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 o 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."
