Soybeans: Too Much of a Good Thing?

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 beneficial.

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).

Checked 3/15/19

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