Why are Children Starting Puberty Earlier?

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Early onset of puberty is considered a risk factor for a number of diseases in adulthood, including hormone-related cancers, a shorter lifespan, metabolic syndrome, and cardiovascular disease.

The conventional thinking has been that the age of puberty has been getting earlier and earlier because our children have been getting fatter and fatter. However, European kids are also getting heavier, yet there has not been a steady decline in puberty onset (see graphs here). So it may be less about how much kids are eating and more about what they’re eating.

The most consistent link between diet and premature puberty has been found to be animal protein consumption. Every gram of daily animal protein intake—that’s just like the weight of a paperclip—has been associated with a 17% increase in the risk of girls starting their periods earlier than age 12.

Why this link between animal protein and premature puberty? We know meat increases the level of IGF-1 and that alone is associated with early onset puberty. If you’re not familiar with insulin-like growth factor 1, I have a series of videos about the growth hormone (though mostly in relation to cancer risk). See, for example, The Answer to the Pritikin Puzzle and Cancer-Proofing Mutation.

The early onset of puberty in girls associated with animal protein consumption may also be due to endocrine disrupting chemical pollutants in the meat supply. Watch my 4-min video Protein, Puberty, and Pollutants.

For more videos on premature puberty see:

I talk more about endocrine disrupting chemicals in particular in:

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2014 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, and From Table to Able.

Image credit: Nanagyei/Flickr

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  • Liviu Deacu

    It is said that besides the above mentioned consequences of early onset of puberty another big problem would be that maids won’t grow in length more than one more year after menarche. Afterwards they wouldn’t grow any more. If this happens when being for instance only 11 years old, it
    could lead to a pretty short body length. Is there any science behind this? I’d regard this point as very important as maids soon become women and if they will have health problems in the distant future it is bad indeed, but if they don’t even enjoy a happy life until they get sick it is even worse – their love life and happiness would be affected.

  • Padma Garvey

    At the time of the Revolutionary War, the average of menarche (when a girl gets her first period) was about 17. Around the 1900′s, in America, the average age was about 14 to 15. Currently it is about 11-14, but girls as young as 9 can get their periods now. Moreover, we are seeing signs of the start of puberty….hair under the arms, pubic hair, etc in girls as young as 6. It is due to the increased saturated fat in their diet. The more periods a girl has in her lifetime, the higher her risk of breast, uterine, and ovarian cancer. Plus, early menarche robs girls of their childhood.

    • beccadoggie10

      I am now 72, but my peers and I entered puberty at age 11. Today, many physicians are seeing signs of puberty in little girls age 3 and 4.

    • smallfootprintmama

      There is zero evidence to support this. In fact, there is no evidence to support that saturated fat is harmful at all. The biggest heart study in the world found saturated fat and cholesterol to be protective!

      There is however, substantial evidence that all the soy, growth hormones and xenoestrogens in everything all around us are huge factors in our health. I’d start there.

      • Marcella

        Actually, I agree with Padma, being another person that ACTUALLY WORKS with patients, I have helped deliver babies from 12 yr olds. We are seeing children as young as 8 yrs old in puberty. this was not common in the 70′s when I began practice. And BTW, There is no legitimate study I have ever seen that says saturated fat is protective, it is EB knowledge that saturated fat is very inflammatory and destructive to the inner lining of our arteries, that includes brain, heart, kidneys…

  • Wegan

    Wouldn’t all the hormones they feed cows have something to do with it?

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

      If you are consuming dairy products that have had added female and male hormones that would be a contributing factor. However, most of the female hormones in milk are there naturally due to the pregnancy. Most of today’s “improved” dairy cows are kept pregnant over 300 days of the year. So they are usually milked while pregnant. Pregnancy is a very high estrogenic state. Dr. Garvey would be more qualified as a gynecologist to comment further. Being nursed and pregnant at the same time is not a prescription for long and productive life. Most dairy cows are sent off to slaughter after only about 4 years. Of course they live longer then the male dairy cows who are diverted to veal production and live for about 6 months before slaughter.

    • beccadoggie10

      Not all cows receive rBGH,

  • beccadoggie10

    Remember, recombinant bovine growth hormone which was injecting into cows to force them to give more milk. This was implicated early on during the 1990′s. And came onto the market with Michael Taylor, now food czar for the U.S. FDA, but in the 1980′s, a lobbyist with Monsanto worked to get it widespread into dairy.

    This was the reason I began buying certified organic Organic Valley and Stonybrook Farms dairy milks and yogurt, and I was not alone.

    However, now with an injured spine, my calcium comes from beans, certain fruits, and mostly dark leafy greens. They don’t make my body hurt the way dairy did.

  • Real World Vegan

    the average menarche of the maasai is almost 14 years. considering their diets are almost entirely animal foods [high protein and high saturated fat] shouldnt their menache be somewhere around age…4?

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

      I couldn’t find any references on age of menarche for the Maasai but assuming 14 is accurate there are many reasons why it should be higher then folks on the standard american diet but not as high as those on a WFPD. The two that come to my mind are activity and calorie intake based on food availability. Photo’s of the Maasai show them to be very lean. Since fat cells produce estrogen women who have higher per cent of body fat will have higher estrogen levels. As Jeff Novick points out so well in his Calorie Density DVD you can eat higher calorie dense foods if your physical activity level is high enough. Like any complex system there are many factors contributing to the outcome.

      • Paleo Huntress

        The Massai consume about 3500 calories per day and though “active” in the sense that they walk a lot, they aren’t as active as American athletes. The Massai are lean while eating crazy levels of saturated fat.

  • smallfootprintmama

    This article sadly conflates modern, industrially produced, hormone-laden animal foods with ALL animal foods. It’s not like humans haven’t been eating meat, dairy, fish and eggs for, oh, thousands and thousands of years now. Mongolians, Maasai, and other heavy meat eaters don’t have early puberty, so this theory, without qualification, is bunk.

    And the author hasn’t even factored in the fact that almost everything processed contains some form of SOY now–a known source of phytoestrogens. Nor considered all the industrial chemicals used in the U.S. in everything from furniture to clothing that are known xenoestrogens! We can’t just lay it all on animal protein, it doesn’t make good sense or science.

    It is totally possible to get wholesome meat, dairy, fish and eggs that haven’t been tainted by industrial chemicals, hormones and soy additives. Just ask your local family farmer.

    • Toxins

      Ignoring the fact that you did not cite any evidence for your claims, the issues primarily discussed here do not have too much to do with contamination. The most convincing evidence to cut out animal products is ubiquitous among factory farmed meats and organic grass fed meats. That issue being endotoxemia and elevated IGF-1.
      http://nutritionfacts.org/topics/endotoxemia/
      http://nutritionfacts.org/topics/igf-1/

      In addition, human evidence shows that soy phytoestregons do not function like xenoestrogens and are beneficial to ones health and negligible in terms of negatively effecting hormonal balances. This remains true as long as one is below the 3-5 serving per day mark. After this point, one can expect raised IGF-1 levels which in turn may affect early onset of puberty in children and promote tumor growth. This is true due to its protein quality, not necessarily the phytoestrogens.
      http://nutritionfacts.org/video/dairy-sexual-precocity/

      http://nutritionfacts.org/videos/breast-cancer-survival-and-soy/

      In addition, poultry is a highly concentrated source of arachidonic acid which is highly inflammatory.
      http://nutritionfacts.org/video/inflammatory-remarks-about-arachidonic-acid/

    • Marcella

      Meat eating is only in recent human history, there are only scant findings before a few hundred years ago. Not too many humans can run down a deer or even a rabbit, the muscles in our legs are not designed to do such a thing, but our hands are perfectly designed to grab those apples off a tree, or our teeth to chew on a handful of grass seeds. Our intestines, gastric juices, pancreatic enzymes, and bacterial flora are perfect to digest fiber in plants and fruits, not decayed meat. Only a carnivore can eat an animal carcass that has sat in the sun for a week, guess what would happen to you!

  • invegat

    Another possibility is that the Europeans are getting a smaller dose of the super-estrogen steroid Bisphenol A (BPA).

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

      It certainly could be a contributory factor along with many others. Since it has been introduced into the food chain relatively recently compared to the declining rates of puberty it most likely isn’t a major one. That said I advise patients to avoid it applying the precautionary principle.

      • invegat

        I don’t know how widespread but BPA has been in use since the 1950s http://www.enhs.umn.edu/current/2008studentwebsites/pubh6101/bpa/history.html

        • Marcella

          I did not see this early puberty in vegan children, mostly overweight flesheating children. Everyone was exposed to BPA without realizing it back then, even the veggie kids. 30 yrs ago when I worked at a city hospital we were helping pregnant 12-13 yr olds deliver babies. In MHO, believing meat is ok to feed young girls is living in a fool’s paradise. Recently, I saw a little girl that was months from puberty at 8 years old, we see that more and more at 9 and up, but 8 really throws you. I hate to say this, but this information has been out for decades, meat eaters are fools

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

            I would add those who eat dairy and eggs to your list as well. I think they are only fools once they learn about the dangers and continue to consume them. Unfortunately many health care professionals are missing the opportunity to point out the way to eat as well as its importance.