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Stefani on Soy

Phytoestrogens in the Body: How Soy Interferes with Natural Hormone Balance

Soy is perhaps, second to chocolate, the food most closely associated with women. It is not only a vegetarian staple, which automatically makes it a womanly food, but it also acts as an estrogen in the body. Yet interpretations of what this means for the female body vary: is soy (and flax, another potent phytoestrogen) the fountain of youth, or is it a toxin?

What advice do we heed? What’s actually going on inside of our bodies?  It’s hard to tell.  But with just a bit of science the waters become less murky, and we can glimpse the truth of why eating soy, flax, and other phytoestrogens can be so risky.

What is a phytoestrogen?

Phytoestrogens are a class of chemicals that resemble estrogen, but are not identical to estrogen. The whole category is called xeno (= false) estrogens.  And then as a subclass come then phytoestrogens. Phyto means plant. Estrogen means estrogen. Phytoestrogens are plant estrogens.

There are, moreover, several varieties of phytoestrogens.  The primary kinds are coumestans, isoflavones, and lignans. Coumestans are found in split peas, pinto and lima beans, alfafa sprouts, and most importantly, red clover and clover sprouts. Isoflavones are found in soy (powerfully), green beans, alfafa sprouts, chick peas, peanuts, and red clover. Lignans include flax seed and sesame. Other less potent sources are rhy, wheat, oal and barley, nuts, and some fruits and vegetables. Note that there is often significant overlap of phytoestrogens between different foods.  Here is the most comprehensive and scientifically accurate list of phytoestrogen content of foods I have yet been able to find that is publicly available.  Here is the journal article (even more comprehensive) that gave birth to the bulk of the information out there.

Soy and flax are the most potent phytoestrogens by far.  Yet all legumes, seeds, and nuts are phytoestrogens. Please note, moreover, that phytoestrogens are orders of magnitude less potent than regular estrogen. This means that a healthfully functioning man or woman should be able to handle consuming phytoestrogens from time to time.  However, women with hormone balance issues, as well as people who regularly consume vegetable oils, nuts and soy, would do well to consider how potent their phytoestrogen intake can really be.

What is estrogen?

Estrogen is actually a catch-all term for a wide variety of chemicals with similar shapes and functions, such as estrone (E3) and estradiol (E2). During a woman’s reproductive years, estradiol levels are much higher than other estrogens, so for these women, referring to estrogen almost always means estradiol. During menopause, estradiol levels drop off, and the bulk of a woman’s estrogen content becomes E1 and E3. This is important because E2 is the form of estrogen the ovaries pump out, and is also what is has the greatest effect in a woman’s reproductive years on partitioning fat to the hips and thighs rather than the abdomen. Plummeting E2 is why many women experience increases in abdominal fat during menopause.

How does the body perform estrogen signalling?

Estrogen is a hormone, which means that it is one of the chemicals in the body that works primarily as a signal: it tells cells and organs what they should be doing.  The sex hormone signalling process “begins” in the pituitary (with overhead influence from the hypothalamus in the brain).  It is up to the pituitary to tell the ovaries what to do, and they, in turn, produce estrogen.

The hypothalamus and pituitary glands have estrogen receptors liberally positioned through them.  These receptors tell them how much estrogen is circling throughout the body at any given time.  Think of it like keys and locks: estrogen receptors are the locks, and estrogen molecules are the keys.   With more keys, more locks can be filled. With fewer keys, locks end up sitting there empty, and rusted.

When the locks are filled, the pituitary detects “estrogen sufficiency!” in the body, and it down-regulates the strength of the “please pump estrogen” signal it sends to the ovaries.  This makes the ovary produce less estrogen.  The whole purpose of this system is to maintain stable estrogen levels in the blood.  If estrogen levels get too high, then the pituitary (in a healthy body) tells the ovaries to back off.  If estrogen levels are low, the pituitary (in a healthy body) revs up estrogen production.

So is the problem that phytoestrogens, in resembling estrogen, bind to estrogen receptors and mess up hormone production?


Does it get more complicated?

You bet your sweet ass it does.


What the medical community recognizes phytoestrogens do

Phytoestrogens act as estrogen in the body.  But here’s the trick: while phytoestrogens have a pretty good ability to bind to estrogen receptors, they have less of an ability to give instructions the way true estrogen does.

This fact is so important it bears repeating.  Phytoestrogens look enough like estrogen to bind to estrogen receptors, but they do not look exactly like estrogen.  This makes their ability to perform estrogen functions inferior to true estrogen.

When we eat phytoestrogens, they enter our bloodstreams.  This means that, to many doctors, women with low estrogen levels should eat phytoestrogens. Phytoestrogens would signal “fullness” to the estrogen receptors, sure, but they would also perform the normal functions of estrogen in the body.  If a woman has low estrogen, the medical community doesn’t really think she can boost those levels by any means other than supplementing with food or with drugs, right?, so adding some phytoestrogen into her diet could do her nothing but good.  Like I said, she may be signalling estrogen ‘fullness’ to her hypothalamus and pituitary, but perhaps it would be worth it if it could boost estrogenic activity.

By the same token, many doctors argue that women with high estrogen levels also should supplement with phytoestrogens.  This is because the phytoestrogens would flood the estrogen receptors, which in turn wuld down-regulate estrogen production, without really increasing estrogenic activity too much.  Or so the theory goes.

In reality, however, women with low estrogen often suffer more from the binding of estrogen receptors than they might benefit from limited increase in estrogenic activity (particularly if by filling the estrogen receptors they actually reduce their already limited estrogen stores.)  Women with high estrogen levels clearly already have flooded receptors, so adding more estrogen into the mix is not necessarily going to help anybody.

The solution might be, then, to restore estrogen balance by other methods.  Increase fat mass, if underweight.  Decrease fat mass if overweight.  Exercise when it feels right.  Eat anti-inflammatory, paleo foods.  Sleep.  Etc. You can read about all of these in my book, available here.

Does it get even more complicated?


What we have dealt with so far are phytoestrogens and estrogen receptors.

What the body is actually dealing with are three primary types of phytoestrogens (plus dozens of sub-types): lignans, coumestans, and isoflavones, and two types of estrogen receptors: estrogen receptor alpha (ERa) and estrogen receptor beta (ERb).

Different estrogen receptors have different shapes, and are distributed unevenly throughout the body.  ERa is concentrated more heavily in the hypothalamus than ERb, for example.  ERb is concentrated more heavily in skin tissue.    It also varies for fat cells, for ovarian cells, for different types of brain cells.  It is a complicated mix.

Coumestans have a unique chemical shape (with two hydroxy groups in the same position as estradiol).   Coumestol has the same binding affinity for the ERb receptor as estrogen, but it has much less of an afinity for ERa.  This fact means that ERb’s will get filled up by coumestans, but ERa-heavy tissue might suffer a decrease in estrogen-like activity because estrogen production in general gets down-regulated by the hypothalamus, pituitary, and ovaries, etc, in response to the coumestol, thus making estrogen levels decrease in ERa tissues relative to ERb.  Additionally, the shape of coumestans means that coumestans have the ability to inhibit aromatase.  Aromatase is the process of converting testosterone to estrogen in cells.  This is a big deal for women with PCOS who have high testosterone and low estrogen levels.

Different isoflavones bind to different estrogen receptors differently (my head is spinning, too).   Some bind more strongly to ERa, and others to ERb (genistein, dihydrogenistein to ERb, equol to ERa).  Yet most importantly, many (though not all) isoflavanones that have been tested have the same binding affinity as actual estrogen, but half the receptor-dependent transcriptional power.   This is a powerful fact, that isoflavones have half of the ability to perform estrogenic function as they do to take up space.

There are so many different kinds of lignans that it’s best to just walk away and shake your head.

As a matter of fact, that notion applies I believe to all phytoestrogens.   Walk away and shake your head.  I have included this last section about estrogen receptors and phytoestrogens in this post not to incite anyone to figure out which plant they should be eating in order to fix which specific tissue in their body, but rather to demonstrate the enormous complexity of phytoestrogen biochemistry.

The takeaway

Phytoestrogen biochemistry is complicated.  Some studies have shown that phytoestrogens boost estrogen activity, and others have shown that they decrease estrogen activity.   This varies widely by the population studied, too.  What were the women’s estrogen levels beforehand?  Were they healthy women?  Fertile women?  Women who grew up eating soy?  Women who are routinely exposed to xenoestrogens?  There are too many questions still yet for real answers, yet above all I believe it indicates that we should step lightly around soy.

The fact of the matter is that while the medical community has yet to understand and come to grips with phytoestrogen biochemistry, it is clear that phytoestrogens can cause unnatural hormonal disruptions.  This is especially problematic for people with high or low estrogen levels or other reproductive issues.  If estrogen seems to be increasing by one measure in one type of receptor and in one type of tissue, it is possibly decreasing in others.  And vice versa.   This can do real damage, since it is impossible for us to understand what is going on in every kind of our tissues at once.

The solution, then, is in my opinion to minimize the influence entirely.  You are welcome to disagree.  Many doctors do.  Yet in my personal and research-based experience, soy is not a way to find hormone balance.  Even if it patches a leak for a long time, it may be creating other holes, and it will never repair the bottom of the ship.

Instead, as I mentioned briefly above, I believe that holistic healing, stress reduction, paleo foods, and weight management all fare much better for women in the long term, and definitely with fewer risks. You can find more about how to live a healthy, whole foods lifestyle in my book, Sexy By Nature.

This post did not even touch on breast and other estrogen-dependent cancers.  That pool of research is a conflicting box of vipers all on its own.  But I will cover it in due course.  Suffice to say, it is an uncertain and risky landscape.




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Managing director of Paleo for Women and author of Sexy by Nature.


  1. Oh my goodness. I stumbled on your site yesterday and I cannot believe how much it resonates with me. I spent years damaging my hormonal balance, thyroid, gut, etc by eating according to the food pyramid, and really upped the ante by going vegetarian/vegan for about 2 years. My health crumbled in every way you’ve written about. I’ve been eating paleo/perfect health diet for about a year now and things are better, but not perfect. I’m wondering-how long does it take to get these systems back up and running? Is there anything that can accelerate the process? Perhaps you’ve written about that already; if you have, can you direct me to it? If not, I’d love to hear your thoughts.

    • Hi Kerry. I think you know as well as I do that I really can’t answer that question. It is entirely dependent on what your actual problem is (as I do not know), on your own history and your genetics and epigenetics, as well as what you are doing right now. For me, it has taken… well, I don’t like the idea of “arriving.” I have been continually improving for two years, and I am now in a place that feels safe and good. The best way to look at it, I believe, is as a journey of progress. And so long as we are getting better, we can’t complain about much, can we?
      In terms of speeding it along, I think the absolute most important thing is to reduce stress and sleep well. Period. Stress is REAL. All the steps you try to take with diet will not fix you if you are worrying and obsessive and harried and working too hard and treating yourself poorly.
      And nourish yourself. Eat enough calories, enough fat, enough carbohydates.
      And again, I’m sorry I can’t give you a better answer, but it does so much depend on what has happened to you and what you are doing, now.

      • Thanks for your response. Though my surface question isn’t answerable, I think that you actually addressed my real question (which I didn’t realize was my question until I read your response and felt better). I feel reassured that there still is progress to be made and that it isn’t a quick fix. That means it’s not that I’ve just missed something, or that there’s something more wrong with me than anyone else. It’s also a reminder to give myself a break (a lesson I will probably learn again and again). Oh- and stress, yes. I’ve got lots of that, but hope that some of those situations are finally finding resolution.

        • Exactly! You are not broken. Just continually seeking better health and nourishment. And it’s on it’s way! 🙂

      • I am a 55 year old woman who is postmenopausal and have not had a period for over 7 years. I recently started to take soya lecithin as I had heard of its health benefits. Well after 3 weeks I devloped really tender breasta and nipples and 7 days later started to bleed with all the syptoms of a period. Do you think it was the soya that upset my hormone balance? Has anyone else had the same problem ?

        • Kim,
          I’m 58 and started having the same issue last week but with flaxseed. From what I’m reading here, the short answer is yes.

    • Hi Kelly, I have a similar situation as you! I started as 95% vegatarian at the age of 15 and got closer to vegan for a good 8 years there, switching to soy milk and eating more soy products. Paleo was a godsend and I already feel much better, but still have some issues I’m dealing with. I’m thinking more and more that maybe I should see a naturopath or something, to get my issues figures out. It will be expensive, but I’m not seeing further progress on my own right now.

      Stefani, I just started reading your blog and I really like it. I saw your guest post over at freetheanimal and was a bit miffed by how many people got all freaked out that you used the term patriarchy. And that (I think female) commenter who kept trying to push standard gender roles and saying women make bad leaders was driving me crazy! I’ve actually been worried about paleo ending up going to way of evolutionary psychology in pushing gender roles based on what we perceive to be an evolutionary advantage for women and men to conform to stereotypical roles. That might be a cool post for you to do in the future…what does the evidence collected from modern hunter gatherers plus any anthropological evidence say about gender roles?

      On a side note, I’m incredibly bitter towards the whole vegetarian propaganda machine for convincing me when I was so young to go vegetarian for all the purported health, environmental and moral benefits. Funny how being veg seems to be ESPECIALLY bad for females due to hormonal stuff. Since the books I read that had me convinced were written by men (T Colin Campbell, John Robbins), I’m almost feeling like this is another aspect of the stupid patriarchy, pushing an unhealthy diet that gets taken up by more women than men. But I’m probably just pissed off that I sacrificed my health for half of my lifetime for a bunch of lies.

      Thanks Stefanie for the wonderful blog!

      • Hahaha, Stephanie, that’s amazing. And you’re totally right. Patriarchy patriarchy! Everywhere. And I’m not… UPSET… at men or anything, that would be ridiculous. They are victims of this, too. I hate when people think feminism = men-hating. What the hell. Thanks, Fox news.

        Gender roles… they blow my mind. Why do anything because it’s normal? Lots of things are normal that we know are bad. For example, eating potato chips. There are about a million ways in which social norms constrain our lives, and I hope to write a powerful book about them someday. The primary goal of my life is liberation. For myself and for others. From all of the stuff keeping us down.

        All of it!

        🙂 Thanks for the lady love. Welcome to the fray!

    • Hi Kerry,

      My situation is very similar to yours, I, too had the brilliant idea of going vegetarian for about 6 years, and the last couple of years I got really strict, vegan-style… I so everythings fail! I’m working on healing and paleo has done wonders for me, but as you said, not 100 percent yet.
      For me, I was without a natural period once off the BC pill after 9-10 months of waiting, I had 3 or 4 cycles, and it’s been gone for the last 3 months or so. I still feel good, but I do want to get it back, so I’ve cut down my exercise a bit and upped my carbs a tad, I’ll se what that does. It’s just been a couple of days and I see improvements in my mood, I feel way more calm, my gut….different story there, since it is used to VLC-LC, it’s not very happy with me now…
      Anyway, good luck!!

    • It took a couple of years to feel 80% better and the blood work and thyroid nodules decreased (which had the doctor scratching his head). :o) Just stick with it and the body will go back to what it does naturally….support life. Good luck! And Congrats on finding your way back to health; millions of people don’t.

  2. Thank you for this! Very timely, as my husband and I are trying to get more estrogenic foods out of our diet. It’s tough – eggs are often from soy-fed chickens and I’ve seen some numbers that indicate that soy does pass through to the eggs. Lovely! =(

    I have had to eliminate way too many foods due to sensitivities (nightshades. I’d shiv for a tomato some days) But onions and coffee? out of my cold dead fakely-estrogenic hands… 😉

  3. Thanks for all the great posts on paleo lady issues! You are a breath of fresh air. 🙂

    I had been warned off of phytoestrogens by my endocrinologist 2 years ago, which helped a TON with my endometriosis. I think that all the soy from my semi-vegetarian days were aggravating the endo tumors. It makes more sense to me now that I know that they can take over the estrogen receptors without actually doing the correct job of estrogen.

    I didn’t know that green beans have them too though… Any idea on how much compared to soy?

    • Less, but present. Check out the links I provided on phytoestrogen content for details 🙂

      • Doh! Sorry for the reading fail. It was right there in your link. 🙂

        Soy: 103,900
        Green Beans: 105

  4. My comments are not directly related to this post; they are just my general thoughts after browsing your site for a few hours yesterday. Thank you for all of the (clearly very) hard work you’ve put into this website 🙂 I too came here from Free the Animal, and I’m so happy to add this site to my list of regularly read blogs, because I find that I need a female-centric paleo perspective. The stuff about how the fasting studies don’t really apply to women was an eye-opener. I’ll continue to come here because I need your graspable technical information, and I need the psychological stuff too. I’m reflecting now on the body image mania we have to put up with and I find myself trying to reconsider my notions of beauty. I’m seeing the ‘battle of last 5-10 lbs’ in a different light — the idea that our bodies don’t want to let it go because it serves a vital purpose. The last time I tried to see through this lens was when I saw some old Marilyn Monroe movies and realized, it’s not just the absence of fat that makes her desirable, but the presence of fat.

  5. Wow you are making huge waves in the paleo community! MDA post on your women’s fasting post… Bad ass!

  6. I found your post interesting. I came here looking for info on phytoestrogens, paleo eating and menopause. I’m really struggling with hot flashes and I’m finding few effective ways to deal with it. Most of the info is vague, contradictory and anecdotal.

    I’m somewhat overweight but have been losing by eating paleo and exercising with an emphasis on weights but I do fair amount of cardio too. And doing cardio while having hot flashes is exhausting.

    I’ve been taking Estroven (black cohosh is a key ingredient) for the past month; I’m not convinced it’s helping with hot flashes but my memory noticeably improved right away. I really thought I was suffering from Alzheimers or something after looking for my keys, glasses and cell phone repeatedly. It was quite frightening and was becoming apparent to others.

    So, what’s a menopausal women experiencing hot flashes and night sweats supposed to do? I’m eating right, exercising, getting plenty of sleep, reducing my stress and still having hot flashes and my belly fat is making itself more and more at home even as the rest of me is getting stronger and leaner. Do I consume or avoid phytoestrogens? (This is mostly a rhetorical question.) Doing nothing and staying the course isn’t working and I don’t want to go as far the other way and try HRT.

    • To be honest, I’m not sure. If they make you feel better, perhaps its worth a shot. I don’t like what they to do a lot of bodies, but on the other hand a lot of people swear by them.

    • Sandra,
      I’ve been going through menopause the past year (age 56) and also eating paleo for over year. Have been experimenting with and noting how a day’s food choices affect night sweats, flashes, mood etc. I don’t use anything to deal with it other than food. So far I notice (for me) alcohol; sugar–if in excess of once-a-day coffee and/or square of chocolate; and very low carb day, are triggers. I thank Stefani for drawing my attention to that last one. Since I’ve added more carbs back into my diet with a banana or potato, the past week has been symptom free. I don’t know if that’s a cyclical thing, or if it’s a blood glucose thing so will try this for a few months and see how it goes.

      Other things I’ve considered are thyroid (use dulse flakes for iodine as seasoning; reduced goitrogenic foods); and exercise (am moderately active so don’t think this is an issue).

      Your body will be different, so encourage you to find the optimum food choices for you.

      • Might be interested in Righteously Raw chocolate mint. It’s the purest one I have found so far. Anyone else know of a pure chocolate that taste good?

    • I too am interested in what works for menopause. I’m paleo, and so far hot flushes have been minimal (I’m nearly 53) But I dont like the sudden 5 pound weight gain, although it seems to have stopped. I’m trying alcohol free strict paleo for a month. Also trying Maca, and have found green tea extract seems to help as well. My Holistic Doctor recommended cobalt drops as they help the body retain estrogen. Which I haven’t yet tried. My brain is definitely fuzzier. So I find your Estroven experience interesting.
      Will do a bit of research soon and hopefully post something useful.

      • Hi Julianne – appreciate your comment is over twelve months old and you may have found this out for yourself by now. However, I wanted to add that I can vouch for the cobalt comment. I’ve also read about and therefore tested manganese – very estrogenic. Copper is another – there’s a study cited on pubmed and endojournals re the estrogen-like activity of metals in breast cancer. Unsure if posting a link will be successful but will try: Endojournals


  7. I was mostly vegetarian for many years and ate a fair amount of soy. Then Fibroids, Fibroids, Fibroids! I had surgery (19 removed, 5 of them large)and my doctor told me to stop eating soy. Bacon is the gateway drug back to eating meat. Mmm, bacon. I had to have more treatment later (embolization), but I credit paleo with keeping the returning fibroids small enough where I could keep my uterus. The fibroids were only marble sized the second time around instead of oranges and tangerines. I think I had done too much damage with soy/low fat/high carb “healthy” foods to make them stay away without medical help, and while I can’t say for sure that soy caused my fibroids, it certainly didn’t help!

    Also, saw your post of Free the Animal and was happy to see what you had to say about women. My hair starts falling out if my carbs get too low (Mmm, sweet potatoes), and fasting any more than just skipping breakfast tends to make me want to binge.

  8. Thank you Stephani for your insights and passion. I’m 49 but still have fairly regular periods (sometimes stretching to a 34 day cycle). I transitioned to Paleo about a year ago following lab results that indicated that my thyroid was out of whack (TSH a bit high – T-4 a bit low), fasting glucose was high (enough to concern me but traditional docs were fine with my fasting glucose hovering near 100), inflammatory markers C-Reactive Protein and Lp-PLA2 were REALLY high. I had a DEXA scan that revealed my body fat % was a whopping 31%! I couldn’t believe it! I’m 5’2″ 122lbs and size 4. How was it possible that nearly 1/3 of me was fat?! And inflamed fat at that! The DEXA scan also revealed that I had osteopenia.
    Ok, fast forward a year. I still weigh EXACTLY the same. However, my thyroid is now great (turns out that unlike most women in this country – mine stemmed from an iodine deficiency rather than autoimmune causes). My fasting (and postprandial) glucose is great. My inflammatory markers are way, way down – at the bottom end or below normal. And remarkably, my osteopenia has reversed! Anyway, this has all taken a full YEAR. I just had a followup DEXA scan and it revealed that my body fat went from 31% to 27%. I’m really happy that I look so much better on paper (at a bit better naked – a nod to MDA and his LGN goal). It’s super frustrating that it’s so hard to lose that fat. I mean I’ve undertaken MAJOR life changes. My goal is to get to 20 – 22% body fat. Is there any specific advice for the perimenopausal gal to get there? I’ve recently started rock climbing and pilates so I guess we’ll see where that takes me. If nothing else, it’s fun!
    Thanks again for your female focused info!

    • @ Kim, and osteopenia
      Osteopenia happens when a person eats too many acidic foods (grains, potatoes, legumes, sugar, dairy). The body takes calcium from the bones to maintain an acid-alkaline balance. The meat, fish and eggs in the Paleo diet are also acidic. Too much of those foods will create osteopenia also. Look up acid-alkaline diet. Anybody can get osteopenia on any type of diet, it is all about balance. Vegetarian and vegan diet do not have to lead to osteopenia, it depends on what foods the vegetarian/vegan person eats most of, if leafy greens in salads, juices and smoothies, which are alkaline, then there won’t be any osteopenia.
      I think the Paleo diet, which I have never tried, could be dangerous if the dieter is eating too much proteins (meat, eggs). It would lead to all kinds of modern world diseases b/c of the saturated fat.
      I am trying out raw food diet now, concentrating more on the leafy greens than the phytoestrogens in nuts, sprouts and beans. I am feeling great, not missing meat or eggs or fish at all. To me cooked food is dead, no enzymes. Fresh organic veggies are live, full of enzymes. I used to eat meat, years ago, but didn’t feel good. Now I feel good, finally, after trying so many different things. I think living foods are better than dead foods. But I don’t mind that other ppl eat other diets.

  9. I’m very skeptical of supplements to effect hormones, but when I went through menopause, I figured it couldn’t hurt to try Estroven (max strength, mostly soy isoflavones). My major symptoms were occasional hot flashes and serious, often multiple change-the-PJ’s serious, night sweats. Honestly, I did not notice mood issues. Estroven, amazingly, worked to where there were only minor night sweats on much more rare occasions. Hubs claims my moods were better … I’ll take his word for that.

    • Evelyn – did you notice memory issues with menopause? Did Estroven help if so?

  10. Testing again. Last test went into the ethers

  11. Another great post, Stefani.

    I would like to point out the phytoestrogens interfere with the natural hormone balance of more than just women (and men). Our bodies excrete them, and they end up in our wastewater(sewage) systems, where some- but not all- are removed by sewage treatment systems. The remainder stay in the effluent water which is released back into the environment – oceans for coastal towns, rivers for inland.
    There, these estrogens, and other hormones and pharmaceuticals become endocrine disrutptors to fish, frogs, etc – most often causing the “feminisation” of males.

    If you do some googling on waste water and endocrine disruptors, (or estrogens, or hormones, or pharmaceuticals, or personal care products) you will find all sorts of studies on this stuff.

    I’ll quote from a Minnesota study, emphasis mine;

    Fish studies were conducted at five WWTP locations. Fish were exposed to dilutions of WWTP effluent and to water upstream and downstream of the WWTP using a mobile laboratory that provided controlled conditions. Although the observed biological effects were subtle, vitellogenin concentrations in the male fathead minnows increased with the proportion of and time of exposure to WWTP effluent. Vitellogenin is a protein naturally found only in female fish, but is often found in male fish after they have been exposed to EACs. Changes in physical sex characteristics in male fish exposed to WWTP effluent were observed.

    Water that contains a mixture of chemicals may have estrogenic properties, or, in other words, mimic the effects of hormones. The effluent from most of the 25 WWTPs tested had this hormone-like effect, although the degree of this estrogenicity varied from plant to plant. This also was observed in water collected upstream and downstream of the WWTPs.
    At three WWTPs, effluent, upstream water, and downstream water were tested for the ability to turn on or turn off a wide variety of genes in fish using specific gene assays developed for this purpose. Water that contained effluent influenced the expression of several hundred genes in ways that upstream water did not.

    There is more to this than just phytoestrogens, of course, but you get the picture. You can just imagine what the phytoestrogen load is in the wastewater from a soy processing plant !

    So, when those vegans think they are helping the animals by eating tofu etc, they can be hurting other animals at the same time.

    Keep up the good work
    (why do a I feel like a token male here?)

    • Fascinating! Thank you, Paul. You are right… goodness. So much of what we do echoes in the rest of the world, and it is nearly impossible to see all the downstream effects. amazing.

      Because you ARE the token male.

      But also NOT. Other very cool males have also been to this website. At least for a second or two. I appreciate your endurance in that regard. Please hang in there. We need you.

      • Thx Stefani,

        You might guess I work in doing wastewater treatment – everything we eat, eventually ends up in there. Needless to say, the amount of hormones and pharmaceuticals that are in our wastewater – and make it to out environment is staggering. Factory farms, of course, are even worse for this…

        If we all ate, and lived, healthier in the first place, we wouldn’t need this stuff.

        I appreciate your female-oriented approach to this stuff – as your FTA and MDA posts (which is what brought me here) point, out, there are important differences – and this has long been observed with male/female responses to “low carb diets”.

        Keep up the good work!

    • Please recognize that much of the estrogenic effects may be coming from women who take birth control pills as well- that ends up in waste water too.

  12. Great post! So should we also avoid flax? I have never heard that before…I don’t eat a whole lot of it right now but just bought a whole bag of it!


  13. I am a woman with PCOS. When I decided to drop grains from my diet, I added a daily flax muffin, made with about 1/4 cup of ground flax. About 6 weeks in I started with some erratic bleeding. The bleeding continued and became heavier and heavier as EIGHT WEEKS went by. My doctor put it down to peri-menopause (though subsequent hormone testing found I’m not in menopause yet), but I was alarmed by the amount of bleeding that would not stop. And I was becoming anemic.

    I began googling and came across more than one article attributing unusual bleeding to flax. So I stopped the flax and within two days the bleeding stopped too.

    Coincidence? Perhaps. But I treat flax with a lot more caution nowadays. With PCOS, I may be overly sensitive to the phytoestrogens.

  14. Pingback: Lots of Links « Sceptically Fit

  15. Pingback: Phytoestrogens, Not all plants are created equal | CrossFit Athlete Inside

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  21. Truly no mаtter if someone doеsn’t know after that its up to other visitors that they will assist, so here it occurs.

  22. Great explanation!

  23. Pingback: Paleo for Women | Flax, marijuana, hops, and 44 other phytoestrogen sources you might not know you’re consuming

  24. Pingback: Paleo for Women | Tumeric, thyme, oregano, camomille, and other progesterone antagonists, or “phyto-progestins”

  25. Pingback: Soy (The Meat of the Issue) | In My Skinny Genes

  26. Hi Stefani,

    I am currently researching to balance my hormones so as to stop acne. I’m in my thirties and this acne thing has to STOP. I read from other sites that soy milk can help to balance hormones and also taking coconut oil. I have stopped all dairy product – cheese, milk, ice-cream (sigh). My acne has reduced a whole lot but when I am having my period, I am sweating buckets everywhere! I don’t know what to conclude… I am taking organic soy milk… now, I don’t know to stop or continue with the soy.

    • My research has indicated– and I make no promises in this regard — that even while soy might help increase estrogenic activity in some tissues, it downregulates estrogenic activity in the skin. I would recommend at least trying to eliminate the soy and seeing if it helps. As it stands, personally, and I know from many other women anecdotally, eliminating soy was one of the key pieces of improving acne.

      If you eliminate the soy (at least give it a few weeks) and find that it makes no difference, or makes it worse, you can always put it back in! As it stands I believe it is as least worth a shot

      • Jen, Back in the day, I noticed that acne (which I normally don’t have) would appear whenever I ate anything containing flaxseed. I am especially sensitive to phytoestrogens- soy products send my thyroid into total meltdown, but I never noticed acne from it.
        I would suffer other side effects as well, but the acne was the most sudden and obvious effect of flax consumption. If you are currently eating flaxseed, I would try to eliminate it from your diet for a while….hopefully that will help!

  27. Pingback: Avoid Soy, the Minefield at the Grocery Store Part Two by Jeffrey Dach MD - Jeffrey Dach MD -TrueMedMD

  28. Hi, thank for writing this your writing style is so comforting and easy you’ve made my research a lot easier.

    I’m currently being treated for edno (stage 4) and just looking into xenoestrogens and the effects. It is quite important to me as I love soy products and almost everything on the the planet that has these is (phyto and myco not man made chemical) I’m of the belief that your body tells you what you need and I have felt better since these things have been in my diet of the past 5 years or so.

    Really I suppose I wondering if you have any other resources on this in particular (it’s not head spinny for me yet which I’m slightly worried about actually lol)

    I’m hoping I’m not just trying to justify my sweetened soy milk earl grey tea!!!

    Many thanks again for taking the time to produce this and any other information/views/experience you can offer.

  29. Pingback: Why You Should Avoid Soy!

  30. Pingback: Shieldmaid’s Guide to PaleoWorld | Shieldmaid

  31. I thought I was through peri-menopause and all the related symptoms last summer. I have not had my period or any symptoms in 9 months – but after only ONE week of eliminting grains and sugar (I had already eliminated dairy and do not drink alcohol or coffee)I had my first period in 9 months and I began to experience hot flashes again at night. Hmmm.. I am curious as to why this might be happening and what they connection might be? Has anyone else experienced this as well?

  32. I keep arguing with people about this when it comes to horses because of my personal experiences with flax – it would always give me increased breast tenderness, did not matter in what shape or form I consumed it. My Naturopath doctor was baffled…she kept saying “but it is supposed to be good for you!!”…well my body obviously disagreed!

    I have also seen it cause reactions in mares, like increased udder swellings for example and frazzled behavior. A friend of mine spotted every day while drinking soy milk.

    I no longer have any doubt that this sort of stuff should be avoided. ALA conversion for omega 3 in humans has shown to be poorly anyway and I do not believe anyone should eat soy unfermented….

    Thank you for the additional info on this subject here 🙂

  33. Okay, I’m 35 yrs old and I’ve been trying to switch all my facial products (eg: moisturizers, anti-aging serums, face washes, sunscreens, etc.) over to organic products. My monthly cycles are almost always on schedule (give or take a day or two)but since switching all my facial products over to organic ones, now my period is nowhere in sight. I’m currently running 6 days late which is basically unheard of for me. No, I’m not pregnant, of that I’m sure so what I’m wondering is if my organic skin care products could have phytoestrogens in them which is screwing up my hormones. The only other time I’ve had this issue was about 9 months ago ( was running about 5 days late) but as soon as I started taking iron and B12, my period arrived and I haven’t had a problem since. The only other time I had an issue was 5 years ago when I went 54 days without a cycle! I finally figured out that the protein bars I was eating daily were the culprit with their soy protein isolate. I stopped eating them and viola! I was back to normal. Anyway, I’ve been trying to research all my individual products to see if they’ve had the phytoestrogens removed from the plant sources (they’re all botanical or have other sources of phytoestrogen like shea butter, grapeseed oil, vitamin A, C, etc.)that are in the ingredients but I can’t find the answers anywhere! I used to use Aveeno brand and they remove the phytoestrogens from their products but I don’t know about all these organic ones. So, do you think these skin care products could be the source of my messed up cycle and if so, what would you recommend that I do? Go back to my chemical laden products, stick it out and see if it gets better? What’s a woman who’s trying to age gracefully to do?

    • Hi Amber – you could try emu oil. If you do decide to try it and have sensitive skin, I suggest making sure to get certified refined. I found everything else to be terrible – especially cold-pressed oils – to the point I was considering lard or duck fat as moisturiser. When I last checked Aveno, they all seemed to contain soy and colloidal oatmeal – oats are estrogenic. From memory they contain silicon derivatives as well, which can also be irritating to sensitive skin – I avoid like the plague (in hair care products too).



  34. I’m having hot flashes gang busters! I’m on paleo, okay I’ve cheated since its too hot to cook. But I’ve greatly reduced the baddies like sugar, grain, etc. Just not eating as much meat and veggies but more fruits. My physical job has me lose a few pounds on my already slim frame

    I’ve added minerals and vitamin D back. I had hoped being in the sun and eating produce would be sufficient. It has slightly eased my symptoms but still disrupts my day and sleep.

    What can I eat to ease my symptoms? I wake at 4:30 an for work, sleep 7 hours, eat well, in good shape, etc. it would be handy if there was a recipe book to guide us. Does food choice differ for differing menopausal symptoms?

  35. Thank you for this. I’ll be back often. i’m 35 and an effing mess.
    also? you said “you bet your sweet ass it does…” Love your style.

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  37. Hi,

    As someone who has studied biochemistry extensively, I wanted to complement your excellent article. You are absolutely right in basically everything you said; in particular, that phytoestrogens disrupt estrogen activity in complex, unknown, and unpredictable ways, and anyone not wishing to throw their natural hormonal balance to the wind should use great caution with them indeed. For that matter, the same is true for many plant remedies people tout because they are “natural” and therefore harmless (although there are many which are gentle and tested as well).

    This point hit home for me when I tied making some raw onion bread in my dehydrator out of flax and sunflower seeds with a sweet onion. It was unbelievably delicious, but I had night sweats for two nights. Of course I attributed it to the lignans and will no longer consume them in these quantities. I should have known better, but to be honest I was not aware of just how great a concentration of lignans flax seeds had. Well, now I know.

    By the way, I am studying to be a doctor, so I can tell you that at least some physicians (as well as future ones) share these opinions and understand the risks of throwing off the body’s hormonal balance in this way.

    Great job!

    • Wow, awesome, thank you Tatiana. It took me a long, long time to work out my theories of estrogen, and to make sure it was decent, and then rarely have talked about it with people who are also deep in this research. Thank you so much for everything you said, and good luck!

  38. Pingback: Spilling the Beans – 10 Reasons to Avoid Eating Legumes

  39. The research linked on this site is intriguing.

    I have been a vegetarian for over three years (but could never adopt a vegan approach.) I incorporate non-meat Paleo foods in my diet regularly and eat only small amounts of grains.

    I used to suffer from chronic and debilitating allergies – including asthma, crippling sinus headaches, and body-wide inflammation so bad that I could not sleep. My heath improved by 80 percent when I cut out all fish, meat and most wheat and grain. I still cheat and eat it occasionally. But often then my allergies return.

    I would be careful about making broad pronouncements about vegetarianism. I would never change my diet to consume meat on a regular basis, now that I am as healthy as I am at present.

    I would suggest that people carefully evaluate their dietary choices and choose what works based on personal research. I took trusted advice and evaluated it based on my own reactions. It was very important to take prolific notes on diet vs. symptoms on a daily basis. I did this for three or four years. My health is so much better now, it is incredible. And I no help at all from the mainstream medical practitioners I visited constantly when I first became sick. If I had stuck with the doctors – I would be on doses of steroids forever unable to sleep right, bloated and messed up.

    After getting tired of the useless advice I received from my physicians, I carefully changed my diet and environment. I went from crippled by allergies and constant colds to mountain climbing. Now I’ve climbed 35 of the Adirondack high peaks and many of them in winter. There is just no comparison.

    I went from visiting an emergency room to get steroid injections due to out of control asthma and allergies to no inhaler or asthma medicine at all. I have been free of those drugs for over four years.

    Diet and environment have made an enormous difference in my life and health. And like I said – I am a vegetarian. And I was a person who used to make fun of vegetarians. But there are a lot of legitimate studies showing being an educated, aware vegetarian is a healthy lifestyle choice for women.

    Again, it differs for different people. And you have to keep on top of it and not slack off.

  40. Hi! Thank you so much for doing all the leg work and summarizing all the masses of info on this for us. I really appreciate it!!

  41. Hi, I am a 55 year old woman who has not had a period for over 4 years so I guess that makes me menopausal. I say guess because I do not suffer any of the symptoms associated with the menopause. I believe it has to do with my life style which is whole food with a lot of raw salads, including raw butter, raw milk and raw cheese. Also only when my body requirers it grass fed meat. I do intuitively listen to my body, which I believe is also the key as all bodies are unique. I have never believed in medication, vaccinations or pain killers. I don’t drink alcohol or black tea or coffee, my body has never liked them. When I did have periods sometimes I would get headaches which were cured by eating milk chocolate which I now believe was the milk that cured them, as the only thing I have noticed since being menopausal is that if I stop drinking milk for more than a couple of days I will get irritable. My granddaughter as recently started her periods and when she complained of a headache I offered her raw milk, she normally hates milk but her body said yes and her headache went. I have come to the conclusion that it is possible due to the cows diet of plant oestrogen that I and my granddaughter are obtaining from the raw milk due to the grass fed cows diet. I should also mention that I have been in great health all my life and rarely if ever get a cold or virus. When I was younger a cold would last a week, then days and now hours but mostly they bypass me completely. I hope this helps all those who are looking for clues to their ailments.

    • It could be the calcium. Low calcium can cause headaches, irritability, PMS, painful periods, hormonal issues, dry skin, fatigue, etc etc.

  42. Hi!

    I am 23-years old and I have type II PCOS, where my estrogen is on the low end. I keep getting these hot flashes after meals since I changed to Paleo a week ago. Before I was eating legumes almost on daily basis in the last month (mostly chickpeas and lentils). I was vegetarian for about 9 years, and tried vegan-low GI-gluten free for a month before switching to Paleo – but it made me crazy hungry. But on Paleo I am full and happy with my meals. It’s just the hot flashes after eating and extra sweating while exercising that started to happen. Could this be because my body has to get use to meat? Or maybe the estrogen is lowered, because i cut out legumes?

  43. “It is not only a vegetarian staple, which automatically makes it a womanly food,…”

    Why? Your comment claimed vegetarian lifesytles for women and not for men. Sounds like discrimination. I don’t understand why you would write this?

    • 60 percent of vegetarians are women, and vegetarianism has a long history of being associated with women.

      • Your statistics look correct. By declaring food groups and eating habits as womanly you may drive men away, because of our messy gendered society where men think masculinity != femininity. The more we cry its ours they’ll just eat more meat and have more heart attacks! My apologies for hijacking your thread 🙂

  44. This article is really interesting. I was considering trying to adopt a Japanese style diet, and I noticed that they eat a lot of soy and soy products. And then your article really made me wonder. The Japanese seem so healthy and youthful, and yet they eat so much soy and rice. Do the phytoestrogens not affect them, somehow? Do you have any thoughts? I’m really curious.


  45. Hi, I didn’t understand most if the terms and sped read through the article you wrote but I did understand the gist of it.
    What do you think about DIM? I also was researching what could possibly be the cause of endometriosis which is bad liver or not cleansing liver. I went to the health food store to buy a liver cleans and all the ingredients in every bottle contained some form of root, herb, or plant that has estrogen derived. Milk Thistle, hops, etc. So I grabbed this tea off the shelf called Tulsi Cleanse. After getting home and researching every herb in the tea, I stumbled across your site because one of the herbs has phytoestrogens. I think it was phyllanthus. Anyhow, I read that Tulsi (alone) is an estrogen blocker. I’m so confused! I hate messing with my hormones! I hate estrogen. I can’t even live or eat without finding out that there’s some sorta estrogen in it. All I’m eating right now is crucifer veggies. I’m not enjoying food right now. Any advice?

    • So much to think about! I wish there was a simple solution! I’m 55 years old, not sleeping well due to hot flashes. I’m trying a phytoestrogen but now, I’m just not sure. Thanks for the info.

  46. Pingback: Paleo for Women | Six Reasons I Don’t Eat Nuts

  47. Great article! Thank you.

  48. Hi Stefani,
    Three years ago I married a very sexy man who is now 75. He’s still very sexy, I mean a big appetite for it. I am now 73 and haven’t felt very sexy since I went off of the Bezwecken PhytoB (estrogen) two years ago which I had been on for several years. So for about 2 years I’ve been trying to create more youthful sexiness with food estrogen, using ground flaxseed for the lignan, and fermented soy for the isoflavanones, combined. My background: From the age of 36 (had a radical hysterectomy losing ovaries) until about age 50 I had taken prescribed Primarin, then after that started taking a prescribed phytoestrogen 9from my naturapath) which continued to keep me sexy. I had read that the chance of breast cancer (taking phytoestrogren) was very slight for a woman without ovaries.
    In ’09 I learned that I had lost 40% of my bone density, but I brought it up naturally for the next 3 years, gaining over 10%. Here’s the kicker. Last month (Sept 2014) I learned that I have lost 5 % of my bone density in just the past two years. And I haven’t felt sexy in spite of the flax seed and fermented soy. So I thought about going back to the prescribed Bezwecken PhytoB, but I just learned that now this Bezwecken phytoestrogen has been discontinued.
    I read in your excellent article here that you recommend just staying away from these phytoestrogens, at least in a high quantity, and I read all the complications you mentioned. Trouble is, what I wanted to start back on because it seemed to be helping me in both bone growth and libido is now no longer available. My rapid bone loss in the last 2 years could be caused by other factors than the soy and flaxseed or loss of the Bezwecken, like my poor sleep, stress, major surgery, maybe even a prescribed drug I’m on for atrial fibrillation. So I’m reversing the stress and sleep problem. The osteoporosis doc predicts dire possibilities walking around with these very porous bones, but I won’t take the dangerous drugs that are available for that condition. Do you have any thoughts on where I might turn? I am a health nut, have been on Paleo for 2 years (but cheat with grains), I work outat a gym 3Xweek and walk daily, and my naturapath has me on supplements for my conditions. But I can’t keep up with my healthy man, and I love him dearly!

    • Well, first: hats off to you. That’s awesome.

      Second: I think it’s worth it to quit the soy and flax and at least see what happens. Make sure you’re eating both plenty of saturated fat and plenty of fruit / starchy carbs (you need carbs for a sex drive!) On the other hand, I don’t think they should cause bone loss per se. Have you considered alternative therapies to the Bezwecken? I know you don’t want to endanger yourself with estrogen supplementation, but a low dose could be enough of the kicker you are looking for. Drugs have also come a long way and appear to be much less associated with risks like blood clotting and cancer than they used to be.

      You are right that the other factors are a problem. Stress and surgery can, especially, draw on the body’s nutrients as well as cause inflammation in the gut, which can impair nutrient absorption, and therefore bone density.

      You may also be helped by vitamin A, D, and K supplementation for your bone strength. D and K are absolutely crucial for strong bones and A D and K work synergistically. If you’re low in one the other two can’t work right. The best way to get these vitamins is with a cod liver oil / butter oil blend supplement made by Green Pastures. Seriously. It’s the best, and could help a lot with your bones.

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  50. WOW- I was diagnose with estrogen receptive breast cancer 3 1/2 years ago. It is nearly impossible to avoid soy. It is in nearly every product many times as soy lecithin, but still there. I did not know about chickpeas, green beans, and peanuts. What can I eat without increasing my chances of breast cancer again?

    • You should be fine eating low-moderate doses of foods like chickpeas. The real important ones to avoid are soy and flax, and just to be careful not to make, like, 90% of your diet chick peas. 🙂 A diet rich in fruits, vegetables, and animal products should be in correct estrogen balance. 🙂

  51. Pingback: Planteøstrogen og hormonbalance | felbyen

  52. great post,Very insightful, Thank you for sharing!

  53. This article was written before I subscribed to you a couple years ago, and I happened to stumble upon it because I’m trying to figure out what effect phytoestrogens have on my body. I started doing the fertility awareness method about 5 years ago and for years my periods were somewhat irregular. Sometimes it would take up to 25 or 30 days for me to ovulate. That combined with my body type and other factors made me suspicious that I have slightly lower estrogen levels that take a while to build up to ovulation. This is all speculation because I’ve never had my levels tested. When I was trying to conceive back in 2013, I was getting really tired of my longish cycles because I had fewer opportunities to conceive. I ended up supplementing my diet with about a 1/4 cup of whole flax seeds (ground fresh and mixed with yogurt) during the first half of my cycle until I confirmed ovulation by a basal body temperature shift. I could see on my charts that this was making me ovulate around a week earlier than I usually did, but I ran out of data because I got pregnant the second cycle of doing this. haha I think that the flax helped raise my estrogen level somehow. I believe that these phytoestrogens do affect our hormone levels, but like you said, it is very complicated! I’m awaiting the return of my first postpartum period since my daughter was born 18 months ago (lactational amenorrhea). I’m excited to see what my cycles will be like, and if they are long like before, I will definitely try eating some flax to see what will happen. I just thought maybe you would find that interesting, since I haven’t heard of many women who only supplement through half of their cycle (and almost all only supplement through the second half, post ovulation). Have you expanded your theory since writing this article?

    • Great question, Jen. Yes and no. Phytoestrogens remain very complicated and I’m not sure I understand them most of the time, but I am totally on board with playing with phytoestrogens in your diet. I personally have found that alcohol, oddly enough, is a good estrogen-booster for me? Please let me know what you find out!

  54. Just by reading the first 3 paragraphs, I can say that you have no clue what you’re talking about and I’m immediately writing off everything you say as potentially false information. Watch your wording and do some more research, please.

  55. this is a informative post and i think we all need to take our own case as our own. The world of centenarian women eat foods full of phytoestrogens and have levels of estrogen as high as those 30 years their younger in a developed region of the world. Phytoestrogens weaker act on the body does help in ways of preventing environmental xenoestrogens from their more stronger negative impact. Our environment is full of bad estrogen. So its about using these foods as a part of a diet….i see drastic changes using these foods as a healer/medicine is probably not the best. Go to pubmed for all the resources on phytoestrogrens, although most of them are linked to prevention of breast cancer. great post for raising awareness!

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