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Health Dangers of (Unfermented) Soy

  • Published on: 22 September, 2014
  • Last update: 10 August, 2017

LET’S TALK ABOUT SOY. When it first blew up as a “health food” in the 1990s, advertisements and veggie burger packages touted claims of lowered cholesterol and cancer prevention. Twenty years and a ton of controversy later, we’re finding out what it really does to our health.

Many people consume soy and soy milk as an alternative to animal products, while others enjoy edamame every now and then at their favorite sushi spot. Some of us ingest it consistently and unknowingly, since “soy lecithin” is used as an emulsifier in everything from candy bars to salad dressing – even tea bags! (Ahem, I’m looking at you Celestial Seasonings).

So, what’s the verdict? Is soy some magical health food or an over-consumed fad that could be harming us in the long run? Unfortunately, the answer seems to be the latter.

Soy is linked to digestive problems, thyroid dysfunction, cognitive decline, reproductive disorders, and so much more. This is because it contains a high amount of naturally occurring toxins. All legumes (meaning all soybeans, beans, lentils, peanuts, peas, etc.), grains, and nuts inherently contain built-in toxins, such as phytic acid. This is why you should always soak and sprout legumes, grains and nuts before eating them! Phytic acid forms insoluble complexes with calcium, zinc, iron, and other nutrients, which prevents them from being absorbed by the body. Soaking and sprouting foods containing phytic acid will greatly reduce its presence.

Simple answer, right? Not exactly. It turns out that sprouting works for everything…. except soy. Soy takes long, slow fermentation to be consumable, and was always traditionally prepared this way in Asian dishes such as miso, natto, and tempeh. The soy that is found in modern food products is unfermented and still chock full of phytic acid and harmful compounds.

Top 5 Reasons to Avoid Soy

1. Anti-nutrients: In the introduction to this post, I mentioned phytic acid, which is a major offender on the anti-nutrient list. Anti-nutrients are substances to which we are all exposed through food and water that antagonize the nutrients needed for health. Some anti-nutrients bind to other nutrients, making them useless. Others tie up enzymes needed for digestion and other bodily functions. Some cause problems by creating a greater need for nutrients that would otherwise be readily available. High levels of phytic acid in soy specifically reduce assimilation of calcium, magnesium, copper, iron and zinc. Zinc is called the intelligence mineral because it is needed for optimal development and functioning of the brain and nervous system.

2. Soy phytoestrogens disrupt endocrine function and have the potential to cause infertility and to promote breast cancer in adult women. The estrogen-like compounds in soy, called isoflavones, actually work against the body’s natural systems, and can aid in the progression of thyroid diseases. Isoflavones act as the plant’s natural pesticides, causing insects to become sterile. Research has shown that isoflavones can prevent ovulation and stimulate the growth of cancer cells. They have also been shown to cause reproductive problems, infertility, thyroid disease and liver disease in mice, rats, cheetahs, sturgeon, quail, sheep, pigs and marmoset monkeys.

3. Goitrogens. Soy contains heavy amounts of thyroid-suppressing goitrogens. Anyone who regularly consumes soy must make sure they are consuming sufficient iodine to balance everything out. However, goitrogens naturally block the absorption of iodine, so even this may not suffice. 96% of the population is severely deficient in iodine to begin with, so adding soy/goitrogens to the mix is quite counterproductive. Other foods that contain goitrogens (in lesser amounts) are broccoli, brussels sprouts, cabbage, cauliflower, kale, etc. Be sure to lightly cook these foods before consuming them to minimize/inactivate goitrogenic compounds, and as always, everything in moderation! I would much rather spend my daily goitrogen allowance on broccoli instead of tofu.

4. Genetic Modification. Nuff said. 93 percent of soy is genetically modified and it is one of the most pesticide-contaminated foods grown in the U.S.

5. Trypsin Inhibitors & Hemagglutinin. The trypsin inhibitors (growth inhibitors) in soy interfere with protein digestion as well as enzyme production, and may cause pancreatic disorders. The lack of enzymes creates digestive stress which leads to intestinal permeability – hello leaky gut! Soy also contains hemagglutinin, a blood clot-forming substance. Some of these compounds, however, can be deactivated during the process of fermentation. The Chinese did not include soy in their diets until they learned to properly ferment it – and I guarantee you 99% of the soy you’ve eaten in your life was not fermented.

In conclusion, avoid un-fermented soy like the plague! Traditionally fermented Asian dishes like Natto are great in moderation, and can provide much-needed K2 to vegan diets.

To read more about soy, please see Weston A. Price‘s extensive collection of articles and resources.

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Hi Olivia, I have a question for you. My friend recently adopted a newborn, she got breastmilk from several nursing moms for his first 6weeks but supply is running low and it’s time for formula. Clearly soy is out of the question. What formula do you and Lilly recommend? Thank you!


I do not believe this is a very factual or well researched article. You say soy will increase ones chance of breast cancer when in fact it’s quite the opposite.. I’ll jus leave this here.. From a real doctor who references scholarly articles at the bottom of all his..



You can believe what you like, but I stand behind my factual article which mentions phytic acid, isoflavones, and goitrogens — complete with linked sources. 😉

carrie arsenault

I've switched to Bragg's Liquid Aminos…but do I really have to give up my edamame if it's non-gmo and organic? Please say no…please say no….but I will if I HAVE to. 😛


Almond milk would be an alternative?

Olivia A.


Yes! If you are eating a vegan diet, homemade almond, hemp, or any other nut/seed milk is wonderful. Try to soak and sprout the nuts before eating them or making milk. I have a blog on how to do that here: If you do not follow a vegan diet and do not have an allergy to milk, RAW organic pastured goat's milk is an

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