Reducing dietary fat doesn’t cut disease risk -study

By Andrew Stern

CHICAGO (Reuters) – Women who ate less fat and more fruits,
vegetables and grains did not reduce their risk of two types of
cancer or heart disease, though they did show signs of being
healthier, researchers said on Tuesday.

The broad conclusion of the study — that a healthier diet
doesn’t ward off disease — drew criticisms from some experts
who said it could be misinterpreted and taken as an excuse by
some people to eat as much of anything they want.

Editorials accompanying the three related studies published
in the Journal of the American Medical Association pointed to
the relatively healthy population of women in the study, and
noted the women who modified their diets might have cut out
fats found in fish and nuts now known to be healthy components
of the “Mediterranean diet.”

“I encourage people to interpret this with caution because
we have many unanswered questions,” Dr. Jeanette Keith of the
University of Chicago said in a phone interview. She was not
part of the study.

Other outside experts described the large,
multimillion-dollar, government-funded study as the most
definitive to date, upending widely held beliefs that people
can avoid disease by eating healthier foods.

The same Women’s Health Initiative study previously drew
the surprising conclusion that hormone-replacement therapy
carries heightened risks of health ailments such as stroke.

“This large randomized clinical trial provides the most
definitive evidence to date of the impact of a low-fat diet,”
said Dr. Michael Thun of the American Cancer Society.

But Thun cautioned that proponents of low-fat diets could
also draw positives from the findings.

EARLY STAGES

The women on healthier diets did suffer 9 percent few cases
of invasive breast cancer — considered statistically
insignificant — and had 15 percent less estradiol in their
blood, a form of estrogen that raises the risk of breast
cancer. And they had 9 percent fewer self-reported colon
polyps, which are precursors of colon cancer.

“It is important to remember that cancers often take
decades to develop, and we may only be seeing the early stages
of the impact of a low-fat diet intervention on the risk of
colorectal cancer and other diseases,” said study author
Shirley Beresford of the Fred Hutchinson Cancer Research Center
in Seattle.

Nearly 20,000 of the 49,000 women participants, aged 50 to
79, were instructed to reduce dietary fat and to eat at least
five servings of fruits and vegetables daily and six or more
servings of grains. After being followed for a little more than
eight years, they missed the goal of consuming 20 percent of
their calories as fat, instead consuming 29 percent as fat
compared to 37 percent among those who did not change diets.

The small difference in fat intake was evident in the
narrow gap in body weight between the two groups, Dr. Keith
said. In addition, if the women cut out fatty dairy products
they may have reduced their intake of calcium and Vitamin D,
both nutrients known to reduce colon cancer risk, she said.

The impact of a better diet on indicators for heart disease
was mixed, with only slightly lower levels of so-called bad
cholesterol but similar levels of good cholesterol,
triglycerides, glucose and insulin in both groups of women.

Dr. Robert Eckel, president of the American Heart
Association, said diet was just one element of “an integrated
lifestyle program” that should include exercise.

“Just switching to low-fat foods is not likely to yield
much health benefit in most women. Rather than trying to eat
‘low-fat,’ women should focus on reducing saturated fats and
trans fats,” said Marcia Stefanick of the Stanford Prevention
Research Center in California, who oversaw the study.