13.   TO EAT OR NOT? - SOY

Many studies have been conducted on the effects of estrogen (and phytoestrogen) on health and the outcome is mixed.  Health benefits include a lowered risk of osteoporosis,  and menopausal symptoms, the downside is that phyto-estrogens are considered endocrine disruptors, indicating that they have the potential to cause adverse health effects including cancers.

Estrogen is a natural hormone found in both men and women.  Estrogens are produced by ovaries, fat tissue,  the adrenal glands, liver and breast tissue (and placenta  during pregnancy).  It influences many physiological   processes including reproduction, cardiovascular health, bone integrity, cognition, and behavior. Although both genders have this hormone, it is found in higher amounts in women and keeping this hormone at a healthy level is  important for both genders.  An excess can cause ‘estrogen dominance’, a condition associated with fibrocystic breast disease, uterine fibroids, breast cancer, endometriosis, infertility problems, endometrial polyps, auto-immune disorders, and menstrual pain, among many others1

Phytoestrogen are naturally occurring substances found in plants (vegetables, fruits, and legumes) that imitate the function of estrogen in the body.  Exposure to phytoestrogen is mainly through  diet.   It is found in a wide variety of foods, most notably soy.   Since it behaves like hormones, too much can alter hormone-dependent tissue functions.

Foods high in phytoestrogens

  •  Legumes, and especially soybeans, they contain isoflavonoids, a type of phytoestrogen.
  • Bran, beans, fruits and vegetables, they contain lignans, another type of phytoestrogen.
  • Peas, pinto and lima beans, they contain coumestan, another type of phytoestrogen.

 Should I take soy products?

The question of whether or not phytoestrogens are beneficial or harmful to human health remains debated - there are many pros and cons associated.   Researchers today are still trying to make sense of these competing findings. 

On the consumption of soy and soy products please be aware of the following:

  • Soy is a rich and primary dietary source of the phytoestrogen class known as isoflavones. Isoflavones are present in relatively large amounts in virtually all soy foods. The primary isoflavones found in soy are genistein and daidzein; these are known endocrine disruptors (chemicals that may interfere with the hormonal system).
  • Its everywhere - Unbeknownst to you, soy products are not only found in soy milk, tofu, tempe and soy oil they are also found in more than 60% of processed foods. Textured soy protein (50 -70% soy protein) is a meat substitute found in ‘imitation vegetarian meat’, hotdogs, hamburgers and other meat products.  Soy protein isolate (90% soy protein) is used in enriched energy bars, sports drinks, infant formula, cereals, imitation dairy products, ice cream2
  • In natural foods, phytoestrogens are present as mixtures and only constitute a small part.
  • Soy isoflavones and other phytoestrogens are also widely available as dietary supplements at far higher concentrations than found in soy-based foods. Excessive consumption of estrogen – rich foods may stimulates tissue growth making it unsafe and very likely to cause ‘estrogen dominance’ syndrome.
  • Cancer may respond to signals from estrogen in the body. Most breast cancers, are estrogen-receptor positive, meaning the  cancer may respond to signals from estrogen in the body   For that reason, we would advise that you stay away from soy and soy products.  We would also recommend that those undergoing treatment for other estrogen dependent cancers like endometrial, colorectal and ovarian to limit your intake of soy. 
  • Estrogen is suspected of being a carcinogen, and various studies have associated it to breast, endometrial, and uterine cancers in women and prostate cancer in men.  
  • 91 percent of soy grown in the US is genetically modified (GM). The genetic modification is done to impart resistance to the toxic herbicide Roundup. While this is meant to increase farming efficiency and and thus a less expensive soy, the downside is that the soy is loaded with this toxic pesticide. The plants also contain genes from bacteria that produce a protein that has never been part of the human food supply.
  • Soy contains goitrogens the substances that block the synthesis of thyroid hormones and interfere with iodine metabolism, thereby interfering with your thyroid function.

Soy infant formula

Do you know that while adults eating a  vegetarian diet or those taking dietary supplements containing phytoestrogens have high levels of exposure, infants drinking soy-based formula have the highest exposure levels by far.   In most cases, the soy formula is the only source of nutrition for these infants during their first few months of life. The infants, then, are exposed to 10 times greater concentrations of phytoestrogens than adult vegetarians and infants fed soy formula have up to 20,000 times the amount of estrogen in circulation as those fed other formulas!

 Limit Xeno Estrogen Exposure — Estrogen is not only produced naturally in the body, we also get a lot of “natural” estrogens known as ’Phytoestrogens’ from foods we eat as well as our exposure to the synthetic chemicals which acts like ’estrogen’ called ’xeno estrogen’ - all these are ‘endocrine disruptors’.   Avoiding chemical estrogens is one of the most important strategies for preventing cancer and protecting yourself.  Chemical estrogens are everywhere and can come from plastics like BPA, petroleum based products,       detergents, cosmetics (parabens), furniture, carpeting and on our food from agriculture chemicals like pesticides, herbicides and fungicides. 

 Our recommendations

As has been highlighted before, there are currently differing opinions about the role of phytoestrogens in health.   Soy can be healthful, but ONLY if it is organic and properly fermented.  We would like to emphasize that should you wish to consume soy, it should be non-GMO, organic and preferably fermented such as tempeh, natto and miso, and be eaten as part of a  balanced and varied diet.  Many people make the mistake of ‘overeating soy’ as it is often promoted as a healthy protein alternative for people who would rather not eat meat.  it is important not to focus on a single food or nutrient and moderation is key.  Make your dietary choice accordingly.

Listed below are fermented soy products you can find:

  • Tempeh a fermented soybean cake with a firm texture and nutty, mushroom-like flavor.
  • Miso, a fermented soybean paste with a salty, buttery texture (commonly used in miso soup).
  • Natto, fermented soybeans with a sticky texture and strong, cheese-like flavor.
  • Soy sauce, which is traditionally made by fermenting soybeans, salt and enzymes; be wary because many varieties on the market today are made artificially using a chemical process.

Please note that tofu is NOT on this list. Tofu is not fermented.

One of the main benefits of fermented soy, especially natto, is that it is the best food source of vitamin K2. Vitamin K2 is essential to preventing osteoporosis, cardiovascular disease, and diseases of the brain such as dementia, and protecting you from various cancers including prostate, lung, liver cancer and leukemia. Vitamin K acts synergistically with vitamin D to keep you healthy. Vitamin K is sometimes referred to as the "forgotten vitamin" because its benefits are often overlooked. It was named after the word "Koagulation," to reflect its essential role in blood clotting. In fact, the enzyme nattokinase—derived from natto—is safer and more powerful than aspirin in dissolving blood clots, and has been used safely for more than 20 years3.

 Note: Soy has been eaten for a long time in China and Japan.  It was the organic and non-GMO type — and not the concentrated type like the textured soy protein.   During that time people eat small amounts of whole non-GMO soybean products, modern diet on the other hands are mainly processed into two - protein and oil. And there is nothing natural or safe about these products.  The skyrocketing cancer incidence in China is a more recent phenomenon and is likely associated with modern day GMO soy, corn, wheat, concentrated isolates  in  addition to other risk factors concurrent with industrialization.  



You can read more on estrogen at:

  1. Estrogen Dominance
  2. The pros and cons of phytoestrogens Heather B. Patisaul and Wendy Jefferson Department of Biology, NC State University, Raleigh, NC 27695, United States



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