Articles, Blog

Who Shouldn’t Eat Soy?

August 17, 2019

“Who Shouldn’t Eat Soy?” 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, estrogen has positive effects,
the Women’s Health Initiative found, such as reducing menopausal
symptoms and improving bone health, reducing hip fracture risk,
but also negative effects: increasing the risk of blood clots
in the heart, brain, and lungs, as well as breast cancer. So ideally, to get the best of both
worlds, we’d need what’s called a selective estrogen
receptor modulator, something that has pro-estrogenic
effects in some tissues, like bone, but anti-estrogenic effects in
other tissues, like the breast. Drug companies are trying to
make them, but phytoestrogens, natural compounds in plants–
like genistein in soybeans, that are structurally
similar to estrogen– appear to function as natural selective
estrogen receptor modulators. 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 you drip more and more soy
compounds on 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, but 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
we discovered there are two types of estrogen receptors in the body,
and so how a target cell responds depends on which type of
estrogen receptors they have. This may be the key to understanding
the health-protective potential of soy phytoestrogens, the existence
of this newly discovered estrogen receptor–called
estrogen receptor beta, to distinguish it from the classic
estrogen receptor alpha– and unlike our body’s
own estrogen, soy phytoestrogens preferentially
bind to the beta receptors. If you have people eat about
a cup of cooked whole soybeans, within about 8 hours,
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 that. So let’s see what that means
for estrogen receptor activation. This is the graph that explains the
mysterious health benefits of soy foods. Down around the effective levels
you’d get eating a cup of soybeans, there’s very little alpha activation,
but lots of beta activation. So now let’s 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
all these extra clotting factors. But guess what? The human liver only contains alpha
estrogen receptors, not beta receptors, and so maybe if we ate like 30 cups of
soybeans a day that could be a problem. But at the kinds of
concentrations one would get with just normal soy consumption, no wonder this is a problem with drug
estrogens, but not soy phytoestrogens. The effects on the uterus appear also
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 10-fold, phytoestrogen-
containing foods are associated with significantly less
endometrial cancer, in fact, protective effects for these
types of gynecological cancers in general. Women who ate the most soy had
30% 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, but still can dramatically improve
menopausal symptoms. The Kupperman Index
is like a compilation of all 11 of the most common
menopausal symptoms. 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, consistent with population data
suggesting high consumption of soy products is associated
with increased bone mass. But can they prevent
bone loss over time? Soymilk was compared to a
transdermal progesterone cream. The control group lost significant
bone mineral density in their spine over the two year study period, but the
progesterone group lost significantly less and the two glasses of soymilk
a day group ended up actually better than
when they started. This is probably the most
robust study to date, comparing the soy
phytoestrogen genistein to a more traditional hormone
replacement drug regimen. In the spine, over a year, the
placebo group lost bone density, but gained in the phytoestrogen
and estrogen groups, and the same with the hip bones. The study clearly shows that the
soy phytoestrogen prevents bone loss and enhances new bone formation, in turn
producing a net gain of bone mass. But the only reason we care about bone mass
is that we want to prevent fractures. Is soy food consumption associated
with lower fracture risk? Yes. A significantly lower risk
of bone fracture 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. So that’s just like
one cup of soymilk, or even better, a serving of a whole
soy foods like tempeh or edamame, or the beans themselves. We don’t have fracture data
on the soy supplements though, so if we seek 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? Well, some people have soy allergies. But a national survey found that
only about 1 in 2,000 people report a soy allergy. That is 40 times less than the most
common allergen, dairy milk, and about 10 times less than all
the other common allergens like fish, eggs, shellfish,
nuts, wheat, or peanuts.


  • Reply Maxim C. November 26, 2016 at 10:31 am

    6:26 — Japanese eat a lot of fermented foods and sea algae… Could it be that fermented soy (natto) has different effects on the body than not fermented soy…?

  • Reply zukodude487987 November 26, 2016 at 1:06 pm

    Got soy?

  • Reply Amanda Mate November 26, 2016 at 2:59 pm

    can somebody tell me, why I have to cough after drinking energy drinks? It maybe hast to do with blood clothing? The cough even tastes little bit like blood.

  • Reply CAIrondad November 26, 2016 at 3:03 pm

    Wow…. amazing video…thanks for this one!!!!!!!!!!

  • Reply lightdark00 November 26, 2016 at 8:51 pm

    My diet is almost 50% legumes. Why is soy the only one singled out?

  • Reply Griffin November 26, 2016 at 9:41 pm

    Should we add a serving of soy to the baker's dozen?

  • Reply 245194LAC November 27, 2016 at 4:16 am

    Would there be a therapeutic affect if soy were to be ingested in higher amounts in patients with bone cancer?

  • Reply I LOVE MAI November 27, 2016 at 4:56 am

    theory: (you are awesome)
    A) vegan homocysteine is beneficial "IF" enough plant antioxidants are present in the diet.
    B) vegan homocysteine levels are decreased by plant antioxidants "IF" enough plant antioxidants are present in the diet.

  • Reply girlgrace November 27, 2016 at 5:47 am

    This all goes over my head, can someone break it down to a 15 year old level haha

  • Reply Liam Gutierrez November 27, 2016 at 8:20 am

    Weston Price and their soy scare mongering… The truth is, soy is good for you!

  • Reply farfiman November 27, 2016 at 2:32 pm

    Russian propaganda I say !!

  • Reply O. J. November 27, 2016 at 6:35 pm

    I dont know what it is, but i never understand a single video by him. Is it the way he arguments? Or his voice? Or is it me, im not a native english speaker…? I never have problems with english, politics, science, you name it. But this channel makes me feel stupid…

  • Reply Brett111 November 27, 2016 at 8:50 pm

    Yo Doctor Greger. Are you planing on doing a video about the latest meta analysis on Milk "Milk and dairy products: good or bad for human health? An assessment of the totality of scientific evidence"
    sponsored by the dairy industry and friends

  • Reply 59seank November 28, 2016 at 3:03 am

    Should men eat soy?

  • Reply GrummanPilot99 November 28, 2016 at 4:09 am

    Is it safe for men? Will we grow breasts?

  • Reply Never-die Young November 28, 2016 at 9:41 am

    Humans don't need any soya products.
    Soya is fucked-around with acids etc. – stay away.

  • Reply pedro silva November 29, 2016 at 12:56 pm

    dr michael can you do a vídeo on soy and testosterone?does it affect testosterone levels?

  • Reply Debbie Bunny November 29, 2016 at 8:00 pm

    I have hypothyroid disease. I've been told several things by various doctors; 1) avoid soy products or 2) take a higher dose of sythroid when consuming soy or 3) keep a 4 hour window between taking synthroid and eating soy products. Which is the best medical advice concerning soy and hypothyroid medicine?

  • Reply bbenabe December 1, 2016 at 1:03 pm

    What about soy with hypothyroidism?

  • Reply Maxwell Spiers December 3, 2016 at 9:45 am

    my brain hurts

  • Reply MissAllanPoe1989 December 4, 2016 at 5:22 am

    Liposomal Vitamin C absorbs far better. Take that human body!!

  • Reply Bruce Wayne December 4, 2016 at 1:14 pm

    In other words… Soy= perfect muscle food for men.

  • Reply They are everywhere December 6, 2016 at 11:50 am

    how about GMO soy

  • Reply Catherine Forristal December 7, 2016 at 10:46 pm

    What about soy for kids (ages 2+)? Is there any truth to phytoestrogens in soy being bad for sexual development? Thank you so much for all the information. This is such an amazing resource!

  • Reply Des Troya December 8, 2016 at 3:20 am

    No thanks soy lowers testosterone

  • Reply paul eluard December 8, 2016 at 3:20 pm

    aushwitz diet made greger the walking dead the he is. don't follow his bs unless u wanna loose all ur hair, have the muscle density of a 12 year old and Bernie Madoff as ur friend

  • Reply simranjeet singh December 9, 2016 at 8:00 am

    that good bcoz i take 1 kg of soya yoghurt daily

  • Reply TEFL Hero December 11, 2016 at 8:25 pm

    Does this include tofu?

  • Reply Talitha Vrey December 12, 2016 at 4:27 pm

    will you please make a video on intermitted fasting?

  • Reply Alex Ember December 12, 2016 at 8:10 pm

    soy is NOT a food

  • Reply MathCubes December 15, 2016 at 6:05 am

    I thought you said to not eat say due to IGF-1?

  • Reply Dysprosium December 27, 2016 at 7:57 pm

    Fibroids affect 1/5 women and is the leading cause of hysterectomies in women which can have significant long term health impacts.  Any research on affects of soy and other dietary patterns on fibroids?

  • Reply Sara v December 31, 2016 at 5:54 am

    Ever since I've increased my soy intake I've been getting acne and what seems to be hormonal imbalance.. Is it connected? I'm trying to limit my soy intake to find out!

  • Reply Jaded K January 3, 2017 at 8:03 am

    But a 2013 study "observed lower testosterone responses following supplementation with soy protein":

    So, shouldn't men who don't want to lower testosterone avoid soy?

  • Reply Rational Learner January 22, 2017 at 12:12 pm

    How about soy effects on men?

  • Reply gmflashmx January 24, 2017 at 3:01 am

    So what is a reasonable amount? Im eating 200grams of soy spaghetti with 1 vegan burger right now, I used one spoon of soy in my smoothie earlier. Am I overdoing it?

  • Reply Yael Gil January 30, 2017 at 10:47 pm

    what about women taking pills? should they reduce their soy-intake?

  • Reply Zach Ricca February 15, 2017 at 4:02 pm

    Dr. Greger, thank you for the video, but while I am not concerned about phytoestogen, is seems soy also contains phytic acid which acts as an "anti-nutrient" ( Is this a major concern compared to potential benefits? And do you recommend a way to mitigate it if not? I know fermentation takes care of it but this is not always available in America.

  • Reply Olivia Love Worthy March 9, 2017 at 2:57 am

    It's so exciting to finally have this info!

  • Reply Mari March 30, 2017 at 12:55 am

    China and Japan have been eating soy for over 2,000 years! Yes, 2,000 years!!! And we are the healthiest :)))

  • Reply Vegan Buddhist April 2, 2017 at 5:59 am

    Why isn't this information more well known by doctors? I have a friend who's breast cancer is in remission but was told by her doctor to completely avoid soy. This and many other personal experiences of total incompetence and carelessness with other people's lives is why I don't trust the majority of doctors for a single second??

  • Reply PsychoMancy April 3, 2017 at 4:59 am

    So Soy is good?

  • Reply Rainy seasons April 11, 2017 at 5:53 am

    What about people with anxiety, should they eat soy?

  • Reply Kane Alson April 12, 2017 at 4:33 am

    Soy is a rich source of omega 6. Not a good idea as our diets provide way too much omega 6 as it is. This lower omega 3 profile is a real problem to our health and drives many inflammatory conditions. Soy is a poor food choice. Not talked about on here. Think it's time to go elsewhere to get info.

  • Reply Michiel Vanderheyden April 17, 2017 at 10:15 am

    So the answer to the title is… people who are allergic to Soy. Hahahahah

  • Reply danpt2000 April 22, 2017 at 3:53 pm

    binge watching Nutrition videos confirms the traditional Asian diet my parents ate is so much better than today's diet.

  • Reply Michelle Larsen April 28, 2017 at 7:53 am

    I think I have soy allergy…. ;( but I can eat tempeh with no problems. You should make a video about processed soy products and the dangers behind. I still find it hard though to understand that soy milk is okay to consume. It is also processed.

  • Reply Nicki LovesDogs June 5, 2017 at 11:43 pm

    Thank you Mike. I have been researching soy milk side effects recently and I am coming across a bunch of scary stuff including the blogs by Dr. Mercola telling us that soy contains aluminum particles, toxins and growth stunting chemicals. Haha. Now you are saying that soy is beneficial for us even soy milk. Thank you for this video that saves me from having to return 10 cartons of soy milk to the Dollar Tree store. I'm only drinking one carton of soy milk a day blended with fruit in blender and it tastes so great and creamy. I think that one carton a day can't prevent cell division right? Why is Dr. Mercola alarming people about soy? I am very confused. Is he paid by the meat industry? Ha.

  • Reply Billy Rosewood June 22, 2017 at 2:41 am

    What is the effect of soy on men?

  • Reply MrFritzthecatfish June 29, 2017 at 9:34 am

    Estrogens are bad for males …

  • Reply Fanny Bass July 26, 2017 at 5:06 pm

    I am 54, vegan, and thank God I don't suffer from menopause simptoms at all I would say. I do skateboarding, and my bones resist pretty well the falls.

  • Reply HecateofDarkMoon July 29, 2017 at 5:52 am

    Does anyone know if soy can make birth control less effective? Particularly the depo provera shot?

  • Reply Warfield Alexandre August 11, 2017 at 3:23 am

    What brand is the best for organic soy milk?

  • Reply Bruce Devaux August 17, 2017 at 12:48 pm

    Too much technical talk for a dumb boy like me Maybe doctors can understand what he's talking about

  • Reply Kamil Osięglewski September 13, 2017 at 10:12 am

    Soy reduces testosterone dramatically. No wonder more and more people have no idea whether they a male or a female. Gender crap LGBTAHULnGfUakKhGGJKkK+ is a fucking hormonal hoax!!

  • Reply Jose Lara October 5, 2017 at 6:14 am

    For years I have been consuming whole milk , now after being more inform and educated I'll start consuming more almond and soy milk .

  • Reply huriye kantar October 23, 2017 at 2:20 pm

    This is good to know since I have a genetic illness called hypermobility syndrome EDS and at the age of 26, my bone mass is already low and doctors said I’m gonna get worse and there is nothing I can do to stop it but I refuse to believe it. Yes, there is no cure for me but I believe that a healthy diet along with my strength training workouts, can help manage my health in the long run.

  • Reply 80's Nostalgia Guy October 26, 2017 at 6:47 pm

    You should have been a voice over actor. You have a cool and persuasive voice. If they ever do an animated version of the X Files, you would be perfect for Mulder.

  • Reply Phi1eap November 11, 2017 at 3:09 am

    What about hops? And what about phytoestrogens in man health?

  • Reply EliasAlucard November 23, 2017 at 6:25 pm

    Excellent review! I eat anywhere between 250 to 500 mg of soy phytoestrogens per day, and even my multivitamin pills contain 40 mg of soy phytoestrogens. I also take probiotic pills containing the proper bacteria strains that convert daidzein into (S)-Equol (which is a metabolite of daidzein with the highest "estrogenicity" of all phytoestrogens. Indeed, I've been trying to explain this topic to mainstream anti-intellectuals and iGnorant iDiots for years now, that soy phytoestrogens are good for both men and women alike, because they're SERMs-like molecules, not actual estrogens. Mainstream thinkers however, don't understand what the hell a SERM is, so there's always that cognitive dissonance. Anyway keep up the good work.

  • Reply SexyJamal77 November 24, 2017 at 10:01 am

    This is nice and all, but I'm not a woman. What about soy in men?

  • Reply Happytobe Here November 26, 2017 at 3:15 pm

    Isn’t soy one of the top GMO food ?!?

  • Reply Cisco Garcia December 6, 2017 at 11:33 pm

    Hi Dr Greger, I cited this video in an essay for my nutrition class in community college.
    Thank you for the knowledge and expert analysis!

  • Reply Raffaele Demonte December 27, 2017 at 2:22 am

    I was just wondering does the High Levels of Magnesium contribute to the Higher Bone Densities in those who consume Soy Products? Isn't there a correlations to those who eat Mag-Rich foods?

  • Reply pgrothschild December 27, 2017 at 5:12 pm

    A recent study found a compound within Soy helps fight HIV too.

  • Reply The Body December 30, 2017 at 4:44 pm

    Thank you for donating your time and energy to mitigating the confusions regarding soy.

    I greatly appreciate your channel!

  • Reply Will V. R. of Chicago January 9, 2018 at 11:47 pm

    I supposedly had a soy allergy when I was tested as a kid… but I ate soy products anyway (it's in so many things) and over time I lost faith in the accuracy of the allergy test since I've never had a reaction.

  • Reply Hulagu Kahn January 28, 2018 at 3:58 am

    Not to be confused with the crappy garbage GMO soy.

  • Reply Frank Brown February 2, 2018 at 8:25 pm

    Dr. McDougal has a vid out that says that 40 grams of soy protein/day
    increases Insulin Life Growth factor 70%. Does Dr. Greger address this?

  • Reply Straight February 5, 2018 at 1:59 am

    Soon all we'll be able to eat is air and water. I reckon 99% of "net Doctors" talk through their arse.

  • Reply Mike AN February 5, 2018 at 7:59 pm

    Isn't the estrogenic effects of soy supposed to be not so good for males as it can fuck with their estrogen/testosterone balance?

  • Reply Ken Carey February 8, 2018 at 1:27 am

    What about men?

  • Reply redsnowgoon February 15, 2018 at 7:28 pm

    can i consume 100-200 gms of soy nuggets per day to support my protein needs for bodybuilding??

  • Reply sooooooooDark February 20, 2018 at 3:15 pm

    a: humans who can buy any other food

  • Reply Patty Gardner March 12, 2018 at 5:05 am

    Thank you for that fine information. I was hoping you would address the effects of soy and breast cancer. I have read a couple of studies that said soy is an estrogen mimicker and may set women up for increased risk for breast breast cancer. I’d love to hear your thoughts on this. Thanks you.

  • Reply Markus Seiter March 20, 2018 at 8:17 pm

    what about the testosteron, i mean what about testicle cancer?

  • Reply Austin212 March 24, 2018 at 12:57 pm

    If you don't have far-east asian genes, you shouldn't be eating soy regularly.

  • Reply The Personal Health Coach Acupuncture April 1, 2018 at 12:21 pm

    Soy is not health, it is only health when fermented and organic, but it still blocks many nutrients from entering our bodies. It needs to be fermented in order to stop this from happening.
    The soy nowadays is gm based soy. It has been formulated to stop the soy plant from dying when sprayed with weed killers. If the plant is safe, then these chemicals with do the damage.

  • Reply Sheila House April 1, 2018 at 11:10 pm

    can anyone explain why dr. mcdougall is against soy products saying, "Why you might not want to consume isolated soy products! In this audio excerpt Dr John McDougall explains the connection between these soy products and increasing IGF-1 levels. When you raise your IGF-1 levels you greatly increase your risk of cancer.

  • Reply John Keane May 24, 2018 at 12:30 pm

    Is soy ok for Men ?

  • Reply Al Cameron June 17, 2018 at 3:36 am

    Will I become less masculine eating soy?

  • Reply mermaid July 26, 2018 at 3:59 pm

    I watched this video to see if it was good to take protein powder no gmo daily 30 grams in my breakfast, until the end of the video disappointed me.

  • Reply NET MATE September 17, 2018 at 2:16 am

    I appreciate the info contained in these videos But this guy puts me to sleep better than any sleeping pills

  • Reply deborah lewis October 17, 2018 at 4:05 pm

    Does miso count for bone health?

  • Reply Devine Massage October 20, 2018 at 5:58 am

    Thumbs down for click bait title. You didn't answer the question. Merely touched on it as an afterthought. You mentioned those with allergies, but not any other conditions, like hypo- or hyper- thyroid. I've "heard" those with thyroid issues should avoid soy, but it was not from people with medical or scientific backgrounds. And no doctor has addressed this question fully. Merely glossed over it. Leaving me highly dissatisfied.

  • Reply wayne carswell October 25, 2018 at 2:05 pm

    You're totally ignorant if you consume soy! No one should eat soy! It is poisonous frankenfood 98% GMO.

  • Reply Lukas Fraley November 11, 2018 at 12:24 pm

    I've always been taught that it lowers testosterone in men, is this not true?

  • Reply Victoria Ryan November 18, 2018 at 10:36 pm

    Hi! I am writing a paper for medical school and I really want to use the graph that was in this video from Mueller et al. However, in the original study, the graph is more complex. Did you simplify the graph yourself, or is there a place that I can obtain the simplified graph?

  • Reply FBlueJay 1 November 27, 2018 at 5:42 pm

    Am afraid dr.greger is not telling the whole story, see this video:

  • Reply Mike December 6, 2018 at 1:09 pm

    So what about soy boys?

  • Reply Sukhareva Syndrome December 15, 2018 at 9:22 pm

    I want to say something about the whole "soy boy" myth:

    Are you worried about "phytoestrogens?" Okay… scientists are at work on that. They'll get back to us when they have an answer. There is some evidence that too much soy can mess with your thyroid. But making you less of a man (smaller penis, mantits, etc.). Probably not.

    Even if so, many of these same people who push this "soy boy" crap seem to worry little about the REAL ESTROGEN in beef. Big Ag pumps what is essentially birth control (female hormones, estrogen) into beef and you consume it every time you eat beef, cheese, or drink milk. Real estrogen does the very thing "soy boy" pushers worry about.

    As far as we can tell, soy boys can actually have more testosterone. This may be because the beef-eaters have more estrogen in their systems than soy boys, which has an effect of cutting down testosterone. But "phytoestrogens" don't appear to have this effect. How ironic.

    For evidence, look at the study "Hormones and diet: low insulin-like growth factor-I but

    normal bioavailable androgens in vegan men," by "NE Allen, PN Appleby, GK Davey, and TJ Key," which is available on the website of the NIH.

  • Reply godstomper January 8, 2019 at 8:09 pm

    My question is are these women eating a vegerarian diet? Or junk food and milk?

  • Reply Tallie Allen January 18, 2019 at 9:50 am

    Ok. But can soy cause early puberty in girls?
    I keep hearing this rumor. I’d like to know the truth. Do you have a video about this issue?
    Thank you ?

  • Reply Adam Alfred January 28, 2019 at 5:03 am

    Just eat soy products every now and then there you go case solved ?

  • Reply Belleza Y Equilibrio March 28, 2019 at 11:13 am

    Nowadays still a lot of popular doctors say soy is dangerous. I don't understand why there are so different points of view.

  • Reply Happy Comfort April 21, 2019 at 3:10 pm

    I am eating vegan but had a reaction to soy milk , so had to switch to almond milk. I started getting an eczema condition that was getting worse and worse till I cut out soy milk. I wasn’t very happy about that since soy is a good source of protein. I wonder if I could get away with soy products and it’s only soy milk (no sugar added) I need to avoid ?

  • Reply Thủy Vũ Thu May 17, 2019 at 3:46 pm

    Thank you very much for your video Dr. Greger

  • Reply jacksoncrate May 21, 2019 at 9:55 pm

    soy lowers testosterone. a new breed of weak pussy soy boys are coming. fuck your soy. get your meat in and start benching.

  • Reply Genesis Veritas June 16, 2019 at 12:27 pm

    I have osteoporosis on my spine. Would a 250g serving of organic soy yoghurt improve this? The brand Sojade is an organic soy brand without any additives or added sugars, so I'm tempted to try there milk and yoghurts. Is 250g a day a safe amount?

  • Reply maya Jaz June 28, 2019 at 9:24 pm

    can any one make it simple and easier explain to me pls?

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