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Everything We’ve Been Told About the Health Benefits of Soy Is Wrong

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If asked, most people would probably say that they consume soy when they eat edamame, tofu or soy sauce. That answer would be correct, but incredibly limited. The truth of the matter is that soy is in nearly everything that we eat.

Do you eat cereal or crackers? Soy’s probably in there. Do you try to avoid dairy products? It’s likely that they’re substituted with soy. Have you had gravy from the store? Yep, it has soy. Do you give your baby formula? If so, they are also digesting soy.

There’s little wonder then, that “what was once a minor crop, listed in the 1913 US Department of Agriculture (USDA) handbook not as a food but as an industrial product, now covers 72 million acres of American farmland1,” Dr. Mercola explains.

At this point, you may be thinking, so what? Soy is probably a vegetable or something; so it’s likely good for you. It turns out, everything we’ve been told about the health benefits of soy is wrong.

an image from Setsubun mamemaki
Print shows family members eating soybeans in a room and a man, with a box of beans, appears about to toss a handful into the room; scene taking place during the annual soybean throwing festival to expel demons from the dwelling. Courtesy: Library of Congress

In this article, we will try to explain what soy really is, and why it’s not so good for us. We will also uncover why you’ve probably never heard about why soy is unhealthy, and why we’ve been led to believe otherwise (hint: could it be because most of the studies on soy are funded by the multi-billion dollar soy industry?)

What Is Soy?

Discovered as early as 9,000 BC, soy is a legume that comes from Asia. Soy was not intended to be a food at first, though, and was primarily used to promote soil quality during crop rotation. When it was planted in between cycles of other crops, it helped retain nitrogen in the soil, which is needed to promote plant life. Once fermentation was discovered, the soybean was used to ferment soy sauce, miso, natto and tempeh, which was when soy became a part of the Chinese diet.

Soybeans and edamame, which are immature soybeans, are examples of unprocessed soy, but only edamame is popular in the U.S.

RELATED: The Hidden History of Why Vegetable Oil Is in Your Kitchen Will Shock You

Soy is popular around the world because it can be eaten whole, or can be processed in different forms, which is why it’s so prevalent in processed foods. Soy can be chemically processed into a powder, made into a beverage or turned into soy fiber. This is the main reason why you can find soy in many foods, condiments and beverages.

How Did Soy Become Popular in the U.S.?

How did a crop that is not native to the U.S. become its biggest export in the 1950s? It’s actually an interesting story!

an image of Raking soybean hay, Lake Dick Project, Arkansas
Raking soybean hay, Lake Dick Project, Arkansas. Courtesy: Library of Congress

The person some historians claim is responsible for bringing soy to the U.S. is a farmer named Samuel Bowen. Bowen tried to grow soy on his farm in Atlanta, Georgia in 1765 in order to make soy sauce. But he wasn’t the only one. There are records of Civil War soldiers trying to brew makeshift coffee from soy. Soy has also been used as a wheat flour substitutive to bake bread for diabetics and even as cattle feed.

Car-manufacturing mogul Henry Ford was also a notable soy enthusiast. Ford directed his employees to make an automobile using plastics made from soy. Even Ford himself made a suit made from soy plastics.

A 1946 Ford advertisement describing Ford's commitment to using agricultural products for industrial use.
A 1946 Ford advertisement describing Ford’s commitment to using agricultural products for industrial use. The Henry Ford/CC BY-NC-SA 2.0

Even before the 21st century, the U.S. had a wide range of uses for soy, which is why it was called “the magic bean” and “miracle crop.”

In 1904, agricultural scientist George Washington Carver discovered that soy was a source of plant protein. This was great news during World War I when meat was scarce, and soy was able to substitute meat protein. The U.S. government sent envoys to China to learn about tofu, and the USDA even worked on developing soy recipes, but Americans found it difficult to cook with and were not quite sure what to do with soy.

Then, God came into the picture — or the Seventh Day Adventist Church to be exact.

“It ran a number of health sanitariums and colleges,” explains Matthew D. Roth, assistant director of the Andrea Mitchell Center for the Study of Democracy at University of Pennsylvania and author of the book Magic Bean: The Rise of Soy in America2. “These institutional customers for imitation meat and milk products provided a steady source of income to Adventist food factories, which also then supplied a network of health-food stores which grew beginning in the 1930s. Adventists started offering canned green beans in the 1910s, imitation soy meats in the 1920s and soy milk in the 1930s.”

During the Great Depression and World War I and II, commodities were scarce, and food manufacturers began to refine soy and add it to foods as a fat. That was the birth of soy as a “hidden ingredient” in much of American food and other products.

“The chemical characteristics of its oil allowed a great variety of uses, including in cooking, margarine, soap, dynamite, plastics, candles, paint and varnishes, and waterproof fabrics,” according to a source3.  “The soybean could also make an excellent animal fodder and fertilizer.”

an image of Raking soybean hay, Lake Dick Project, Arkansas
August Feck and a load of soybean hay. Feck’s three hundred twenty acre farm near Templeton, Indiana. Courtesy: Library of Congress
an image of a soybean farm in Kansas
Emporia, Kansas. Passing the Kansas soybean mill inc. on an Atchison, Topeka and Santa Fe train. There are fifty storage bins, each holding 2800 bushels. The plant processes soybeans for oil and feed. Courtesy: Library of Congress

“Soy was becoming a major part of the American diet, providing a rapidly growing share of the fats Americans ate and an underpinning to the meat industry,” Roth says. “But in its journey from farm to fork, soy lost its identity, refined into generic salad oil or margarine or transformed, by way of livestock, into pork, chicken, beef and milk.”

In 2018, soy was produced by more than 300,000 farmers across the U.S., and it’s ranked as one of the top 10 crops in America.

“In the 1980s, tofu built a reputation as a cholesterol-free meat and milk alternative among health-obsessed yuppies, who flocked to Tofutti and similar products,” Roth continued. “By the 1990s, the discovery of phytochemicals in soybeans – thought to combat certain forms of cancer – lent soy, itself, the aura of healthfulness, helping to drive a market in soy milk, soy-protein bars and a growing array of health foods.”

an image of A soybean field ready for harvesting in late summer in Carroll County, Indiana
A soybean field ready for harvesting in late summer in Carroll County, Indiana (2016). Courtesy: Library of Congress

What Foods Contain Soy?

It’s easy to identify soy in certain foods and supplements, such as miso soup and soy protein. However, it’s much more difficult to identify soy in other products, such as:

  • Meat Alternatives
  • Sauces
  • Breaded Foods
  • Meat Products with fillers
  • Tempeh
  • Baking Mixes
  • Canned Fish and Meat
  • Gum
  • Seasoning and Spices
  • Protein Bars
  • Frozen Dinners
  • Ice Cream
  • Vitamins

The list goes on, and on and on. If you are concerned about the amount of soy you may be consuming, learning the many ways soy is labeled on food products is important. Nutritional labels should be easy to read because of allergy concerns, and some will clearly state “Contains Soy” in the list of ingredients.

an image of contains soy
It’s important to read nutrition labels to spot unwanted ingredients.

Unfortunately, that is not always the case, especially since the U.S. Food and Drug Administration (FDA) doesn’t consider highly refined soybean oil and soy lecithin to be allergens, and products that contain them may not clearly label soy as an ingredient.

Here are the top ingredients that will make it clear that a food contains soy 4:

  • Edamame
  • Kinako flour
  • Kyodofu (freeze-dried tofu)
  • Lecithin (sometimes in cooking sprays)
  • Miso
  • Monoglycerides
  • Diglycerides
  • Natto
  • Okara (soy pulp)
  • Shoyu
  • Soybean
  • Soy sauce
  • Soya
  • Supro
  • Tamari
  • Tempeh
  • Teriyaki sauce
  • Textured soy flour (TSF)
  • Textured soy protein (TSP)
  • Textured vegetable protein
  • Textured vegetable protein (TVP)
  • Tofu
  • Yakidofu
  • Yuba

What Other Products Contain Soy?

Many consumers are shocked to discover that soy is added to products that are not foods. Soy is added to:

  • Makeup
  • Skin Products and Soaps
  • Medication

Therefore, you may not only be putting soy in your body, but also on your body, which amounts to a whole lot of soy you are consuming without ever realizing it.

The Negative Health Impacts of Soy

Soy contains isoflavones, a type of plant estrogen, which the body turns into phytoestrogens, which mimics the effects of estrogen in the body. Estrogen consists of steroid hormones that are responsible for helping women develop female characteristics and the development of the female reproductive system.

MORE: Here’s How Flaxseed Are Destroying Your Endocrine System

Soy isoflavones, especially the two main ones, genistein and daidzein, can bind to estrogen receptors in the body and lead to estrogenic activity. This simply means that it can create more estrogen than a body needs (especially men, who have very low levels of estrogen in their body), or hinder the creation of minimal levels of estrogen.

Many factors may influence the effect soy has on the body 5, such as:

  • Ethnicities: Different ethnic groups may digest soy differently; and it may be more beneficial for ethnic groups who are prone to eating the most soy, such as Asians
  • Type of Soy: Natural or processed soy affect the body in different ways
  • Existing Hormone Levels: Existing levels of hormones may react differently to the same type of soy; so pregnant and pre-menopausal women may not be affected by soy in the same way.
Planavin Cotton Soybean Herbicide Shell 1968 Original Vintage Advertisement via Amazon

Health Concerns About Soy

Remember this fact6 — the Chinese never ate unfermented soybeans because they believed they contained a large amount of “anti-nutrients.”  Could the Chinese have been right about this “miracle crop” that is so widely used in American foods today? Many scientists and medical professionals agree with this ancient wisdom, and warn the public against consuming soy because they believe it can lead to a myriad of health concerns.

Soy and GMO

Over 90% of soy grown in the U.S. is genetically modified (GMO). This means that its seeds are modified to withstand diseases and pests and increase crop yield. The problem is that more and more evidence is becoming apparent that GMO crops pose big health risks to those that consume them.

World renowned biologist Pushpa M. Bhargava reviewed over 600 scientific journals, and concluded7 that genetically modified organisms are largely responsible for “the sharply deteriorating health of Americans.”

The Cornucopia Institute 7 explains that “there is more than a casual association between GM foods and adverse health effects … The strength of association and consistency between GM foods and disease is confirmed in several animal studies.”

Health concerns caused by GMO include:

  • Immune problems
  • Faster than usual aging
  • Disruption in insulin regulation
  • Changes to major organs
  • Gastrointestinal system problems
  • Infertility

Soy Adversely Affects Pregnant Women, Fetuses, Babies and Children

Aside from pregnant women, the ones most at risk for adverse health effects from eating soy are those that have no control over it: fetuses, babies and children. The Cornucopia Institute reports on a study that had the most grim outcomes when pregnant rats were fed a diet full of GM soy, and most of their babies died within three weeks of being born. The ones that survived were very small in size and had reproductive problems later in life. As a comparison, the control group of rats that were fed non-GMO soy only had 10% of their litter die.

IN-DEPTH: What It Means to Have a Hormone Imbalance

GMOs are not only bad for females, however, as they affect males as well. The Institute cites studies where animals who were fed GM soy had their testicles change color and had lower sperm count.

Soy Disrupts Estrogen Levels

Phytoestrogens from soy can either activate or inhibit estrogen receptors ERalpha and ERbeta, which may induce or inhibit estrogen action and signaling8, which may disrupt the endocrine system. What does this mean in laymen’s terms? That soy messes with the levels of estrogen in our body that can interfere with the production of hormones that control:

  • Metabolism
  • Tissue Function
  • Reproduction
  • Sleep
  • Growth Development
  • Mood

Two studies9 10 found that non-steroidal estrogens in soy caused changing to the menstrual cycle by either prolonged or delaying in healthy women.

an image of bacon v tofu
A novelty product that depicts the positive buzz around soy and tofu. Courtesy: Creative Commons

Soy Causes Thyroid Issues

The thyroid is a small gland in the neck that is shaped like a butterfly. Although it’s small; the thyroid is mighty as it controls our hormone levels. Many, many studies have reported that soy can cause problems with the thyroid and prevent the absorption of synthetic thyroid hormone, which wreaks havoc on our entire body.

One study11 confirmed these findings and discovered that soy may cause goiters (abnormal enlargements of the thyroid glands) to develop in completely healthy people, as well as cause hypometabolic symptoms (malaise, constipation, sleepiness).  These changes were evident after only three months of consuming soy, but disappeared after the diet was stopped for one month.

Soy-based formulas given to babies may cause autoimmune thyroid disease in children; a study12 found that 31% of babies that were fed soy formulas developed this condition, while only 12% of their siblings who did not consume soy in infancy developed this disease. As many soy-based formulas are available on the market for babies who are either allergic of sensitive to dairy, it’s vital that parents discuss health concerns with their pediatricians before choosing this option.

Reproductive Consequences for Females

A study13 of pregnant and lactating rats found that consumption of soy phytoestrogen had long term consequences on the reproductive development of their babies. “Soy milk exposure induced a significant increase in progesterone receptor (PR) in the uterine glandular epithelium of the 2-month-old pups,” the study found. “In pregnant dams… PR expression in the uterine glandular epithelium … was also significantly increased. Diethylstilbesterol (DES) also stimulated uterine PR expression only in the glandular but not luminal epithelial cells.”

Hamsters didn’t fare much better with soy — Russian biologist Alexey V. Surov 15 reports that the third generation of hamsters who were fed soy stopped being able to reproduce altogether.

Another study14 observed mice that consumed phytoestrogen and found that they had “statistically significant decreases in the number of live pups over time with increasing dose.” Additionally, the mice had “abnormal estrous cycles, altered ovarian function, early reproductive senescence, and subfertility/infertility at environmentally relevant doses.”

Soy Lowers Testosterone in Males

While there is a lot of research that shows how soy can adversely affect female health and reproductive function, males are not exempt from the side effects. A study16 of male monkeys who were fed soy-based formula reported that they had significantly lower levels of testosterone. After 35-45 days on the formula, testosterone levels dropped by as much as 70%.

NOW: These 6 Nutrients Help Restore Testosterone

Why is this important? Because testosterone is a vital male sex hormone that leads to the development of sperm, bone density, muscle strength and sex drive. The results of study17 on adult males that were part of sub-fertile couples confirmed these findings when they observed that soy lead to lower sperm concentrations.

There Is a Link Between Soy and Breast Cancer

Another frightening affect of soy is that it may cause various types of cancers. A study17 showed that main phytoestrogens in soy cause an increase in MCF-7 breast cancer cells. A study18 on mice also found that estrogenic soy isoflavones caused breast cancer cells to grow, but removal of the isoflavones from the diet caused the tumors to regress. This is important because breast cancer is “the leading cause of cancer death among females, accounting for 23% of the total cancer cases and 14% of the cancer deaths19.”

A vintage poster depicts the need nation’s sentiment around soybeans in 1944.

Problem with Studies on Soy

If you Google the term “soy,” most of the results will show articles and studies touting the benefits of soy. While soy may have potentially positive benefits, there is ample evidence that they may come with some pretty serious consequences.

Why aren’t the adverse health concerns as widely reported or known by the general population? Possibly because many of the studies on soy are sponsored by the manufacturers of this food.

All soybean producers must pay an assessment — which amounts to about $80 million dollars per year — to support the United Soybean’s program to “strengthen the position of soybeans in the marketplace and maintain and expand domestic and foreign markets for uses for soybeans and soybean products20.”

On top of that, soybean councils from seven states add $2.5 million, and companies such as Archer Daniels Midland add more on top of that21.  All of this money is used to pay public relations companies and government lobbyists to secure positive regulations and news about the benefits of soy.

There is so much money backing soy that they even managed to “buy” the Federal Food & Drug Administration (FDA). Although the FDA has a very rigorous approval process, they took quite a few unprecedented turns when it came to soy, as Dr. Mercola1 explains.

They rewrote the original claim submitted by Protein Technology International, which originally “requested a health claim for isoflavones, the estrogen-like compounds found plentifully in soybeans, based on assertions that only soy protein that has been processed in a manner in which isoflavones are retained will result in cholesterol lowering. The FDA actually removed “any reference to the phyto-estrogens and substituting a claim for soy protein – a move that was in direct contradiction to the agency’s regulations. The FDA is authorized to make rulings only on substances presented by petition.”

This was quickly done because researchers and scientists presented evidence that isoflavones are toxic and has very serious side effects. However, the FDA chose to side with the evidence from a meta-analysis sponsored by, you guessed it, Protein Technologies International! The problem with a meta-analysis, especially one funded by the very organization that seeks certain results, is that they can include and leave out any studies they want. And, it was quickly found, that they did leave out studies1.

What Can You Do?

Unfortunately, it has been proven time and time again that we cannot rely on “experts” to have our best interest at heart. Big money plays a big role in America, and companies are often able to steer both science and legislation in their favor, despite some protest.

RELATED: Corporate Food Is Slowly Stealing Your Health

It is up to the individual to learn about what they are eating and what is inside their foods. The first step is to learn how to properly read nutrition labels. Know the different names for soy and look for them when purchasing common food products, vitamins and medications. You will be shocked once you see how often soy products come up in your favorite items.

If you choose to eat soy (come on, we all want a little soy sauce on our sushi), opt for organic and GMO-free soy. Although it will still have some not-so desirable consequences, at least you won’t be getting the additional toxins from the GMO seeds.

If you love soy, consider eating fermented soy, which has a host of nutritional value. It helps our bodies absorb nutrients, and the probiotics in this type of soy introduce good bacteria that promotes positive gut and digestive health. No wonder the Chinese only ate fermented soy and stayed away from other types!

Citations and Sources

1.
Newest Research on the Dangers of Soy. Mercola.com. https://www.mercola.com/article/soy/avoid_soy.htm. Accessed May 6, 2019.
2.
Seven J, Remsburg/VW Pics/Getty Images E, Henry Ford/CC BY-NC-SA 2.0 T, Paradigm/Getty Images A. How a Chinese Crop Became an American Winner. HISTORY. https://www.history.com/news/soybean-china-american-crop-tariffs. Published September 25, 2018. Accessed April 30, 2019.
3.
köln frankfurt sunzinet typo3 und reddot programmmierung internetagentur. The Soybean in Global Perspective, 1900–1950. ghi-dc.org. https://www.ghi-dc.org/research/staff-research-projects/prodoehl/the-soybean-in-global-perspective-1900-1950.html?L=0. Accessed April 30, 2019.
4.
Soy Allergies: Spotting Problems on Food Labels. WebMD. https://www.webmd.com/allergies/soy-allergies-food-labels#1. Accessed April 29, 2019.
5.
Straight Talk About Soy. The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/soy/. Published August 6, 2018. Accessed April 29, 2019.
6.
Newest Research on the Dangers of Soy. Mercola.com. https://www.mercola.com/article/soy/avoid_soy.htm. Accessed April 30, 2019.
7.
Genetically Modified Foods Pose Huge Health Risk – Cornucopia Institute. Cornucopia Institute. https://www.cornucopia.org/2009/05/genetically-modified-foods-pose-huge-health-risk/?gclid=EAIaIQobChMIxrCBiaSH4gIVFMJkCh0dKg_AEAAYAiAAEgJFUfD_BwE. Published May 22, 2009. Accessed May 6, 2019.
8.
Mueller S, Simon S, Chae K, Metzler M, Korach K. Phytoestrogens and their human metabolites show distinct agonistic and antagonistic properties on estrogen receptor alpha (ERalpha) and ERbeta in human cells. Toxicol Sci. 2004;80(1):14-25. https://www.ncbi.nlm.nih.gov/pubmed/15084758.
9.
Watanabe S, Terashima K, Sato Y, Arai S, Eboshida A. Effects of isoflavone supplement on healthy women. Biofactors. 2000;12(1-4):233-241. https://www.ncbi.nlm.nih.gov/pubmed/11216491.
10.
Cassidy A, Bingham S, Setchell K. Biological effects of a diet of soy protein rich in isoflavones on the menstrual cycle of premenopausal women. Am J Clin Nutr. 1994;60(3):333-340. https://www.ncbi.nlm.nih.gov/pubmed/8074062.
11.
Ishizuki Y, Hirooka Y, Murata Y, Togashi K. [The effects on the thyroid gland of soybeans administered experimentally in healthy subjects]. Nihon Naibunpi Gakkai Zasshi. 1991;67(5):622-629. https://www.ncbi.nlm.nih.gov/pubmed/1868922.
12.
Breast and soy-formula feedings in early infancy and the prevalence of autoimmune thyroid disease in children. Taylor & Francis. 10.1080/07315724.1990.10720366″ target=”_blank” rel=”noopener noreferrer”>https://www.tandfonline.com/doi/abs/10.1080/07315724.1990.10720366. Accessed May 6, 2019.
13.
Hughes C, Liu G, Beall S, Foster W, Davis V. Effects of genistein or soy milk during late gestation and lactation on adult uterine organization in the rat. Exp Biol Med (Maywood). 2004;229(1):108-117. https://www.ncbi.nlm.nih.gov/pubmed/14709783.
14.
Jefferson W, Padilla-Banks E, Newbold R. Adverse effects on female development and reproduction in CD-1 mice following neonatal exposure to the phytoestrogen genistein at environmentally relevant doses. Biol Reprod. 2005;73(4):798-806. https://www.ncbi.nlm.nih.gov/pubmed/15930323.
15.
Genetic Roulette by Jeffrey M. Smith at Chelsea Green Publishing. Chelsea Green Publishing. https://www.chelseagreen.com/product/genetic-roulette/. Published May 6, 2019. Accessed May 6, 2019.
16.
Sharpe R, Martin B, Morris K, et al. Infant feeding with soy formula milk: effects on the testis and on blood testosterone levels in marmoset monkeys during the period of neonatal testicular activity. Hum Reprod. 2002;17(7):1692-1703. https://www.ncbi.nlm.nih.gov/pubmed/12093826.
17.
Morito K, Hirose T, Kinjo J, et al. Interaction of phytoestrogens with estrogen receptors alpha and beta. Biol Pharm Bull. 2001;24(4):351-356. https://www.ncbi.nlm.nih.gov/pubmed/11305594.
18.
Allred C, Ju Y, Allred K, Chang J, Helferich W. Dietary genistin stimulates growth of estrogen-dependent breast cancer tumors similar to that observed with genistein. Carcinogenesis. 2001;22(10):1667-1673. https://www.ncbi.nlm.nih.gov/pubmed/11577007.
19.
COMŞA, Ş, MARIA CÎMPEAN⇑ and A. The Story of MCF-7 Breast Cancer Cell Line: 40 years of Experience in Research. ar.iiarjournals.org. http://ar.iiarjournals.org/content/35/6/3147.full. Accessed May 6, 2019.
20.
How to Get the Benefits of Soy Without All the Health Risks. Mercola.com. https://www.mercola.com/Downloads/bonus/dangers-of-soy/report.aspx#_edn4. Accessed May 6, 2019.
21.
How to Get the Benefits of Soy Without All the Health Risks. Mercola.com. https://www.mercola.com/Downloads/bonus/dangers-of-soy/report.aspx#_edn5. Accessed May 6, 2019.
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Renata Ilitsky

Renata Ilitsky is a professional content writer and editor with over a decade of experience. Although she writes for various industries, she is the most passionate about health and holistic niches. Aside from her personal blog, Simple Natural Solutions, she has created content for Healthline, Dr. Willard's, Westside NeuroTherapeutics, EC3 Health and more!
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