Disease Proof

Girls are reaching puberty earlier than ever

Today in the U.S., about 16% of girls enter puberty by the age of 7, and about 30% by the age of 8 – A recent study determined that the number of girls entering puberty (defined by breast development) at these early ages has increased markedly between 1997 and 2010.1 

Girl looking at ocean. Flicrk: sskennel

Trends in Age at Menarche

The average age at menarche in Western countries began declining during the early part of the 20th century due to increased consumption of animal products and  increasing calorie intake; the decline slowed in the 1960s, and now in the U.S. there has been a more recent surge in early puberty starting in the mid-1990s.2 In Europe, in 1830, the average age at menarche was 17.  Similarly in the 1980s in rural China, the average age at menarche was 17.3 In the U.S. in 1900, the average was 14.2.  By the 1920s, average age at menarche in the U.S. had fallen to 13.3  and by 2002, it had reached 12.34.Similar trends are occurring in other Western nations.5,6 For example, age at menarche in Ireland has declined from 13.52 in 1986 to 12.53 in 2006.7 In Italy, a recent study showed that girls’ age at menarche was on average 3 months earlier than their mothers’.8  

Taking all this data together, we can estimate that the normal, healthy age at menarche under conditions of excellent nutrition without caloric excess, would probably fall somewhere between 15 and 18.  But today in the U.S., about half of girls begin developing breasts before age 10, and the average age at menarche is less than 12 ½ and still declining. 

Why is this happening? 

The neurological and hormonal systems that regulate pubertal timing are complex, but research has identified a number of environmental factors that may be contributing to the decline in age at puberty:

Increasing rates of childhood overweight and obesity

Several studies have found associations between higher childhood BMI and earlier puberty in girls.4, 9-11

Excess body fat alters the levels of the hormones insulin, leptin, and estrogen, and these factors are believed to be responsible for the acceleration of pubertal timing by obesity.  Also, physical inactivity may decrease melatonin levels, which can also affect signals in the brain that trigger pubertal development.4, 12 

Increased animal protein intake

Higher total protein, animal protein, and meat intake in children age 3-7 have been associated with earlier menarche in multiple studies.13-15  In contrast, higher vegetable protein intake at age 5-6 is associated with later menarche.15  High protein intake elevates IGF-1 levels and promotes growth, which could accelerate the onset of puberty – IGF-1 contributes to pubertal development on its own and in part by its involvement in estradiol signaling.4,16  Meat and dairy consumption in children may also reflect ingestion of environmental endocrine-disrupting chemicals (EDCs) that have accumulated in animal tissues (see EDCs below).

Other dietary factors: 

High dairy consumption is associated with earlier than average menarche.17  Soft drink consumption is associated with early menarche.18

Children with lower nutrient diets (based on analysis of macronutrients, vitamins, minerals, and certain whole foods) tend to enter puberty earlier.19  Overall our modern diet rich in processed foods, dairy, processed meats and fast food is disruptive to normal development and aging.  Early puberty is an early sign of premature aging.  

Exposure to endocrine-disrupting chemicals (EDCs)

EDCs are hormonally active synthetic chemicals that either mimic, inhibit, or alter the action of natural hormones.  These chemicals are ubiquitous in our environment, and are considered by scientists to be a significant public health concern. Although EDCs are thought to pose a threat to adults as well, children’s bodies are more sensitive to exposure to exogenous hormones.20 Chemicals are not currently tested for their endocrine disruption potential before they are approved for use and enter our environment, and there are endocrine disruptors in a vast array of products we come into contact with every day, including organochlorine pesticides, plastics, fuels, and other industrial chemicals.21 

The substances of most concern currently are BPA and phthalates. BPA is one of the highest volume chemicals produced in the world.  It is used in the manufacture of polycarbonate plastics, such as rigid cups, water bottles and food storage containers; BPA is also found in the linings of food cans and dental sealants.  BPA can leach from containers into food and beverages, especially during heating and washing.4  BPA exposure is associated with early puberty in girls.22

Phthalates are chemicals used to make PVC plastics more flexible, and are found in a variety of products including toys, food packaging, hoses, raincoats, shower curtains, vinyl flooring, wall coverings, lubricants, adhesives, detergents, nail polish, hair spray, and shampoo. Phthalates are associated with early breast development in girls.22,23 They are considered chemicals of concern to the EPA and may be phased out – some phthalates have already been removed from children’s toys and cosmetics.24

Additional EDCs that have been associated with dysregulation of pubertal timing include industrial chemicals such as PCBs, pesticides such as DDT and endosulfan, the flame retardant PBB, and dioxins and furans, which are formed during incineration of waste, chlorine bleaching of paper, and chemical manufacturing. 22,23,25,26

It is important to note that EDCs break down very slowly and accumulate in the fatty tissues of animals, so animal foods contain higher levels of these chemicals than plant foods.

 

Why is this troublesome?  

The most significant and alarming consequence of early maturation is an increased risk for breast cancer in adulthood.  Early menarche is an established risk factor for breast cancer, and this is believed to be due to the extended lifetime exposure to ovarian hormones.10,27,28  Similarly, exposure to EDCs during childhood is associated with hormonal cancers, such as breast and testicular cancers.29-31

Seven, eight and nine year old girls are not emotionally or psychologically equipped to handle puberty.  As such, earlier puberty is also associated with a higher risk of psychological problems during adolescence such as anxiety, depression, and eating disorders.  Girls who mature earlier are also more likely to take part in risky behaviors like smoking and alcohol use.4,12 

What can parents do to protect their children?

  • Children’s diets should focus on whole plant foods rather than animal foods – this will keep protein intake in a safe range and reduce their consumption of EDCs.  

  • Minimize dairy products in children’s diets – use almond and hemp milks instead of cows’ milk
  • Encourage children to exercise and exercise with them.
  • Minimize processed foods – these are calorie-dense and nutrient-poor, and they promote obesity and other diseases.
  • Children’s diets should include a wide variety of natural plant foods as possible including, green vegetables, squashes, corn, carrots, tomatoes, onions, mushrooms, nuts, seeds, avocados, beans, fruits and whole grains.  This means that healthy eating is a lifetime event.  
  • Buy organic produce when possible to avoid synthetic pesticides.
  • Minimize children’s exposure to BPA: 
    • Avoid using of rigid polycarbonate plastics (recycling label #7) whenever possible. 
    • Do not use plastic water bottles if they are old or scratched. 
    • Do not microwave in plastic containers.
    • Minimize the use of canned foods and avoid canned infant formulas.32
  • Minimize children’s exposure to phthalates
    • Avoid plastics marked with recycling label #3 (PVC) whenever possible.
    • Check ingredient lists on personal care products for phthalates. Also be aware that “fragrance” listed as an ingredient often means that the products contains phthalates. For more information, visit the Environmental Working Group’s guide to children’s personal care products.

 

To conclude, the earlier occurence of puberty is an ominous event that we can stop.  We can even win the war on breast cancer in America and prevent millions of young females from developing it.   The answer however, must begin in the way we feed ourselves and our children.  The most effective type of health care is vigilant and excellent self care.  

 

References:

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

2. Biro FM, Khoury P, Morrison JA: Influence of obesity on timing of puberty. Int J Androl 2006;29:272-277; discussion 286-290.

3. Gates JR, Parpia B, Campbell TC, et al: Association of dietary factors and selected plasma variables with sex hormone-binding globulin in rural Chinese women. Am J Clin Nutr 1996;63:22-31.

4. Steingraber S: Tha Falling Age of Puberty in U.S. Girls: What We Know, What We Need To Know. In Breast Cancer Fund; 2007.

5. McDowell MA, Brody DJ, Hughes JP: Has age at menarche changed? Results from the National Health and Nutrition Examination Survey (NHANES) 1999-2004. J Adolesc Health 2007;40:227-231.

6. Anderson SE, Must A: Interpreting the continued decline in the average age at menarche: results from two nationally representative surveys of U.S. girls studied 10 years apart. J Pediatr 2005;147:753-760.

7. O'Connell A, Gavin A, Kelly C, et al: The mean age at menarche of Irish girls in 2006. Ir Med J 2009;102:76-79.

8. Rigon F, Bianchin L, Bernasconi S, et al: Update on age at menarche in Italy: toward the leveling off of the secular trend. J Adolesc Health 2010;46:238-244.

9. Aksglaede L, Juul A, Olsen LW, et al: Age at puberty and the emerging obesity epidemic. PloS one 2009;4:e8450.

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

11. Kaplowitz PB: Link between body fat and the timing of puberty. Pediatrics 2008;121 Suppl 3:S208-217.

12. Burt Solorzano CM, McCartney CR: Obesity and the pubertal transition in girls and boys. Reproduction 2010;140:399-410.

13. Berkey CS, Gardner JD, Frazier AL, et al: Relation of childhood diet and body size to menarche and adolescent growth in girls. Am J Epidemiol 2000;152:446-452.

14. 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 2010:1-12.

15. Gunther AL, Karaolis-Danckert N, Kroke A, et al: Dietary protein intake throughout childhood is associated with the timing of puberty. J Nutr 2010;140:565-571.

16. Veldhuis JD, Roemmich JN, Richmond EJ, et al: Endocrine control of body composition in infancy, childhood, and puberty. Endocr Rev 2005;26:114-146.

17. Wiley AS: Milk intake and total dairy consumption: associations with early menarche in NHANES 1999-2004. PloS one 2011;6:e14685.

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

19. Cheng G, Gerlach S, Libuda L, et al: Diet quality in childhood is prospectively associated with the timing of puberty but not with body composition at puberty onset. J Nutr 2010;140:95-102.

20. Aksglaede L, Juul A, Leffers H, et al: The sensitivity of the child to sex steroids: possible impact of exogenous estrogens. Hum Reprod Update 2006;12:341-349.

21. Diamanti-Kandarakis E, Bourguignon JP, Giudice LC, et al: Endocrine-disrupting chemicals: an Endocrine Society scientific statement. Endocr Rev 2009;30:293-342.

22. Roy JR, Chakraborty S, Chakraborty TR: Estrogen-like endocrine disrupting chemicals affecting puberty in humans--a review. Med Sci Monit 2009;15:RA137-145.

23. Den Hond E, Schoeters G: Endocrine disrupters and human puberty. Int J Androl 2006;29:264-271; discussion 286-290.

24. Chemical Families: Phthalates. In Environmental Working Group.

25. Schell LM, Gallo MV: Relationships of putative endocrine disruptors to human sexual maturation and thyroid activity in youth. Physiol Behav 2010;99:246-253.

26. Massart F, Parrino R, Seppia P, et al: How do environmental estrogen disruptors induce precocious puberty? Minerva Pediatr 2006;58:247-254.

27. Leung AW, Mak J, Cheung PS, et al: Evidence for a programming effect of early menarche on the rise of breast cancer incidence in Hong Kong. Cancer Detect Prev 2008;32:156-161.

28. Pike MC, Pearce CL, Wu AH: Prevention of cancers of the breast, endometrium and ovary. Oncogene 2004;23:6379-6391.

29. Cohn BA, Cirillo PM, Christianson RE: Prenatal DDT exposure and testicular cancer: a nested case-control study. Arch Environ Occup Health 2010;65:127-134.

30. Cohn BA, Wolff MS, Cirillo PM, et al: DDT and breast cancer in young women: new data on the significance of age at exposure. Environ Health Perspect 2007;115:1406-1414.

31. Maffini MV, Rubin BS, Sonnenschein C, et al: Endocrine disruptors and reproductive health: the case of bisphenol-A. Mol Cell Endocrinol 2006;254-255:179-186.

32. Consumer tips to avoid BPA exposure. In Environmental Working Group.


 

 

 

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Comments (11) Read through and enter the discussion with the form at the end
Mark Osborne - May 4, 2011 12:15 PM

I have a four year old daughter and this is a subject that really concerns me. I want her to have the best chance at a healthy life.

dalene - May 4, 2011 12:25 PM

I am a mother of two seven-year old daughters, one of whom is showing signs of puberty. While her doctor is not concerned, I am. She eats a relatively healthy diet, with plenty of fresh vegetables and fruits, and very little meat. I was glad to see you include statistics about Chinese women. I would like to see statistics from all over the world, including Micronesia, Polynesia, and Africa. Too much statistical information is based on white European ancestry, which my daughter doesn't have.

Elisa Rodriguez - May 4, 2011 12:50 PM

Thank you for this incredibly informative article!

James Robert Deal - May 4, 2011 5:51 PM

There is another major factor in early puberty. Fluoride loves calcium. It goes to bones and to the pineal, which is rich in calcium, where it reduces melatonin production, which kicks in early sexual maturity.

M.K. - May 5, 2011 12:58 PM

I commend you heartily for so many well written and well researched articles. However, I have two criticisms.
One is that recommending so many greens and very restricted fats and proteins could be problematic for thin people, children and pregnant women, especially those who do not have your scope of knowledge, interest and experience.
Second is that your own Dr. Fuhrman canned soup is not BPA free the last time I checked.

Joel Fuhrman, M.D. - May 5, 2011 1:52 PM


Your criticism is not accurate. I only restrict seeds, nuts and avocado (healthy fats) to one to two ounces in overweight people, not thin people, and otherwise my recommendations of fats are commensurate with caloric and bodily need. So your comment just speaks to your lack of knowledge about my nutritional recommendations. Neither are my recommendations low in protein, my dietary recommendations are more than adequate in protein for all ages and groups and I generally comment on the inadequacies in fat and protein in some extremely low fat vegan diet advocates and give specific remedies to improve the nutritional quality of such diets. However, I accurately report on the dangers of excessive consumption of animal protein and the need to eat more plant sources of protein to reduce risk of both heart disease and cancer. If you are interested, you should read my newsletter on IGF-1, protein and cancer.

I have been working for a long time to solve the BPA issue and my canned soups are being replaced by BPA-free, boxed soups within a matter of weeks, and this has been in the works as quickly as we were able to accomplish it, as the BPA-free cans were not forthcoming as quickly as we had hoped or planned. My goal is to remove impediments to healthy eating.

Jacki - May 6, 2011 12:42 AM

Are there any studies on the age at menarche of American children raised vegan? I will be interested to see if my efforts will result in later puberty for my daughters relative to myself as well as to their peers.

Daniel - May 6, 2011 10:22 PM

I don't think there is any issue with too little fat or protein recommendations, but I think the food pyramid here is too low in complex carbs, especially for thin and athletic people. I love nuts, seeds, and avocados, but I certainly wouldn't want fat to be 40 or 50% of my caloric intake. I'm not sure why that category come first before whole grains and potatoes. I would say no to that.

Claudia - May 9, 2011 10:10 AM

Hi Daniel,

Actually, if you look at the graphic depiction of the food pyramid, you will see that whole grains and potatoes are located on the same level of the pyramid as nuts,seeds, and avocados. The recommendation is that we get 10-40% of our calories from nuts, seeds, and avocados, and 20% or less from whole grains and white potatoes. So, the maximum would from nuts, seeds, and avocados would be 40%, and this would not be exactly the same as getting 40% of your calories from fat since nuts and seeds are not 100% fat, but are probably more like 75% fat. At the base of the pyramid, is the Vegetable Group, which includes starchy vegetables. As a lean, athletic nutritarian, if you need more calorie-dense carbs to meet your higher caloric needs, the colorful starchy vegetables are preferred over whole grains and potatoes because they are more nutrient-dense. For those who need to lose weight, the starchy vegetables as well as the whole grains and potatoes are limited to 1 serving per day, with the starchy vegetables still being preferred over the potatoes and whole grains. The potatoes are particularly problematic for some people who are diabetic or need to lose weight due to a very high glycemic index. Most recently, after the nutritarian food pyramid was already published, Dr. Fuhrman has been talking about beans as being a preferred starch for people who are diabetic or need to lose weight because it contains resistant starch, and is effective for satiating hunger as well as for regulating blood sugar.

Daniel - May 10, 2011 9:04 PM

I'm confused about how you can actually get 30-60% of calories from non-starchy vegetables and greens. If for example someone needs 2500 calories each day, that would be about 800-1300 calories. How do you eat like that? That would be at least 5 pounds of vegetables each day. For those who need much less calories such as 1000-1500 per day, these percentages would be more realistic, but not for others. The higher one's calorie needs,especially for those very active, the more filling foods you need such as whole grains, potatoes, pasta, etc. That would at least be the healthiest way, rather than having a lot of junky carbohydrates and sugary foods. Therefore, recommending that "everyone" should have whole grains and potatoes as 20% or less of their caloric intake is not the best advice.

Annamaria - March 23, 2013 4:45 AM

Posts like this always make me wonder what about Dr Fuhrman's own daughter? Did she escape early puberty? After all, she was raised on this way of eating, so she's the perfect example.

This problem is fascinating to me, since I read an autobiography of a European woman around the early 1900s, who took it as normal and common that she and her peers didn't menstruate before 16, 17 or 18. It made me wonder, "What changed? And why?"

Could there be other environmental factors besides the most obvious link to our environment (that is, what we eat from our environment)?

And I'd really, REALLY like to hear from parents of girls who have been raised Nutritarian to find out how late their girls went into puberty. A study - or even anecdotal evidence - about the menarche of nutritarian-raised girls would be very enlightening here.

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