Despite the fact that girls don’t mature mentally any earlier, they are reaching puberty at ever younger ages. An article in The Sunday Times last week announced that girls now begin puberty at age 9. The article cites a Danish study, which looked at a sample of 1000 girls, and showed that breast development started on average at age 9 years and 10 months, a full year earlier than it did in a similar group studied 15 years earlier.
Entering puberty is cause for celebration and a good sign of reproductive and overall health. Yet the novelty of getting your periods wears off all too soon and many a girl/woman/mom has wondered what possible advantage is menstruating from such early an age, when none of us wish parenthood on teens.
Is early puberty a new phenomenon and yet another sign of our unhealthy lifestyle?
There’s been a dramatic fall in the age girls start puberty (the first sign of which is usually breast development, or in medical terms: thelarche) and start getting their periods (the medical term for which is menarche) in the 20th century. The age at which girls started getting their periods has been dropping by a few months every decade, and western European girls, who started menstruating on average at the age of 16-17 in the 1840’s are now getting their periods at around age 12-13. But as a matter of fact this trend has been leveling-off in the past 30 years.
So no, this is nothing new, and if anything the rate of advancing puberty has slowed down, at least in the US.
What affects earlier puberty
The most significant factor affecting the age of puberty onset is nutrition. The single best predictor of the onset of a girl’s first period is her weight and there’s plenty of evidence suggesting that the nutritional state of a population accounts for most of the variation in the timing of puberty. It’s well established that obesity and extra calories initiate puberty sooner, while severe caloric restriction (as seen in girls with Anorexia Nervosa or in ballet dancers) delays puberty.
But it’s not just the calories: Certain foods and nutrients seem to affect puberty onset more than others. A new study in Public Health Nutrition followed more than 3000 British girls’ diets at age 3, 7 and 10 years of age, and correlated diets to age of onset of the girls’ first period.
They found that higher intake of meat and animal protein at age 3 and 7 correlated strongly with earlier periods (high meat intake at age 3 was defined as 8 portions a week or more, and 12 portions of meat a week or more at age 7). This finding was independent of the girls’ body weight, and the age at which their mothers menstruated. As expected, they also found that higher caloric intake overall correlated with early periods.
Discussing their findings, the authors, led by Imogen Rogers, suggest that diet in early and mid-childhood may affect the onset of puberty much more than the diet in later childhood, and conclude that higher intakes of meat and protein in childhood may promote earlier periods.
The onset of puberty is influenced by genetics, and there’s some correlation between a mother and her daughter’s age at puberty.
There’s a reasonable concern that chemical contaminants and hormonal residues in the food chain and in our drinking water may affect puberty in humans. The Times’ article also suggests BPA is a suspect worth investigating. The mechanism seems plausible—hormonal residues and hormone-like chemicals can potentially affect the complex and finely tuned system that initiates puberty, and there are some animal experiments that support this notion.
It’s going to be quite difficult to prove or disprove that these contaminants are implicated in human puberty, but as always, prudency suggests that it’s not a very good idea to be exposed to or ingest contaminants with potential hormonal activity—that stuff definitely isn’t food.
Is early puberty a health issue?
Earlier periods are associated with an increased risk of breast cancer. Less established is the correlation between early periods and ovarian cancer and heart disease. On the other hand, early periods may protect against osteoporosis.
No less important are the social issues related to early puberty: It’s never easy to be a teenager; being different and precocious at that tender age is even harder. And I must say, earlier puberty makes a severe mismatch worse. The human reproductive system seems to kick-in once it figures out there are enough nutrients stored to support a pregnancy—too bad it has no gauge for mental maturity, as, at least in general, girls’ judgment, mental development and independence seem too ripen a full decade after their bodies do.
Can we influence the age of puberty? The most modifiable and proven factor affecting puberty onset is weight. Preventing obesity and eating a balanced, plant-rich diet is a good recipe for overall health anyway—if it also prevents early puberty that would perhaps be an extra bonus.
Reposted as part of Food Renegate's Fight Back Fridays--go join the food fight!