Soy and Your Health

It seems as though there are new soy foods added to the market every day. It’s hard to know which ones we should be adding to our diet and if we should be adding them at all.

I have recently received many questions and/or concerns about soy safety. They include:

I’ve heard soy can cause thyroid problems.

Is soy safe for cancer survivors?

Has soy been shown to cause breast cancer?

I’m approaching menopause and am having horrible hot flashes. My doctor told me to drink soy milk , does it help?

Soy products have recently enjoyed increasing popularity. Soy products include soybeans (also called edamame) and any other items made from soybeans, including soymilk, tofu, tempeh, miso, and vegetarian meat and dairy substitutes like soy meats and soy cheeses. Like most other plant foods, the most healthful choices are those that are minimally processed so they retain all of their original nutrients. Soy foods contain compounds called isoflavones, phytochemicals found to behave like the sex hormone estrogen. But because soy products are so widely consumed, some people have raised the question as to whether they are safe. Let’s take a look at what medical studies show:

Thyroid Health
Clinical studies show that soy products do not cause hypothyroidism. However, soy isoflavones may take up some of the iodine that the body would normally use to make thyroid hormone. The same is true of fiber supplements and some medications. In theory, then, people who consume soy might need slightly more iodine in their diets. (Iodine is found in many plant foods, and especially in seaweed and iodized salt.) Soy products can also reduce the absorption of medicines used to treat hypothyroidism. People who use these medicines should check with their health care providers to see if their doses need to be adjusted.

Other concerns include whether soy has a negative effect on reproductive health. However, studies in both men and women have shown that soy did not hinder reproduction.

Male Hormones
Soy products have no adverse effects on men and may help prevent cancer in men. A study published in Fertility and Sterility, based on more than 50 treatment groups, showed that neither soy products nor supplements that contained soy isoflavones affect testosterone levels in men.

Breast Cancer
Studies have shown that Asian women who have consumed traditional soy products since childhood or adolescence have significantly lower rates of breast cancer. There have also been some conflicting studies on the breast cancer preventing effects of soy. Overall, however, large reviews of studies (called meta-analyses) show that soy consumption either has a beneficial impact on breast cancer development, or no impact, but it does not pose a risk.

Treatment of Menopausal Symptoms
Studies on the benefits of soy isoflavones on various menopausal related symptoms have shown generally favorable improvements in hot flashes.

Evidence to date indicates that soy products do not adversely affect fertility, may reduce the risk of breast cancer and breast cancer recurrence. They do not appear to have adverse effects on the thyroid gland, but may reduce the absorption of thyroid medications. The benefits of soy products appear to relate to traditional soy products, not to concentrated soy proteins.

Eat only organic, non-GMO, traditional soy foods, particularly fermented forms (organic fermented miso, tempeh and Nama Shoyu), as a small part of an overall healthy, plant-based diet.

Eat soy, in moderation, as a small part of an overall healthy, plant-based diet. Soy should only be a complement to your diet, not a mainstay. I generally recommend a maximum of 2-3 servings/week.

Soy Allergy
Soy is a common food allergen. If you are allergic – or even sensitive (you have digestive or other symptoms after you eat it) — avoid it, or work with your primary doctor to see if an elimination diet with later re-introduction is a possibility. Organic, non-GMO soy may be less allergenic.

The Bottom Line

Many people enjoy eating soy products, the key, is balance. While it is possible that there are those who gain substantial health benefits from soy, there may be others who do not. So, if consuming soy worries you, don’t eat it. But remember, many plant-based foods contain similar phytoestrogens.

The best possible suggestion is always to listen to what your body is telling you.


8 thoughts on “Soy and Your Health

  1. Great article Harriet! You’re right there are so many new soy products coming out on the market. I believe people are confused on whether or not it’s safe to eat. You summed it up perfect! (:

  2. Hi Harriet! Great article on soy! So many people ARE confused with all the new convienience products. You were very thorough and summed it up great! Think I will share this on my fb page sometime! 😉

  3. Great article, thank you so much for posting this!!!
    I researched and read a lot about soy after being diagnosed with kidney cancer. My bottom line was exactly your bottom line – I didn’t feel good eating it, so decided not to eat it.
    Thanks again! x

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