Frequently Asked Questions
October 2006
By Althea Zanecosky, MS, RD, LDN
Mid-Atlantic Dairy Association
Q: I've read that a hormone in conventional milk may be harmful to the development of children by leading to the early onset of puberty. Are there studies comparing organic and conventional milk and youth development?
A: Many consumers are confused about what organic milk is and whether it is healthier than conventional milk. Organic refers to foods that are grown without artificial pesticides, fertilizers or herbicides. Organic dairy products are obtained from animals that are fed organic feed and are not given hormones or antibiotics.
If you do choose organic foods, new labeling requirements are in effect to ensure that what you are buying is organic. The Organic Foods Production Act and the National Organic Program (NOP) are intended to assure consumers that the organic foods they purchase are produced, processed and certified to be consistent with national organic standards. You can find out more about the labeling requirements at www.USDA.gov or www.FDA.gov.
Conventional milk may come from cows who have received the synthetic bovine growth hormone, rBST. BST, or bovine somatotropin, itself is a naturally occurring protein hormone made by cows. It is normally found in small quantities in milk and meat from cows. The synthetic hormone, rBST, can be given to cows as a supplement to improve their efficiency in producing milk. With rBST supplementation, a cow's milk production goes up, but normal levels of the hormone in milk do not change; the cow uses it up herself. Also, BST does not survive pasteurization and even if it did, it has absolutely no effect on human growth. There's no change in flavor or the nutritional qualities of the milk, either. That's why milk labels are not required to indicate if rBST was used in milk production.
In 1990, the National Institutes of Health reinforced the safety of BST for humans. (http://consensus.nih.gov/1990/1990BovineSomatotropinta007html.htm.). In 1993, the Food and Drug Administration approved BST supplementation, based on its safety for humans, cows, and the environment. And regulatory agencies in 20 countries have authorized milk and meat from cows receiving BST for people of all ages.
Several studies regarding early puberty in girls have recently been published in the American Academy of Pediatrics' journal Pediatrics, and other leading medical journals. In 1997, a study from the Pediatric Research in Office Settings Network found that some physical signs of the onset of puberty are occurring earlier in some girls. This study indicated that some signs of puberty are being achieved approximately one year earlier in Caucasian girls and two years earlier in African-American girls. New guidelines propose that girls showing early signs of puberty should be evaluated by their pediatrician. No changes in the current guidelines for evaluating boys have been made at this time. If you're concerned that your child is entering puberty too early, talk with your pediatrician.
Why girls might be maturing earlier, no one knows for sure. Theories abound: Girls are better nourished. They have more body fat these days. They are exposed to more chemicals. But the changes documented in Pediatrics study cannot be attributed, even in part, to bovine growth hormone for one important reason: The data for the study were collected in 1992 and 1993, before rBST was available for dairy herds in the United States (1994). And there’s another problem with the BST and early puberty theory: Children today drink less milk than they did a generation or two ago. According to the U.S. Department of Agriculture (USDA), milk consumption among girls ages 6 to 11 dropped by about one-third from the late 1970s to the late 1990s.
A study published in the American Journal of Public Health found that girls who experience menarche before age 11 are more likely to be overweight than girls who undergo menarche later. Currently there are no studies showing that milk produced from cows given rBST is related to the onset of early puberty. FDA is continually evaluating the safety of our food supply and the effects of biotechnology; to learn more about these issues, check out www.FoodSafety.gov.
Marcia E. Herman-Giddens, Eric J. Slora, Richard C. Wasserman, Carlos J. Bourdony, Manju V. Bhapkar, Gary G. Koch, and Cynthia M. Hasemeier, Secondary Sexual Characteristics and Menses in Young Girls Seen in Office Practice: A Study from the Pediatric Research in Office Settings Network, Pediatrics Vol. 99 No. 4 April 1997, pp. 505-512
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1456335&dopt=Abstract
[No authors listed], Obesity and cardiovascular disease risk factors in black and white girls: the NHLBI Growth and Health Study, Am J Public Health. 1992 Dec;82(12):1613-20
Other Resources:
USDA:
http://www.nal.usda.gov/bic/BST/Misc/bst.bauman.html
Utah State Cooperative Extension:
http://extension.usu.edu/files/foodpubs/foodsaf6.pdf#search=%22bovine%20somatotropin%22
American Council on Science and Health:
http://www.acsh.org/publications/pubID.320/pub_detail.asp