Cow milk insulin like growth factor-1: risk or benefit for human health?

Cow milk is widely consumed by human children and adults due to its nutritional value. Besides nutrients, milk contains naturally occurring hormones, including insulin like growth factor-1 (IGF-1), that may alter their blood levels in the consumers. At the same time, the impact of IGF1 on human health is still unclear and controversial. The aim of the study was to determine IGF-1 concentrations in cow colostrum and milk and to discuss them from the aspect of human health. Twenty Holstein cows were enrolled in the study and subjected to colostrum, milk and venous blood sampling in order to determine the IGF-1 concentration by the radioimmunoassay (RIA). Colostrum was sampled at 2, 14 and 26 hours (1st, 2nd and 3rd colostrum) after calving, while milk and venous blood were taken 10 days after calving. The concentration of IGF-1 was the highest in the 1 st colostrum and decreased significantly with each subsequent sampling, so the lowest concentrations were detected in milk sampled 10 days after calving. High concentrations of IGF-1 observed in colostrum, especially in the 1st colostrum, reflect its potential for eventually use in the treatment of various intestinal diseases. However, further research should determine the conditions and limitations of its application. On the other hand, additional research is needed to determine whether IGF-1 in milk has harmful effects on human health and whether it is necessary to limit the permitted presence of this hormone in cow milk