Soy is a controversial food. I’ve had many people ask me lately about various forms of soy and whether it is really healthy or not.
On one side, some experts say it has numerous health benefits for hormones and cholesterol, as well as being a vegan source of protein and fiber.
On the other side, experts say it is an allergenic food that is often genetically modified. It can also cause thyroid problems.
So who’s right?
This post will explore what soy is, the different types of food that soy is in, and how it might affect health.
What Is Soy?
Soy is a legume, in the bean family, and is often used as a plant-based source of protein and fiber. From the raw soybean, numerous products are made. Common soy foods include:
- Soy oil
- Soy meal (for animal feed)
- Soy milk
- Soy flour
- Soy protein
- Tofu
- Soy sauce or tamari
- Tempeh
- Miso
- Edamame (whole soybeans)
Soy is traditionally consumed in some Asian cultures but is also a staple of the U.S. agricultural industry. According to the USDA, 94 percent of soybeans grown in the United States are biotech (genetically modified). Most soy produced in the U.S. is for animal feed, but a high volume—43 million metric tons—is exported to other countries, with China being the biggest consumer.
Soy is also found in many processed foods. Soy is one of the “top eight” food allergens and must be declared on labels if products contain any soy.
Even if you don’t overtly eat soy products, it may be found in foods with the following ingredients listed on labels:
- Soy lecithin
- Soy protein concentrate
- Texturized vegetable protein
- Soy protein isolate
- Hydrolyzed vegetable protein
- Vegetable oil
- Any other phrase containing the word soy
Are There Soy Health Benefits?
Soy contains isoflavones, compounds that give soy its assumed benefits. Soy isoflavones are phytochemicals that are associated with positive effects on risk factors of breast cancer, heart disease, prostate cancer, and blood pressure. However, not all research agrees.
One of the reasons that some experts use as proof of soy benefits is how often soy is consumed in traditional Asian cultures. The assumption is that because many Asian cultures have longevity and don’t have the obesity epidemic, as we do in America, that this must be because of soy.
However, soy alone is not responsible for these health differences. Consider, for example, how often traditional Asian cultures also eat higher amounts of seaweed and seafood compared to traditional American diets. These foods also contain significant health benefits and are often eaten in higher quantities than soy foods.
If you read studies and research done on soy, you’ll sometimes find that those showing overtly positive effects have a conflict of interest. This 2016 review in Nutrients, for example, was funded by the European Soy and Plant-Based Foods Manufacturers Association. Of course those who have a financial interest in selling soy are going to say it’s healthy!
Another factor is that a lot of the research done on soy benefits are animal studies, so the benefits are not necessarily transferable to humans. Human benefits from soy consumption are still widely unknown due to animal research and research funding bias. More human studies need to be done, without conflict of interest, to really understand the potential ups and downs of soy intake.
That being said, soy is not all bad. A 2020 review in Antioxidants presents research that notes the potential for good health effects like lowering LDL cholesterol and reducing mortality from cancer, without being funded by the soy food industry.
Still, the question is: do the benefits of soy outweigh the potential risks from eating it?
Dangers of Soy Consumption
While soy may have some health benefits, there are some serious risks to consider.
Antinutrients
Antinutrients are compounds found in legumes and grains that change the way that the gut is able to absorb certain nutrients, like minerals. They can also affect the gut lining and inflammation. Antinutrients are found in soy, beans, and other legumes, as well as grains and some nuts.
Eating a high volume of non-fermented soy foods could result in gut problems, irritation, and problems absorbing certain minerals and vitamins.
Soy isn’t the staple food in Asian cultures that some Americans assume. While it is traditionally consumed, it is often used as a condiment in small quantities. When soy is eaten, it is often fermented, which minimizes the anti-nutrients that soy contains.
Soy is often promoted as an alternative food for those who have celiac disease or are intolerant of gluten, but the antinutrients that soy contains—lectins and phytates—can interfere with gut health and still cause issues. Lectins are proteins found in beans and other similar foods, and unlike some antinutrients, cooking or fermenting does not deactivate them. Anyone dealing with inflammation, leaky gut, or intestinal issues may be susceptible to negative effects from lectins.
Goitrogens
Another problematic compound, goitrogens are substances that can interfere with thyroid function. They can block the way that the thyroid takes in iodine, resulting in decreased thyroid hormone production and conversion.
Hypothyroidism is one of the most common health conditions, where the thyroid hormone levels are too low. While Hashimoto’s, an autoimmune disease, is the biggest cause of hypothyroidism in America, inflammation and gut health problems are closely related. The antinutrients found in soy foods can negatively impact the thyroid gland in many ways.
A common alternative formula for babies with allergies is made from soy, but this is problematic for many reasons. A 1990 comparative study from the Journal of the American College of Nutrition found that infants who were fed soy formula had a higher incidence of developing autoimmune thyroid disease. While this research is considered old by today’s standards, newer research from 2004—a Cochrane database systematic review—found that soy formula should not be fed to infants at high risk of food allergy or intolerance.
Turns out, soy proteins affect the gut so much that they can take infants who don’t currently have food allergies and cause inflammatory changes that cause them. While other foods contain goitrogens, like broccoli and cabbage, cooking deactivates them. No amount of cooking or fermentation deactivates goitrogens in soy.
Phytoestrogens
Soy contains phytoestrogens. These compounds mimic the human body’s natural estrogen hormones. Some experts say that these health effects of soy are a good thing, helping women in perimenopause and menopause experience fewer hot flashes as they interact with estrogen receptors.
If you think of the way that soy can have an estrogen-like effect on women, the concern is that it could do the same thing to men or to children. While many studies show that soy is safe and only rarely leads to “feminizing” effects in humans, it is shown more widely to do so in animals. An article from German Medical Science in 2014 noted that animals who are fed soy can experience reduced fertility, stunted sexual development, and behavior changes.
Even if soy is largely safe in humans—and again, many of the studies done have been biased—the fact that the risk exists for testosterone imbalance, infertility, feminization, and sperm changes in men is concerning. Even though some research, as mentioned above, says it can help women with hormone changes, it can also potentially cause problems with ovarian function and even cancer.
Are these risks really worth small potential benefits, when there are so many other whole foods that can lower the risk of health problems?
My take: You don’t need soy to have a nutritious diet.
Environmental Concerns
Soy isn’t great for humans and it’s not good for animals, either. The production of soy is harmful to the environment, too. Most soybeans today—at least 94 percent of them—are genetically modified (GMO) to be resistant to pesticides.
There is not much evidence on glyphosate (the pesticide applied in most conventional farming today) and how it affects human health. This is partly because a lot of money from agricultural food lobbies goes into preventing any type of restrictions on how glyphosate can or can’t be used. That being said, some scientists are concerned about it, although more evidence is needed to present a fully unbiased and evidence-based picture.
Even if you ignore potential specific concerns about glyphosate, the fact that soy products are heavily treated with pesticides is worrying enough for me. That alone means there are concerns for the gut health of both humans and feedlot animals who eat soy-based feed.
Soybean crops are also damaging to soil, as they strip it of nutrients. Foods obtain nutrients from nitrogen-rich soil. When the soil has already been depleted, crops that are grown—even organic ones—are going to be less nutritionally rich.
Should You Avoid Soy Products?
I’m not here to tell you what to do. Everyone needs to make the right decision for their health and their family, but I do not eat soy. I do not feed my children soy. We aren’t allergic, there just doesn’t seem to be any benefits for us. And there is definitely a risk.
If you are going to eat soy products because you’re not allergic or intolerant, or because you follow a vegan diet, make sure you’re only eating fermented soy. Traditionally fermented soy foods, like miso and tempeh, create fewer health challenges. The fermentation process helps to deactivate antinutrients that can cause gut problems—although it does not remove all of them. Soy products should still be eaten in moderation even if they’re organic and fermented.
Soy does not provide a complete form of protein either—containing all essential amino acids. If you are using it as a protein source, consider that you’ll also have to carefully pair it with other vegan sources to ensure you are not missing crucial amino acids.
Ultimately, soy products seem to offer more cause for concern than benefits.
This article was medically reviewed by Dr. Scott Soerries, MD, Family Physician and Medical Director of SteadyMD. As always, this is not personal medical advice and we recommend that you talk with your doctor.
What are your thoughts? Do you consume soy? Have you in the past? Tell me below!
Sources:
- United States Department of Agriculture. (2015). USDA coexistence fact sheets: soybeans. https://www.usda.gov/sites/default/files/documents/coexistence-soybeans-factsheet.pdf
- Messina M. (2016). Soy and Health Update: Evaluation of the Clinical and Epidemiologic Literature. Nutrients, 8(12), 754. https://www.mdpi.com/2072-6643/8/12/754
- Rizzo G. (2020). The Antioxidant Role of Soy and Soy Foods in Human Health. Antioxidants (Basel, Switzerland), 9(7), 635. https://www.mdpi.com/2076-3921/9/7/635
- Galán, M. G., & Drago, S. R. (2014). Effects of soy protein and calcium levels on mineral bioaccessibility and protein digestibility from enteral formulas. Plant foods for human nutrition (Dordrecht, Netherlands), 69(3), 283–289. https://link.springer.com/article/10.1007/s11130-014-0432-y
- Panacer, K., & Whorwell, P. J. (2019). Dietary Lectin exclusion: The next big food trend?. World journal of gastroenterology, 25(24), 2973–2976. https://www.wjgnet.com/1007-9327/full/v25/i24/2973.htm
- Fort, P., Moses, N., Fasano, M., Goldberg, T., & Lifshitz, F. (1990). Breast and soy-formula feedings in early infancy and the prevalence of autoimmune thyroid disease in children. Journal of the American College of Nutrition, 9(2), 164–167. https://www.tandfonline.com/doi/abs/10.1080/07315724.1990.10720366
- Osborn, D. A., & Sinn, J. (2004). Soy formula for prevention of allergy and food intolerance in infants. The Cochrane database of systematic reviews, (3), CD003741. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD003741.pub2/full
- Ahsan, M., & Mallick, A. K. (2017). The Effect of Soy Isoflavones on the Menopause Rating Scale Scoring in Perimenopausal and Postmenopausal Women: A Pilot Study. Journal of clinical and diagnostic research : JCDR, 11(9), FC13–FC16. https://pubmed.ncbi.nlm.nih.gov/29207728/
- Jargin S. V. (2014). Soy and phytoestrogens: possible side effects. German medical science : GMS e-journal, 12, Doc18. https://www.egms.de/static/en/journals/gms/2014-12/000203.shtml
- Chavarro, J. E., Toth, T. L., Sadio, S. M., & Hauser, R. (2008). Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic. Human reproduction (Oxford, England), 23(11), 2584–2590. https://academic.oup.com/humrep/article/23/11/2584/2913898
- Jefferson W. N. (2010). Adult ovarian function can be affected by high levels of soy. The Journal of nutrition, 140(12), 2322S–2325S. https://academic.oup.com/jn/article/140/12/2322S/4630735
- Gillezeau, C., van Gerwen, M., Shaffer, R. M., Rana, I., Zhang, L., Sheppard, L., & Taioli, E. (2019). The evidence of human exposure to glyphosate: a review. Environmental health : a global access science source, 18(1), 2. https://ehjournal.biomedcentral.com/articles/10.1186/s12940-018-0435-5
- Mesnage, R., & Antoniou, M. N. (2017). Facts and Fallacies in the Debate on Glyphosate Toxicity. Frontiers in public health, 5, 316. https://www.frontiersin.org/articles/10.3389/fpubh.2017.00316/full
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I think God gave us soy just like all plant foods and it is extremely good for our bodies. It has helped me in several major areas since I started drinking several glasses of milk a week and taking soy isoflavones daily for almost 3 1/2 years now. I am no longer lethargic. Most of my yeast problems are gone. My hair stopped falling out. My nails are much stronger. My children that can’t tolerate dairy drink it and give it to their children. NO MORE CRAMPS!! SOY is the perfect food for ME!!!
First, it is important to note that there is a big difference between eating whole, fermented soy and eating processed and refined soy products, which have no health benefits. Just because a food causes nutritional improvement, does not mean that this food is necessarily good for a person. Most people will see some improvement from eating only whole grains over processed grains. This doesn’t mean that whole grains are good, rather just that they are slightly better than what the person was eating before. Most people do not tolerate soy well, and especially for men, it can be very problematic.
Amen, wellnessmama!
I have been soy free for 8+ years, it gives me horrible migraines. My son has autism and he is soy free because of headaches and other bad side effects. I am disgusted corporations shove it in anything and everything they can! I wouldn’t take 4 birth control pills in a day, this would be the equivalent of a baby eating 4 birth control pills- sick! Check out the movie Food, Inc., it had good info about soy that you could see first hand.
I have been trying to avoid soy for several years now. I have severe hypothyroidism that is not yet under control. It’s a battle, what with soy flour in breads and cereals, and everything else that has some form of soy in it. Not only do I avoid it for my thyroid problem, when I eat soy products I get painful gas pains that at times have doubled me over with the pain. I wish it weren’t so complicated to eat these days. Right now I’m doing low carb so it’s not as bad, but when I wasn’t it was hard to even eat out. I had to look up ingredients in different restaurants menus to figure out things I could eat.
I really love this post – I have read it numerous times and suggested it to many friends. Thanks for making this a resource.
One thing I am wondering about – if it has so much phytoestrogens then couldn’t women eat a ton of soy to rid themselves of menopause symptoms? Not saying that the other possible health problems (cancer for example) wouldn’t outweigh the want to rid the menopause but would that be possible?
The one time that it can be somewhat ok is during menopause, but there are some much healthier herbal options…
Hi, I have known from reading about how soy in the past was the worst crop because of the amounts of pesticides used, but I have not heard these claims for many years. I recently was told by my doctor to drink soy based shakes for hormonal replacement, which of course I have been trying to do every morning. It does give me that full feeling for a while. I need to consume a lot of protein because I am hypoglycemic and have a tendency to use up my energy quickly. I have a very physically active job. So what’s your diet for these conditions?
So what is your take on this Whey muscle craze?
Lots of grassed meat and dairy/butter (if you tolerate it), fermented cod liver oil, maca herb etc are much better for hormones than soy, and a few eggs added in should keep you full a lot longer…
Why do you think other articles that you have written are credible sources to back up your claims? I find that so odd. I’ve seen you do that to other people too. Sure, you can get vitamin A from butter, but there are many healthier options than milk fat to get your Vitamin A, c’mon. I’m just really disappointed. I didn’t know you were so surface, I suggest you dig deeper if you’re making it your life goal to offer “healthy” advice to the masses. They need/want so much for the truth, they just want to be healthy, and to keep their families healthy. Really, dig deeper. Do the research yourselves lovelies! You’ll be so glad you did! Not trying to hate on you mama, but I am just very passionate about people knowing the truth behind the foods they’re eating. Everyone deserves that.
There are many other effects than just the phytoestrogens (ie. thyroid issues), as Wellness Mama points out. In addition, almost ALL of the soy grown in the US is genetically modified–as they hybridize the soy plant more and more for industrial convenience, they don’t look at the possible effects on the human body from soy consumption. It’s not a natural product as it was sold to us to be in the 70’s, it’s an industrial product and the consequences of the industrialization have only just begun to be understood.
I have only just started reading your site as i was keeping my daughter off dairy in an attempt to clear her eyelid eczma. I have read what you have written about soy, but had so far understood that phytoestrogens where good for preventing symptoms of the menopause. I have actually been feeling guilty that my famiky don’t consume enough legumes and beans. Now i am a little confused.?
There isn’t anything in beans and legumes that isn’t found in meat, vegetables, fruits and other foods, so there certainly isn’t a need for them. Have you removed any other foods from your daughter’s diet? In my past experience, eczema is almost always related to a grain, dairy, or occasionally nightshade or egg allergy. Taking gelatin (available in my “store” tab will also help the skin healing.
About the eczema… My son developed it on his hands, only after he started kindergarten where he washed his hands with antibacterial soap. Try some all-coconut oil saponified soaps instead. They clean wonderfully, don’t strip your skin of its natural protective oils, and as a bonus, coconut oil is naturally anti-bacterial and moisturizing.
In my experience, a zinc deficiency &/or gut dysbiosis is most commonly found in eczema sufferers. Yes, food intolerances accompany this too but where the gut mucosa is healthy, fewer and fewer food intolerances occur. Interestingly, a search in Pubmed for zinc deficiency will find you a few cases which describe the mineral deficiency in many Arab countries which consume plenty of legumes… Yes, published in medical journals too! I thought this was really intriguing!
I have chronic hypothyroidism and for the longest time I had trouble getting my thyroid medication regulated. My doctor didn’t understand why the medicine wasn’t helping. Then we found out the culprit. I was drinking soy milk regularly. The soy prevented my thyroid from absorbing any of the thyroid medication! Soy is soooooo horrible for the thyroid and definitely slows down your metabolism. I hate that many weightloss shake mixes contain soy or soy protein, like Herbalife. It defeats the purpose of loosing weight. Shakeology doesn’t have any soy, so I stick with that.
It’s terrible that the “soy is healthy” trend was just lead by soy advertisements to make the moolah.
Just a quick comment. If drinking soy defeats the purpose of losing weight then why has Herbalife helped Millings of people lose weight while getting healthy? They are the number 1 nutrition company in the world and have over 32 renoun doctors on their staff. They reached 5.5. billion last year and have been doing great for the 32 years they they have been in business. So before you go putting companies under the bus you might want to do some research yourself. I’m all for others believing what they will but when you want to bring up names and bash them for things you might not know anything about, then thats where its not right. WIth all do respect!
I’d be cautious about using business success as a measure of the quality of a product. Coca Cola and McDonalds typically do great, business-wise each year, but make nutritionally awful products. There are also companies like SlimFast which help people lose weight, but aren’t healthy.
The difference is Herbalife has business success because of the proven product results. I know countless people who have lost weight, lowered there body age, improved overall health, etc, just by using Herbalife products consistently.
I’m with WellnessMama on this one – All of these things (“people who have lost weight, lowered there [their] body [biological] age, improved overall health”) can be achieved without any branding – through a properly balanced diet & exercise – the natural way. Please don’t assume I’m against any business but to say that a company is responsible for the success of these people is incorrect. These people did it through their own determination & perseverance, with help from BrandX… but in doing it without formulated products, you are able to make it a lifelong change for the better. See a professional naturopath/nutritionist/herbalist instead of a sales rep who hasn’t formally studied this area.
I agree 100% that these things CAN be achieved without any branding. I also love and appreciate Wellness Mama. I am lucky enough to be a stay at home. I follow her blog and use her recipes for my children and myself. I also incorporate Herbalife shakes and supplements each day, because I believe it to be extremely difficult to eat enough food each day to get the best nutrition. I believe Herbalife goes hand in hand perfectly with my grain-free, low sugar diet. I am pregnant and have used this approach throughout 3 pregnancies and breastfeeding. I would not have it any other way. It requires a lot of time and money to be able to eat a properly balanced diet each and every day. Many people are simply unaware that a whole grain diet is in fact not healthy and sugar is poison. Those that ARE aware, may not have the time to prepare each meal from scratch. Herbalife is the best nutrition company in the world, backed by doctors, scientists, and even a Nobel prize winner. Given the time to learn about Herbalife, you will see it IS in fact a natural way and also encourages a healthy diet and exercise. Distributors of the products do not need to have “formally studied” because, if used properly and consistently, the products do all the work. Just as important, Herbalife enables people of all backgrounds and income levels to have perfect nutrition. 🙂
Please do correct me if I’m wrong but… Don’t Herbalife shakes contain over 30% sugar? Are you familiar with the work of endocrinologist Professor Robert Lustig and the discoveries regarding the effects of sugar on leptin/grehlin and insulin production? I tried to post a link to an article here but it doesn’t appear to have posted, so you may need to google “the real reason you eat too much” – it explains it all very clearly 🙂
Spoiler alert: sugar actually increases our appetite…
That article makes no mention of the amount of sugar in a Herbalife shake??
Slim fast which is very high in potassium which can lead to problems if you down too many.
That shake also contains approx. 35grams of SUGAR! It contains more sugar than protein… This means you will lose muscle mass too – meaning your metabolism/energy burning ability will slow down, so when you stop using the shake, it’s easier to rebound-weight-gain… No thanks, I’ll pass on that one too 😉
Try iodine therapy for hypothyroidism. Dr. Brownstein is THE authority on this. Your regular MD will NOT support you in this protocol unless he/she is cross trained for natural therapies as well
It beats me as to why all along this non-health food was touted as a health food. So what were the researchers actually doing?
Views will constantly morph and change as new information comes to light. This is inevitable.
I had no idea soy was so bad. My son drinks non GMO organic soymilk like it is going out of style. This is really the only soy we consume. Looks like we will have to make a switch.
Try So Delicious Coconut milk instead. It is so good! And when I need a treat, I have chocolate hemp milk.
Have you READ the ingredients for the So Delicious coconut milk? I have and have never bought one because of it. I prefer to buy cans of coconut that are JUST COCONUT. Makes a world of difference! Here is a printscreen I took of this yucky “coconut milk”
Soy milk given to baby boy can cause their reproductive anatomy to be small due to the fact that soy mimics estrogen which is a female hormone. It also causes baby girls to have early puberty and can disrupt the thyroid because it gives them too much estrogen. It can also increase the risk of breast cancer in adults.
what milk do you recommend? Dose it have to be powedered milk?
Your article is great! Soy is so scary and as a vegetarian, it’s really the primary substitution for nearly everything. I developed negative reactions to it, relating to hormones. It’s just bad stuff. Keep up the good writing!
Vegetarianism is bad, scientists have done studies saying that vegetarians would die off due to lack of protein leading to a smaller brain.
Are you serious? Haha
Its true, humanity evolved only because we started eating meat, which caused our brains to grow.
Humans wouldn’t even be here today if we hadn’t started eating meat.
Sure, it’s an established theory. But the requirement was more likely energy, rather than flesh per se, meaning that high-calorie foods such as nuts would be as preferable to water-filled fruit. Anyway, there’s also the suggestion of how we started to cook food, which releases calories that are not accessible through raw food, and that this invention contributed to how our big brains started to become assets rather than energy-demanding burdens. It makes sense of course that if one doesn’t have to spend all day foraging, then there’ll be more time on hand to develop other skills. My issue is just that it’s a bit much to say that MEAT IS THE ONLY REASON. You know? I guess it’s not really that relevant, in the end.. Because we’re here now, evolved. And with a mind that’s at least capable of making rational and moral choices.
Happy new year!
lol well duh
Except you can’t pass on acquired characteristics to your children…
Even if eating meat gave you a bigger brain, your kids would have the same size brain that their genes determine.
Similarity, even if a vegetarian diet *did* cause smaller brains (something I hotly contest given that vast swathes of the world are vegetarian due to economic or religious reasons) their children’s brain size would be decided by their genetics – NOT their parents diet…
Brain size has very little to do with genetics. Look up brain health in TED Talks. There’s a psychologist who did a number of studies to brain health and size. His findings clearly were bigger people had smaller brains. However he goes on to say that it’s about how the brain looks as well, if the activity is symmetrical and even throughout, that brain is healthier, and you will be healthier all around.