D A L L A S, Feb. 13, 2001 -- Turning the conventional medical wisdom on its
head, a study found that a diet extremely low in saturated fat may
raise the risk of a rare type of stroke in some women.
But researchers cautioned that the study does not mean peopleshould stop trying to reduce the amount of saturated fat in theirdiets.
"I wouldn't want to give anyone the impression here's anexample where saturated fat is good for you," said Dr. Meir J.Stampfer, co-author of the study and professor of epidemiology andnutrition at the Harvard School of Public Health. "We still wantpeople to eat a low saturated fat diet."
The researchers analyzed data from the long-running Nurses'Health Study that began in 1980 with 85,764 women. By 1996, theones who ate the least saturated fat (about 20 grams per day) wereabout twice as likely as women eating moderate amounts (25 to 36grams) to have suffered a particular type of stroke called anintraparenchymal hemorrhage.
Most strokes are ischemic strokes, which result from theblockage of an artery carrying blood to the brain. Hemorrhagicstrokes occur when a blood vessel in the brain leaks or bursts.Intraparenchymal hemorrhage is one of the rarer forms ofhemorrhagic stroke. Of the 690 strokes observed in the study group,74, or nearly 11 percent, were intraparenchymal, or occurringwithin the brain tissue.
The increased stroke risk in the low-fat group occurredprimarily among women with high blood pressure.
Stampfer said the extremely low fat intake, combined with highblood pressure, may contribute to a structural weakness in bloodvessels that causes them to rupture. He said the findings probablyapply to men, too.
A cooked 3-ounce patty of 80 percent lean ground beef has 6grams of saturated fat. A 4-ounce serving of skinless chicken has 1gram.
The findings were published in Tuesday's issue of Circulation, ajournal of the American Heart Association.
The more common form of stroke — a blockage in the blood vessel— is typically caused by fatty deposits in the arteries, a processthat saturated fats contribute to.
People trying to lower their risk of a stroke by reducingsaturated fat should try to do it in moderation, Stampfer said.
"They shouldn't strive to go to the lowest possible level ofsaturated fat," he said. "But they should still be on the lowside."
The impetus for the study was the finding that in rural Japan,where people eat very little animal fat, the incidence ofhemorrhagic stroke is twice that of urban Japan. Stampfer said thenew findings may help to explain that situation.
Dr. Steven Nissen, vice chairman of cardiology at the ClevelandClinic in Cleveland, said reducing saturated fats is a better goalthan trying to eliminate them altogether. "Extremes of diet don'tseem to be particularly healthy," Nissen said.
He particularly cautioned against subscribing to ultra low-fatfad diets. "Good, healthy diets are not obtained by buying cheappaperbacks in the checkout line," Nissen said.