Abstract
Insulin-like growth factor (IGF-1), present in varying amounts in all mammalian milks, is a major regulator of the growth gene signaling system in the newborn. The main biological functions of IGF-1, an important anabolic hormone, are the regulation of cell metabolism, growth, cell proliferation, and programmed cell death (apoptosis). There are studies that reveal positive and negative effects or disease risks on human health with the level of IGF-1 in serum. A low level of serum IGF-1 is associated with the risk of cardiovascular diseases, cardiac autophagy, hypertension, sarcopenia, nervous system diseases, and type 2 diabetes, while a high IGF-1 level is associated with prostate, premenopausal breast, and colorectal cancers and short life expectancy. IGF-1 is known to have a protective effect against Alzheimer's, dementia, and Parkinson's disease. When systematic reviews and meta-analysis studies are examined, it is clear that more studies are needed to obtain more consistent results regarding IGF-1 levels and the health effects of milk consumption. In addition, there are insufficient studies on how IGF-1 in milk is affected by milk processing and digestion, in terms of quantity and molecular level.