Read more: http://www.foxnews.com/health/2012/10/05/hidden-hormones-can-bring-about-early-puberty-in-kids/
In the U.S., the number of
girls that reach puberty early is growing last 30 years. We have heard a lot of
people or the media talked about this phenomenon and worried about it. Of
course, I think early puberty is an issue and we should care about it. However,
when the media tell stories about some girls develop pubic hair or breast at 8
years old; and ask you to be careful with the food you eat. The audiences will
be very sensitive to what they have for dinner everyday. Some people (some are
my friends) and the media linked early puberty to many factors including
hormone in the foods like milk and meats. There is no a definite answer to the
question what on earth causes early puberty. I think that is the reason why
people come up with so many hypotheses, which were reported by the media and
spread all over. Therefore, back to the question “what causes early puberty?”
The
best explanation is fatness: when the body reach a threshold level of fatness,
it will tell the brain to transit more energy to reproductive development, thus
the puberty starts. It is not about the age so 12 years old does not define the
term “puberty”. Although there are many criteria to define puberty, the
requirement of GnRH (Gonadotropin-releasing hormone) amount is key to initiate
puberty. Therefore, the problem may shift to obesity, which is the main reason
causes early puberty. Other factors like environment cues may play a
role but definitely not hormones in the meats.
Then some people may ask “so what happen to the hormone from our milk and food? There is no effects of using synthetic hormone in animal feeds and eventually left in the foods?” It is true that a lot of dairy farms (30% of the nation) use synthetic version of hormone to increase milk production, to improve growth rate and to keep animal healthy. However, FDA has concluded that milk produced by treated cows is as same as untreated cows. Protein hormones in both plant and animal foods are digested and broken down into amino acids and peptides in the stomach and then absorbed by the intestine. You may argue that steroid hormones, like estradiol, which are not completely digested by the body, can accelerate initiate puberty or breast development. Yes, meat and milk have this type of hormone but at very low level compared with the amount of our body produces everyday. A glass of whole milk contains 3ng of estradiol and a serving of beef from a treated steer has 1.2ng of estradiol, but a prepubertal girl produces 54,000ng of estradiol everyday, and an adult woman produce 630,000ng per day (Ann Macrina 2012). Imagine how much of milk and meat a girl should take to elevate her estradiol level to an adult woman level.
Even
though I still find some news claiming hormones in the food can bring early
puberty in kids, in fact, I am glad I can find a lot of information and
resources online defending some miscommunication by the media about early
puberty. We are trying to correct that misunderstanding but it will be
difficult; because if you can not prove that 3ng of estradiol in the milk would
not impact the body, people will keep cautious and suspicious. I think this is
the destructive power of miscommunication in science.
-Harry Zhao Yuanfeng
This topic seems to be a common misconception among consumers and has fueled some of the organic food diets we now have. I remember being in middle school and having a friend tell me too much milk was bad because “girls would become women too fast”. That seemed silly to me because I grew up with the FDA encouraging three servings of dairy a day which I strongly followed in the hopes that I would become taller as I grew older. Sadly, for me I did not grow much taller than predicted. And oddly, enough I developed at a seemingly normal rate due to my petite body type. So this misconception of hormones causing early puberty seems to be completely irrelevant to how my personal development went. As for many Americans however, they are not petite but overweight. Which as you pointed out is more likely the cause of early puberty. So as usual instead of changing our American lifestyle to address early puberty we blame the insignificant contribution of hormones into our diet from dairy and meat products. This way of thinking seems completely illogical to me but to someone who is uninformed of the actual amount of hormones we eat verses the amount we produce it may seem legitimate.
ReplyDeleteIt is funny to me the different types of things that the media emphasizes on. Especially when they take a truth (like estradiol and puberty) and completely exaggerate them just to get a rise out of people. People in general don't like to blame themselves for anything, it's much easier to blame other people for faults in your own life. Instead of taking responsibility and eating healthier and exercising so your not overweight it is easier to blame the people providing that food for you. Knowing what I do and being able to understand that hormones in meat and milk don't cause early puberty makes it difficult for me sometimes to understand where someone comes off when they say things like that. If those people would make a decision to get their head out of the sand and read just a little something (like this blog post) they would understand that it's not the farms that are the problem.
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