Low-fat diets have long been hailed as defenders against many diseases. But results of research involving 49,000 women show the diets don't significantly affect the risk of breast cancer, colorectal cancer, heart disease or strokes in older women, at least in the short run.

After eight years of eating low-fat foods, along with increased fruits, vegetables and grains, thousands of postmenopausal women had no less chance overall of having the diseases or strokes than others, scientists in Seattle and other cities said today.

"I think a lot of people will think it disappointing that there are not clear beneficial results. ... But we do see some favorable trends," said Ross Prentice, a Fred Hutchinson Cancer Research Center scientist and lead author of the breast-cancer research reported in today's edition of the Journal of the American Medical Association.

Studies of the effect of low-fat diets on each of the diseases — the largest ever — involved women aged 50 to 79. Forty percent of the women had low-fat diets, along with increased vegetables, fruits and grains. The rest ate like they always had.

The research was part of the Women's Health Initiative, a 15-year study of 161,000 postmenopausal women nationwide that focuses on ways to prevent breast and colorectal cancer, heart disease and bone fractures. The $725 million project is coordinated by the Hutchinson Center. The diet studies cost about $415 million and were financed by the National Heart, Lung, and Blood Institute.

Prentice agreed with an institute official who said there was no reason to believe the low-fat diets would affect men differently with regard to colorectal cancer and heart disease.

Some useful trends

Although women on the diets had no statistically significant lower risks for the diseases and strokes, several findings suggested trends that did encourage the scientists.

In the breast-cancer study, the dieting women were 9 percent less likely to develop the disease, although those results could have been due to chance. (For every 10,000 women in the study, an average of 42 in the low-fat group and 45 in the control group developed breast cancer each year.) The scientists also found that women who started with the diets highest in fat and those who decreased fatty foods the most cut their risk by 15 to 20 percent.

In addition, the diet reduced by 15 percent women's blood estradiol (estrogen), a hormone that increases risk of the cancer. And it lowered the risk of developing a less-common type of breast-cancer tumors by 30 percent.

"I think that's generally encouraging information, and maybe it will enhance interest in a low-fat eating pattern," said Prentice, principal scientist in the initiative's coordinating center.

Dieting women in the colorectal-cancer study had a 9 percent decrease in colon polyps, which can be the beginning of cancer. And the dieters in the cardiovascular-disease study lowered their LDL cholesterol — the so-called bad cholesterol — slightly. Those who ate less saturated- and trans-fat-rich foods and the most vegetables and fruits fared best with heart disease.

"The studies do not say, 'Don't worry, eat what you want,' because there were these [beneficial] trends from the diet," said Shirley Beresford, lead author of the study on colorectal cancer and director of the Seattle arm of Women's Health Initiative. Considering many studies, women probably would benefit from diets rich in vegetables, fruits and grains and from increasing exercise, she said.

The researchers will continue to track the health of all study participants for five more years to see whether there might be clear benefits from the diets over a longer period.

Tough diet to follow

At the beginning of the studies, 48,835 women, including more than 1,000 in the Seattle area, were randomly selected to either continue their present diet or go on the special diet: limiting fat consumption to 20 percent of their daily calories and consuming at least five servings of vegetables and fruits and six or more servings of grains a day.

The special dieters started out by cutting fat consumption from an average 35 percent of daily calories to 24 percent, but by the end of six years had crept up to an average 29 percent. The dieting was not easy.

"It was hard to have my family accept the concept that this was the way to go to improve health," said Judy LaCour, a Kent resident who went on the diet initially to be a good example for her husband, who had health problems.

LaCour, 66, and her husband grew up in families where high-fat foods were standard fare, and that carried over into their own family: Breakfast wasn't breakfast without bacon. Fried chicken, burgers, hot dogs, pork chops and ribs were always good for dinner.

But after enrolling in the study, LaCour quickly got plenty of help from Hutchinson Center nutritionists. During the first year, they met 18 times in small groups, and less frequently later, for encouragement, recipes and advice on dieting.

"I was really enthused by it, and I got into the routine really fast," said LaCour, a Boeing computer programmer.

That meant new dishes on the table: broiled or baked chicken and other lean meats; vegetables such as carrots, broccoli, potatoes, peas and spinach; lots of salads; plenty of fruit such as bananas, blueberries and juices; and whole-wheat bread and cereals.

LaCour joked that her diet was "about 90 percent" fat before entering the study. Since then, she has held at about 33 percent. Though it's not what the study calls for, she sees improvement.

Her health is good. Besides a good diet, she regularly does low-impact aerobics and walks her dog Kela daily. Since starting the diet, her husband has his blood pressure and diabetes under control.

LaCour said she will continue on the diet, study or no study: "It's a commitment. I basically believe it's just so much better for me," she said.

Warren King: 206-464-2247 or wking@seattletimes.com

Material from the Chicago Tribune is included in this report.

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