Milk is a good source of protein and is therefore recommended for growing children. It is also a good source of calcium and is recommended for preventing or forestalling osteoporosis. Though some fat is needed in a child's diet, some choose low-fat versions because of concerns about the high quantity of saturated fat contained in whole milk and its negative effects on cholesterol levels. Some people have intolerance to the lactose in milk, and rare cases of allergy to milk have also been reported. Now the presence of growth hormones in milk is an additional cause for concern.
Growth hormone is a protein hormone produced by the pituitary gland. It is responsible for the normal growth and development of the body. When injected into cows, it can lead to increased milk production. Since the 1980s, a recombinant bovine growth hormone (rbGH) produced by using recombinant DNA processes has been used in a routine manner to increase milk production in cattle.
Ever since the U.S. Food and Drug Administration (FDA) gave its approval for the use of rbGH in cattle, questions have been raised about its safety. The opponents of growth hormone in milk claim that long-term toxicology studies to ascertain its effect on human health were not carried out. However, according to the FDA, such long-term studies are unnecessary as bovine growth hormone is inactive in humans and rbGH is inactive when ingested orally.
According to reports from the Royal College of Physicians and Surgeons of Canada, Insulin-like Growth Factor-I (IGF-I) is present in abundant quantities in milk from rbGH- treated cows. A nested case-control study within the Physicians' Health Study also revealed a strong positive association between IGF-I levels in plasma and an increased risk of prostate cancer. But according to the FDA, although the mechanism responsible for cancer is not fully understood, it is clear that IGF-I is not the causative agent.
Dr. Samuel Epstein, Chair of the Cancer Prevention Coalition, has expressed his concern about the risk of breast cancer from consumption of rbGH milk. However, the FDA states that there is no substantive evidence that IGF-I causes normal breast cells to become cancerous.
According to a Joint Expert Committee on Food Additives, the concentration of IGF-I in milk from rbGH-treated cows is orders of magnitude lower than the physiological amounts produced in the gastrointestinal tract and other parts of the body. The IGF-I entering into the body’s circulation is rapidly bound to serum binding proteins that moderate the biological activity. Hence, the potential for IGF-I consumed from rbGH milk to promote tumor growth is minimal.
- Report on the Food and Drug Administration's Review of the Safety of Recombinant Bovine Somatotropin
- Science: Plasma Insulin-like Growth Factor-I and Prostrate Cancer Risk: A Prospective Study
- Cancer Prevention Coalition and National Family Forum Coalition: rbGH Milk and Risks of Breast Cancer
- American Cancer Society: Learn About Cancer: Recombinant Bovine Growth Hormone
- Health Canada: Report of the Royal College of Physicians and Surgeons of Canada Expert Panel on Human Safety of RBST
- Jupiterimages/Comstock/Getty Images
This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.