Balanced Approach to Obtain the Benefits of Soy

Expert’s Name: Robin Pruitt

Most forms of soy are rich in isoflavones, or plant estrogens. These hormonally-active substances can mimic estrogen in the body, which is why we often hear the advice for women in mid-life to eat more soy products. But does that mean we should all eat as much soy as possible?

There are genuine benefits to soy: it is a superior protein source and is high in cholesterol-lowering phytosterols as well as antioxidants that may reduce cancer risk. And it is true that appropriate amounts of soy isoflavones can have a balancing effect on menopausal hormone levels.

However, there is another side to the soy story.

A number of health practitioners have reported that many menopausal women-and particularly overweight women-have sluggish thyroid function, although this deficiency may not be reflected in the results of the common thyroid blood tests. One of the isoflavones plentiful in soy products, genistein, has been shown to diminish thyroid function if consumed in significant amounts or if the diet lacks sufficient iodine.

Additionally, soy products contain phytates, a family of chemical compounds that make it more difficult for the body to absorb key nutrients such as zinc and iodine as well as calcium, magnesium and iron. Soy also contains a high level of enzyme inhibitors that block the action of digestive enzymes.

So, should we purge our pantries of all soy products? Fortunately, that’s not necessary.

The good news is that when soy products are fermented, the thyroid-disrupting effects of genistein are dramatically reduced. Additionally, fermentation breaks down the enzyme inhibitors and the nutrient-blocking phytates. Cooking is not enough-only fermentation will rid soy products of these negative effects. As a bonus, the fermentation process adds beneficial probiotics that aid digestion and nutrient absorption.

A balanced approach to obtaining the benefits of soy:

  • Eating small amounts of the fermented soy products tempeh, miso and the less familiar natto will provide an excellent source of protein and the benefits of soy’s phytosterols, isoflavones and antioxidants without the negative thyroid-disrupting and nutrient-blocking effects. Note: Natto is rich in nattokinase, an enzyme that can break down blood clots and act as a blood thinner. Therefore, if you’re taking an anticoagulant (blood thinner) such as Coumadin, aspirin, or other medicines or herbs that thin the blood, consult a health professional before including natto in your diet.
  • Don’t overdo it-limit your soy intake to a 4-ounce serving of a fermented soy product 2 or 3 times a week, especially if you’re overweight or have reason to believe that your thyroid function is sluggish.
  • It is advisable to eat organic soy products whenever possible. Most soy grown in the U.S. is genetically modified and is subjected to high quantities of pesticides and synthetic fertilizers.
  • Tofu, edamame, roasted soybeans, soybean flour and soy milk aren’t fermented. Therefore, the thyroid-disrupting and nutrient-blocking properties have not been broken down.
  • Avoid concentrated products such as soy-based protein powders and soy protein isolate due to the high level of thyroid-disrupting isoflavones.
  • Soy sauce and soybean oil are not good sources of valuable nutrients; view them only as condiments.

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