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How Phytoestrogens Can have Anti-Estrogenic Effects

When the Women’s Health Initiative study found that menopausal women taking hormone replacement therapy suffered “higher rates of breast cancer, cardiovascular disease, and overall harm,” a call was made for safer alternatives. Yes, the Women’s Health Initiative found that estrogen does have positive effects, such as reducing menopausal symptoms, improving bone health, and reducing hip fracture risk, but negative effects were also found, such as increasing the blood clots in the heart, brain, and lungs, as well as breast cancer.

Ideally, to get the best of both worlds, we’d need what’s called a selective estrogen receptor modulator—something with pro-estrogenic effects in some tissues like bone but at the same time anti-estrogenic effects in other tissues like the breast. Drug companies are trying to make these, but phytoestrogens, which are natural compounds in plants, appear to function as natural selective estrogen receptor modulators. An example is genistein, which is found in soybeans, which happen to be structurally similar to estrogen. How could something that looks like estrogen act as an anti-estrogen?

The original theory for how soy phytoestrogens control breast cancer growth is that they compete with our own estrogens for binding to the estrogen receptor. As more and more soy compounds are dripped onto breast cancer cells in a petri dish, less and less actual estrogen is able to bind to them. So, the estrogen-blocking ability of phytoestrogens can help explain their anti-estrogenic effects. How do we then explain their pro-estrogenic effects on other tissues like bone? How can soy have it both ways?

The mystery was solved when it was discovered there are two different types of estrogen receptors in the body and the way in which a target cell responds depends on which type of estrogen receptor they have. The existence of this newly discovered estrogen receptor, named “estrogen receptor beta…to distinguish it from the ‘classical’ estrogen receptor alpha,” may be the “key to understanding the health-protective potential of soy” phytoestrogens. And, unlike our body’s own estrogen, soy phytoestrogens preferentially bind to the beta receptors.

For instance, within eight hours or so of eating about a cup of cooked whole soybeans, genistein levels in the blood reach about 20 to 50 nanomoles. That’s how much is circulating throughout our body, bathing our cells. About half is bound up to proteins in the blood, so the effective concentration is about half the 20 to 50 nanomoles. What does that mean for estrogen receptor activation?

In my video Who Shouldn’t Eat Soy?, I feature a graph explaining the mysterious health benefits of soy foods. Around the effective levels we would get from eating a cup of soybeans, there is very little alpha activation, but lots of beta activation. What do we find when we look at where each of these receptors are located in the human body? The way estrogen pills increase the risk of fatal blood clots is by causing the liver to dump out extra clotting factors. But guess what? The human liver contains only alpha estrogen receptors, not beta receptors. So, perhaps eating 30 cups or so of soybeans a day could be a problem, but, at the kinds of concentrations we would get with just normal soy consumption, it’s no wonder this is a problem with drug estrogens but not soy phytoestrogens.

The effects on the uterus also appear to be mediated solely by alpha receptors, which is presumably why no negative impact has been seen with soy. So, while estrogen-containing drugs may increase the risk of endometrial cancer up to ten-fold, phytoestrogen-containing foods are associated with significantly less endometrial cancer. In fact, protective effects are found for these types of gynecological cancers in general: Women who ate the most soy had 30 percent less endometrial cancer and appeared to cut their ovarian cancer risk nearly in half. 

Soy phytoestrogens don’t appear to have any effect on the lining of the uterus and can still dramatically improve some of the 11 most common menopausal symptoms (as compiled by the Kupperman Index).

In terms of bone health, human bone cells carry beta estrogen receptors, so we might expect soy phytoestrogens to be protective. And, indeed, they do seem to “significantly increase bone mineral density,” which is consistent with population data suggesting that “[h]igh consumption of soy products is associated with increased bone mass…” But can soy phytoestrogens prevent bone loss over time?

In a two-year study, soymilk was compared to a transdermal progesterone cream. The control group lost significant bone mineral density in their spine over the two years, but the progesterone group lost significantly less than that. The group drinking two glasses of soymilk a day, however, actually ended up even better than when they started.

In what is probably the most robust study to date, researchers compared the soy phytoestrogen genistein to a more traditional hormone replacement therapy (HRT) regimen. Over one year, in the spine and hip bones, the placebo group lost bone density, while it was gained in both the soy phytoestrogen and HRT estrogen groups. The “study clearly shows that genistein prevents bone loss…and enhances new bone formation…in turn producing a net gain of bone mass.”

The main reason we care about bone mass is that we want to prevent fractures. Is soy food consumption associated with lower fracture risk? Yes. In fact, a significantly lower risk of bone fracture is associated with just a single serving of soy a day, the equivalent of 5 to 7 grams of soy protein or 20 to 30 milligrams of phytoestrogens, which is about a cup of soymilk or, even better, a serving of a whole soy food like tempeh, edamame, or the beans themselves. We don’t have fracture data on soy supplements, though. “If we seek to derive the types of health benefits we presume Asian populations get from eating whole and traditional soy foods,” maybe we should look to eating those rather than taking unproven protein powders or pills.

Is there anyone who should avoid soy? Yes, if you have a soy allergy. That isn’t very common, though. A national survey found that only about 1 in 2,000 people report a soy allergy, which is 40 times less than the most common allergen, dairy milk, and about 10 times less than all the other common allergens, such as fish, eggs, shellfish, nuts, wheat, or peanuts.


What if you’re at high risk for breast cancer? See BRCA Breast Cancer Genes and Soy

What if you already have breast cancer? See:

What if you have fibroids? See Should Women with Fibroids Avoid Soy?.

What about hot flashes? See Soy Phytoestrogens for Menopause Hot Flashes.

What about genetically modified soy? See GMO Soy and Breast Cancer.

Not all phytoestrogens are beneficial, though. See What Are the Effects of the Hops Phytoestrogen in Beer? and The Most Potent Phytoestrogen Is in Beer.

How deleterious is hormone replacement therapy? See How Did Doctors Not Know About the Risks of Hormone Therapy?.

Synthetic estrogens used in animal agriculture are also a concern. For more on this, see Zeranol Use in Meat and Breast Cancer.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Discuss

Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.


85 responses to “How Phytoestrogens Can have Anti-Estrogenic Effects

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  1. Thanks for posting this.

    I was drinking soymilk in my green tea latte, but haven’t been having it since I quit my Starbucks habit and I knew that I liked soy, but forgot why.

    “In what is probably the most robust study to date, researchers compared the soy phytoestrogen genistein to a more traditional hormone replacement therapy (HRT) regimen. Over one year, in the spine and hip bones, the placebo group lost bone density, while it was gained in both the soy phytoestrogen and HRT estrogen groups. The “study clearly shows that genistein prevents bone loss…and enhances new bone formation…in turn producing a net gain of bone mass.”

  2. By the way, my keto friends are listening to you now. You did the keto videos and now you are doing diet. I mentioned a few of the studies from How Not to Diet and they were already watching the talk.

  3. Thank you for sharing all of this great info! I have endometriosis and have found articles claiming that soy is either great for controlling spread of the disease as well as articles claiming it fuels spread. Can anyone here speak to this?

      1. I’m sorry. The article I referred to were not in my initial posting. Here they are:
        https://nutritionfacts.org/video/how-to-treat-endometriosis-with-seaweed/
        https://nutritionfacts.org/video/what-diet-best-lowers-phthalate-exposure/
        https://www.ncbi.nlm.nih.gov/pubmed/17474167 Effect of soy isoflavones on endometriosis: interaction with estrogen receptor 2 gene polymorphism.
        “Higher levels of urinary genistein and daidzein were associated with decreased risk of advanced endometriosis (P for trend = 0.01 and 0.06, respectively) but not early endometriosis. Higher levels of urinary genistein and daidzein were associated with decreased risk of advanced endometriosis (P for trend = 0.01 and 0.06, respectively) but not early endometriosis…CONCLUSIONS: Dietary isoflavones may reduce the risk of endometriosis among Japanese women.”
        https://www.ncbi.nlm.nih.gov/pubmed/23419794 Diet and endometriosis risk: a literature review. “At present, evidence supporting a significant association between diet and endometriosis is equivocal. Further studies are needed to clarify the role of diet on endometriosis risk and progression.”
        https://www.ncbi.nlm.nih.gov/pubmed/28326519Influence of diet on the risk of developing endometriosis.” Further research is needed in order to fully understand the influence of consumed food products on the risk of development of this disease.”

    1. The articles you referred to need to reviewed carefully, because as Dr. Greger pointed out just because a food contains an estrogen-like substance, that doesn’t meed the body will react the same way as with estrogen itself. I pulled up two article Dr. Greger prepared discussing research on the treatment of endometriosis as well as three articles that conclude soy can be helpful with this condition or at least studies show there is not a response with soy that increases endometriosis risk. Check these out and hopefully they will answer your questions.

  4. This is a very timely article. I just found out that I have a breast cancer recurrence and will likely be put on some hormone therapy. I previously did horribly on Femara (I felt like crap). But we are looking at possibly Ibrance, Arimidex or Tamoxifen. I know how important hormones are to overall health, so I am wondering what your thoughts are on how much soy I need to eat (and how often) to offset the side effects of these drugs. Given this is a recurrence, the option to NOT take these drugs is no longer on the table for me. I got away without taking them for 7 years, but I don’t feel I have a choice any more. So how much soy, how often, and in what forms? Soy beans don’t sit well in my belly, but could I do tofu or tempeh? Thank you for this important information!

      1. Thank you, Blair! I have read HNTD but I will definitely go re-visit the breast cancer chapter. Good advice there. In terms of mammograms, I don’t have those because I have no breasts. Double mastectomy in 2012. I’m wondering if I need to increase my phytoestrogens even more to offset the effects of the medicines that will remove estrogen from my body (or prevent me from making it in the first place).
        Thanks for replying!

        1. Michele,

          Dr. Greger has a limit on how much soy to eat because too many servings of soy can cause IGF-1 to increase and that undoes the benefit of using it.

          He has a video on that, too.

            1. Michele O,

              I’m so sorry about your breast cancer recurrence.

              And I want to respond to your question about what kinds of soy foods to eat. I am now a whole plant food eater after discovering this site while researching nutrition after being diagnosed with breast cancer myself 5 years ago (it runs rampant through my family). I was a vegetarian for about 45 years, but dropped dairy products and eggs, and avoided even more processed food.

              I eat soy milk (which I make at home from soybeans and water, and I don’t filter it, because I want to eat the whole bean; besides, I couldn’t figure out what to do with the solid materials if I did filter it), soy yoghurt (which I also make at home from commercial soy milk — mine has too many solids in it — made only from water and soybeans, with no additives), edamame (shelled or in the shell), tofu, and tempeh. I’ve never tried natto which I’ve heard is an acquired taste, and I’ve used soy flour in baking. I probably consume 1-2 servings a day, sometimes none.

              Oh, and I don’t drink my soy milk; I use it on morning cereal, and cook and bake with it.

              I’d love to know if there are other ways to eat soy beans.

              1. I eat natto daily. It is easy to culture. 24 hours and it is done, A complete semi pre digested protein. My favourite is natto with maple syrup.

    1. Very sorry to hear about your occurence. If given green light to eat soy, I find for myself, it I soak dried organic soybeans for 24 hours, discard the soaking water, and then pressure cook them in fresh water, they are much more digestible..as in no flatulence, belching or cramping. Best of luck to you.

    2. Michele

      I am probably teaching grandma how to suck eggs here but don’t forget the importance of engaging in regular physical exercise

      ;’A recent review of the effect of lifestyle factors on breast cancer mortality concluded that physical activity has the most robust effect of all lifestyle factors on reducing breast cancer recurrence.22 Lowered endogenous hormone levels, reduction of inflammation and reversal of insulin resistance have all been hypothesized to mediate the effects of exercise.23

      A meta-analysis of 22 prospective cohort studies found that breast cancer mortality was significantly reduced among women who reported participating in recreational physical activity after their breast cancer diagnosis (HR 0.59, 95% CI 0.45–0.78). However, there was considerable heterogeneity across studies. The effect was stronger among women who met recommended levels of physical activity…….’
      https://www.cmaj.ca/content/189/7/E268

      1. Thank you for your reply. I had to go look up “sucking eggs”, though! LOL! Yes, I am aware of the beneficial effects of exercise. I do yoga or tai chi a few times a week, but definitely need something more. New treadmill will be purchased on Black Friday! Thanks again!

    3. I’m sorry you are now having to deal with a recurrence of breast cancer, Michele. I see you have been advised to review the research Dr. Greger has highlighted on breast cancer.and I encourage you to do just that, as well as reviewing with your doctor research specifically on how soy might affect both your diagnosis and the effectiveness of the meds you’ll be taking.As to see research or speak with a knowledgeable dietitian, if you are not comfortable with a non-researched remark about “use caution.with soy” remark. I could not identify any specific studies speaking to exact dosage or servings of soy that were associated with less breast cancer risk. And as far as best form. As you probably know, the less processed the better, but if you can’t eat soybeans, tofu and tempeh do have soy, just not as direct an effect as the whole soy bean. .

    1. I hope our experience might shed some light on this. My husband is on thyroid replacement after treatments for cancer nearly 10 years ago. In his liquid diet (he has a PEG tube), which is plant based, organic whole food, I can add 24 grams of soy protein (3 cups whole bean milk or tempeh daily) without needing to adjust his medication. Years ago, when I changed the recipe (the amount of soy in his smoothies), the thyroid blood test results did change, but the doctor simply said, “No problem. We’ll add 25 mg. more in his daily dose.” (And, to encourage others, I’d like to report that my husband’s general health impresses all his doctors!) So we feel that, while soy can influence the uptake of thyroid meds, it doesn’t mean you have to do without…just be consistent and perhaps have your blood work done to find the right amount. Best of luck!

    2. https://www.ncbi.nlm.nih.gov/pubmed/16571087
      Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature.

      “In total, 14 trials (thyroid function was not the primary health outcome in any trial) were identified in which the effects of soy foods or isoflavones on at least one measure of thyroid function was assessed in presumably healthy subjects; eight involved women only, four involved men, and two both men and women. With only one exception, either ***no effects or only very modest changes*** were noted in these trials. Thus, collectively the findings provide little evidence that in euthyroid, ***iodine-replete***individuals, soy foods, or isoflavones adversely affect thyroid function. In contrast, some evidence suggests that soy foods, by inhibiting absorption, ***may increase the dose of thyroid hormone required by hypothyroid patients***. However, hypothyroid adults need not avoid soy foods”

      1. Good morning, Gengo-gakusha,
        It just occurred to me that Asians, who eat plenty of soy and suffer less from certain Western diseases accordingly, also tend to consume seaweed which would presumably be high in iodine. I wonder if that’s part of the picture about soy and iodine….

    3. The “many” who recommend “no soy products” have not reviewed reliable research that does not show a connection or does not consider how iodine affects thyroid function. These may be helpful as you consider the relationship between soy and hypothyroidism: https://www.thyroid.org/patient-thyroid-information/ct-for-patients/vol-6-issue-11/vol-6-issue-11-p-4/
      https://nutritionfacts.org/video/avoiding-iodine-deficiency-2/
      https://www.mayoclinic.org/diseases-conditions/hypothyroidism/expert-answers/hypothyroidism-diet/faq-20058554

  5. Wow, great food for thought, Doc! My wife, kids, and I reflexively stayed away from soy due to my pointing out to them its estrogen-like properties and its possible pro-cancerous effect. Thanks for bringing the findings of the two types of receptors and the varied presence of them in tissue and organs. I am now open to bringing soy into my diet (I have always used fermented soy — e.g., natto and miso — here and there). Great news that I no longer have to pass on eating edamame and tempeh!

    1. John,

      The only qualifier that Dr. Greger added was not too many servings per day. Too many servings per day can raise IGF-1. Dr. Greger has a video on how many servings.

  6. Any thoughts on soy for men with prostate cancer? Some studies link genistein with stimulating progression of prostate cancer, at least at levels of consumption obtainable through diet.

    1. Stephen M Roush,

      Deb provided two good links. And my husband, diagnosed with prostate cancer 14 years ago, eats soy foods, based upon the information provided in those videos, as well as in the original papers. We probably consume 1-2 servings a day, sometimes none. We eat soy milk (home made), soy yogurt (made at home from commercial soy milk with no additives), edamame (shelled or in the pod), tofu, and tempeh. Someone mentioned miso, which I keep forgetting: we eat that every now and then, too.

      We’re keeping our fingers crossed! For you, too.

  7. What about soy intake for those with sub-optimal thyroid function- high TSH, low T3 & T4 levels. What does the literature say about its impact on thyroid function in general? I’ve read mixed reviews yet would hesitate to dive into a diet with daily soy based foods for fear of exacerbating potential sub-clinical hypothyroidism. Any thoughts?

    Thanks in advance.

    1. Here is a PubMed article about it

      https://www.ncbi.nlm.nih.gov/pubmed/16571087

      After 14 trials the conclusion given was:

      Thus, collectively the findings provide little evidence that in euthyroid, iodine-replete individuals, soy foods, or isoflavones adversely affect thyroid function. In contrast, some evidence suggests that soy foods, by inhibiting absorption, may increase the dose of thyroid hormone required by hypothyroid patients. However, hypothyroid adults need not avoid soy foods. In addition, there remains a theoretical concern based on in vitro and animal data that in individuals with compromised thyroid function and/or whose iodine intake is marginal soy foods may increase risk of developing clinical hypothyroidism. Therefore, it is important for soy food consumers to make sure their intake of iodine is adequate.

    2. >>>sub-optimal thyroid function
      I earlier posted this article
      https://www.ncbi.nlm.nih.gov/pubmed/16571087

      but just found this 2019 review
      https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6408586/
      Systematic Review and Meta-analysis on the Effect of Soy on Thyroid Function

      which states:
      ” Soy supplementation has no effect on the thyroid hormones and only very modestly raises TSH levels, the clinical significance, if any, of the rise in TSH is unclear.”

      Nevertheless if it were me I’d be cautious and not overdo it.

      Do you get enough iodine?

  8. My question is about todu. I do a scrambled tofu breakfast 3-4 days a week. I have a history of osteoporosis, and am wondering if I get enough genistein with these 3-4 meals. I do eat tempeh once or twice a week also, as well as soy curls every other week. (And you should see what my spell checker tried to do to some of these terms!)

    1. Barbie. I love a good tofu scramble myself. But I believe that dr. Greger doesn’t really like you to eat to much tofu because it’s processed. Tempeh an all whole soybeans are a better option. I still eat my tofu scramble but not as much as you mentioned. Whole organic soy milk is good. I just recently purchased the soy curls. Those are all soybean I believe. I haven’t made anything with them yet. I wander what dr. G would say about soy curls.

      1. Margaret soy curls are identical to edamame as they are whole soybeans in the pods. The individual pods have been dehydrated, which is why soy curls have to be soaked before using them. Soaking them serves to rehydrate them before they are used to cook with.
        They are a whole plant food with nothing added or taken away aside from their moisture.
        I hope this is of help to you.
        Enjoy your holiday season.
        With peace, gratitude, grace and light!

  9. Great article. It’s nice to debunk the myths about soy. What about Natto can you get the same benefits from eating Natto. Any one no or did dr. Greger already mention it. I may have missed it.

    1. Fermented soy doesn’t have all of the same benefits of regular soy.

      For instance with prostate cancer, to quote Dr. Greger’s transcript:

      And, it turns out that only the unfermented soy seemed to help. Tofu and soy milk consumption were associated with about a 30% reduction in risk, whereas there didn’t appear to be any protection linked to fermented soy foods.

      But if you look up osteoporosis on PubMed, it helped bone metabolism in rats. I don’t have time to see if there were human studies specifically on Natto, but rats got less osteoporosis after long term use.

      https://www.ncbi.nlm.nih.gov/pubmed/10701161

  10. Please distinguish and educate the public on the severe difference between bio-identical estrogen and Premarin- which is NOT human estrogen (is is derived from horse urine and is NOT molecularly identical to human Estradiol) Premarin was the subject of the Woman’s Health Initiative Study and Premarin AND Provera (fake progesterone) are both responsible for all the toxic side effects! Bioidentical hormones taken at physiological doses do NOT have toxic side effects, but instead promote heathy, vibrant function in the human body. This is going to be the transformative health care strategy for the next leap forward in health maintenance practice. Coupled with science-based nutrition, bio-identical hormone replacement as both women AND men age, is the foundation for wellness into old age. More than just diet fixes are needed for most Americans to repair and PREVENT cardiovascular deterioration and mental decline, memory problems and osteoporosis – these all respond brilliantly to physiological doses of bio-identical hormones as we all age. The endocrine system is more critical than the digestive system alone for establishing and maintaining wellness.

    1. Per Dr. Greger

      Microwave or grilling them when it comes to antioxidant activity

      Boiling or frying them may destroy their nutritional value.

      https://nutritionfacts.org/video/best-way-to-cook-vegetables/

      And…”microwaving and grilling were established as the best processes to maintain the nutritional profile of mushrooms.” For example, a significant decrease was detected in the antioxidant activity of mushrooms, especially after boiling and frying, while grilled and microwaved mushrooms reached in some cases higher antioxidant activity.

      But he doesn’t usually recommend grilling for AGE’s not sure if that includes mushrooms. To quote Dr. Greger “AGE levels are found in broiled, grilled, fried, and roasted foods of mostly “animal origin,”

      He said grilling because that was what they tested for antioxidants. They weren’t testing AGE’s and I am not sure whether a portabello burger would have an AGE problem or not.

      He does say “modes of cooking” in his glycotoxin video.

      “And so, we should eliminate the foods and modes of cooking associated with the highest AGE content.”

      Well, microwave is what I would be recommending, but I am not 100% sure.

  11. After a brush with acromegaly, I am convinced that tumors feed on animal protein. Presumably people consuming soy are not consuming much if any animal protein.

    1. Susan,

      First, yes, Dr. Greger might agree to eat organic soy. Someone started a myth that most soy on the market is gmo, but most gmo soy is fed to animals. Look for the words organic and you will find them.

      The soy in processed food is not in line with a Whole Food Plant-Based diet, but even Morningstar farms is non-gmo. It is still a processed food and still isn’t what you should be eating all of the time, but the whole all soy products are gmo myth is a myth.

      As far as the anti-nutrient part, phytates partially block nutrients – emphasize partially. But people eating Whole Food Plant-Based get so much nutrition that it isn’t generally a problem.

      There are foods like onions and garlic which increase the absorption of nutrients by 50%, so if you eat those, they counteract the big bad phytates, which turn out to be really good for you.

      If you don’t like garlic and onions, you can eat a serving and a half of whole grains.

      https://nutritionfacts.org/video/new-mineral-absorption-enhancers-found/

      https://nutritionfacts.org/2015/05/28/phytates-in-beans-anti-nutrient-or-anti-cancer/

      https://nutritionfacts.org/video/phytates-for-rehabilitating-cancer-cells/

      https://nutritionfacts.org/video/phytates-for-the-treatment-of-cancer/

      https://nutritionfacts.org/video/phytates-for-the-prevention-of-osteoporosis/

    2. Susan,

      In the prostate cancer study, tofu and soy milk consumption were associated with about a 30% reduction in risk, whereas there didn’t appear to be any protection linked to fermented soy foods.

    3. Susan,

      Also, respectfully, I genuinely like Dr. Berg’s personality and find him, of all of the Keto doctors, to almost be Whole Food Plant-Based, but he definitely leans Keto and his advice tends to skew that direction.

      http://nutritionfacts.org/video/Keto-Diets-Muscle-Growth-and-Bone-Density

      https://nutritionfacts.org/video/does-a-ketogenic-diet-help-diabetes-or-make-it-worse/

      https://nutritionfacts.org/what-causes-insulin-resistance

      And I will add Mic The Vegan’s recent video on a Dr. Berg video where he said that he eats 5 eggs every day.

      https://www.youtube.com/watch?v=25oDZHb4jrk

      In the end, he isn’t a medical doctor or a nutritionist, but Dr. Berg has such a nice personality and he tells people to eat 10 servings of vegetables per day and tells them to keep their intake of animal products to 5% of their calories, though I am not sure how people eat the 5 eggs he tries to get them to eat.

  12. I am surprised that no one has mentioned bio-identical hormones which come from plants. Conventional doctors and some alternative nutritional doctors have not had experience with them. Synthetic hormones cause the problems because they are recognized by the body as foreign.

  13. Dr. McGregor,

    Thank you for your blogs and videos, love them. Question… the women in the WIH (as far as I’ve discovered) were on synthetic estrogen replacement. It’s my understanding the synthetic and bio-identical estrogens don’t work exactly the same in the body, specifically regarding the estrogen receptor sites. Do you have any studies that compare bio-identical BHRT w/soy? That would be a more apples and apples comparison in my mind.

    1. Hi, Agnes! I am not aware of any negative effects of soy consumption in normal, dietary amounts for women with PCOS. Soy phytoestrogens are not estrogens. They have both estrogenic and anti-estrogenic effects in the body, and can have protective effects for many hormone-sensitive conditions. You can find everything on this site related to PCOS here: https://nutritionfacts.org/topics/pcos/ Everything related to soy may be found here: https://nutritionfacts.org/topics/soy/ I hope that helps!

    1. Doug,

      Here is Dr. Fuhrman’s answer (somewhere in the middle)

      https://www.drfuhrman.com/elearning/eat-to-live-blog/137/dont-fall-for-the-myths-about-soy

      I will add in his thyroid and soy comments

      Only one study has been conducted in a population with borderline hypothyroidism (subclinical), in which 30 grams/day soy protein powder containing either a low (2 mg) or high (16 mg) dose of soy phytoestrogens was taken for 8 weeks, followed by 8 weeks with no soy supplementation, then a switch to the other dose for 8 weeks. Only a small number (6 out of 60) in the high isoflavone group demonstrated a mild worsening of their thyroid function.25 However, this study did not examine the effects of consuming soy as edamame or tempeh, soy in its natural state, but used a concentrated soy protein powder, which may have different effects. So no clear conclusions can be made.

      Of interest was that other health parameters improved with the higher isoflavone containing soy powder, including insulin resistance, blood pressure, and C-reactive protein levels. These results suggest that soy phytoestrogens have cardiovascular benefits, but for a small subset of people with already compromised thyroid function, excessive soy products may exacerbate that condition.25

      The IGF-1 concept was interesting because it raised IGF-1, but also raised IGF binding proteins along with IGF-1, and therefore may not have a significant effect on free IGF-1.

      That is interesting.

      I wonder about the study where too much soy undid its benefit, was that taking the IGF-1 binding proteins into account? Hmmm.

        1. Dr McDougall is against the soy protein isolate because of osteoporosis getting worse when supplemented with it.

          Nations, where they eat soy in the whole food form, don’t have high rates of osteoporosis or cancer.

    1. Phil,

      There’s far more to the story……. please see: https://www.ncbi.nlm.nih.gov/pubmed/16571087 and follow with https://www.nature.com/articles/s41598-019-40647-x, an up to date meta-analysis done this year regarding soy and thyroid considerations.

      I am familiar with the published work of some health practitioners who claim substantial amounts of soy sensitive people also have Hashimoto’s. With that said I wonder if their iodine and other nutrient values are indeed appropriate and there is no correlation with soy intake, per the published work above.

      Having a soy allergy is not unknown by any means and I’m not suggesting or implying that one should continue to eat foods that affect them.

      A blanket statement, ie. avoid if you have Hashimoto’s is perhaps inappropriate based on the current level of our knowledge and lack of good studies, that include more than just the estrogen fractionations and allergic individuals but lack their other nutrient values to clearly understand if there is any correlation with soy.

      Dr. Alan Kadish moderator for Dr. Greger http://www.Centerofhealth.com

      1. Thank you so much for the additional studies, Dr. Kadish.

        I genuinely appreciate it.

        I was just looking at my bottle of Phosphatidylserine and was wondering suddenly if it was an isolate or a concentrate or what. It just says: Ingredients: soy.

        I haven’t taken it very often over the past two years because I have been testing out WFPB as a diet, but when I took NT Factor before finding WFPB, it did seem to help.

        WFPB has helped more, but I contemplate PS100.

        I know Dr. Greger recommended against Phosphatidylcholine because of TMAO, but I don’t know if the “other soy lecithin” has risk factors.

        1. Obviously, I don’t understand the science yet at all, but what struck me when I was looking up PS-100 was that they mentioned:

          “the synaptic plasma membrane, olfactory bulb and hippocampus of rats and mice contain markedly higher PS”

          Olfactory was what the peanut butter Alzheimer’s test was about and the hippocampus is also involved in Alzheimer’s.

          Yes, they didn’t point to Alzheimer’s and it was just a sentence and my mind pointed to Alzheimer’s, but I will keep trying to understand it.

  14. Deb, your brain seems to be your latest Ongoing Project. Only you think you know how it should behave; it certainly sounds fine to me.

    You haven’t mentioned your doggie in a really long time. Do I dare ask about his health/diet? If you don’t want to talk about him, that’s fine.

  15. Hi, I noticed Dr. Greger didn’t mention tofu in the quote below – was this an oversight or is there some reason not to get your soy in the form of tofu?

    “Is soy food consumption associated with lower fracture risk? Yes. In fact, a significantly lower risk of bone fracture is associated with just a single serving of soy a day, the equivalent of 5 to 7 grams of soy protein or 20 to 30 milligrams of phytoestrogens, which is about a cup of soymilk or, even better, a serving of a whole soy food like tempeh, edamame, or the beans themselves.”

  16. Remember when a study says HRT or hormone replacement therapy they are referring to a combination of Premarin and Provera. It has been known for many years that Provera is known carcinogen and in the Nurse’s Study was discontinued due to this effect. However even the Premarin only group (strong horse estrogen)had a very small if any difference in cancer development than women who never took hormone therapy. Nurses Study was not done with natural estradiol, or natural Progesterone.

  17. Anyone have information on food supplement Femarelle?
    Came across this while researching alternatives to hormone replacement therapy.

  18. I ask about Femarelle because the supplement addresses vaginal dryness, atrophy and mood swings. I haven’t seen these addressed with eating whole soy and flax.

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