IGF-1 or Insulin growth factor-1 is a hormone produced in the liver which plays a significant role in cell growth and development, particularly in childhood. IGF-1 occurs naturally in dairy milk, but some modern production methods can increase those concentrations. Milk from cows treated with recombinant bovine growth hormone or rBGH contains higher concentrations and can increase levels in the body. IGF-1 has come under scrutiny in recent years, but there are doubts regarding any negative impact on health according to the American Cancer Society.
Definition
IGF-1 also known as somatomedin C, naturally works in conjunction with human growth hormone or HGH. An increase of HGH in the blood induces the liver to produce more IGF-1. The surge in IGF-1 encourages growth of various cells in the body including muscles, ligaments and bones, while deficiency in can cause retarded growth according to a study at Tel Aviv University reported in the October 2001 issue of "The Journal of Clinical Pathology."
Arguments regarding any impact on food safety of increased levels of IGF-1 due to rBGH supplemented cows have been largely dismissed. Currently, the FDA maintains that levels of IGF-1 as a result of that exposure are minimal when compared to levels found naturally in humans.
Considerations
IGF-1 is found naturally in the milk of lactating mothers. The amount of IGF-1 in dairy milk depends on the age of the cow, its diet and stage of lactation according the U.S.Food and Drug Administration. Milk from cows injected with rBGH to increase milk production contains higher levels of IGF-1, according to the American Cancer Society. The FDA argues that the increase is minimal and within the normal variation of IGF-1 levels in milk.
Muscle Building
Due to its growth enhancing properties, some supplement companies promote IGF-1 as a muscle building compound. Some athletes believe IGF-1 reduces catabolism or muscle breakdown and increases fat loss. However, the medical division of the University of New South Wales in Sydney recently published a report which emphasizes the lack of clinical trials to confirm these beliefs.
Health Issues
IGF-1 in milk is not rendered inactive by pasteurization, but it is unclear how much IGF-1 is absorbed via the human digestive system. High levels of IGF-1 may cause the growth of certain tumors, with a heightened risk of breast, colorectal, and prostate cancers. However, the exact nature of the link with IGF-1 is uncertain according to the American Cancer Society. Dairy cows treated with rBGH are more prone to udder infections. This necessitates greater use of antibiotics which could lead to an increase in antibiotic resistant bacteria and passed along the food chain, impact on human health.
Organic Milk and Non-Mammalian Alternatives
All mammalian milk including goat and sheep milk naturally contain IGF-1. Milk from sheep and goats treated with rBGH contains higher levels of IGF-1. The U.S Department of Agriculture mandates organic milk must come from mammals not treated with rBGH. Organic milk contains less IGF-1. However, according to Dale Bauman, professor of animal science at Cornell University, there is minimal difference in levels of IGF-1 between organic and non organic milk. Milk derived from grains, nuts or beans, such as rice milk, oat milk, almond milk, hazelnut milk and soya milk do not contain IGF-1
Human Breast Milk
Human breast milk has higher concentrations of IGF-1 than milk from cows treated or untreated with rBMG according to a report of the Royal College of Physicians and Surgeons of Canada, prepared for Health Canada in January 1999.
References
- The American Cancer Society: Recombinant Bovine Growth Hormone
- "Journal of Clinical Pathology";Insulin-Like Growth Factor 1 (IGF-1): a growth hormone; Z. Laron: October 2001
- U.S. Food and Drug Administration: FDA Responds to Citizen Petition on BST: April 2000
- University of New South Wales in Sydney:Insulin-Like Growth Factor(IGF-1)
- Nutrition Notes on Msnbc.com: Organic Milk: Are the Benefits Worth the Cost?
- Health Canada: Report of the Royal College of Physicians and Surgeons of Canada - Expert Panel on Human safety of rbST
