Does Soy Interfere with a Healthy Thyroid (Thyroid Health Q & A) : An Exlusive Renegade Health Article by Dr. J.E. Williams

Wednesday Jul 6 | BY |
| Comments (36)

An estimated 13% of the population is deficient in iodine. For these people, thyroid function can be disrupted by eating high doses of soy isoflavones.

Resident Medical Authority: J. E. Williams, OMD, FAAIM


Q: I am working with my doctor to lower my dose of levoxyl I take for hypothyroidism. Years ago I was told I had Hashimoto’s Disease and would need thyroid medicine for the rest of my life. While my doctor has been working with me to help me lower my dose as I make lifestyle changes to become healthier, she isn’t trained or educated in the field of study that states it is possible to regain total health and no longer need the thyroid meds. Does your thyroid program with Dr. Williams help for people currently on thyroid meds and wish to slowly and properly lower their dose to regain endocrine optimal health or just for people with borderline thyroid issues?

A: It’s possible, but not easy, to restore the thyroid gland to normal health. You’ve taken a good first step my getting the excess production of Thyroid Stimulation Hormone (TSH) under control with thyroid hormone replacement. The next step is to change from synthetic T4 (Levoxyl) to a bio-identical form like Armor Thyroid. When your thyroid blood tests, including antibody tests, are normalized, you can begin adding in endocrine corrective supplements like iodine, tyrosine, and selenium, as well as eating a thyroid friendly diet. Hashimoto’s Disease is a complex autoimmune disorders, so you’ll need a physician partner with experience in thyroid health to guide the process.

Q: Does anybody remember how Oprah talked about drinking her soy smoothie every morning, and now has a problem with hypothyroid? Is there a connection?

A: American women have taken to soymilk for their café lattés and smoothies like fish to water. However, though soy when eaten in moderation is healthy and balancing, too much soy consumption can dampen thyroid function is some people. Thousands of years of eating soy in China and modern science informs us that soy doesn’t disrupt thyroid function in those with normal thyroid function and adequate iodine. Postmenopausal women between the ages of 64 and 83 seem to handle soy isoflavones well. In one study, after six months, the differences in thyroid hormones between the groups who ate soy and those who consumed a placebo were statistically indistinguishable. However, soy isoflavones in high doses can disrupt thyroid function in those who are iodine deficient (an estimated 13% of the population), in those who have compromised thyroid function, and should be used sparingly in younger women.

Q: My concern is that I no longer have my thyroid (removed 43 years ago) and all the information I have found talks about strengthening and helping the gland. When I find information that does, in fact, talk about the removal of the gland, it is usually just one line indicating that the person will be on synthetic thyroid replacement the rest of their lives. I would like more specific information, i.e. would the regular blood tests for free T4 and T3 and TSH be the same for me (and others like me) or not. The endocrinologist I attend is lowering my dose, and I am suffering with every symptom of hypothroidism.

A: When your thyroid gland is completely removed, you need thyroid hormone replacement, and possibly also parathyroid hormone. However, synthetic T4 is only a part of the answer. It may make the blood test numbers for TSH and free T4 fit the accepted ranges, but you can still have low thyroid symptoms. Unless T3 is addressed adequately through replacement with a synthetic form (Cytomel) or a bio-identical T3/T4 combination, or a natural T2/T3/T4 dessicated form (Armor), you will continue to function below optimal. You also need to support T4 to T3 conversion with vitamin A, D, and selenium, as well as have adequate dietary iodine.

We want to know your thoughts: Do you eat soy or not? Think it’s healthy?


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Dr. J. E. Williams has over 30 years of clinical experience in the natural health world and has had over 100,000 patient visits over that time.

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These programs include how to improve thyroid function, how to read your blood tests, and how to support your adrenals naturally.

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Dr. J. E. Williams


Dr. Williams is a pioneer in integrative and functional medicine, the author of six books, and a practicing clinician with over 100,000 patient visits. His areas of interest include longevity and viral immunity. Formerly from San Diego, he now resides in Sarasota, Florida and practices at the Florida Integrative Medical Center. He teaches at NOVA Southeastern University and Emperor’s College of Oriental Medicine.

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  1. Kim says:

    I am hypothyroid, take medication and I do drink soy milk occasionaly. My question is, are broccoli SPROUTS ok to eat with this condition? I grow my own broccoli, sunflower and buckwheat sprouts – to try and stay away from kale, collards, spinach, etc.
    Thanks, Kim

  2. Thomas says:

    I used to use Silk soymilk on cereal. I stopped a few years ago when I noticed a drastic change in it that had an adverse effect on my digestion.

    Then I read the report from Cornucopia ( that described how Silk had been bought out by Dean Foods, a large cow milk corporation that markets across America under different brand names. They (Dean) wouldn’t pay the price any longer to American farmers for organic soy beans, and had substituted Chinese soy beans in their “organic” products.

    Cornucopia also has an article describing how the Chinese “organic” label is a fraud, so now I don’t buy any “organic” labeled foods from China (including goji berries). They just ‘pay off’ the ‘organic’ certification inspectors. Too much corruption in the Chinese food industry. 🙁

  3. hyesun says:

    only fermented soy, like miso, tempeh, natto, and some fermented korean soy foods. when i eat anything goitrogenic i also eat seaweed for iodine.

  4. There’s so much controversy on soy! It’s so hard to know who’s right or not. I personally agree that it’s probably healthful in moderate amounts. Not tons of it daily as some do, but a few times a week.

    The “meat alternative” soy based products are probably as bad for you as processed meats IMO. They contain a lot of gluten, flavours and MSG type substances, TVP, excitotoxins etc. A lot of vego/vegans live on this stuff and it is soo not good! Some of it is ‘so good’ that it actually does taste like chicken! That can’t be a good thing unfortunately, lol.

    Here’s an article by Dr Andrew Weil on the benefits of good soy products. He talks about trypsin inhibitors and so on:

    Really good, he’s a smart man 🙂 My vote is for fresh tofu etc a few times a week.

  5. casey says:

    mmmm soy but non gmo

  6. Nikki says:

    I love soy milk. I only use it in moderation though due to it’s high price and high level of processing. I think that in comparison to dairy (especially when you cannot afford organic dairy) it is a better choice. It is good when I am craving cereal with milk.

  7. Marilyn says:

    Why not use almond milk?

  8. Melissa says:

    I had trouble with soy and my thyroid. I have since switched to almond and hemp milk. I still eat soy when I go out to Thai or Chinese or when partaking in the occasional latte but I keep it fermented or whole at home. I eat quite a bit of sea vegetables and doubt my iodine intake has any effect on my ability to consume soy. Since lowering my consumption of processed, unfermented soy, my medication is now at the lowest prescribed dose and my goiter has all but disappeared.

  9. Cherie says:

    I used to eat soy because it was so good for you. Then in trying desperately trying to figure out why my thyroid was so very low, in the 90’s, I eliminated it. I was SHOCKED when with in 3 weeks my thyroid was in normal range. I do not eat soy on purpose anymore.

  10. Janet Doane says:

    I’m always surprised to not see much about soy and estrogen, which I had a big problem with. My hormones were always whacked out and I ate a lot of tofu for 30 years. When it was time for my change of life passage, my husband said I went through “tofupause”… after we finally figured it out, and stopped eating it! I also had low thyroid, but it’s gotten better and better. I don’t touch soy, even miso!

  11. Elo says:

    After the Chinese melamine scare a few years ago I decided to avoid all Chinese food products including Chinese food at restaurants. All I use now from China is green tea. If we speak with our actions and our wallets the Chinese may learn about the value of quality control.

  12. Donna says:

    Soy – ask 100 people – 50 will say it is the best thing since sliced bread – 50 say it is poison. I agree with those who have found that it affects thyroid – one month on a daily cup of soy milk (instead of milk) and I gained a few pounds – no other dietary changes – and developed some other low thyroid symptoms such as sore / bleeding nasal passages. I now drink almond milk. Have read soy is estrogenic and that the GMO stuff is bad; and that only small amounts of fermented organic soy products are advisable. Read for an extreme view of why soy is bad. (e.g., evidently, the GMO soy has been modified to withstand huge amounts of RoundUp to kill weeds and increase crop production – I really don’t want to eat all that pesticide, other soy issues aside!) Have heard (Lorna Vanderhaeghe – ladies, see her website – amazing!) that you have to consume many pounds of crucifer vegetables for them to affect thyroid. (She also says flouride competes for thyroid hormone at the receptor sites and therefore, lowers thyroid function – so get rid of flouridated water and other fluoride products). She sells an excellent supplement, ThyroSmart. Also buy / read Dr. Eric Berg’s eBook – Bell Fat Control – How to Have a Healthy mid section – for a diet that will re-boot thyroid, adrenal, liver and ovarian function (e.g., for me, in 3 months, 55 years of psoriasis is gone and I am now weaning off of many hormone meds. And btw, his at home acupressure techniques are nothing short of astounding for chronic pain).

  13. Sarah says:

    I feel as though I need to write something here on this subject. I am a nutritionist and have worked with this issue for 15 years. I also lived in Japan for 7 years and while there, studied macrobiotics with an Ohsawa Institute instructor and also studied traditional Japanese cooking. Upon returning to America, I attended many seminars with Naturopath Dr. Bill Timmonds who was an expert in adrenal health (among many other things) and who I consider to be one of my most cherished mentors. I also happpen to currently be the chapter leader for the Weston A. Price Foundation in Marin. So, for what it is worth, I’ll put my thoughts here. Regarding soy: the soy beans of America are totally different from the soy beans of Japan. I don’t know if this makes a difference or not, but they don’t even look the same. I do know that soy here is one of the most common GMO crops (along with corn). Now there are many questions regarding whether organic soy here is affected by neighboring GMO crop soy or not – I don’t know. In Japan, soy is often fermented and is eaten sparingly in very specific ways. Small bits of tofu in miso soup (miso is fermented), Natto, miso and tempeh (not Japanese) are all fermented. No Asian culture I know of eats huge amounts of soy as a meat substitute. So large glasses of soy milk are not drunk, western dishes like lasagna are not made vegan by substituting slabs of tofu for meat, highly processed foods such as soy hot dogs, soy cheese and soy hamburgers are not eaten. It is eaten respectfully and in small amounts. By respectfully, I mean that there are special soy food shops where you can buy soy products traditionally made, usually by a family who has produced soy in a traditional manner for generations. Soy is part of a varied diet. So as a WAPF chapter leader I am “outing” myself, but I don’t see soy as a total enemy – only highly processed and certainly GMO soy. Now, regarding thyroids: My mentor, Bill Timmonds, always used to say that he strongly felt that most hypothyroid was actually NOT primary thyroid, but was adrenally driven. He always pointed out that the body, in its infinite wisdom, would lower the thyroid activity if one were stressed and pumping out cortisol, which results in a catabolic (break down)state. Why would you want your engine to be revved up if your body was in a break down state? So he often advocated treating hypothyroid as an adrenal problem and voila! Many times, adrenal function would be recovered and thyroid would correspond accordingly and TSH levels would level out. So bottom line for me is: soy in moderation, eaten as an organic whole food and in a fermented state is O.K. (unless you have an allergy to it).(O.K. I have just outed myself here, WAPF) Soy infant formula is NEVER a good idea. And in a nutshell, if you are hypothyroid: do some adrenal saliva testing and see if there is a problem here. If you have been diagnosed as having Hashimoto’s, that is autoimmune. Look at a possible gluten intolerance and get tested for your vitamin D levels. (Vitamin D really helps to stabilize autoimmune conditions, but don’t self-diagnose! Work with a health professional on this one!) O.K. I’ve written too much again! Sorry! I am just passionate about all of this and Kevin and Annmarie give us such a wonderful platform to offer our thoughts and opinions. Oh and BTW: eating a boatload of iodine containing food might not be a good thing if you are autoimmune as well. I am putting a plug in here also for another mentor: Donna Gates of the Body Ecology Diet. I think she really has a lot of this all figured out. Thank, Kevin! 🙂

  14. Anne says:

    Great Post Sarah,

    I have to say that what you say about Thyroid/Adrenal relationship does make sense to me as I’m going through something related to this. In Feb I was having many issues causing me digestive problems and inability to gain weight. Blood tests revealed I was extremely low in Iron (ferritin levels way below the norm) and had other problems like slightly elevated Liver enzymes (which had however come down a bit from the last test in the fall). My TSH however at 1.4 was great.

    My holistic practitioner put me on a variety of things many of which helped but one of them was lugols iodine which I took religiously as indicated (first flooding the system in the first two weeks then two drops in water). Some of my symptoms (digestion) were getting better and a blood test in May revealed my iron stores were going up (without the inclusion of iron supplements in my diet). But I was feeling tired and my blood test revealed my TSH was 3.8 which was way over what it normally is. I suspected the iodine was harming me rather than helping so I stopped taking it orally and just put a drop on my wrists in the morning and also have been taking an Adrenal support formula (with Fo-ti, Schizandra, Ashwangandha, Royal Gelly, Ginger, Rhodiola and Eleutherococcus and I feel so much better.

    So I was really getting to the point of seeing a relationship between the adrenals and the thyroid.

    Anyway, long way around to say this but this totally feels right to me. Much more than avoiding so many foods that could suppress the thyroid. that is for me because my thyroid has always been fine in the past.

  15. Gini says:

    I was drinking soy milk every day when I went through menopause. I had no negative symptoms at all and attributed it to the soy, but don’t know if it really was the reason. I no longer use unfermented soy products and drink unsweetened vanilla hemp milk (& sometimes add some stevia). Unsweetened organic almond milk is very good too.

  16. Gini says:

    Also– I used to make my own almond milk when organic almonds were more affordable. Sooo good.

  17. JT says:

    NO SOY for all…ever. We can live without it. Even if there is a chance it can mess up your hormone balance or your thyroid, why take the chance? It doesn’t make any sense when there is so much really good fresh organic vegetables out there to nourish us. I need my husband and my teenagers to have as much balance as possible. Ever tried living with a person who is hormonal?? Not a pretty thing to see.

  18. JT says:

    To Sarah #13 above, thank you for your comments. They were intriguing and insightful. Something for me to think on. That is what I like about this format.

  19. Teresa Lawrence says:

    I sooo connect with Sara’s statement. As for the article, it pretty much covers the soy questions. Thanks Kevin and Ann Marie.

  20. Nihacc says:

    I eat soy regularly, but not everyday… it depends: sometimes I eat it more frequently and sometimes less or even nothing. My last thyroid hormones test was ok, so I guess I can keep on like this.

  21. Gretchen says:

    I have Hashimoto’s Disease and for the past 5 years I have been consuming soy products like tempeh, miso, tamari, and occasionally sprouted tofu. I did drink soymilk 4 years ago, but with all the hype, I switched to only Almond milk and I often make my own.

    The small amount of soy has made no difference in my TSH levels. I get annoyed with people who are completely anti soy and think that it will harm their thyroid to consume any soy at all, yet consume bacon and eggs every day. Minimally processed soy has health benefits, the stuff we should all avoid is “Isolated Soy Protein” which you find in commercially prepared shake mixes, supplement bars and veggie burgers.

  22. Carol O'Connell says:

    Visalus which is a meal replacement uses Non GMO Soy Protein with Trisorb. I have not had any issues while using this and am not aware of others using it having a problem with the quality soy that is in the product. The quality of this soy may have something to do with it. I am aware that in some people soy can be estrogenic, but I believe it’s an individual thing when it comes to soy…I just know if you consume it…non GMO is essential.

  23. Dianne says:

    I do eat soy products that are non GMO and organic. That includes tofu frequently and veggie burgers on occasion, as well as miso and tempeh and yuba. I am healthy with healthy thyroid levels which I recently had checked. I also eat seaweed, mainly because I enjoy it.

    Dr Weil does support soy. As well as several other doctors. Another good article is:
    Enjoy Soy: Dr.Debunks Scaremonger Stories, Says Soy Beneficial For People And The Planet

    Read more:

    I have to comment on Japan. I lived there for 5 years and had many Japanese friends and ate out frequently and shopped at the stores and ate at their homes. The Japanese ate large amounts of tofu daily, not just small chunks in their miso soup (which they also did). No they did not eat soy milk, cheese, hot dogs. Diary products and hot dogs were not part of their diet (which unfortunatley may change). They ate more tofu than I could, and they are smaller framed people than Westerners. They sold cold tofu at their convenience stores in packages to consume as snacks (large pieces). Yes, they do eat more iodine than we do. They ate copious amounts of tofu. They had shops on every corner where fresh tofu was being made and it was sold in the grocery. They also ate yuba. We enjoyed it. Yuba is skin from the beancurd. Soy milk is boiled (so I guess they do eat soy milk in this form) and the film on top is dried into a skin and eaten. They use all of it.

    We traveled extensively throughout Indonesia, Thailand and China. China ate tofu and Bali a lot of tempeh. Again, unfortunatley in China, they are adopting our eating habits and their health is changing.

    Yes, the bean may look different, but soy beans were introduced to Japan and the US from China’s beans. I do agree about the problems with Silk, since it has been sold out. Silk is trying to correct this. There are several other good brands of soy milk at Whole Foods, Trader Joes, etc.

    I do agree that it should be organic and non GMO and that iodine should be consumed, but the iodine does not have to be in huge amounts. Also, maybe more ginger.

  24. Sandy says:

    The thing is that Asians never ate soy in the amounts that Americans are eating today. They used a little on the side as a condiment, not the huge slabs of tofu or gallon-size smoothies most people today are consuming. Only in the case of famine/poverty did they ate it as a main staple.

    Also, there is something to be said about the use of soy by Buddhist monks to rid themselves of sexual desire, thanks to the estrogen. That extra shot of estrogen can also further suppress the thyroid.

    Having hypothyroidism/digestive issues/fibrocystic breasts, I’ve cut soy out almost completely (only soy sauce occasionally). I immediately noticed the difference in my breasts. I don’t eat raw cruciferous vegetables – and consume them cooked only occasionally.

    If there’s nothing else available to eat, that’s one thing. By why choose these problematic foods on a regular basis when there are so many other choices out there?

  25. steve says:

    The reason we don’t do soy; is we heard it can line the small intestine and block some extortion of nutrients, so my question is this: Does soy actually do this?

  26. Leslie says:

    Very interesting observations!
    I have varying amounts of coffee depending on if it is summer or if I am in Finals, etc. I was depending on a bit of unsweetened soymilk in it predominantly, until it went off sale and almond milk went on. Coincidentally I noticed that for O blood types, almonds are beneficial whereas soy is merely Ok. I also am a few years into menopause with few side effects but still ran hot as always. I noticed my sexual finish was more obscure after menopause (something you are still aware of even if without a partner, I think having a partner probably eliminates this problem due to the outside stimulation of just having him around). After 2 months or so relying on almond milk, it returned, but at a time when I either had poison ivy or shingles, a one time outbreak in my life, down there, so don’t know how related it is. Maybe it would have evend out on its own.
    (I suspect the soy is GMO/tampered too). The rashing is gone, the “normalcy” remains, which is reassuring to my identity. A lot of our motivation is based on the pleasure we anticipate in life, and our identity is tied up in this (how we feel). You don’t have to be “active” to notice a change.
    Anyway it was just before ending a really hard portion of my life where I had to close down a house and work long hours, which is concluded. Now I am doing raw even more and making (so sourcing) my own snacks and drinks!
    By the way, the first study on soy isoflavones relating to breast cancer came in showing they do not encourage it. there are other phytoestrogens in herbs and all our natural food, so this makes sense. But for soy, in moderation still!

  27. Leslie says:

    Also, as a teenager on Okinawa (early 70s)many locals had adopted the American diet (which was not as bad then, though on base candy was stale and milk was reconstituted)and their kids were bigger. I do eat seaweeds and Martha Stewart showed a DLT (dulse, lettuce and tomato sandwhich) which I make on Ezekiel bread, but don’t fry it in olive oil as I have seen her do, it is best out of package (not fishy this way). I use avocado, celery, red bell, onion etc.

  28. Greg says:

    Thank you all for your comments. I am a Level II Vegan (McDougall/Esselstyn) for just over a month from the SAD diet because I want to be heart healthy. I was encouraged by a visit to the Hospital for A-Fib. I am also hypo-thyroid and on levothyroxine for about 10 years. I am a retired fireman 2009. The adrenal failure from stress makes a lot of sense, but my Dr’s never tested me for that. I have never had the energy I used to have even with many tests of my T3 and T4 levels to check and adjust meds. Since becoming Vegan I have lost 20 of my 250lbs, and I am very happy about that, but I still lack the energy. (I don’t miss my 3-4 cups of coffee a day.) I am glad to read about concerns with using Soy as I have Silk in the frig and tofu and tempeh. I am going to cut the soy and see if that helps. Thank you all again for your comments.

  29. renee says:

    I now have known 3 people, 2 adults and 1 teenager that ate tons of soy products and soy meat replacers and soy milk. All three of them developed tumors on various organs. Mostly, liver and ovaries. It should be noted that soy is in almost every packaged food product so people are getting bombarded with soy in very unnatural forms. I have also read extensively that, yes, while in China for thousands of years tofu and other soy products were eaten without problems, the fermenting and processing of soy was very much different. It could take years for tofu and tempeh to become ‘ripe’ for use. It breaks down the poisonous aspects. The forced processes today do not allow for this. Most soy is GM in the world. Can’t get away from it, and tests have shown that GM products like soybeans cause tumors and shrink major organs. Soy acts as a estrogen mimicker so that would tell us that too much soy would cause a lot of hormone imbalances which could be especially troublesome in children. It should also be understood while in China for thousands of years of use, only small amounts were ingested. Not like today where people are downing their soy smoothie, having a soy chai, moving onto their tofu lunch and soy meat replacer dinner. Along with any packaged foods that have soy lecithin, soy protein isolate, soy oil, or soy flour amongst others in it. Just like anything, if you have the smallest amount at any time, it won’t kill you but I would seriously have everyone consider removing the bulk of soy from their diets. We are seeing most almonds in this country if sold commercially are irradiated as well which to me is also of a huge concern. I also found that hemp seed is as well, most of what is sold on the commercial market. It is very hard to find pure products anymore.

  30. JC says:

    I love the taste of tofu and soy milk. I have been eating tofu almost daily and drinking at least 2 glasses of soy milk a day for over 20 years. No problems with my thyroid. My health is great. After reading this site it makes me want to try to reduce my soy intake. But it taste so GOOD!!

  31. Elisabeth says:

    i am hypothyroid and eating more kelp for the iodine but concerned about the toxicity of sea weed (heavy metals). i am considering bying iosol iodine. are there any certified non toxic sea weed out there?

  32. Luke says:

    As a healthy guy who worked out lots, I found out years ago that soy caused pain in my joints. I had noticed my shoulder started hurting when I worked out, and when I stopped drinking my soy drinks it got better. Each time I started drinking them again, my shoulder would become inflamed. I started reading about the negatives of soy, and have since stayed away from all except fermented soy. Soy is in sooo many foods in different forms, and most people don’t realize this.

  33. O.M.G. I dont believe im seeing this. If youre stressed and producing high levels of CORTISOL this will impact other hormones.
    I can tell by the fact that no one replies to my posts about dadamos blood type system that you guys dont believe in it. What a shame. Im blood type A and have used soya milk and tofu since adopting blood type diet as Dadamo recomends. He also says that soya products are not good for everyone. READ AND LEARN.
    Dadamo is a blood type A himself.
    Would he reccomend soy for blood type A if it was bad for him ?

  34. Eve says:

    Is soy and gluten in facial skincare product significant to effect your thyroid? I can’t find a skincare that doesn’t have soy or gluten.

  35. Nazia says:

    Hi,I am nazia I have thyroid from 3years I don’t know is it good or not but from last 6 mouths I was taking soy milk with my cereal.and I don’t feel any thyroid levels are in control.even I use soy sauce in cooking some times.

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