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How Soy Can Kill You and Save Your Life

How Soy Can Kill You and Save Your Life

EATING SOY CAN KILL YOU! Scan the media reports and surf the Internet, and you’re bound to come across scary claims that would lead you to believe this is true. You may have heard:

  • Soy will give you breast cancer.
  • Soy formula is dangerous to babies.
  • Genetically modified soy foods may modify you.
  • Soy foods block your thyroid function.
  • Soy prevents the absorption of minerals and interferes with digestion.
  • Tofu causes Alzheimer’s disease.

As some of you may be aware, I often recommend soy as part of a whole foods diet. Many people question why I include these foods in light of such startling media coverage on the dangers of soy. The reason is relatively simple.

I have reviewed reams of research and many claims for and against soy foods. From the studies available, I can tell you that soy is neither as good as the proponents say, nor as evil as the critics claim. I wish we had more convincing science to report, but we don’t. The key is to take all the available evidence together and see what shakes out.

In today’s blog I have done that for you. I will review some of the recent data for and against soy, and provide you with a few guidelines and things to remember when choosing soy foods.

What the Data Says about Soy

If you want an excellent, unbiased, scientifically sound review of all the relevant human data on soy, I recommend reading the 100-page report from the Agency for HealthCare Research and Quality entitled, The Effects of Soy on Health Outcomes, which reviewed thousands of studies based on rigorous criteria for scientific validity. Its conclusion was this: There is no evidence of significant benefit or harm based on the quality of evidence that exists today.

The dangers of soy are overstated. The benefits may be too.

So what’s a confused consumer to do? Give up on soy until we know for sure? Or chow down on soy nuts? Don’t panic. There are some things we do know about soy, both good and bad.

First, you should be aware that the amount of soy used in many of these studies was much higher than what we normally consume — the average dose of soy was equivalent to one pound of tofu or three soy protein shakes a day. That’s a lot of soy! Most people just don’t eat like that. So when you read negative things about soy, remember that many of those claims are based on poorly designed studies that don’t apply to real-world consumption.

You could apply that thinking to other studies, too — like those that show that broccoli contains natural pesticides or that celery is high in toxins. Sure, those foods might cause you some problems — but not in the amounts that most of us eat. The same is true for soy.

Second, it’s important to recognize that many of the common claims about soy simply don’t pan out when you look at the evidence carefully. Let’s review four of these claims and the science behind them so you can have a better understanding of the real relationships between soy consumption and potential health threats.

#1 “Soy Causes Breast Cancer”

Because soy foods contain natural plant compounds (called isoflavones) that appear to work like hormones, some people worry that they could increase hormonally driven conditions like breast cancer. But that doesn’t seem to be the case. In fact, research findings (i) suggest just the opposite:

  • All population studies (studies of groups of people) of soy either show reduced breast cancer risk or no effect.
  • The only studies to show increased cancer risk are on mice with no ovaries or damaged immune systems who eat high amounts of processed soy.
  • Studies in mice WITH ovaries and functioning immune systems show inhibition of tumor growth.
  • Mice studies may not reflect the effect of soy on humans (in case you didn’t notice, mice and humans are not the same species).
  • High breast tissue density is linked to a higher risk of breast cancer. Breast tissue density increases with estrogen replacement, but decreases with isoflavone consumption in postmenopausal women. That’s a good thing.
  • Eating soy foods at an early age (childhood and the teen years) appears to have a significant protective effect against breast cancer.

If you really want to reduce your risk of breast cancer, drink less alcohol and eat less trans and saturated fats — all of these compounds may raise risk in high amounts. If it’s a choice between chicken nuggets and tofu, I recommend tofu!

#2 “Soy Formula Could Harm a Baby’s Development”

Some 20 million infants have used soy formula since the 1960s — but some people are concerned that the isoflavones it contains could affect a child’s growth and reproductive development. Yet the only large, long-term study on humans, published in the Journal of the American Medical Association, (ii) found that there were no major health differences in 811 men and women between the ages of 20 and 34 who had been fed either soy or milk formula as infants.

More recently, a report issued by the National Toxicology Program Center for the Evaluation of Risks to Human Reproduction concluded that there just isn’t enough human or animal data to say for sure whether soy formula harms a baby’s developmental or reproductive health.

So what should a mother do? First, breastfeed if at all possible, for as long as possible — ideally until your child is one year old. If that’s not possible and you have to use soy- or dairy-based formula, don’t beat yourself up about it. If there are any risks, they are likely to be very small. Hopefully, continuing research will shed more light on this question.

#3 “Soy is a Thyroid Poison”

I think this claim makes a mountain out of a molehill. Yes, there’s no doubt that soy can affect your thyroid gland — the real question is, how much does it take? If you’ve read that soy is bad for your thyroid, you’re probably reading claims based on a few poorly-designed studies that have been blown out of proportion.

Instead, consider this: A review of the research found no significant effects of soy on the thyroid except in people who are iodine deficient — a condition that is rare in this country.

Another well-designed study in the American Journal of Clinical Nutrition (iii) studied the effect of realistic amounts of soy protein on hormones, including thyroid hormone. It found that soy had no significant effects on these hormones.

Based on my assessment of this and other research, I am convinced that normal amounts of traditional soy foods pose no risk to thyroid function.

#4 “Fermented Soy is Better than Non-fermented Soy”

Now here’s a claim that DOES have some basis in fact. That’s because soybeans — along with other beans, nuts, and seeds — contain compounds called phytates, which bind to minerals inside your body and contain some potentially harmful compounds.

The Asian cultures that have traditionally consumed soy typically ferment it first. This process breaks soy down and makes it easier to digest. Plus, fermentation adds extra nutrients and probiotics (“good” bacteria) to soy. For these reasons, I prefer fermented soy foods, like miso, natto, tempeh, tofu and some brands of soy milk.

So, should you eat soy? My answer is YES — but with two very important guidelines:

  1. Say YES to whole, real soy. The Okinawans are the world’s longest-lived people, probably in part because of their diet. For more than five millennia, they’ve eaten whole, organic and fermented soy foods like miso, tempeh, tofu, soy milk, and edamame (young soybeans in the pod). One to two servings a day of any of these foods are fine.
  2. Say NO to processed soy. That includes soy protein isolate and concentrates, genetically engineered soy foods (typically made from Monsanto’s Roundup soybeans), soy supplements, and soy junk foods like soy cheese, soy ice cream, soy oil, and soy burgers. They don’t have the thousands of years of traditional use that whole soy foods do, are processed, and contain unhealthy fats and other compounds. I have real concerns about these types of soy.

In truth, good human studies on soy are limited, but those we do have suggest that soy may help lower cholesterol, prevent cancer, increase bone density, protect the kidneys of people with diabetes, and relieve menopausal symptoms like hot flashes.

When you are considering the media reports about soy, here are some things to remember:

  1. The dangers of soy are overstated (and the benefits may be, too).
  2. We eat far too much processed soy (and processed foods in general). Stay away from those in your diet including soy protein concentrates or isolates, hydrolyzed or textured vegetable protein, hydrogenated soy bean oil, non-organic sources of soy, and soy junk food like soy cheese and ice cream. Don’t eat them.
  3. Whole soy foods can be a source of good quality protein and plant compounds that help promote health.
  4. Eat only organic soy. Stay away from genetically modified versions.
  5. Replace soy oil with olive oil, fish oil, nuts, and seeds.
  6. Breastfeed your child. I prefer that no one feed dairy or soy formula to their babies, but if you have to, try not to worry about it.
  7. Don’t worry about soy’s effect on breast cancer if you eat it in the forms and amounts I recommend. It has even been shown to protect against breast cancer if you start eating it at a young age.
  8. The effects on the thyroid are not significant or relevant unless you are deficient in iodine (which you can easily get from eating fish, seaweed or sea vegetables, or iodized salt).

I’m eager to see more research on the effects of soy on our health. But as we wait for more studies, there’s no need to pass up this healthful and delicious food. It can be safely included as part of a whole foods diet — which is one of the most important keys to lifelong vibrant health.

Have you experienced any health problem because of eating soy?

Have you experienced any health benefits from consuming soy?

Do you agree or disagree with any of the arguments about this controversial subject that I’ve listed?

Let me know your thoughts by leaving a comment below.

To your good health,

Mark Hyman, MD


(i) Messina, M. 2010. A brief historical overview of the past two decades of soy and isoflavone research. J Nutr. 140(7): 1350S–4S.

(ii) Strom, B.L., Schinnar, R., Ziegler, E.E. et al. 2001. Exposure to soy-based formula in infancy and endocrinological and reproductive outcomes in young adulthood. JAMA. 286(7): 807–14.

(iii) Persky, V.W., Turyk, M.E., Wang, L. et al. 2002. Effect of soy protein on endogenous hormones in postmenopausal women. Am J Clin Nutr. 75(1): 145–53.

Mark Hyman MD is the Medical Director at Cleveland Clinic’s Center for Functional Medicine, the Founder of The UltraWellness Center, and a ten-time #1 New York Times Bestselling author.

Comments (90)

  • What about non-GMO soy lecithin. Is it rich in isoflavones and is it bad for the thyroid?

    • Hi Maria,

      If you have a sensitivity to soy than you might note a reaction. Typically, soy lecithin has higher amounts of omega 6 fatty acids, lower anti-inflammatory omega 3. This might provoke a reaction if you are very inflamed. This being said, it is best for you to note how your particular system responds to it by keeping a detailed food journal such as the one suggested by Dr Hyman in his book, The Blood Sugar Solution.

      For more personalized nutrition advice, Dr Hyman’s nutrition coaching team would be happy to work with you on an individual level to help you reach your goals. To work with the nutrition coaching team please go to: OR call (800) 892-1443 to get started.

  • Dr. Hyman, could you please specify the brand sof soymilk that you DO recommend? Thanks!

  • Hi, what are your thoughts on Metagenics ultra meal plus 360? It contains soy isoflavones as its protein source.

    • Hi Dipa,

      This is a great protein powder for your shakes depending on your ultimate health goals. What are you looking to achieve?

      For more personalized nutrition advice, Dr Hyman’s nutrition coaching team would be happy to work with you on an individual level to help you reach your goals. To work with the nutrition coaching team please go to: OR call (800) 892-1443 to get started.

      • Metagenics powders are loaded with sugar and are a source of the unhealthy processed, unfermented soy. In my practice I recommend Vega One or SunWarrior protein powders which do not have any added sugars (just a bit of stevia) and add a bit of fruit for a healthier and more balanced carb source. They are also sprouted and far easier to digest than the Metagenics powders, which tend to cause a lot of bloating and digestive issues for many.

      • Thankyou Mark and staff – as a long time integrative health professional who has been forced into early retirement, being a whistleblower and health writer who will not put up with the rubbish that even the natural health industry is spouting today, with TV health celebrities and so many untrained health professionals getting kickbacks in areas for which they are not trained to advise, I LOVE that I am not alone. Thankyou for this article – it is very similar to one I wrote some time ago. Really great validation.

  • I know a little bit about soy and have seen some benefits. But, recently was told that soy should not be a part of my diet due to me going through menopause. I beg to differ. i don’t consume that much at all. Maybe in smoothies and very seldom use soy milk. I take Iodine Plus 2, Vitamin D3 with Krill oil together to prevent inflammation, SuperC22, several B’s at different times, Cal Max, seldom eat meat, love fish and some chix. The rest in fruits and vegeatables. Seldom eat pasta or bread unless I splurge

    • Hi Antionette,

      Eat whole food-based soy products that are labeled as NON-GMO and preferably organic, if possible. Try edamame, tofu, miso or tempeh. If you are interested in learning more about these foods or how to prepare them hop on over to Dr. Hyman’s nutrition coaching for more guidance.

      To work with the nutrition coaching team please go to: OR call (800) 892-1443 to get started.

  • Thank you for this informative article but I’d like to know the effects of traditionally prepared Soy formular on an infant. I exclusively breast fed my baby for six months and since last week been feeding her on cereals mixed with soy formular. I made it myself using soybeans, crayfish, oven baked unripe plantain and a little quantity of peanuts. Am nigerian and it is common here. I was alarmed when I accidentally read abt all the evil sides of soy. Though this article has relieved me ssomewhat.

    • Dear Geraldine,
      Thank you for your interest in Dr. Hyman’s work. Is your infant responding well to the formula? Dr. Hyman would suggest using NON-GMO soybeans if possible. If you would like to work with Dr. Hyman’s nutrition coaches, please hop on over to: OR call (800) 892-1443 to get started.
      In Good Health,
      The Nutrition Team

  • Good article. I appreciate your balanced advice. I was struggling with low thyroid that was undiagnosed. Looking back, I still have no clue why my dr never checked my thyroid. I know my thyroid was low because my hair was thinning and I lost the majority of my right eyebrow when I was 30. After being diagnosed with fibromyalgia, I began eating a whole foods diet which was a huge improvement in my health. But still no eyebrow. 2 years ago I started making green smoothies with organic soy milk, green leafy veggies and sea greens. I drink one per day. Not only did my eyebrow fully come back, my hair has gotten so thick my hair stylist has to thin it out with thinning shears or I look like one of the Beatles (I have short hair ) For me the results have been dramatic. I do not use a lot of soy, but I try to get in one serving per day.

    • Hi Shay,

      I was wondering how old you were when your hair became very thin and your right eyebrow more or less disappeared? Also, what green leafy veg did you use and what are sea greens (?) for the smoothies you drank per day? My hair has gone very thin but I think its medication that has caused it. But I wouldn’t mind trying what you did to see if I got a similar result. I am however, in my early 60’s and wear a wig if I go out, which isn’t very often.


  • Hi,

    I get soy chunks (nuggets) which I roast and eat. I don’t get so tired or my feet don’t hurt so much if I eat about a cupful of these roasted nuggets. But I have heard soy is very bad for the pancreas. Can I continue eating soy in this manner?


  • Dr. Hyman,

    I have been on hormone replacement and thryoid meds for 20 years. I am 52 years old. I want to start taking non-GMO fermented soy products. Would this interfer with any of my medications? Should I stop taking my hormone replacement, which I’m only taking 3 days a week, but still on my prometrium daily. Synthroid 125 daily. Please advise.

  • You know I love science,but I see a flaw in modern science as well. Knowing how big money influences most things, to me it seems it also influences science, what is known, or allowed to be known, and what studies get the most publicity. Which makes it hard to sometimes figure out the real truth. Perhaps everything has pro`s and con`s but which is publicized the most seems to relate to which has big money behind it.

  • It seems easier to just cut Soy out of your diet.
    Anytime I hear “as long as you dont have a certain amount,” I question it.
    That amount, which we dont know the quantity of, has different effects on different people.

    • Hey Joey,

      All food is meant to ate in moderation. I wouldn’t recommend eating anything EVERY day. Seems better to mix it up. Since there is much inconclusive data.

  • I used lasco soy milk instead of milk for 2 weeks without sugar adding sugar and i lost 30 pounds also ate whole grain products and limited oil to olive oil for that same period… but even with my pms.. when i started bk the milk i got pms symptoms like cramps n bloating up 2 2 weeks before it periods n bad migraines… poor skin acne n discoloration i started bk my soya 2 months now n no bad tummy aches or headaches and skin cleared up hugely…. so yep n i lessen my meat intake and eat veggie or beans n on an off soya chunks and chicken breast… n still use oil n flour…. so yep i love soya…

  • I have been using now for one month a new product at GNC called Vege Fuel. It is a soy based protein powder. It is working well for weight loss and muscle health. I have no complaints so far and the improvement seems to be compounded each week. I still eat healthy and well balanced. I have a shake with water and cacao for taste first thing in the morning then 3.5 hours after, Then 3.5 hours after I eat normal. My diet is based on the Qivana diet which was designed by Dr. Layman, head of nutrition at Illinois University. In any case I am wondering if i am having too much…

  • Thank you Dr Hyman for your balanced review on soy research. I have been consuming soy products for 22 years (vegetarian for 27 years).
    I became aware of danger alerts that seemed to gain momentum about 15 years ago. Many high profile health experts whom I have great respect for and follow much of their advice, are alarmist in their attitude towards soy. I decided to trust intuition and my own reasoning, so hence I am so very grateful to stumble on your well considered report.

    My diet consists of a wide variety of organic, whole plant foods and whilst soy is definitely in the mix, it doesn’t over dominate and which includes: soy milk, miso, tofu, tempe and tamari sauce. To be honest I didn’t feel that much different switching from animal proteins to vegetable proteins, the transition for my body was easy. Is it because I am Type A blood type ?? However when I gave up dairy a few years on, the difference was profound. My energy levels skyrocketed, and basically I never knew that I was sluggish because that was what normal had always felt like. Omitting dairy meant that I switched to soy milk.
    I enjoy good health without the consumption of flesh foods or dairy, had a blessed pregnancy, birth and breastfeed for 2years with plenty of milk supply. My daughter is now 14 and has never eaten meat, vegan for first 7, now has home eggs since became available to us and rarely eats dairy. She has above average health, no allergies, or anything to remark on, rarely gets sick… is tall and not emaciated. All the things she shouldn’t be according to all the advice???

    • Hi… Being vegan is the only way to eat … To omit cruelty and flesh from ones diet is so obvious … Yet few fail to see … Yes we eat soy at times.. but also we eat a rainbow of colours and enjoy great health… And if we keep away from processed rubbish we are usually slim and full of energy. It’s so simple… Eat what grows from the earth… Organic if possible.. And never anything that was born.. Even fish deserve their lives x

      • Potatoes carrots and seeds can all be planted and will grow new little plant beings…yet we boil them or eat them alive!!!

  • What about the soy that Herbalife sells. They also have a non-allergy protein for shakes. Do you consider these two sources safe? I am a new member and each 2 shakes a day, mixed with spinach, kale, flax, chia seeds, oatmeal, carrots and an apple. Please advise. Thanks.

  • Regarding soy having no effect on hormones. I have read that soy contains a phytoestrogen or at least something that acts similar to estrogen. I have found this to be true, because both times I started eating it in my salad, my body would fill out as though I had more estrogen. It was actually a nice effect. That’s my experience, all science aside.

  • I’m allergic to dairy, all dairy, and I’m also allergic to tree nuts. Soy milk and soy protein powders (not used in high amounts) are basically my only options. I have used rice milk but don’t prefer it as I’ve had bad reactions to it from time to time. I’ve heard over and over again how consumming too much soy, or soy at all depending on who you talk to, isn’t the best idea. Since soy is my only option with my dairy and nut allergies is this something I should worry about. I’ve made note of which types of soy (non-GMO and organic) to buy but other than that, is there another option to soy or am I worrying about this too much? Thanks!

  • I have been drinking unsweetened organic soymilk for 23 years. I have a lot of food allergies and hypoglycemia so 7 years ago, I decided to eat according to my blood type. I thought I was a type B blood type because my husband was and according to the book we were already basicly eating that way. So I was a meat eating, milk drinking person although all healthy and organic. Imagine my surprise when I found out I was a type A and should be vegetarian. I was already drinking soymilk so decided to fully embrace this “Eat Right For Your Blood type Diet”.Within a week, I got so sick and remained sick feeling from May to October with symptoms of a bad cold which I rarely ever had. I finally decided I may have to go to the doctor or drink huge amounts of water for a week. After drinking water for a week everything turned completely over and my body started running like a fine tuned machine. I live on soy almost exclusively, unsweetened organic soymilk, tofu, and some edamame. According to that book, my bloodtype is the only bloodtype that should eat soy. I rarely eat meat. I am 62, have no health problems at all…I do aerobics, zumba, lift weights, walk everyday and ballroom dance. I rarely have a hot flash. I did have fibroids when I was younger. They are gone since I entered menopause. I get “yelled at” about soy frequently but all these people have health issues and I don’t so as they say ” that’s my story and I’m sticking to it”!!!

  • Recently I have started becoming very sick after eating soy, so now I avoid it like the plague. I ate soy twice a couple months ago and both times I literally could not get out of bed the next day. Extremely exhausted and achey. The second time it lasted for many days and I feel my body is still recovering months later. I believe the soy had really suppressed my thyroid gland to the point where I could not function. I could even feel my thyroid was swollen in my neck.

    I had no known history of thyroid problems, although I have been struggling with fatigue issues from adrenal problems for the past few years. Right before this happened with the soy, I had started changing my diet by cutting out gluten, eating more meat and lots of kale and other goitrogenic vegetables. All in an attempt to have better health, because I had no idea that health foods like kale, bok choy and sweet potatoes could actually harm your thyroid. So perhaps all these changes were suppressing my thyroid and the soy was just too much for it to handle … all I know is that I never want to eat it again after how sick I got! I know for sure that soy is very bad for me and I don’t care what anyone says about the supposed health benefits. Maybe for some people its fine or even beneficial, since we are all different, but I personally feel soy is WAY overused and promoted in this country when it actually could be a major culprit in the large amount of chronic health problems this society has.

  • In my 50s, postmenopausal. I’ve been hypothyroid for 16 years. I’m pretty sensitive to soy. If I drink as much as 12-16 ounces of common brand soy milk everyday, I’ll start to experience mild hypothyroid symptoms within three weeks. On the other hand, it dramatically reduces menopausal symptoms, which is great. So I try to balance it out. I like soy alot, actually, especially tofu, but for me, it’s quite powerful. I believe it’s an individual thing and some people will be able to eat a lot of it with no ill effects, whereas others of us will need to see how much they can tolerate. I tihnk it’s all part of knowing your body and also not buying into the hype from one camp vs. the other.

  • As far as I can see the question about soy milk never got answered and the link recommended seems only to deal with other beverages.

    I want to ask the same question. I drink Silk Original unsweetened, about 2 cups a day. Why such specific information in answer to some questions and a blank about others?

  • I am glad to see the discernment between processed soy and other versions, like fermented. Soy is a term that covers a lot of different things. My experience was that I ate a lot of Kashi products, particularly the bars, often one at breakfast and one at lunch. They contain the soy protein isolate as the protein source, as do many bars that profess to be high in protein. My thyroid production became an issue (low), so they put me on meds, with little change. When I cut out the bars with soy protein isolate, my body’s production went back up, so they took me off the medicine. My thyroid has been fine ever since.

    • If Meneta’s results are truly correlated to consuming bars containing soy protein isolate, then it sounds like consuming soy protein isolate, or maybe something else that is in that bar, would be helpful with hyperthyroidism.

  • Dr. Hyman, I have been doing a lot of things to reduce blood pressure. One breakfast item I saw on a list of recommendations for this was a smoothie made of a banana, blueberries, juice or skim milk, ice cubes, and a scoop of SOY protein powder. What do you think?

    Also, you are a male. So why is there a picture of a blond woman with all your responses here?


  • I live in NZ where Iodine deficiency is more common. I drank soy for all of my 20’s and by my early 30’s was on 200mcg of Thyroxine per day. FYI.

  • Thank you SO MUCH for this article. Your research & kind articulations are such a life savor! 🙂

  • Hi,

    What do you think of Non-GMO Soy Protein Concentrate?

    It’s in a drink.


  • Dear Dr. Hyman,

    Thank your for your considered report on soy. I have avoided soy for some years due to hearing of its dangers. I have several friends who ate tofu and soy milk all the time and got breast cancer. Of course they didn’t eat enough green vegetables either. For myself I never ate that much soy, and have all along eaten a lot of vegetables. However recently I have discovered I react to many foods due to severe histamine and gluten sensitivity and a couple of bouts of over strong antibiotics a few years ago. Strangely enough, now when I eat sprouted organic tofu, it gives me a noticeable boost. Perhaps because I am well past menopause? It feels like there is something in it my body needs. I can’t have fermented food except for plain yogurt, so I avoid fermented soy. I am glad I can have a bit of tofu now and then without having to worry that it may bring on cancer or some other dread disease. I don’t get soy in my diet otherwise since I cook everything from scratch and throw it out if its over two days old. I also don’t eat much meat these days due to its high amine content which unfortunately usually gives me a migraine. Ditto with fish unless I catch it myself and cook it almost immediately. Fortunately I don’t seem to have any kind of allergic or sensitivity response to fresh sprouted organic tofu. Weird eh? Since soy is so highly allergenic. However I have used nattokinase capsules (which are derived from fermented soy) to good effect for years, so I guess I just am not allergic/sensitive to it.

  • I’m allergic to soy and it has terrible consequences for me. So I personally am disgusted that they are putting soy in everything and they aren’t required to let you know. Only veggies and fruit for me now.

  • I am 60 and for 20 years I made and drank soy milk everyday.I was advised by a friend who saw my inflamed feet due to arthritis. For 20 years the arthritis I suffered before was gone. But now just 6 month a ago I have to stop drinking soy milk because of the rumors of its bad effects. And more especially that our soybeans in the Philippines come from China. I suspect they are GMO. After a month of not drinking soy milk my right hand thumb was sore. It became inflamed. I was forced to make soy milk and after a week of drinking my thumb healed. I stopped drinking soy milk. Just a month ago my left thumb is sore and I tried to avoid soy by taking other supplements but it does not heal. So the other day I started drinking soy milk again. With all my fears I goggled the internet and found the version of Dr. Mark Hyman. I am happy about it but still I have to control my intake.
    How about soy yogurt? Will it be better than soy milk because it will be fermented?

    • China does not allow GMO foods in their country. So,if you’re getting soy from China it should be GMO free.

  • My pituitory gland doesn’t work very well, therefore I take thyroid tablets for my thyroid. I also suffer from IBS. Since starting aceliac diet including soya milk I have been a lot better. No symptoms when I miss a tablet or three. Sleeping better and all over good health. Even my nerves are better. No panic attacks and no bad days with IBS.
    I like the Alpro soys milk. I don’t know if this is one of the most healthy ones but I like it.
    Great article and it has put my mind at eade, thank you.

  • I agree with this post and really appreciate the fair representation of the arguments for and against soy, including the logic against processed products: “they don’t have the thousands of years of traditional use that whole soy foods do. However, you also advise against saturated fat in breast cancer prevention. In the context of a whole foods diet including a variety of organic plants, don’t naturally-occurring saturated fats have thousands of years of use behind them in traditional cultures? It is not my intent to stir the pot in a high fat vs. low fat debate; I am genuinely interested in your view.

  • Can i give soya chunks to my kids, aged between 2 and 10years. They love soya chunks.

  • I was snacking on whole roasted soy nuts for sometime, and I have been diagnosed with enlarged goiter, not sure if soy had something to do with it, but what I have noticed is that my hot flushes were gone.
    I stopped snacking on soy nuts and my hot flashes are back.
    So I do believe that soy nuts had some effect on both the goiter and the hot flashes. This is my experience, and I don’t eat fish at all.

  • j

    I was born in Asia, but grew up here, eating a Western diet. While I’ve had Asian fermented soy milk, I was never fond of it (and it wasn’t regularly consumed in my particular Asian culture).

    When I was in college and started drinking coffee, I used Western soymilk instead of cow’s milk. My periods got heavier and lasted for over a week, I had the worst lower back pain that kept me in bed, and I was very irritable. Thinking it was the coffee, I managed to stop drinking coffee for about 20 years. At the same time, I had stopped drinking soy milk, since I personally can’t stand the taste of either the American brands or the fermented Asian brands.

    One day I decided to make soy milk because it was the equivalent of the gluten-free fad that is prevalent today. I made sure to cook the soy for at least 30 minutes because of the mineral leaching issue. All of a sudden all of the menstrual symptoms I thought I was avoiding by not drinking coffee came back with a vengeance. Realizing that soy milk was the only thing new I introduced to my diet within the previous 30 days, I resolved to never drink the stuff again. My periods in successive months occurred without any problems. I knew it was the unfermented soy that was giving me issue.

    To be clear, I have no issue with soy sauce. I don’t eat tofu (not something my family grew up eating). But I always read food labels to make sure that I get no soy isolates or soy proteins in my system. If I didn’t have an aversion to fermented Asian soy milk, I would try it to see if it’s all soy that gives me problems, or just unfermented soy, such as the Western-style soy milk.

    I also started drinking coffee again, after an absence of 2 decades. Instead of soy, I used cow’s milk. No difference in my period.

  • I used to be super sick from fibromyalgia & ever since I started drinking organic whole Soy milk Earth balance brand I am a new person & I rarely ever get sick anymore!!!

  • i have recently been living with my boyfriend who is vegan and eats TVP 2-3 times a day. At this same time i have been getting my period 3x in one mth. is soy the reason. I am 41 and have never had this happen before starting this new diet

    • Hi Tara,
      Thank you for your interest In Dr. Hyman’s work. Unfortunately he cannot provide you personalized medical advice in this forum. In order to provide you the proper care you need we hope you will seek the attention of a local qualified Functional Med practitioner soon. To locate a doctor near you who practices functional medicine like Dr. Hyman, go to and scroll down to where it says “locate a practitioner” and enter your location. Progress accordingly from there.
      Wishing you the best of health,
      Dr. Hyman Staff

  • Thank you for this brief, but very informative article on soy. I have been enjoying a mostly vegan/plant based diet for the past 2 1/2 years with excellent results (lower cholesterol, weight loss, increased energy, better mood). However, the downside is that I have experience a reduction in my muscle mass. I feel that this is because I have significantly reduced my protein intake. I am still learning about the plant based foods that provide a good source of protein. I’m 41, and a firefighter, so I need to be physically fit as far as strength and endurance are concerned. I enjoy soy based foods, but I have been hesitant in using soy based products because of all the negative statements I have heard about eating too much soy. Thus, I cannot comment on whether or not soy has had a positive or negative impact on my overall health. I do enjoy, tofu, tempeh, and edamame, but how can I find out if the type of tofu I am using is fermented or not? Which brand of tofu do you recommend? I also use Bragg Liquid Aminos. Is this good to use even though it is not fermented? Is the type of soy used in Tofurkey products considered good or bad?

    Thank you for any information you can offer,

  • I was able to reduce my daily levothyroxin dosage by eliminating soy products from my diet…my dose continues to drop every six months.

  • I drank Herbalife shakes and became increasingly achey under right arm and in right breast. Stopped the shakes – noticed all the aches went away. Forgot about that connection and started them up again a year later – aches came back very quickly that time! Friend of mine been using Herbalife mornings and some lunchtimes – was having lumps investigated. Happened to tell me about it, I told her about my brush with who-knows-what. She stopped the Herbalife and all her problems went away too – over time but without intervention. This anecdotal ‘evidence’ would suggest to me there could be a strong link between drinking soya and developing breast cancer – it is certainly not something I would be prepared to knowingly drink ever again. I also had extreme fatigue during that time and was told my thyroid was underactive – took some tablets for that at the time but am taking nothing now.

  • Is the soy isolate healthy in the product gardein okay? They claim they use organic soy.

    • Hi Sharon,
      Dr. Hyman recommends choosing whole, organic and fermented soy foods like miso, tempeh, tofu, soy milk, and edamame (young soybeans in the pod), but not processed foods containing soy protein isolate.
      Wishing you the best of health,
      Dr. Hyman Staff

  • I’m a 16 year old girl, I weight train 3 times a week and I like to go running, ran cross country this fall (though that was a sought disaster since I was really low on iron). I’m vegetarian, 5 ft 5 and 108 lbs. Also I havent had my period since August. I’ve lost my proofs once before from being underweight, but I’m not anymore. I was reading on how soy can mess up estrogen and phytoestrogen levels. Do you think that soy could be a cause of my amenorrhea?

    • Hi Debra,
      It is common for female athletes who are very lean to experience amenorrhea. We recommend that you work with a dietitian experienced in sports nutrition to help you customize your diet to balance your hormones and optimize your performance in your sport.
      Wishing you the best of health,
      Dr. Hyman Staff

  • I knew a healthy, thin woman, about 50, post menopause, who had to have her gall bladder removed because of stones. This woman made a shake for breakfast every single day made from an entire block of tofu. Like a small size sour cream container size. She also drank soy milk. She did this to replace the estrogen. Could this have cause her gall stones? (it was not me) I decided to give up all soy.

    • Hi Peggy,
      Some of the risk factors for the production of gall stones are defects in cholesterol metabolism, reflux, heartburn, colitis, constipation, obesity, hormone imbalance, hypochlorhydria (low digestive acids), sluggish liver function and bile movement. There is no way to know if her high consumption of soy contributed to her condition. As recommended by Dr. Hyman, it is best to choose only whole forms of soy in reasonable portions as part of a healthy diet.
      Wishing you the best of heath,
      Dr. Hyman Staff

  • I breastfeeding fed my daughter for 5 months successfully until my supply decreased and my job became more demanding and I failed to keep up with my dear daughter’s demand. It was heart wrenching but I felt it necessary to start supplementing which in turn led to switching entirely to bottle feeding. My Dr recommended soy formula. I chose organic soy so that I might not need to worry about the GMO concerns but then I read about the effects on the thyroid and I became worried because both of my sisters had thyroid cancer. We were raise near soy farms and now I wonder if that was the link because the cancer was apparently not genetic but environmental. Should I switch to a milk based formula now that I know this?

    • Hi Lizzy,
      We recommend that you discuss this question with your doctor/pediatrician to customize your feeding plan for your daughter.
      Wishing you and your family the best of health,
      Dr. Hyman Staff

  • Dear DR, is the soy yogurt “fermented” such that the substances causing adverse effects to the thyroid and hormones (like pythic acid, enzyme inhibitors, goitrogens, etc,) are gone? I’m considering cultivating my own yogurt using soy milk and the Bio K probiotics as a starter culture, but I don’t know whether those aforementioned substances would be eliminated from the soy milk in the same way as tempeh and natto cultures do.

    • Hi Elijah,
      No, soy yogurt still does contain the same nutrients as unfermented soy. If you are concerned about consuming too much soy in your diet, try homemade coconut yogurt as an alternative.
      Wishing you the best of health,
      Dr. Hyman Staff

      • Wanting to understand your comment more here, as your reply to Elijah seems in contradiction to the theme of this article and comments that fermented soya is far safer than non-fermented. Are you saying that soymilk cultured with typical yoghurt bacteria doesn’t count as fermented (in that is is with bacteria and not with yeast).

        This seems a very important issue, and aside from your comment I have not been able to locate any other views about ‘cultured soya yoghurt’. Please can I enquire what research you are basing your statement upon.

        Also, what about ‘kefired’ soya milk ‘yoghurt’ where would that stand.


  • Dr Hyman
    I had a series of GI problems that started over a year ago. I began a diet change and took on a bland food diet and gave up red meats and other proteins and basically replaced everything with tofu. I also started to drink whey protein shakes which also contained soy. So, I ate tofu with rice or vegetables twice a day for an entire year. I had no idea I was doing something so threatening to my health. Now, I have an inflamed bladder condition now which is very painful, I am also thinner than I was, and have low estrogen levels. This is a new discovery. It took my doctors a while to find the cause of blood in my urine. I now have a new dietary guide safe for bladder–and soy is a big red flag! I am now so worried that the soy could have ruined my health and caused irreversible damage. Can one year of big time soy consumption cause irreparable damage or cause future conditions??

  • Why do you reccomend avoiding GMO soybeans? You give well reasoned arguments for avoiding overly processed soy, but I don’t see any rationale put forth for avoiding GMO. Couldn’t you make just as healthy a tofu out of a GMO as a conventional bean?

  • Asian countries such as Japan and Chinese have a high soy diet yet their cancer rate is MUCH lower then the US or Europe, anyone care to explain that if soy is so bad !

    • China and Japan have a ban on GMO foods. Studies indicate that GMO foods may cause cancer.

  • About the comment that iodine deficiency is rare in the US…can you post a link or two to back this up? I read the opposite opinion from other experts. I rarely eat fish, and don’t use iodized salt or sea vegetables. I have read that iodized salt doesn’t really help, anyway. If over 90% of Dr. David Brownstein’s patients are deficient when tested, I don’t see why I wouldn’t be. I do have Hashimoto’s and low thyroid function, and have been working to reverse it with diet and supplements for a couple of years. But the experts disagree so sharply about iodine that this topic is extremely confusing to the average patient trying to learn!

  • I have been diagnosed for hypothyroidism/Hashimoto and been taking levothyroxin daily. Also I am continue to consume tofu in my food (weekly 3 or 4 times). I was alarmed articles sent by Hashimoto support group informing that non-fermented soy are not advisable. Do you think tofu is aggravating my hypothyroidism?

    • Hello Swati,
      The best way to determine if your tofu intake is affecting your thyroid function is to see your doctor for new labs. It certainly doesn’t sound like you are eating an excessive amount of tofu in your diet.
      Wishing you the best of health,
      Dr. Hyman Staff

  • I was just wondering what your thoughts were on sprouted soy, which is found in Ezekiel bread.

    I was also wondering what your thoughts on sprouted grains.

  • Dr Hyman, may I know is it suitable for me to consume lecithin 1200mg if I had hyperthyroidism? Do you think that I need to avoid any soy food? Thanks

    • Hello Ting,
      Thank you for your interest In Dr. Hyman’s work. Unfortunately he cannot provide you personalized medical advice in this forum. In order to provide you the proper care you need we hope you will seek the attention of a local qualified Functional Med practitioner soon. To locate a doctor near you who practices functional medicine like Dr. Hyman, go to and scroll down to where it says “locate a practitioner” and enter your location. Progress accordingly from there.
      You can also make an appointment to be a patient at Dr.Hyman’s UltraWellness Center in Lenox, MA. If you would like information on becoming a patient at The UltraWellness Center, please see “How to Become a Patient” at You may also feel free to call The UltraWellness Center at (413) 637-9991.
      Wishing you the best of health,
      Dr. Hyman Staff

  • I am currently looking for a multi vitamin and some the ones I’m researching contain soy (some of the vitamins and minerals are soy-derived). I’m seeing maybe 200-300mg worth of soy consumed in a daily serving. Is this something I should avoid if possible? I currently don’t consume any soy products and really don’t know that I should start, considering all of the questions concerning soy today. Thank you!

  • Dr. Hyman,
    I have read this entire article because I have just begun, in the last 30 days, to eat Ezekiel Bread with sprouted, organic soybeans and other sprouts. I also have a iodine allergy, but my levels from bloodwork, have never been low.
    Therefore, will my risk of eating this type of soy be higher because I cannot access iodine rich foods? I have other food allergies as well which make it even more difficult to access fish or eggs. I still eat meat.
    Thanks very much.

  • I have been drinking organic soy and eating it in cereal everyday for two months and i actually feel better then when I drank milk.My bones aren’t popping as much and my skin has a dewy fresher look making me look at least a year or two younger.I drink 32 fluid oz. of this soy a day so i think it is very good and feel really great and I just turned 38.I feel better then when I was 35.:)

  • Thank you for championing soy. One comment, though – to the best of my knowledge, although tempeh, natto, miso and soy sauce are fermented, tofu and soy milk are not.