Roles of erythropoietin in human milk

Erythropoietin (Epo) is one of many biologically active growth factors present in human and animal milk. Accumulating evidence shows important developmental roles for these milk‐borne growth factors. Although Epo is present in biologically relevant amounts in mammalian milk, the roles of Epo in milk are incompletely defined. A significant proportion of milk‐borne Epo resists proteolytic degradation. Epo receptors (EpoR) have been found on gastric mucosa and intestinal mucosa, and in mesenteric vessel endothelium. Evidence to date shows that intact Epo reaches these local organs, as well as distal organs. After feeding Epo, local gastrointestinal physiological effects are seen in suckling rats. In humans and rats, short‐term feeding of high‐dose Epo increases reticulocytes, but it is unclear whether sustained treatment increases red cell mass. Conclusion : Further work towards understanding the physiological and potential pharmacological roles of enterally administered Epo is necessary. Summary Evidence to date supports the theory that Epo is present in biologically relevant amounts in mammalian milk, is protected from gastrointestinal proteolytic degradation and probably plays a role in local neonatal gastrointestinal development. Animal data show that milk from hypoxic mothers appears to stimulate erythropoiesis better than pharmacological doses of Epo added to normal milk or formula. The lack of efficacy of pharmacological doses of rhEpo in studies to date may be secondary to several factors, including local utilization of the hormone, the need for Epo to work in conjunction with another hematopoietic growth factor in milk, or nutritional factors, such as iron deficiency, interfering with the rhEpo response. Whether milk‐borne Epo plays a significant role in stimulating erythropoiesis is still unclear and more work is necessary to determine the physiological and pharmacological roles of milk‐borne Epo.