Hormones are chemicals naturally produced in humans and animals. Secreted by organs in the body, they travel through the bloodstream as messengers that help with growth, development and reproduction. Sometimes hormones are given to cattle and dairy cows to make them gain weight more quickly or increase their milk supply. There have been concerns about the use of hormones in the meat and dairy industry and the possible side effects to human health.
In the United States, there are two types of hormones used in the food industry: steroid hormones and protein hormones. They each act differently in your body, according to New York University Medical Center. When you eat foods with steroid hormones, they go into your bloodstream and are carried to your cells. The protein hormones in food are broken up into smaller molecules and digested in your stomach, where they lose their strength. This is why some foods with hormones may have more impact on your health than others.
Hormones in Dairy
Hormones are often used to increase milk production in dairy cows. Recombinant bovine growth hormone or rbGH -- also known as bovine somatotropin or rbST -- has been approved by the U.S. Food and Drug Administration for use in dairy cattle since 1993. When used, the drug is injected under the skin of the cow. The FDA has determined that drinking milk or eating dairy foods with slightly higher levels of rbGH has no bad health effects, according to Cornell University's Sprecher Institute for Comparative Cancer Research. Because rbGH is a protein hormone, it does not go into your bloodstream like steroid hormones. However, milk from rbGH-treated cows contains chemicals called insulin-dependent growth factors. Although higher levels of these proteins have been found in women with breast cancer, there is no proof yet that dairy products with rbGH contribute to a higher risk of breast cancer, according to New York Medical Center.
Hormones in Meat
Cattle and sheep are the two meat sources that may contain steroid hormones. Estradiol, progesterone, testosterone, zeranol, trenbolone acetate and melengestrol acetate are approved by the federal government for use with cattle and sheep, but not for use with poultry or hogs. There has been public concern about the possibility of these steroid hormones increasing a risk of breast cancer or causing early puberty in girls, according to the Sprecher Institute. However, there is no conclusive link and further research is needed.
Foods Without Hormones
If you have concerns about hormone-treated animals, look for foods that are hormone free. Dairy products without hormones will have a label that says "no rbGH," or "no rbST." Beef and sheep products produced without hormones are labeled stating that steroid hormones were not used. Chicken, turkey and pork will always be hormone free since they are not approved by the United States for supplementation with hormones.