High-fat, low-stroke tie perplexes researchers Medical study denies accepted diet ideas

December 24, 1997|By Jonathan Bor | Jonathan Bor,SUN STAFF

In a study that could complicate popular notions of healthy eating, researchers found that middle-aged men who ate diets high in total fats seemed to lower their risk of stroke.

Scientists with the Harvard Medical School and Boston University found that men eating the largest amounts of total fat suffered the lowest rates of ischemic stroke, a potentially fatal condition caused by the interruption of blood flow to the brain.

Two types of fats -- saturated and monounsaturated -- were particularly linked to the low stroke rates.

Saturated fats are derived mainly from meat and dairy products, and monounsaturated fats from canola oil and olive oil.

The findings come at a time when the nation's health establishment is working hard to steer Americans away from fats.

The move has been driven by the widespread belief that people can protect themselves from heart disease -- the nation's No. 1 killer -- by avoiding fats.

To further confuse the issue, saturated fats have become one of the biggest demons in the fight against heart disease because they are known to drive up cholesterol levels in the bloodstream.

Advocates of "heart-healthy" eating warned against drawing sweeping conclusions from the new study.

"The take-home message from this is that there is no take-home message," said Dr. John La Rosa, who helped draft fat-reduction guidelines of the National Cholesterol Education Program of the National Institutes of Health.

"I would certainly not take this to mean that people should start eating saturated fats to avoid strokes," said La Rosa, chancellor of the Tulane University Medical Center in New Orleans.

Writing in today's issue of the Journal of the American Medical Association, the stroke researchers also warned against making major changes in the prevailing dietary recommendations.

They said the study must be confirmed by research involving broader population groups.

"Nonetheless, the results of this study raise the possibility that restriction of fat intake among residents of Western societies, as recommended by the U.S. National Cholesterol Education Program and others, does not decrease -- and could increase -- overall risk of ischemic stroke," they wrote.

Ischemic strokes are responsible for 80 percent of all strokes in the United States.

All told, strokes claim a half-million people in the United States each year -- making it the third leading killer behind heart disease and cancer.

The Heart Association issued a statement contending that the study was severely limited -- in part because dietary habits were gleaned from interviews in which the men were asked to remember what they had eaten over the preceding 24 hours.

The association stuck by its recommendation that people should limit dietary fats to no more than 30 percent of total calories.

The stroke findings were gleaned from the Framingham Heart Study, a continuing effort to learn about the risk factors for heart disease and other ailments.

In today's article, researchers analyzed stroke rates among 832 men over a 20-year period.

The study was led by Dr. Matthew W. Gillman of the Harvard Medical School.

In an editorial accompanying the article, Dr. Roger Sherwin and Dr. Thomas R. Price of the University of Maryland Medical Center said the study should not overturn the prevailing dietary guidelines.

But they said it might serve as a warning to people considering fad diets that call for extreme reductions in fat.

They also said a Mediterranean diet -- rich in olive oil and low in red meat -- could serve as a "way out" of the confusion some people might be feeling in the face of mixed messages about heart disease and stroke.

This diet has the potential to protect people against both illnesses because it is high only in monounsaturated fat -- the one fat that has been not been implicated in either disease.

"Crete is the best example," said Sherwin, an epidemiologist. "They have among the lowest incidence of heart disease and stroke in the world.

"I'm beginning to think we should pay more attention to the diet they've been eating for three or four thousand years."

Price said the study could lead to a more sophisticated view of fats, in which people no longer view all fats as harmful.

He compared this to current understandings of cholesterol, in which the public has begun to learn about good (HDL) and bad (LDL) cholesterols.

The study, said Price, also underscores the fact that the mechanisms behind heart disease and stroke are not necessarily the same.

"There's this idea that stroke is just a heart attack in the head, and it is clearly not," said Price, director of the the University of Maryland's stroke program.

Fatty deposits that clog arteries are responsible for about 95 percent of all heart attacks but only a minority of strokes, Price said.

Strokes are most commonly caused by blood clots that pass from the heart to the brain, an event that hardly ever causes heart attacks.

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