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Study: Low-Fat Diet Failed to Cut Risks: Little Heart, Cancer Benefit in Women

Posted on: Wednesday, 8 February 2006, 12:00 CST

By Marie McCullough, The Philadelphia Inquirer

Feb. 8--A study of thousands of women over 50 who stuck to a healthy, low-fat diet for more than eight years showed no significant effect on their risks of breast cancer, colon cancer, stroke or heart disease.

Researchers who led the federally funded diet study -- the largest ever -- are trying to put the best face on the results, stressing that breast-cancer numbers hinted at reduced risk, although that could have been just by chance.

"This study shows that just reducing total fat intake does not go far enough to have an impact on heart-disease risk," said Jacques Rossouw, the physician who directed the federal study.

Others said that following the 48,000 women for an additional five years, as planned, might show clear benefits.

Meanwhile, public-health officials who have long exhorted Americans to eat the kind of diet prescribed in the study -- low in fat, high in fruits, vegetables and grains -- may find it an even harder sell.

"That's part of the concern when you do these trials -- women throwing in the sponge and eating anything they want," said Lewis Kuller, a cardiovascular-disease expert at the University of Pittsburgh Graduate School of Public Health and a leader of the study. "Unfortunately, a lot of women do that anyway."

The dietary-trial results, published in three articles in today's Journal of the American Medical Association, are part of a larger $700 million federal study of postmenopausal health called the Women's Health Initiative.

The study randomly assigned about 19,500 volunteers across the country to cut fat to no more than 20 percent of their daily calories; increase fruits, vegetables and grains; keep food diaries; and attend periodic sessions with a nutritionist. The rest of the women in the study didn't change their eating habits.

Rates of diagnoses and death from certain cancers, heart disease, and stroke were the same in both groups.

Current federal dietary guidelines, which came out last year, are even more sophisticated and less permissive than the study's diet, urging yet more servings of fruits and vegetables, and distinguishing between the "good" fats found in fish and the "bad" trans fat found in processed foods.

This distinction was not part of the study. Nor were the women required to drop a few pounds, even though most were overweight or obese, because weight loss would have made the results tougher to interpret. The average age of the women was 62.

If the $400 million study were being started today, the design would probably be different, researchers said.

"The problem is, we told them to reduce all fats," said Norman L. Lasser, director of preventive cardiology at the University of Medicine and Dentistry of New Jersey, which enrolled about 1,800 women. "Just eating a low-fat diet by itself is not enough."

It was, however, difficult for many of the women. On average, they reported reducing their fat intake from about 35 percent to 29 percent of daily calories. While that was significantly lower than the comparison group's 37 percent, it was short of the goal of 20 percent. And some volunteers may have fudged their reports.

"Most people do overstate -- they tell you what you want to hear," Lasser said.

Despite the study's findings, the theory that food affects cancer risk remains "intriguing," Aman U. Buzdar of the University of Texas M.D. Anderson Cancer Center wrote in an editorial in the journal. Asians, for example, have low breast-cancer rates on the traditional East Asian diet, yet their rates increase on a Western diet.

The role of diet in heart disease is even clearer. Studies have shown that major risk factors for heart disease -- blood pressure, diabetes and high cholesterol -- can be reduced through dietary changes. A growing number of studies also suggest that fish and fish oil may keep hearts healthy.

The Women's Health Initiative researchers "designed an intervention that was feasible and state-of-the-art at the time the study was initiated," Johns Hopkins University physicians Cheryl Anderson and Lawrence Appel concluded in an editorial in the journal.

"Since then, there has been a major evolution in the thinking about the role of fat intake... . Dietary changes can have powerful, beneficial effects" on heart-disease risk factors.

For Susan Yemin, 64, of Westfield, N.J., being in the study has been "wonderful," even though the overall results have been disappointing.

"I met some lovely people in my group," she said. "I met a fabulous nutritionist. And I lost about 10 pounds, even though I wasn't really looking to."

Judging by rising obesity rates, many Americans do not share her attitude.

"You can write all the guidelines you want," Kuller said, "but you're living in a society where food is our number-one social behavior."

Contact staff writer Marie McCullough at 215-854-2720 or mmccullough@phillynews.com.

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Source: The Philadelphia Inquirer

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