SOYBEANS TOO MUCH OF A GOOD THING
SOYBEANS: TOO MUCH OF A GOOD THING?
Gabe Mirkin, M.D.
There are so many articles on how soybeans can improve health that
some people eat soybean products at every meal. You shouldn't do
that because too much of anything can be harmful. Mary Enig has
written a very thought-provoking article about soybeans (1), and
while I don't agree with a lot of her conclusions, it does underline
the risk of eating too much of any food.
You have heard us say many times that plants contain chemicals that
make us healthy and chemicals that can harm us. Fortunately for us,
our ancestors picked out plants that contain more good chemicals and
therefore are healthful, and taught us to avoid those that are
poisonous. However, if you eat large amounts of one food, you can
poison yourself, even though reasonable amounts are harmless or
An example is soybeans. Soybeans contain genistein, a weak estrogen
that may help to prevent breast cancer. They contain omega-3 fatty
acids that help prevent heart attacks, and are loaded with fiber
that helps to prevent diabetes.
But soybeans contain trypsin inhibitors that block protein
consumption and hemagglutinin that causes clots to form. It you take
in huge amounts of soybeans, you increase your risk for pancreatic
damage and even pancreatic cancer because the trypsin inhibitors
block protein use and therefore make your pancreas work too hard to
overcome this effect. Huge amounts of soybeans can also make clots
that can form in your heart or lungs. Soy contains goitrogens that
block thyroid function. In small doses these goitrogens do not harm
you, but large doses can slow your thyroid. Soybeans (and many other
plants) also contain phytates, which can block the absorption of
minerals. Nobody has shown that phytates in soybeans are harmful;
this is a theoretical concern.
Dr. Enig is particularly concerned about the widespread use of
infant formula made from soybeans. We have no data yet on the
consequences of feeding plant estrogens to small children. If you
choose to use feed you baby soy milk, cow's milk or any formula
other than breast milk, I recommend that you introduce other foods
as early as possible to add variety to the diet and reduce your
infant's reliance on any single food.
When you hear about the health benefits of any food, don't believe
that you should start eating it to the exclusion of other foods.
Huge amounts of any single food can be harmful. A healthy diet
contains a WIDE variety of fruits, vegetables, whole grains, beans,
nuts and other seeds; and modest amounts of any foods you enjoy.
1) Fallon, Sally, and Mary G. Enig, PhD, Tragedy and Hype: The Third
International Soy Symposium, Nexus Magazine, Volume 7,
No. 3(April-May 2000).