Soy protein can be a meal, a side dish, a snack, or a drink. Made from the
soybean, it's a staple of Asian diets. Yet it's largely been the butt of jokes
about hippies and vegans -- until recently. Today, the buzz about soy is
serious. Can it lower cholesterol naturally? Some studies say yes. But,
unfortunately, research shows mixed results. We may not know the answer for
Is the cholesterol in egg yolks the "good" or "bad" kind? Can you "burn" cholesterol by exercising? Which has more cholesterol, a tablespoon of butter or a cup of peanut butter?
Most people know that fat is bad for them, but two-thirds of Americans are confused about how dietary cholesterol differs from fats in your diet.
A number of studies over the past decade seemed to show soy protein could
lower "bad" LDL cholesterol and triglycerides without lowering
"good" HDL cholesterol. Researchers aren't exactly sure how soy protein
might help. It could be a combination of the effect of the protein and natural
chemicals in soy called isoflavones. But in January 2006, the American Heart
Association announced some surprising news. A review of 22 clinical studies
concluded that eating soy-based foods has only minimal impact on cholesterol
and other heart-disease risk factors.
Until further research clears up the controversy, should you dump soy from
your diet? Not at all, says Tufts University nutrition researcher Alice
Lichtenstein, DSc, who helped write the AHA statement. "Soy is a great
food. It is low in saturated fat and it is a good-quality protein," she
says -- even if its heart benefits are less than expected.
Conflicting Evidence on Soy
There have been many studies of the effects of soy on cholesterol. One major article published in
TheNew England Journal of Medicine found that replacing animal
protein with soy protein could lower levels of total cholesterol, bad LDL
cholesterol, and triglycerides. At the same time, it didn't significantly lower
levels of "good" HDL cholesterol.
Some studies have shown
that soy protein, when eaten along with other cholesterol-lowering foods, can
have a big effect. In a study published in the American Journal of Clinical
Nutrition in 2005, researchers tested cholesterol-lowering drugs against
cholesterol-lowering foods in a group of 34 adults with high cholesterol.
People ate 50 grams of soy protein daily along with other cholesterol-lowering
foods. The results were striking: the diet lowered cholesterol levels about as
well as cholesterol drugs.
However, not all studies agree. An
analysis of various studies led by the U.S. Agency for Healthcare
Research and Quality found that soy had a modest effect on cholesterol levels.
Researchers found that eating a high amount of soy -- equal to about a pound of
tofu a day -- only added up to a 3% reduction in "bad" cholesterol
Based on those more recent studies, the AHA Nutrition Committee no longer
recommends eating soy specifically to lower cholesterol. However, the AHA does
consider soy burgers and other soy foods a healthy replacement for high-fat