The increased use of hormones in meat has the American public concerned for many reasons. Chief among them is that girls in the United States are entering puberty earlier than girls just a century ago. They are starting their periods earlier, too. Girls who mature faster in this way have a higher risk of some serious illnesses, including breast cancer and heart disease, say a group of British scientists in the journal "Public Health Nutrition." They indeed found a link between how much animal protein girls eat early in life and the age at which they hit puberty.
Girls' Puberty
The age at which girls start puberty can vary. Genes play a role in determining when, but so does nutrition, reports National Institutes of Health online medical encyclopedia Medline Plus. Generally speaking, puberty marks the transition from childhood to adulthood, and in girls, the beginning of the ability to bear children. Girls' sexual and physical traits develop as result of changing hormones. Girls' ovaries increase production of estrogen and other female hormones. Breast development is one of the first signs of puberty and menstruation often follows around two years later. In the interim, girls grow taller, have wider hips, experience more vaginal secretions and grow pubic and armpit hair.
Why Hormones are Used in Meat
In the 1930s, meat producers learned the benefits of using hormones in animals. Some hormones make animals gain weight faster, reducing the time it takes to get them to slaughter and into stores. It also cuts down on how much feed they have to provide. In other words, hormones make meat and dairy industries more profitable. There are many types of hormones and different ways they are used in animals. According to a report by the Cornell University Sprecher Institute for Comparative Cancer Research and the Program on Breast Cancer and Environmental Risk Factors in New York State, up to 30 percent of cattle are treated with a type of hormone that increases their milk production. An early mass-produced version of female hormone was once used to fatten calves and chickens, but use was discontinued in the 1970s when it was linked to cancer.
Current Hormone Use in Meat
According to the Cornell report, six hormones are approved for use in food production in the United States -- estradiol, progesterone, testosterone, zeranol, trenbolone acetate and melengestrol acetate. They are only used in growing cattle and sheep, not in poultry or hogs because they are ineffective in the latter. Scientists are still uncovering the implications of the use of hormones in meat in human health. It's not as simple as saying if your daughter eats meat that was treated with a hormone, that hormone gets into her and affects her maturity. Depending on the type of hormone used, cooking and digestion may eliminate the ability of hormone-injected meat to act in her body. But there isn't enough research or oversight to determine how much is normal, what's extra, how remains in meat and milk after processing and the effects of any extra hormone on girls' bodies.
Meat Hormones and Girls' Puberty
That Cornell report, from 2003, along with another early report from the International Food Safety Network, touched on the subject of steroid hormones in meat and early puberty for girls. The Cornell report said at the time that there hadn't been large-scale studies to prove that girls had been exposed to higher than normal levels of hormone through hormone-treated meat. Some early investigational studies demonstrated a link, but other scientists couldn't replicate, and therefore, verify the results. Other studies have even investigated the possible link between residual estrogen in meat and breast enlargement in boys. However, little in the way of hard proof has illustrated a need to increase regulations, ban usage or recommend dietary changes. Both reports agree, quite frankly, there's not enough evidence to answer a lot of questions surrounding early puberty in girls and hormones in meat, as well as the implications for their future health.
What You Can Do
However, research published in June 2010 in the "Public Health Nutrition" found a definite link between girls' meat eating and the early onset of menstruation. Though the report didn't examine hormones, it concluded that the more animal protein girls ate between the ages of 3 and 7, the more likely they were to start their periods before age 12. The authors said girls' diets at these young ages could influence their lifelong risk of breast cancer and osteoporosis, both of which are linked to estrogen. The journal authors and the Cornell report don't advise completely stripping meat from your daughter's diet. After all, it contains important nutrients. However you can reduce her exposure to hormones in several ways. Eat a wider variety of foods, and ensure she eats plenty of fruits, grains and vegetables. Eat meat in moderation, well-done but never charred. Choose lean cuts and remove visible fats. Avoid cuts of liver.
References
- "Public Health Nutrition"; Diet Throughout Childhood and Age at Menarche in a Contemporary Cohort of British Girls"; Imogen Rogers et al.; June 8, 2010
- Cornell University Sprecher Institute for Comparative Cancer Research; Consumer Concerns About Hormones in Food; Renu Gandhi and Suzanne M. Snedeker; May 2, 2003
- PhysOrg.com; High Meat Diet May Lead to Early Puberty for Girls; June 11, 2010
- International Food Safety Network; Growth-Promoting Hormones in Cattle; Rena Orr; Jan. 1, 2001
