Review casts doubt on soy health benefits
JAMIE
STENGLE, Associated Press
DALLAS -
Veggie burgers and tofu might not be so great at warding off heart
disease after all.
An American
Heart Association committee reviewed a decade of studies on soy's
benefits and came up with results that are now casting doubt on the
health claim that soy-based foods and supplements significantly lower
cholesterol.
The
findings could lead the Food and Drug Administration to re-evaluate
rules that currently allow companies to tout a cholestorol-lowering
benefit on the labels of soy-based food.
The panel
also found that neither soy nor the soy component isoflavone reduced
symptoms of menopause, such as "hot flashes," and that isoflavones
don't help prevent breast, uterine or prostate cancer. Results were
mixed on whether soy prevented postmenopausal bone loss.
Based on
its findings, the committee said it would not recommend using
isoflavone supplements in food or pills. It concluded that
soy-containing foods and supplements did not significantly lower
cholesterol, and it said so in a statement recently published in the
journal Circulation.
Nutrition
experts say soy-based foods still are good because they often are eaten
in place of less healthy fare like burgers and hot dogs. But they don't
have as much direct benefit as had been hoped on cholesterol, one of
the top risk factors for heart disease.
"We don't
want to lull people into a false sense of security that by eating soy
they can solve the problem (with cholesterol)," said Dr. Michael
Crawford, chief of clinical cardiology at University of California San
Francisco Medical Center.
"If they
are radically altering their diet where they're only eating soy in the
hopes that this is going to bring their cholesterol down, they're
deluding themselves," said Crawford, who was not on the panel that
issued the new statement.
The FDA in
1999 started allowing manufacturers to claim that soy products might
cut the risk of heart disease after studies showed at least 25 grams of
soy protein a day lowered cholesterol. A year later, the Heart
Association recommended soy be included in a diet low in saturated fat
and cholesterol.
But as more
research emerged, the Heart Association decided to revisit the issue.
The committee members reviewed 22 studies and found that large amounts
of dietary soy protein only reduced LDL, or "bad" cholesterol, about 3
percent and had no effect on HDL, or "good" cholesterol, or on blood
pressure.
They did a
separate analysis of isoflavones. The review of 19 studies suggested
that soy isoflavones also had no effect on lowering LDL cholesterol or
other lipid risk factors.
"Soy
proteins and isoflavones don't have any major health benefits other
than soy protein products are generally good foods," said Dr. Frank
Sacks, a professor of nutrition at the Harvard School of Public Health
in Boston who led the committee. "They're good to replace other foods
that are high in cholesterol."
Still, the
Heart Association statement notes that soy products like tofu, soy
butter, soy nuts and some soy burgers should be heart-healthy because
they contain a lot of polyunsaturated fats, fiber, vitamins and
minerals and are low in saturated fat.
"Soy isn't
a magic bullet, but it can be a valuable contributor to a heart-healthy
diet," said Jo Ann Carson, a professor of clinical nutrition at the
University of Texas Southwestern Medical Center at Dallas who was not
part of the panel.
It's
important not to think about foods in black-and-white terms, said Dr.
Michael Lim, director of the cardiac catheterization lab at Saint Louis
University School of Medicine.
"There's no
quick fix," he said. "Our bad cholesterol numbers would certainly get
worse if instead of eating tofu burgers we went out and had hamburgers
each night of the week."
ON THE
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American
Heart Association: http://www.americanheart.org
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