Low-fat dishes such as these beef and broccoli wraps have tapped into the belief that low-fat meals have significant health benefits. Those benefits are now being questioned.
Low-fat diet debunked
A 10-year study of women finds no significant benefits to prevent disease
» Entertainer Nalani Olds talks about study.
HEALTH benefits of a low-fat diet do not include reducing cancer or heart disease as commonly believed, according to a $415 million national study of women conducted in the past 10 years.
Results of the Women's Health Initiative trial of 48,836 women, including 1,096 in Hawaii, show no significant effect of a low-fat diet on breast or colorectal cancer rates, heart disease or stroke, according to a report in today's Journal of the American Medical Association.
"The diet by itself, at least one that's achievable by most people, is not as effective as we had hoped it would be in changing the total disease picture for women," Dr. David Curb, principal investigator for Hawaii's WHI studies, said in an interview.
But there still may be need for low-fat diets targeted to women with specific issues, such as high LDL or "bad" cholesterol, said Curb, professor of geriatric medicine, University of Hawaii John A. Burns School of Medicine.
"At this point, I think these data show we should not recommend public policy, for women at least," he said. "For men, we may have to take another look. But public policy should not push hard on a low-fat diet."
The findings did indicate that women who reduced their total fat intake had a 9 percent lower risk of breast cancer than those who did not change their diet, said Rosanne Harrigan, director of the medical school's Department of Complementary and Alternative Medicine.
But the difference was not large enough to be statistically significant, and more follow-up is needed, she said.
"The study actually defused some comments being made about diet, like if you have a high carbohydrate diet you're going to get diabetes," said Harrigan, one of the Hawaii investigators. "That wasn't proven by this."
The findings showed a high-carbohydrate, low-fat diet did not increase body weight, triglycerides or blood glucose or insulin levels, signs of increased risk of diabetes.
Women aged 50 to 79 were enrolled in the study from 1993-1998 and followed for an average of 8.1 years at 40 clinical centers.
The clinical trial on diet is one of three conducted as part of the Women's Health Initiative, a comprehensive research effort evaluating causes of major diseases affecting postmenopausal women.
Josephine Nicolo, WHI project coordinator in Hawaii and nurse practitioner, praised the more than 3,000 isle women who have participated in the three trials and "hung in for 10 years."
Of the 1,096 women who volunteered for the diet study, 600 were randomly assigned to the dietary change group and the others to a control group. Those in the diet group had rigorous classes and had to keep diet diaries, Nicolo said.
Even though the low-fat diet did not make a big difference in the health outcomes for which they were looking, she said the study was positive because "we are learning so much."
U.S. dietary guidelines recommend total fat intake between 20 percent and 35 percent of calories for adults, with saturated fats less than 10 percent of calories and most fats provided by polyunsaturated and monounsaturated fats, such as nuts, fish and vegetable oils.
Both groups started at 35 percent to 38 percent of calories from fat and the low fat group ate more vegetables, fruits and grains.
The average total fat intake for the diet group was reduced to 24 percent of calories by the end of the first year but did not meet the goal of 20 percent. By the sixth year, the low-fat diet group was consuming 29 percent of calories from fat.
The non-dieting group averaged 35 percent of calories from fat in the first year and 37 percent at the sixth year.
Classes were conducted "to really motivate and support people to reduce dietary fats, to eat fruits and vegetables and to increase grains in the diet," Harrigan said. "It was a very healthy group."
In announcing the study's results, Dr. Elizabeth G. Nabel, National Heart, Lung and Blood Institute director, said they do not change recommendations on disease prevention.
"Women should continue to get regular mammograms and screenings for colorectal cancer, and work with their doctors to reduce their risks for heart disease, including following a diet low in saturated fat, trans fat and cholesterol."
Curb said: "We still do know there are a lot of people who are genetically susceptible to certain kinds of fats, to high sodium diets, so there's a lot of danger in everybody just saying, 'This doesn't mean anything.'"
He said it will be difficult to convince people of the importance of a low-fat diet "because the message is somewhat mixed here."
"But there's no question that we can associate being overweight with a lot of bad health," he said, pointing out one way for women to reduce weight is to reduce fats and, consequently, calories.
The UH received nearly $13 million for Women's Health Initiative studies, which have been extended from 2005 to 2010 with another $353,533 to UH.
Curb said the researchers wanted women who were not already on a low fat diet for the control group and they had trouble finding enough participants.
The impact of low-fat diets on specific groups and longer-term effects of such eating patterns will be examined in the next five years, he said: "Chronic diseases take a long time to develop, longer than the eight years average follow-up in WHI in most cases."
THE WOMEN'S HEALTH INITIATIVE
» Hawaii has one of 40 centers that have participated in national clinical trials on causes and prevention of major diseases affecting older women.
» Three major clinical trials have been conducted: on hormone therapy, low-fat diets, and effects of calcium and Vitamin D supplements on osteoporoisis-related bone fractures and colon cancer.
» Hormone therapy trials were stopped early, one on estrogen plus progestin in 2002 and one on estrogen alone in 2004, because of increased risk of stroke, blood clots and breast cancer. The Vitamin D study hasn't been completed. The low-fat diet study was extended last year for five years, to 2010.
» The diet study involved 48,836 post-menopausal women ages 50 to 79 divided randomly into a diet group and a comparison group. Hawaii had 1,096 women participating, with 600 assigned to the dietary group.
» No significant differences occurred in rates of colon cancer, heart disease or stroke between the groups. Women reducing total fat intake showed a 9 percent lower risk of breast cancer.
» The University of Hawaii John A. Burns School of Medicine has received $352,533 for research in the next five years, making a total of $13,315,100 for the Women's Health Initiative since September 1994. Principal investigator is Dr. David Curb.
Sources: National Institutes of Health and University of Hawaii John A. Burns School of Medicine
Entertainer finds healthy habits during study
ENTERTAINER Nalani Olds did not go on an eating binge after following a low-fat diet the past 10 years for a national study.
"I'm just going to continue eating well and do simple things like drinking lots of water," she said.
It doesn't matter that there was no significant difference in disease rates between the low-fat diet group and comparison group "because it made me mindful," Olds said.
"I don't know how many other people it made mindful also, but the bottom line is my health is good."
The 69-year-old Hawaiian singer and storyteller said she follows a low-fat, low-salt diet and monitors everything she eats.
She walks on Kailua Beach and goes twice a week to a gym, where she has a personal trainer.
Olds said she read a newspaper story about the Women's Health Initiative low-fat diet study and volunteered shortly after it began 10 years ago. She also participated in the WHI hormone replacement study.
She said the diet study "was very, very easy because they made it so easy. It was done in a most friendly way."
She said she watched what she ate and if she wanted to eat something that was not good for the diet, like kalua pig, she would just have a taste of it or eat one-fourth of what she usually ate.
She said the participants had workbooks and when they went to meetings about once a month, they received recipes and lessons in nutrition and food preparation.
"We went through a period together where we shared what we were doing, what we were cooking and eating and how we were finding it worked. We would bring something, some kind of food or dish, to share with everyone."
She no longer has to go to meetings but will be evaluated periodically by researchers as the study continues for five years, including filling out a questionnaire by mail, she said.
Olds said she liked the national study and a sub-study done locally on Asian and Polynesian women because it could help her three daughters and three granddaughters.
Even her three grandsons could benefit from a low-fat diet, she said, "because when I cooked, anybody who was around ate, male or female. It (healthy eating habits) can be passed down in teaching younger children.
"We're responsible for ourselves, and that's what I have to do is take care of myself because I'm not finished singing or storytelling," Olds said. "I'm not finished by a long ways."