Soybeans are packed with proteins, healthy fats, and nutrients, and nothing that hurts the heart. Some say soy is a miracle food, but others are wondering if that's true.
For years, soy has
been touted as a near-miracle food. Soybeans contain a large amount of protein and nutrients and no cholesterol. Proponents
claim that a diet rich in soy protein can help prevent heart disease, while the
isoflavones contained in soy may help prevent some forms of cancer.
However, some
researchers are beginning to question whether soy really produces so many
health benefits. The U.S. Food and Drug Administration is reviewing its 1999
ruling that a diet including soy protein can reduce the risk of coronary heart
disease, after that claim came under question by the American Heart Association
and other health groups. Also, recent research has undermined claims that soy
isoflavones can prevent prostate or breast cancer.
Soy: What Are the
Benefits?
Soybeans are an
undeniably healthy food for your diet, says Christine Gerbstadt, MD, spokesperson
for the American Dietetic Association. "Soy has a lot of healthy fats,
high fiber, and high protein. There are a lot of good reasons for including one
or two servings every day."
Foods derived from
soybeans, like tofu or soy milk, are good substitutes for animal products that
contain cholesterol. Soy also is rich in healthy nutrients like B vitamins and
omega-3 fatty acids.
Proponents also claim
a number of health benefits, saying soy products can help prevent:
·
Coronary heart disease. The FDA said in 1999
that eating at least 25 grams of soy protein in your daily diet can lower your
total cholesterol as well as your levels of "bad" LDL cholesterol.
·
Cancer. Soy contains large amounts of
phytoestrogens, plant-based chemicals that act like a weak form of the female
hormone estrogen. The most potent phytoestrogens in soy are called isoflavones.
Some research has indicated that these phytoestrogens might help reduce a
person's risk of breast or prostate cancer.
·
Menopause symptoms. Research also has
found that soy-based phytoestrogens might alleviate some menopausal symptoms,
including hot flashes and osteoporosis.
Soy: Drawbacks and
Questions
Despite its positive
nutrients, soy isn’t tolerated by everyone. Many people, particularly children
and infants, can become allergic to soy. When that happens, they will need to
avoid soy completely in their diet or experience an allergic reaction.
In terms of those
health claims, some are now being disputed, or at least questioned. Doctors are
asking whether the phytoestrogens contained in soy might actually promote breast
cancer, Dr. Gerbstadt says. "For some women with increased risk factors
for breast cancer, they might want to watch how much soy they eat," she
says. "It can promote the hormone balance that would be more likely to
promote cancer in some women."
There's also an
ongoing and increasingly contentious medical debate over theheart health claims that have been made about soy. The
FDA is reviewing its 1999 ruling that found a diet including soy protein
effective in lowering cholesterol. The American Heart Association (AHA) asked
for this review, saying the heart health claims may not be supported by strong
evidence.
In its letter, the AHA
said most of the research showed that soy protein in large amounts could lower
LDL cholesterol a few percentage points when it takes the place of meat or
dairy proteins, but only with large amounts of soy. Furthermore, the letter
said, the research was done on people whose cholesterol levels were very high.
Also, the research didn’t show any benefits to blood pressure or HDL, the
“good” cholesterol. Therefore, it concluded, any direct benefit to the heart
was minimal.
Researchers are also
questioning claims related to soy's ability to prevent cancer. For example, a
recently released Canadian study found no evidence that soy could help prevent
prostate cancer in men with precancerous prostate lesions.
The bottom line: Soy
is a great source for certain important nutrients, especially if you avoid meat
and dairy. But consider it just one food of the dozens that make up a balanced
diet.