Insulin growth factor-1 (IGF-1) are part of a complex system that cells use to communicate with their environment.
Once called somatomedin C, IGF-1 is a polypeptide protein hormone similar in molecular structure to insulin. It plays an important role in childhood growth and continues to have anabolic effects in adults.
Human population studies have showed that high levels of IGF-I are associated with an increased risk of several cancers, especially prostate cancer. Researchers believe that IGFs stimulate tumor cell proliferation, survival and metastasis (spread of cancer to other locations in the body).
IGF-1 is present in milk, especially when the cow has been treated with bovine growth hormone.