professor of epidemiology and nutrition at the Harvard School of Public Health, show that there was an increase in the risk of heart disease among those with the highest intake of trans fatty acids.

In an abstract prepared for a meeting last June of the Society for Epidemiologic Research, the researchers reported: "Intakes of margarine, cookies and cake -- major sources of trans isomers -- were significantly associated with a higher risk of coronary heart disease. These data support the hypothesis that greater intake of trans isomers of fatty acids increases the incidence of coronary heart disease."

Researchers said the findings were no excuse for people to revert to butter. "We don't want people going back to saturated fat," said Joseph Judd, the head researcher on the Agriculture Department study.

But the findings do suggest that partially hydrogenated oils, an important ingredient in margarine and baked goods even before the concern over tropical oils, are no better.

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