Rumor: IGF-1 in Cow’s Milk Causes Breast Cancer
Rumor: IGF-1 (insulin-like growth factor No. 1) in cow’s milk causes breast cancer in women and prostate cancer in men. IGF-1 is a carcinogenic hormone in milk, but in lower amounts in previously naturally produced milk. Since people use hormones to induce large-scale milk production in cows, the content of IGF1 in milk has increased several times to dozens of times. Of course, the risk of milk cancer is very serious.
No Evidence That IGF-1 Can Cause Cancer
The full name of the IGF-1 should called “Insulin-like growth factor I”, and the term “insulin-like growth factor 1” is inaccurate. IGF-1 is a protein with important physiological functions that is widely present in the human body. There are some epidemiological investigation shows that IGF-1 seems to associate with cancers such as prostate cancer. However, FDA and JECFA (Joint Expert Committee on Food Additives of the World Health Organization and the Food and Agriculture Organization of the United Nations) agreed that the relationship between IGF-1 and cancer is only a multifactorial correlation, and so far there is no evidence that IGF-1 is carcinogenic s reason.
The Increase in IGF-1 Caused by rbGH was Small
There are indeed reports of milk analysis that the use of recombinant bovine growth hormone (rbGH) increases the content of IGF-1 in milk. But the increase in IGF-1 caused by rbGH was small, even smaller than the normal fluctuations of IGF-1 in milk. That is, a cow that uses rbGH will produce slightly higher levels of IGF-1 in milk, but the elevated levels may still be lower than many milks that don’t use rbGH. It is completely wrong to say that “the content has increased several times to dozens of times”.
Secondly, the content of IGF-1 in milk is very low. Regardless of whether the milk used rbGH or not, the amount of IGF-1 obtained from milk is negligible compared to the amount contained in the human body itself. In addition, after heating, digestion, and absorption, the IGF-1 in food reaches the human body and no longer has biological activity.
rbGH was Rejected Based on Animal Welfare Considerations
Some people will jump out and say, since the use of rbGH is safe, why is it currently not allowed in most countries? In fact, neither the European Union nor Canada raised any objection to the safety of milk using rbGH, but they believe that the use of rbGH harms the health of dairy cows, so the application for the use of rbGH was rejected mainly based on animal welfare considerations.
Conclusion
Rumors debunked. rbGH has no substantial effect on IGF-1 in milk; IGF-1 in milk does not pose a health hazard to humans.
References:
[1] Should dairy be recommended as part of a healthy vegetarian diet? Connie M Weaver Am J Clin Nutr 2009;89(suppl):1634S–7S.
[2] Report on the Food and Drug Administration’s Review of the Safety of Recombinant Bovine Somatotropin
