Doctor's Note

For more videos on this topic, see:

If you’re not familiar with IGF-1, I have a series of videos about this growth hormone (though mostly in relation to cancer risk). See, for example, The Answer to the Pritikin Puzzle, and Cancer-Proofing Mutation. And, if you’ve never heard of metabolic syndrome, I talk about it in Metabolic Syndrome & Plant-Based Diets. Is it possible to overdo soy? Yes, but you’d have to work at it: How Much Soy Is Too Much?

I talk more about endocrine disrupters in:

For additional context, check out my associated blog posts: Why Are Children Starting Puberty Earlier? and Schoolchildren Should Drink More Water.

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  • albert

    I’m wondering if 0.90 and 0.91 are that different (although I totally believe in general message – another point from China Study which gets verified by another resource I trust). btw I noticed Caucasian teen guys who do wrestling get bald extremely early – so I was wondering if it is meat and/or excercise or probably both leading to excessive hormone production..

    • John B

      It might be the steroids young athletes are inclined to take theses days.

    • It could also be the supplements that many young athletes take: whey protein, creatine and I just saw that they have an IGF-1 in powder form.

  • Frank B

    What is the lesser evil GMO plant protein or chemical laden animal protein?

    • Brian C

      Both are avoidable, and the animal has probably been eating gmo all its life anyway.

    • Coacervate


    • b00mer

      1. Is this a genuine question or just a straw man? Why is non-GMO plant protein not an option?

      2. Let’s pretend it’s not an option: 80% of corn and 90% of soy in the U.S. is fed to animals, not people. A pound of meat requires sixteen pounds of grain to produce. Now which seems worse? Especially when you add in all of the other persistent fat soluble environmental toxins accumulated in the animals’ tissues?

      The answer is pretty clear.

      • Bucky

        The answer is clear. Buy meat that is fed what it’s supposed to eat: grass. The difference between a grass-fed cow and a grain-fed cow is night and day. Just like you can buy homegrown organic vegetables you can buy farm raised hormone free animal products.

        • Rob

          Grass fed, organically raised beef A. Isn’t an option for 98% of the world, due to the sheer resources it would require to raise it. B. doesnt change the fact that the animal is still subjected to toxins in the air and general environment that are unavoidable and get stored in the animal.
          So you subject yourself to the animals toxins and your own.

        • b00mer

          What are these magical hormone-free animals you speak of pray tell? What exactly do the use for cell-cell communication, soft whispers?

          Organic vegetables are not contaminant free. Nothing is. Your only choice is between more contaminated and less contaminated.

          A grass fed cow will consume even more food than a grain fed cow due to the lower caloric density. Their food may not be genetically modified, but they are still part of the food chain, their food still contains environmental pollutants, and they are still concentrating them in their tissues.

          How people can think that the nutritional profile of an animal completely changes with its diet is beyond me. If I eat mostly kale, or mostly corn, sure an analysis of my tissues may lead to some detectable differences, but it’s still going to be human flesh. I still produce hormones, I still have dioxin, pcbs, flame retardants in my tissues, I still have saturated fat in my tissues, arachidonic acid, etc.

    • Dave

      Frank, both are still evil! There are plenty of alternatively good options around for choices to keep you well!

  • Thea

    Learning about how much chemicals are circulating through our blood – so disheartening.

    It’s a shame we this info isn’t presented to all parents. It’s so vital.


    This may be a relatively crazy question, but could early-onset puberty have benefits in promoting earlier brain development? I’m thinking especially of prefontal cortex development, which could in theory reduce risky behaviors and therefore reduce overal (all-cause) mortality, despite increasing the risk of certain cancers, etc. I saw that one study says it is not. But this subject/phenomenon is, on the whole, poorly understood.

  • b00mer

    I’m so glad I found this way of eating before i have my own children (which will probably happen in the next few years or so). I’m sure there will be all sorts of comments from the in-laws, but thanks to Dr. Greger I’ll have a mountain of information to respond to them with. I’ll be darned if people want to shame me into intentionally poisoning my children with animal products just to make themselves feel more comfortable.

    • 0reg0n

      I am facing the same issue! My husband and I will probably start trying to get pregnant in a year or two and only one of the four future grandparents has agreed to feed them how I see fit. I foresee this being a big issue in my relationships with my family members.

  • Do vegan children grow to normal height? Can you do a video on that please?

    • Based on the science vegan children should grow taller. Going through puberty early does cause a growth spurt but also closes off the growth plates. Males who have lost their testicles never go through puberty and continue to grow into their twenties and end up taller. A proper vegan diet should result in delay in onset of puberty and later growth spurt and closing off of growth plates. You can eat an unhealthy vegan diet and end up as a Fat Vegan or a Sick Vegan(see Dr. McDougall newsletters on those subjects) December 2008 and October 2002 respectively.

  • Sarah Morris

    My four year old daughter has developed strong body odour, and has always been vegan. Do you have any advice on what I should try to eliminate from her diet? Chat rooms mostly talk of animal products, others sugar & I am thinking to start with removing processed soy products as a starting place eg tofutti cream cheese a d soy sausages! I would appreciate any diet related advice Thanks!

    • Elizabeth

      Hi Sarah: My daughter also has this trouble; she is now twelve. She has been vegetarian all her life. I worked with her on good hygiene (washing under her arms). I didn’t get her a deoderant product until she was 10; and I make sure it is “clean” — no aluminum or other things we can’t pronounce! I do believe there is a link with sugars in her diet (she has a sweet tooth and will sneak sweets, which I limit, but occasionally still have). She admits she used to sneak down and consume leftover frosting from the refrigerator when she was four! I know she “cheats” to this day. My nutritionist suggested her gut flora (or lack there-of) could be a factor. Find a good probiotic for kids and try to give it to her daily. I hope this helps!

    • deborahrabbit

      I have recently read (looked for link, but didn’t find it quickly), that wearing of certain fabrics, usually man made synthetic materials will cause this in some folks. I am vegan, & experimented with myself and my clothes, noting when I wore, what, when I noticed strong odors. I did notice a significant difference when wearing clothes made from nylon and other synthetics, nylon being the worst. Cotton, hemp, linen became sweaty but had had little odor. Seems weird.

  • HCP

    Dr. G

    Thank you for the work you do! I am still going back and forth on the topic of animal protein and I just wish you could help. I read both sides of the debate and I’m just left feeling annoyed. Do any of these studies that point towards a plant based diet compare those who DO eat meat BUT that meat is entirely grass fed, eaten in moderation, cooked in liquid and eaten along with copious amounts of plant foods AND whom also live generally healthy (no smoking, excess sugar, etc.)? I mean really, is ALL meat consumption bad?

  • julie blackwood

    Again Dr Greger is fascinating and enlightening. I am 53 and didn’t start periods until aged 17, I was mainly vegetarian back then, vegan now. Also , the so called ‘change of life’ in women , I believe can be transited in a more gentle way on a vegetarian or better still vegan diet. I had no problems. Thank you Dr Greger for all your work.

  • Frédéric C.B.

    The paper “Effects of lifestyle on the onset of puberty as determinant for breast cancer” is not included in the “Sources Cited” below the video. It can be found here:

    And strangely, I haven’t been able to find the parts that are cited in the video; for example: «children with the highest intakes of vegetable proteins or animal protein experience at least their growth-related puberty onset up to 7 months later […]»

    Where does it come from?

    Thank you.

  • Bob K

    In the early North American trials of water fluoridation Newburgh NY had its water fluoridated while Kingston NY was used as a control and the water did not have its water fluoridated. The trial was started in 1945 and terminated in 1950 and declared a success in reducing tooth cavities. In the mid 1950’s an MD, I don’t remember his name, reviewed the data. One of his many observations was that the girls in Newburgh started puberty 6 months earlier than the girls in Kingston. It should be noted that the water sources for the two cities was different at the time with differing mineral content also. This is described in Christopher Bryson’s book “The Fluoride Deception”.

    However in trials with monkeys and Mongolian gerbils a similar effect is
    observed. These trials were conducted with good protocol.

    Earlier, post 1950, a chinchilla rancher made the same observation in his chinchillas. He also believed that there was a transgenerational effect also.

    These studies give support to the idea that endocrine disrupters are a cause of the early onset of puberty.

    • Toxins
    • The cause of early puberty is probably multifactorial. The trend started before the introduction of the many artificial chemicals such as phthalates. Many of the persistent organic pollutants probably contribute to the problem. Fluoride is another issue that is complex. Interestingly as Dr. Greger pointed out in his video Avoiding Common Disorders dental caries appear to be a more recent problem for us.. courtesy of the food processing industry. From a complex systems perspective introducing one chemical to prevent one problem has the potential for unanticipated consequences which can be either good or bad. We will probably never know about these since we don’t invest the time or have the expertise to look for these effects. Our reductionistic approach to our health has led to many advances but we need to understand its limitations.

  • JackiMS

    Dear Dr. Greger, My family and I began eating a plant-based diet over 10 years ago. I allowed my children eggs and fish sticks for several years. About 4 years ago eggs and fish were eliminated from their diet after reading more about the effects of excessive animal protein. When we attend a social function they are allowed to choose their own food, but have to eat a salad or vegetable. More often than not they choose dairy and meat products. In other words, they don’t eat dairy and animal products often. My 8 year old daughter is beginning to show signs of puberty. I’m very concerned and unsure what to do. I’d like to hear your insight, advice, etc. Thank you.