by Sarah Pope MGA | Updated: Dec 07, 2018 | Affiliate links

Description: Dangers of Soy

With all the loads of scientific data available that soy (even edamame) is not a healthy part of anyone’s diet, it shocks me how many folks are still on the “soy is good for you” bandwagon – even people who should know better like your doctor!

I just got an email from a reader the other day who had been to multiple doctors, both holistic and conventional, and all but one of them were telling her that plenty of soy in her diet would help her menopause symptoms.

I had another shocking conversation recently with a doctor of Internal Medicine who had no idea soy was a potent goitrogenic food and actively suppressed thyroid function.

Be careful folks.  It’s dangerous out there! You really need to do your research and be on your toes at all times when it comes to nutritional advice even from someone in a white coat!



For those of you who just sat down because you are so taken aback by the notion that soy is not actually the healthfood you thought it was, here are 170 scientific reasons to back up this assertion.

Fermented Soy Fine in Small Amounts for Some People

Please note that fermented soy in small, condimental amounts as practiced in traditional Asian cultures is fine for those who have healthy thyroid function. Only miso, tempeh, natto and traditionally brewed soy sauce fall under this category. In addition, if you want to sprinkle a few edamame on your salad or have a few small cubes of tofu in your miso soup from time to time, that is fine too. A little soy lecithin in a nonGMO snack food from time to time isn’t necessarily a problem either. Just don’t make it a regular part of your diet!

If you have any sort of thyroid issues going on, however, it is really the best policy to avoid all soy all the time as soy is a potent goitrogen (thyroid suppressor) even if fermented.

Dangers of Soy #1

A 1991 study found that eating only 2 TBL/day of roasted and pickled soybeans for 3 months to healthy adults who were receiving adequate iodine in their diet caused thyroid suppression with symptoms of malaise, constipation, sleepiness, and goiters (Nippon Naibunpi Gakkai Zasshi 1991, 767: 622-629)!

Still think munching on edamame instead of popcorn is a healthy habit?

Dangers of Soy #2

Six premenopausal women with normal menstrual cycles were given 45 mg of soy isoflavones per day. This is equivalent to only 1-2 cups of soy milk or 1/2 cup of soy flour!   After only one month, all of the women experienced delayed menstruation with the effects similar to tamoxifen, the anti-estrogen drug given to women with breast cancer (American Journal of Clinical Nutrition 1994 Sep;60(3):333-340).

Dangers of Soy #3

Dietary estrogens in the form of soy foods were found to have the potential to disrupt the endocrine system with the effects in women similar to taking the breast cancer drug tamoxifen (Proceedings of the Society for Experimental Biology and Medicine 1995 Jan;208(1):51-9).

Dangers of Soy #4

Estrogens consumed in the diet at low concentrations were found to stimulate breast cells much like DDT to increase enzymatic activity which leads to breast cancer (Environmental Health Perspectives 1997 Apr;105 (Suppl 3):633-636).

Dangers of Soy #5

The soy isoflavones genistein and daidzein appear to stimulate existing breast cancer growth indicating risk in consuming soy products if a woman has breast cancer. (Annals of Pharmacotherapy 2001 Sep;35(9):118-21).

Dangers of Soy #6

Direct evidence that soy isoflavones genistein and daidzein suppress the pituitary-thyroid axis in middle-aged rats fed 10 mg soy isoflavones per kilo after only 3 weeks as compared with rats eating regular rat chow (Experimental Biology and Medicine 2010 May;235(5):590-8).

Dangers of Soy #7

Don’t eat soy when you are pregnant ladies!  Scientific research has shown that the developing male fetus which is exposed to soy phytoestrogens may suffer from higher susceptibility to prostate cancer later in life (Prostate 1994;24(2):67-78).

Dangers of Soy #8

Keep that soy away from your daughters!   Dietary genistein (soy phytoestrogen) in developing female rats had the effect of significantly accelerated puberty (Toxicol Sci 1999 Oct;51(2):236-44).

In addition, early exposure to soy is associated with less female typical play patterns in girls at 42 months of age (Environ Health Perspect v. 119(12); Dec 2011).

Dangers of Soy #9

Hey guys! Soy protein powder strips your masculinity!  A study of 12 men aged 18 years and older experienced a 19% drop in serum testosterone in only 28 days when supplemented with 56 grams of soy protein powder over that same time period (Prev 2007;16:829—33).

Dangers of Soy #10

Do NOT feed soy formula to your babies!  Female newborns who are orally exposed to genisin, the glycosylated form of genistein (soy phytoestrogen) experienced harm to the reproductive system in the form of “delayed vaginal opening… abnormal estrous cycles, decreased fertility, and delayed parturition.” (Environmental Health Perspective 2009 Dec;117(12):1883-9).

More information on the dangers of soy infant formula even if organic can be found in this article.

Convinced yet?   I don’t know about you, but ten reasons is plenty for me!   Still interested to see the remaining 160 reasons?  My friend Dr. Kaayla Daniel, author of the must read The Whole Soy Story, has compiled the rest of the list for you if you click here.

Sarah, The Healthy Home Economist

Sarah Pope MGA

Since 2002, Sarah has been a Health and Nutrition Educator dedicated to helping families effectively incorporate the principles of ancestral diets within the modern household.

Sarah was awarded Activist of the Year at the International Wise Traditions Conference in 2010.

Sarah received a Bachelor of Arts (summa cum laude, Phi Beta Kappa) in Economics from Furman University and a Master’s degree in Government (Financial Management) from the University of Pennsylvania.

Mother to three healthy children, blogger, and best-selling author, her work has been covered by USA Today, The New York Times, National Review, ABC, NBC, and many others.

Posted under: Healthy Living

Comments (365)


Lol the Japanese don’t eat soy as a condiment. They eat plenty of fermented soy, miso, natto, yes, but tofu is a main dish often consumed. Go to their traditional Japanese restaurants or supermarkets and you will find plenty of tofu dishes and packs of tofu being sold. I’m ethic Chinese and we eat tofu all the time and soy milk is sold fresh in markets, and we have many soy milk brands in cartons everywhere. You have these Asians and Japanese come on here and tell you we eat plenty of tofu and you insist that from your visits the Japanese eat small “condimental” amounts. Perhaps you didn’t go to the right places.

March 9th, 2019 1:09 pm Reply

Sarah Pope MGA

The proliferation of soy in processed foods in the Japanese diet is a relatively new phenomenon from just the last few decades. Soy consumption in Japan is traditionally a very small part of the diet in terms of calories. It was small and condimental.

March 9th, 2019 8:45 pm Reply

John Burlingame

Hi, I’m 100% soy/ soy lecithin free not by choice but for me. I have to or it will kill me. A simple whiff of fragrance with soy will give me a brain fog. One Bayer chewable has enough soy lecithin to give me stroke symptoms. A simple handshake can temporarily rob me of my short term memory. I don’t need a cure, there is none for me. Removing from the GRAS would be a start.

March 5th, 2019 1:35 am Reply


I have thyroid or hypothyroidism. I’m eating nutrimeal Usana powder I drink in blender. It contains soy protein isolate as main ingredient. Is that good or bad?

October 12th, 2018 10:12 pm Reply


Any food that contains soy protein isolate should be avoided especially by those who have hypothyroid issues. Here is an article specifically examining that ingredient.

October 13th, 2018 8:11 am Reply

Helen Thomas

I reply to “There is no way a plant can have Estrogenic effect in humans, on the contrary.” This statement is untrue. Soy contains plant oestrogens, that are very close in structure to hormonal oestrogens. The chemical structure (of plant oestrogen) is close enough that cell receptors accept the plant oestrogen structure, boosting the oestrogen levels of the person ingesting soy.

I had severe pre-menopausal symptoms that were completely mitigated by consuming large amounts of soy in my diet (milk, yoghurt, mince etc). A few years later I was diagnosed with an under active thyroid, that was likely caused by hormonal disruptions from consuming soy. I had Hashimoto’s which is the auto immune version and I am now unable to digest gluten, dairy (apart from raw A2 milk and Kefir) egg and soy. It’s taken me 10 years but I am now off my thyroid medication, largely due to healing my gut. So, I’ve been on a long road of ill health, largely caused by consuming far too much soy.

September 20th, 2018 8:33 am Reply


My doctor told me not to eat it after I had uterine cancer.

August 24th, 2018 9:52 pm Reply


Smart doctor!

August 25th, 2018 7:53 am Reply

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