Excess weight and animal protein contribute to early puberty

A study published in Pediatrics measured the proportion of girls who had entered puberty by ages 7 and 8, and saw striking increases compared to data collected in 1997, only 13 years ago. This study of U.S. girls found that by age 7, 10.4% of Caucasian girls (5% in 1997), 23.4% of African-American girls (15% in 1997), and 14.9% of Hispanic girls had already entered puberty. By age 8 the percentages were 18.3%, 42.9%, and 30.9%.1

This is distressing information, since early maturation is a well-established risk factor for breast cancer later in life.2 Cumulative exposure to ovarian hormones is a major determinant of breast cancer risk, and entering puberty early results in increased cumulative hormone exposure in young women.3

Age at menarche has been consistently decreasing over the past 100 years.4 In the medical literature, the probable causes of this continuing trend are clear – excess body fat and excess consumption of animal products are contributing factors to the declining age of puberty. 

Obesity is a factor that increases one’s exposure to estrogen, and multiple studies have found associations between excess weight during childhood and early menarche.5 Soft drink consumption, which is a contributor to the increasing rates of childhood obesity, is also associated with early menarche.2 A study supporting this evidence was also published online in Pediatrics, analyzing connections between early childhood weight and age at onset of puberty. These researchers found that increased weight and body mass index (BMI) even at the early ages of 0-20 months was associated with earlier puberty.6

Total animal protein and meat intake at ages 3 and 7 were positively associated with age at menarche in a British study. Girls with the highest meat intake at age 7 were 75% more likely to have begun menstruating by age 12 ½ than those in the lowest category of meat intake.7

Physicians and parents are concerned about the social implications of this trend toward earlier maturity - seven year old girls are most likely not emotionally equipped to handle the onset of puberty. Unfortunately, the consequences of this trend are not only emotional. Early in life, our bodies are much more susceptible to carcinogenic influences – childhood diets are the major cause of adult cancers.  It is becoming increasingly clear that the Western diet of meat, cheese, and processed food is harming our children, but many parents unknowingly continue to feed their children these disease-promoting foods. As parents, we must be proactive – we want the best for our children, and as such we must feed them the best possible foods. We can help to slow our children’s development by feeding them a diet based on natural plant foods, which will groom their taste buds to prefer healthy foods at a young age and provide them with significant protection against cancers and other chronic diseases as they grow into adulthood.




1. Biro FM, Galvez MP, Greenspan LC, et al. Pubertal Assessment Method and Baseline Characteristics in a Mixed Longitudinal Study of Girls. Pediatrics. Published online August 9, 2010

Puberty coming earlier for U.S. girls: study. Yahoo! Health. August 9, 2010

2. Vandeloo MJ, Bruckers LM, Janssens JP. Effects of lifestyle on the onset of puberty as determinant for breast cancer. Eur J Cancer Prev. 2007 Feb;16(1):17-25.

Leung AW et al. Evidence for a programming effect of early menarche on the rise of breast cancer incidence in Hong Kong. Cancer Detect Prev. 2008;32(2):156-61.

3. Pike MC, Pearce CL, Wu AH. Prevention of cancers of the breast, endometrium and ovary. Oncogene. 2004 Aug 23;23(38):6379-91.

Bernstein L. Epidemiology of endocrine-related risk factors for breast cancer. J Mammary Gland Biol Neoplasia. 2002 Jan;7(1):3-15.

Key T, Appleby P, Barnes I, et al. Endogenous sex hormones and breast cancer in postmenopausal women: reanalysis of nine prospective studies. J Natl Cancer Inst. 2002;94:606–16.

Eliassen AH, Missmer SA, Tworoger SS, et al. Endogenous steroid hormone concentrations and risk of breast cancer among premenopausal women. J Natl Cancer Inst. 2006;98:1406–15.

4. Tanner JM. Trend toward earlier menarche in London, Oslo, Copenhagen, the Netherlands and Hungary. Nature 1973;243:75-76.

5. Mounir GM, El-Sayed NA, Mahdy NH, Khamis SE. Nutritional factors affecting the menarcheal state of adolescent school girls in Alexandria. J Egypt Public Health Assoc. 2007;82(3-4):239-60.

Britton JA, Wolff MS, Lapinski R, Forman J, Hochman S, Kabat GC, Godbold J, Larson S, Berkowitz GS. Characteristics of pubertal development in a multi-ethnic population of nine-year-old girls. Ann Epidemiol. 2004 Mar;14(3):179-87.

6. Maisonet M, Christensen KY, Rubin C, et al. Role of Prenatal Characteristics and Early Growth on Pubertal Attainment of British Girls. Pediatrics. Published online August 9, 2010

7. Rogers IS, Northstone K, Dunger DB, et al. Diet throughout childhood and age at menarche in a contemporary cohort of British girls. Public Health Nutr. 2010 Jun 8:1-12.

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Comments (19) Read through and enter the discussion with the form at the end
Christy - August 11, 2010 10:25 AM

How does this correlate to our sons?

ESTHER HOPPER - August 11, 2010 10:31 AM

Is this study based on regular, commercial meat or does it include hormone free, antibiotic free, grass fed or naturally fed animals? I personally do not eat meat, but if I passed this info along to my friends that eat pretty healthy, it would be the question they would ask.

Matt Stone - August 11, 2010 11:18 AM

It's been shown that meat is by far the lesser player in this scenario, and maybe just a result of the ravenous hunger and overeating induced by excessive consumption of sugar and other unnaturally-cracklike foods (aspartame, saccharine, sucralose, MSG, white bread, etc).

In fact, among Eskimos an increase in sugar and a big decrease in meat intake decreased the age of first menarche and caused a big increase in height, weight, etc. which is correlated to a lot more bad news than just breast cancer - but "Western Disease" in general. Staffan Lindeberg's Food and Western Disease, 2010, was a good comprehensive analysis of this and other phenomena...


Deana Ferreri, Ph.D. - August 11, 2010 11:44 AM

The researchers did not differentiate between "commercial" and "grass-fed" meat. But keep in mind that age of menarche has been declining since before 1900, and hormones and antibiotics are fairly new additions to animal agriculture.

There is similar evidence for boys - early puberty correlates with prostate and testicular cancers. Similarly for boys, total and animal protein are associated with earlier puberty onset(vegetable protein is associated with later puberty onset).
Ref: G√ľnther AL, et al. Dietary protein intake throughout childhood is associated with the timing of puberty. J Nutr.
2010 Mar;140(3):565-71.

Edanator - August 11, 2010 12:05 PM

What about cow's milk? Is there a relation between early maturation and milk consumption?

Deana Ferreri, Ph.D. - August 11, 2010 2:16 PM

I agree that sugar and other refined carbohydrates are playing a role here. As mentioned in Dr. Fuhrman's post above, soft drinks have been linked to earlier puberty as well. The study you mentioned on your site was done in the 1960s, and meat consumption has increased considerably since then - from 169 to 222 pounds/person/year, and the newer research shows that this excess meat intake is contributing to the problem.

The studies that I have seen have looked at "animal protein" as a whole, which would include both meat and dairy. Dairy is known to increase IGF-1 levels, which are associated with cancers, and several links have been found between dairy and hormonal cancers in the literature. Cows' milk consumption during childhood is also associated with adult cancer.

Daniel - August 11, 2010 5:37 PM

That doesn't mean you need to eliminate animal protein from your diet and be a complete vegan. I think there is only merit in not eating bad animal protein sources like hamburgers, cheese, butter, pork, high fat meat and dairy and all the other junk. I would actually argue that you SHOULD have some animal protein at least one or two meals a week if not a little more. Some white meat and fish have less saturated fat per serving than nuts and seeds. I run a lot and I have healthy animal protein sources at most 5 or 6 meals a week if not less often, and I still have plenty of legumes, nuts and seeds. I don't think thats too much. I probably have less than most other runners and even non-runners . My main question to vegans is, what would you do if there were no vitamin b-12 supplements? I can be vegan 3 or 4 days a week, but more than that just doesn't work for me and I would say it's not even beneficial.

mrfreddy - August 12, 2010 9:13 AM

1) Observational study, no conclusions can be drawn.

You'd have to have a serious confirmation bias to believe otherwise.

2) Association is not causation. Association is not causation. Association is not causation. Association is not causation. Association is not causation.

This kind of study can only suggest causative links, further research is required before you could make the claim your headline makes.

You'd have to have a serious confirmation bias to believe otherwise.

3) Animal products have been consumed throughout our evolution. Over millions of years. Early puberty is a new phenomonon. Maybe it's something else?

You'd have to have a serious confirmation bias to believe otherwise.

themoo - August 12, 2010 10:27 AM

B12 is very available and has been for years and years. No need to answer the question about no B12. There is also no reason to eat animal products(meat and Diary)....too expensive,fattening and disease promoting....not to mention the negative affects on our environment that animal production causes!

Deana Ferreri, Ph.D. - August 12, 2010 4:25 PM

If we lived before there were B12 supplements, we would have been eating our produce directly (or at least more directly than now) out of the ground, and we would get the B12 from the soil microorganisms. We only have to take B12 as a supplement because we have become disconnected from nature.

No, association does not prove causation, but in my opinion there have been several studies making similar associations, which strengthens the evidence. And of course, it's close to impossible to prove causation in humans since we are free-living. Also, yes, animal products have been consumed throughout our evolution, but there has been a sharp increase in the past 50-100 years. (See the link in my previous comment) It is certainly reasonable that this change may be affecting our health.

mrfreddy - August 12, 2010 5:09 PM


I think you have to also consider some other possibilities:

* rise in sugar consumption over the past 50 - 100 years. I dont have the numbers but I know it's astronomical.
* most people who eat a lot of meat also eat a lot of bread, starch, sugar, etc. This renders "several studies" equally wrong if they attempt to pin the blame on meat.
* sugar and starches were not a part of our diet in any significant way until 10k years ago.

I'm just sayin, in light of all this, maybe animal protein is not the problem....

Lilly - August 12, 2010 5:43 PM

As a primary teacher, I've witnessed a marked increase in early puberty over the years. It is not uncommon to have first graders, even a kindergartner, developing breasts, body odor and underarm hair. More and more little girls are beginning their periods at 9 and 10. It's a difficult topic to bring up with parents.

daniel - August 12, 2010 7:49 PM

There's a difference between eating excessive animal protein and too much saturated fat versus eating healthier sources and not having too much.The latter is not disease promoting. If someone wants to be completely vegan, that's fine, but it's not true to say that it's healthier.

StephenMarkTurner - August 13, 2010 6:51 AM

Daniel - even the strictest diet phase in Dr Fuhrmans "Eat For Health" allows for a couple of portions of animal foods a week. It is NOT 100% vegan (but it IS mostly unprocessed plants).

Regards, Steve

Amanda - August 13, 2010 8:29 AM

Brendan Brazier (vegan triathlete) is a great source. He gives three great sources for B12. I can only remember 2 at the moment - nutritional yeast (nutty, cheezy flavor and contains protein as well) and chorella. He would also agree iwht Dr Ferreri's comment on the topic. Hope this helps.

Matt Stone - August 13, 2010 8:50 AM


High meat-eating cultures are not huge people with early puberty and high rates of breast cancer and other issues in this post. Examples would be the Mongolians or the Eskimo, both who are decimated with metabolic disease, of which early puberty is but one facet, since having their traditional foods displaced with "Western" fare, which often includes an even smaller intake of animal products than they are accustomed to. But this has been a repeated theme everywhere it has been studied - whether the diet was high or low in animal products prior to the introduction of refined foods.

Consumption of total calories has increased by similar proportions during that same time frame. My argument was that consumption of meat has increased because appetite has increased, and appetite has increased due to other factors. On a diet of lean meat and fibrous whole plant foods including grains and tubers, calorie intake spontaneously decreases in laboratory study, along with insulin and other growth factors that are the drivers of everything from early maturation to nearsightedness to type 2 diabetes and obesity.

I agree that excessive meat intake is more of a health liability than an asset, but in an honest investigation of the world's most major health crises, focusing so heavily on meat intake is like blowing out a candle when your drapes are on fire.

Deana Ferreri, Ph.D. - August 13, 2010 9:21 AM


I agree with you. Sugars and other refined carbohydrates are probably contributors - Dr. Fuhrman mentioned in the post that soft drink consumption was associated with early puberty as well. I think the sharp increases in animal protein and refined carbohydrates have harmed our health, but as you said these things seem to go together and it can be difficult for researchers to control for that.

Joel Fuhrman, M.D. - August 18, 2010 5:08 PM

Although meat consumption and processed food consumption do tend to correlate, this is not simply an association with processed food - the study was designed to look specifically at animal protein intake, and control for other co-factors. I believe that processed foods are contributory, but at age 3 the amount of processed and fast foods is not the most significant contributor, however regardless of its significance the researchers controlled for that and found what they did. The study would not have made it through peer review and been published if the appropriate factors were not controlled for. Sometimes blog commenters assume researchers are ignorant of cofounding variables, when they are very careful to account for that.

DInah - August 29, 2010 8:19 AM

What if a child is in the early stages of puberty. Would eliminating/decreasing animal protein and sugar slow the rate of development?

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