Top 5 Foods to Avoid Series #2 – Unfermented Soy Products | Robert A. Erickson, M.D.

Soybeans are marketed as a “health food.” I used to eat a lot of soy products, but as I became more educated I discovered soy has a number of dangerous components. The first is phytic acid. All seeds and legumes have this, but not to the extent soybeans contain. Phytic acid binds to needed minerals such as calcium, zinc and magnesium. Even slow cooking does not always adequately break down phytic acid, but long fermentation (6 months to several years) does. So eating natto, miso or tempeh, which are fermented foods, is okay. Soy also contains enzyme inhibitors that reduce protein absorption and processed soy contains nitrates and other chemicals that are carcinogenic (cause cancer).

Soybeans are a genetically modified crop. In 1997, only 8% of the commercially raised soybean crop in the USA was genetically modified. By 2010 this figure was up to 93% (National Agricultural Statistics Board annual report, June 30, 2010). Monsanto company in 1996 introduced “Roundup Ready” soybeans so that their herbicide product “Roundup” could be sprayed on the soybean fields without destroying the soybean crop. The U.S. Department of Agriculture has approved the use of Roundup Ready soybeans, but be aware that the FDA does not monitor or even require labeling of genetically modified foods (GMOs). You are unknowingly buying GMOs in your supermarket. The Europeans either do not allow GMOs or they require that they be labeled.

Our readers should also be aware that modern processed soy products, including soy burgers and soy cheese are not the same as traditional Asian soy. Soybean oil I place in this same category and do not recommend using it (olive oil is a much better choice). It is a common ingredient in commercial salad dressings, so read the label. Most soy products are, by and large, unfermented and this includes tofu and soy protein. These products do not provide the same benefits as fermented soy products. Unfermented soy is also the second most common allergen, so babies who are allergic to cow’s milk and are switched to a soy formula often develop an allergy to the soy formula. Soy milk is high in aluminum, because it is processed in large aluminum tanks.

Soy milk also contains large quantities of phyto-estrogens as do soy infant formulas. The soy isoflavones genistein and daidzein are similar to 17 beta-estradiols, but are 100,000 times weaker in estrogenic activity. Although these isoflavones are weak estrogens, over time, high concentrations of isoflavones in the body can have a significant cumulative estrogenic and toxic effect, especially when they are exposed to organs that have sensitive estrogen receptors sites such as the breasts, uterus, and ovaries. I recommend babies or men do not take soy products with any regularity. If a post menopausal woman needs more estrogen, then fermented soy could be of benefit.

Studies have shown that 30 grams of unfermented soy consumed daily can affect thyroid function and has been linked to auto immune diseases such as Hashimoto’s thyroiditis as well as hypothyroidism.

There are some studies that have shown taking 35-60 grams of soy protein a day can protect the body against breast cancer. This is because genistein acts as a natural aromatase inhibitor and because the very weak isoflavones can occupy estrogen receptor sites in the human body, blocking stronger estrogens such as estrone. On the other hand, there are studies showing that women eating soy had a higher incidence of pre-malignant changes in their body’s cellular structure such as epithelial hyperplasia. Whether soy is beneficial or detrimental to those with estrogen dominance or in breast cancer prevention is controversial. There are safe ways to treat estrogen dominance without using soy products.

The bottom line in this update is if you are going to eat soy products, do so in moderation and only choose fermented soy products.