IGF-1, Milk and Cancer

IGF-1 and Milk Health – Cancer Research Resources

U.S. Food and Drug Adiministration has issued numerous statements on IGF-1, milk health and cancer research. These include:

• The consumption of dietary IGF-1 plays no role in either inducing or promoting any human disease, nor does it cause malignant transformations of normal human breast cells… According to cancer research, the suggestion that IGF-1 in milk can induce or promote breast cancer in humans or premature growth stimulation in infants is scientifically unfounded.
• “FDA and other scientific and regulatory bodies have thoroughly examined the safety of milk produced by rbST-treated cows and have concluded that it is safe. There is absolutely no possibility that the consumption of milk from rbST-treated cows could increase the risk of breast cancer. Insulin-like growth factor 1 (IGF-1) is a natural protein which mediates many of somatotropin’s actions. It is required for normal growth and possibly health maintenance. IGF-1 is structurally and chemically similar to insulin and is normally present in most body tissues and fluids including human breast milk and saliva….”

American Cancer Society statement on cancer-links to milk from cows supplemented with bovine growth hormone states “there are no valid findings to indicate a risk of human carcinogenesis.”

Health Canada’s review conducted by the Royal College of Physicians and Surgeons of Canada states: “there is no biologically plausible basis on which to conclude that rbST-associated changes in human exposure to IGF-1 will lead to any immune response, change in neonatal intestinal growth and development, or cancer risk in recipients of milk or food products from treated cattle… there is no evidence to suggest that oral intake of IGF-1 is carcinogenic.”

The World Health Organization statement on the 50th Joint FAO/WHO Expert Committee on Food Additives (JECFA) notes: “The Committee concluded that any increase in the concentration of IGF-1 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. Thus, the concentration of IGF-1 would not increase either locally in the gastrointestinal tract or systemically, and the potential for IGF-1 to promote tumor growth would not increase when milk from rbGH-treated cows was consumed; there is thus no appreciable risk for consumers.”

Consumer Reports addressed the question of IGF-1 of milk and links to causes of cancer, clarifying that: “A high level of IGF-1 in blood - not milk - has been associated with elevated risk for several kinds of cancer.” And further adding that they “see no reason to buy (organic or rbST-free milk) for fear that regular milk is unsafe to drink.”

Children’s Nutrition Research Center at Baylor College of Medicine states: “There is “no scientific basis for claims regarding bovine somatotropin and IGF-1… if (these claims) were true, then human colostrum, human breast milk, and indeed, all milk would be incriminated as a cause of cancer… women and their children have nothing to fear regarding the nations milk supply.”

The National Institutes for Health have also researched and reviewed this milk health issue extensively. One assessment, published in the Journal of the American Medical Association (JAMA) notes: “Because these hormones (IGF-1) are digested in the gastrointestinal tract and are not absorbed… they are not believed to have biological significance…”

The American Academy of Pediatrics Journal peer reviewed article addresses the issue of infant and human safety as relates to IGF-1 and milk or meat from cows supplemented with bovine growth hormone (rbGH). In the article University of California Berkley professor Norman Kretcher, MD PhD, states that milk is “safe for the human infant and adult…”

International Dairy Foods Association notes: “IGF-1 also occurs naturally in humans, and in much higher levels than is found in cow’s milk…. Like any other protein, IGF-1 in milk produces no effects when consumed by humans; it is broken down and digested naturally…”

The Washington Post has reported that claims of IGF-1 in milk linked to cancer were flawed citing Arlan Rosenblum, a professor of pediatrics at the University of Florida who noted, “There is a huge, huge fallacy in that reasoning.” The problem, he said: IGF-1 “is a protein that will get broken down with the digestive enzymes.”

Expert Resources and Commentary

Dr. A. Samad, M.V.Sc., Ph.D., Principal Investigator, Nuclear Medicine Center and Head, Department of Medicine, Bombay Veterinary College: “There is no hard evidence to suggest that milk consumption increases risk of cancer…” http://www.vethelplineindia.com/vet/milkcontroversy4.htm

Cancer Research UK: “There is no real evidence yet that dairy products generally increase cancer risks…” http://www.cancerhelp.org.uk/help/default.asp?page=5184

Journal of Cancer Epidemiology reports on a 2002 study examining dietary influences on blood serum IGF-1 levels which notes “Milk Intake and IGF-1 Concentration. Increasing dairy milk intake was not significantly associated with increasing serum IGF-1 concentration in meat-eaters or vegetarians or among both groups combined. However, vegan women who consumed ¾ pint or more of soya milk/day had a significant 28% higher IGF-1 concentration… ”