Most people today view soybeans as a health food extraordinaire.  But lately you may have seen conflicting opinions as to whether it is healthy or not.  As a common food allergen that is high in goitrogens¹ (substances that interfere with thyroid hormones), there are some valid concerns.

So, should you eat tofu and other soy foods or leave them alone?

Like any food, there are pros and cons, and soy is neither good nor bad. Clearly, Asians have consumed it safely and healthily for centuries, but they also consume a lot of fish and seaweed, foods that are high in iodine and protect the thyroid. When it comes to soy, your individual health situation and other foods consumed in the diet affect how healthy soy will be for you.

Let’s look at the pros and cons of eating soy.

Why Soy Can Cause Serious Health Problems
We had a patient at LMI who was a breast cancer survivor.  Thinking it was better for her health, she had become vegetarian and was eating a lot of soy.  But despite that, she was overweight and her energy was poor.  In addition, she had developed severe arthritis, and was moving toward needing knee replacements.

After a thorough workup, we found that she had low thyroid and had developed an allergy to soy, as well as to wheat and cow’s milk.  After eliminating these foods and working to restore her gut integrity, she was eventually able to eat small amounts of wheat or dairy, but not soy — even eating a small amount would cause severe pain.  The allergy alone meant she should avoid soy, but given her low thyroid, soy would also interfere with her thyroid hormones.

This patient exemplifies the two conditions in which soy is contraindicated and would not be healthy.  Simple testing will tell you if you have either of these issues, and if you do, you should avoid soy foods.

Why Soy Can Be Health Protective
Soy isoflavones are weakly estrogenic, which means they bind to your estrogen receptors and in so doing, they may protect you from strongly estrogenic substances like xenoestrogens (chemicals in the environment that promote breast and prostate cancer).

For example, one study which surveyed breast cancer survivors found that those who consumed soy isoflavones in the diet had lower levels of cancer recurrence compared to those who did not consume them.² Reduced risk of breast cancer was found when soy isoflavones were consumed at levels comparable to those in Asian populations.

A similar trend has also been observed with men and prostate cancer.³ One study found that the highest intake of soy foods reduced the risk of prostate cancer in men by 40%.⁴

What Can We Conclude About Soy?
For people with an underactive thyroid or soy allergy, soy is not at all a healthy food.  But if there are no contraindications, soy foods can be eaten moderately and will probably provide health benefits.  To get the most out of soy, it’s a good idea to make sure you get enough iodine from fish and kelp and supplement with probiotics.

References

1. www.encyclopedia.com/doc/1039-goitrogens.html
2. Guha N, Kwan ML et al. Breast Cancer Res Treat. 2009 Feb 17.
3. Park SY, Wilkens LR et al. Br J Cancer. 2009 Jun 16;16(6).
4. Cancer Epidemiol Biomarkers and Prev. 2007. 16(3): 538-45.

[Ed. Note: Laura B. LaValle, RD, LD is presently the director of dietetics nutrition at LaValle Metabolic Institute.   Laura and her husband, Jim LaValle, R.Ph, CCN, ND have developed the powerful and life-changing Metabolic Code Diet – containing step-by-step, easy to follow recommendations for harnessing optimal metabolic energy and turning your body's chemical make up into a fat-burning furnace.  To learn more click here now.]

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