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The Effect of Soy on Precocious Puberty

Meat, animal protein, and soymilk (soya milk) can affect premature breast development in girls.

August 29, 2011 |
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Acknowledgements

Image thanks to Hamner_Fotos.

Transcript

The age of puberty for girls continues to decline.  Last year researchers published a study of more than a thousand girls across the country  and found a “a higher prevalence of onset of breast development among girls at ages 7 and 8 years old compared with those observed more than just a decade earlier."

This has obvious psychosocial implications, but from a  medical point of view, the reason we're so concerned is that those who start developing at a younger age are at an increased risk of breast cancer later in life, due to the increased estrogen exposure.  For every year puberty can be delayed, risk of future breast cancer may drop 7%. A century a go, girls were starting their periods at around 16, which may help explain why breast cancer is now such an epidemic.

So what’s contributing to this premature development?  New study last year following 3,000 girls found the single most important dietary determinant was how much meat girls eat. “Meat intake, measured, at 3 and 7 years was strongly positively associated with starting their period by 12 years 8 months,  so the trends in "age at menarche" in the West over the last century might reflect the trends in meat consumption.” The  second most powerful predictor was animal protein in general, so it wasn't just meat.

The reason girls eating vegetarian have been found to develop more normally may  also be influenced by their soy intake. Last year a group of German researchers calculated that girls  drinking just like two cups of soymilk a week developing breasts on average 8 months later than those who drank hardly any. Soy  failed to have an effect, however, on timing in puberty in boys.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Dianne Moore.

To help out on the site please email volunteer@nutritionfacts.org

Dr. Michael Greger

Doctor's Note

Related videos on premature puberty include Hormones in Skim vs. Whole Milk and Xenoestrogens & Early Puberty. And there's more than a dozen videos on soy, including Soy & Breast Cancer and Soy & Breast Cancer Survival.

You may also be interested in my blog posts for more context on the topic: Breast Cancer and DietSoy and breast cancer: an update, How Much Soy Is Too Much?, and Why Are Children Starting Puberty Earlier?

  • http://nutritionfacts.org/members/mgreger/ Michael Greger M.D.

    Related videos on premature puberty include Hormones in Skim vs. Whole Milk and Xenoestrogens & Early Puberty. And there’s more than a dozen videos on soy, including Soy & Breast Cancer and Soy & Breast Cancer Survival.

    You may also be interested in my blog post today: Soy and breast cancer: an update.

  • http://nutritionfacts.org/members/msadventuress/ MsAdventuress

    This is all such important information. I find myself fighting my own emotions, based on my past assumptions, upon hearing all this research. And it’s all good. Thank you. ♥

  • http://nutritionfacts.org/members/BenjaminStone/ Benjamin Stone

    We use soy milk to feed our baby girls!

    • 094870

      STOP IT BEFORE IT’S TO LATE.

  • http://nutritionfacts.org/members/bhami/ bhami

    Have their been any studies on the effects of grass-fed organic meat and dairy vs. factory-farmed meat and dairy?

    • http://nutritionfacts.org/members/toxins/ Toxins

      According to T. Colin Campbell, a prominent doctor in the nutritional field, he says that compositionally, conventional meat and organic meat are nearly identical. The difference may be in growth hormones and contaminants but both types of meat cause the same diseases. It’s the animal protein itself that causes harm. All those other contaminants just add on to the load.

  • http://nutritionfacts.org/members/jmerrikin/ jmerrikin

    I have been fielding some questions from a group of about 50 people regarding the Weston A. Price Foundation assertion that consuming soy could be detrimental to one’s health due in part to the high phytic acid content.

    Can anyone please address the nonsense that WAPF has spewed out regarding soy?

    • 094870

      SOY IS NOT GOOD FOR YOU. it mimics the real protein(opposite effect) in your thyroid gland. Soy protein is not a true protien, it mimics a true protein.

  • http://nutritionfacts.org/members/RobertoSotoHernández/ Roberto Soto Hernández

    Hi Doc. I would like to know about the effects of soy protein (trypsin inhibitors, etc, etc, etc) cuz this conserns me a lot.

    • http://nutritionfacts.org/members/aguccionesbcglobal-net/ aguccione@sbcglobal.net

      There are some confusing info regarding soy and it’s more processed versions.
      Try these video leads.
      - Does Tofu Cause Dementia?
      - Milk Protein vs. Soy Protein
      - Soy Foods & Menopause
      - Soy Hormones & Male Infertility
      - Tofu vs. Tempeh
      - Waistline Slimming Food

      Also check this discussion: http://www.drmcdougall.com/misc/pdf/pdf050400nl.pdf

    • Toxins

       These antinutrients are all deactivated with cooking.

  • http://nutritionfacts.org/members/heatheragee/ heatheragee

    I am the mother of 2 little boys (18 months and 2 months). I am breastfeeding my youngest, but am still giving formula (dairy milk based) to my son at night and if he isn’t eating enough during the day. We are transitioning to a whole foods, plant-based diet as a family because of information that we have gleaned from your site (thank you!).

    My question is what, in your opinion, is the BEST milk alternative for older infants and children (that no longer breastfeed). I’ve heard concerning comments about phytoestrogen content in soymilk being harmful to older infants/young children. Is this concern evidence-based?

    • 094870

      I am 72yrs old and was reised on a farm in my early years and am very healthy today. So on saying that I would tell you to keep on feeding your kids cow,goat milk but as they get into their middle ages to go to skim milk and they will be as health as I am today. Stay off all of these GMO type of foods(Genetically Modified Organisms type foods as long as you can. Fresh fruits and veggs is the best way to go.

  • http://nutritionfacts.org/members/drdons/ DrDons

    I would recommend stopping the dairy milk based formula that you are giving your son. The concerns about soy are not evidence based. For information on adverse effects of hormones both male and female in dairy see… http://nutritionfacts.org/videos/dairy-sexual-precocity/. There are other dairy videos on nutritionfacts.org detailing other associations of the consumption of dairy products which are many. A good resource for parents interested in improving their older children’s nutrition is the 28 day pamphlet, Nutrition of Kids, available for free download at http://www.PCRM.org. For infants PCRM’s information sheet is helpful: http://www.pcrm.org/health/diets/vegdiets/vegetarian-diets-for-children-right-from-the-start. Of course each child can have special needs and you need to work with your physicians as needed.

  • Michael Greger M.D.

    Also be sure to check out my associated blog post Breast Cancer and Diet!

  • http://www.facebook.com/julie.wyatt.1232 Julie Wyatt

    Does a vegan diet ( eating soy products: 5 x per week, soy milk) affect a young woman’s fertility?

    • 094870

      YES it does. Stop it now.(the soy products that is)

  • Jola

    Dr. Greger, 

    I was hoping to get your opinion (based on the most current scientific findings, of course) on the topic of soy safety.  

    Recently, my friend and I have been going back and forth about the safety of soy.  I’ve been sending her links to your videos (as well as links to Dr. Barnard’s info) and she would answer back with evidence to support her claims about soy’s danger (http://www.mercola.com/article/soy/avoid_soy.htm, http://www.ncbi.nlm.nih.gov/pubmed/21353476, http://www.usmagazine.com/celebrity-news/news/jeremy-piven-i-grew-man-boobs-from-excessive-soy-milk-2009311 …I realize the latter piece is hardly evidence-and that the “man boobs” were probably just as likely caused by Piven’s over consumption of fish (xenoestrogens) rather than soy, but still she shared it with me).

    The debate we shared left me feeling just a wee bit confused about soy, despite what your videos state. It seems that the topic of soy is still a controversial issue (there is the issue about GMOs). Recent talk about the “paleo” diet seems to be stirring up more confusion these days.
    I am by no means super Rah Rah about soy (everything in moderation, and the more whole the better); and, I still believe that the preponderance of evidence speaks to soy’s safety (except for those who are allergic to it). And, of course, like all our food, it should be produced safely and without GMOs and other bad chemicals.  All the same, I wanted to share the above links with you and get your opinion about them, since you are respected expert in this area and I trust your opinion. Plus, you are not beyond correcting your viewpoint when the evidence suggests that makes sense.

    Thank you in advance for taking the time to address my comments.

    To health!
    Jola

    P.S.  Do you have any videos coming up on GMOs and the Paleo diet.  These topics always come up in conversation. It’d be great to see what the current evidence states about these topics in nutrition. 

    • Toxins

      Hello Jola,

      Firstly, Dr. Greger covers the paleolithic diet here on his free e book here http://www.atkinsexposed.org/

      Now to the point of soy. I find that when debating someone over an issue, it is best to debate using the primary sources. So instead of sharing the whole videos themselves or articles themselves, share some of the sources cited and actually read through the primary source and quote from it. Also, try to google the title of the primary source and you may find the full study available so you can quote from it more in depth rather than just posting from the abstract. When Dr. Greger quotes from it, you can usually expect those same words in the study so you can use these same quotes.

      Now when dealing with the opposing side, when they present to you evidence, look through the study itself and search for inherent flaws. Dr. Mercola is not a very trustworthy doctor and he tends to skew the actual data in the study or ignore other studies that show what he is saying is clearly wrong. This can be seen with his support of coconut oil and spirulina.

      If they simply show you articles without references this does not count as evidence. For you I will pick apart Dr. Mercola’s argument

      Firstly, Dr. Mercola argues that soy beans have many antinutirents, such as protein inhibitors and phytic acid, and that cooking does not completely deactivate these. This is false, cooking does in fact deactivate these antinutrients. Imagine if it didn’t, the epidemic of “protein deficiency” “calcium deficiency” and “zinc deficiency” in Japanese culture, Native American culture and certain parts of western culture would be significant. Cooking deactivates these anti-nutrients which include lectins, phytic acid, trypsin and α-amylase inhibitors. This is fairly well established common knowledge and most beans, from peas and lentils to kidney beans have these antinutrients unless cooked. This is why I say there would be an epidemic of deficiencies in other cultures because all beans contain these antinutrients unless cooked.

      Soy protein isolate is not the whole soy bean, but an extract of soy. It is 100% pure protein lacking all the fiber and phytonutrients found in the original plant. It is highly processed and not really considered a “food”. Soy Protein isolate is established as harmful since is does indeed raise insulin like growth factor quite significantly which accelerates aging and promotes tumor growth. But again, this is when we eat soy protein isolates, not the whole food itself.

      He continues to cite soy protein isolate as the main cause of harm in promoting cancer growth, which everyone is in agreement with. Perhaps some of his audience is confusing the extract with the whole food. This would be like confusing beta carotene with sweet potatoes. There is a lot of human evidence showing that soy prolongs life once one is diagnosed with breast cancer. (cite sources from the video)
      http://nutritionfacts.org/video/breast-cancer-survival-and-soy/

       In laboratory studies, isoflavone from soy can
      inhibit the growth of breast cancer and prostate cancer tissues. http://www.ncbi.nlm.nih.gov/pubmed/1314077 Population studies suggest soy protects against thyroid
      cancer.
      http://www.ncbi.nlm.nih.gov/pubmed/11815400
      Soy isoflavones enhances the immune response and provides a possible
      explanation for lower incidence of certain cancers in soy-eating parts
      of the world.
      http://www.ncbi.nlm.nih.gov/pubmed/12224602
      these are human studies I am presenting, not animal studies that Dr. Mercola persistently puts forward.

      Dr. Mercola goes on to point a finger at the phytoestrogens and cites studies from animals such as birds, pigs rats but not humans. Here is a human study showing the soy phytoestrogens have no negative hormonal effect on humans
      http://www.ncbi.nlm.nih.gov/pubmed/20378106

      His next assumptions on “birth control pills” are based purely upon the premise that soy foods alter hormones negatively in humans which is false.He then confuses animal estrogen studies with phytoestrogens showing a very skewed point of view. He is actually blaming the soy phytoestrogens from soybeans in america for early puberty in girls when it is in fact the xenoestrogens from the much more widely consumed dairy milk that is causing early puberty.
      http://nutritionfacts.org/video/dairy-sexual-precocity/

      Dr. Mercola goes on to cite decreased brain function from middle aged people consuming soy and this could be a precursor to Alzheimer. Alzheimer’s disease and other forms of dementia are actually less common in Asian
      compared to Western populations. Recent studies have
      actually shown improvement in brain functions with the use of soy
      supplements.
      http://www.ncbi.nlm.nih.gov/pubmed/9748017
      http://www.ncbi.nlm.nih.gov/pubmed/12792289
      http://www.ncbi.nlm.nih.gov/pubmed/15772567

      The entirety of Dr. Mercolas argument relies on animal studies, false pretenses and skewed data. He also completely ignores the data showing very healthful outcomes when consuming soy just as I thought he would. I hope my rebuttal to Dr. Mercola’s paper helped you.

      • Jola

        Thank you, Toxins! This is such a great reply, and exactly what I was looking for. In fact, more than I expected as a response! I really appreciate the time you took to respond to me in such great and researched detail!  I will be using the points you shared with me to continue the debate with my friend.

        I was weary of Dr. Mercola from the moment that I started reading the  link my friend sent me, and especially after looking him up on the internet.  He does not seem like a credible medical/nutrition authority. Likewise, the resources he shares seemed highly suspect to me as well.  Of course, your breakdown of the evidence made this all the more clear to me.

        Thank you for clearing up the confusion for me and for fueling me with a great, informed, and up-to-date comeback!

        Best wishes,
        Jola

        P.S. I will definitely look into reading Dr. Greger’s ebook to learn more about the Paleo diet. 

        • Jola

          Do you know whether scientific evidence indicates that when consuming soy, that it should be well fermented such as sprouted soy products, miso, tempeh, tamari? I’ve heard that such soy products are more conducive to healthy digestion than regular tofu, soy isolates (well we know about the soy isolates), soy-milk and soy flour. And, what about the GMO issue?

          • Toxins

            I do not know of any evidence regarding this, I would say consume soy in whichever way entices you to eat it as long as it remains low in sodium (avoiding soy sauce) and its as unrefined as possible.

            As for GMO, there is a lot of mixed opinions on this with little scientific backing, so I do not know. What is clear though
            is that these chronic illnesses are not caused by consuming gmo soy.. What
            we do know about non organic foods is that the pesticides may be of the
            greatest concern.  If one is truly concerned then by all means try and consume organic soy.

          • Jola

            Toxins, I do not know who you are, but you are the best!  Thanks for sharing your insight on all these plant-based nutrition topics.  Are you a nutritionist? dietitian? scientist? How is it you know so much about all these topics. You Rock! 

          • Toxins

             You are very welcome!

          • 094870

            You can read it for yourself if you realy care to. Check out different sites and make your own choices.

          • 094870

            Any time you take anything and heat it to a certin temperature for a certain about of time you change the molecular structure of it , some times it’s good and sometimes it bad in thihs issue it is bad. Think back when you were in hig school and in chemistry class, did you learn about this there ?

        • 094870

          Also you can look-up SOY ALERT by Westin A. Price Foundation and they will tell you the same thing I’ve been telling people for years.

      • WholeFoodChomper

        I finally had the chance to read Dr. G’s ebook:
        http://www.atkinsexposed.org/.  It was very good, but mostly Atkin’s diet specific.  At this point, although it states many truths, it is still a bit dated (written 8 years ago).  

        I was wondering if Dr. G had an up-dated/revised version of the book, especially since the low carb trend seems to be dramatically increasing these days (in the guise of primal/paleo/caveman/etc. diets), rather than fading, as he suggested in the last pages of his book in 2004.

    • 094870

      Stop all those GMO foods as well. Thats what mis.obama is trying to push on our kids today(GMOs)

  • Shiri

    Hi, I read this thread and am still confused about Soy. When I look into the milk alternatives’ ingredients/process, (almond/soy/rice etc), they do not look too healthy.

    Is it possible to clearly publish which milk/meat alternatives are healthy (maybe they were published but I missed it)?
    For example are Edamame beans OK for kids & adults? How many times a week? Other products?

    Please check the following scientific american link for more concerns:
    http://www.scientificamerican.com/article.cfm?id=soybean-fertility-hormone-isoflavones-geniste

    • http://jolkapolkaskitchen.blogspot.com/ WholeFoodChomper

      Hi Shiri, Have you had a chance to watch/read all that Dr. G has to share about soy here? The answers you are seeking should be there.

    • http://www.DonForresterMD.com/ Don Forrester MD

      Guest (??) answered your question about soy whose amino acid profile seems to be more similar to meat than other plant protein sources. As guest points out probably better to limit soy to below 5 servings per day. Children and my grand children love edamame beans as they have higher sugar content than soy beans. However we don’t need to go out of our way to consume alot of protein. Given adequate calories it is impossible not to get enough protein or essential amino acids. You might be interested in three articles written by Dr. John McDougall on proteins. You can find them in his newsletters available free on his website. The month/year and titles are Dec 2003(History of Protein), April 2007(Sources of Protein) and Jan 2001(Protein Overload). Based on current science there are no safe dairy or meat alternatives. Milk alternatives as you point out are processed and have added ingredients. My only other recommendation is to avoid GMO foods. My patients following a plant based diet need to be particularly careful with corn and soy and buy organic. For more information on GMO foods see the Institute for Responsible Technology’s website. Keep tuned to NutritionFacts.org as the science keeps changing.

    • 094870

      Stay away from ALL soy proucts. They are in ALL processed food you buy in the stores today. Read the ingrents on the packages and learn whats in the food you buy. Soy letchen is not a complete protein.

      • Thea

        094870: As this video (backed up by valid studies) and others on this site show, traditional soy products are very healthy. Yes, it is probably best to stay away from processed soy, such as isolated soy proteins. But 2-3 servings a day of traditional soy products, like tofu and soy milk and tempeh etc are quite healthy–according to the vast majority of studies on the subject. I invite you to explore the information on NutritionFacts.org.

        http://nutritionfacts.org/index.php?s=soy

  • Nunya Biznez

    LOVE that there are sane reports on soy! Thank you!

  • Marcello

    My italian great grand mother had her first period at 18 (when she got married!) and lived to 100.