Colostrum

Bovine colostrum — the first milk produced in the 24–48 hours postpartum — is the most concentrated natural source of bioactive immune and growth factors known. It contains immunoglobulins IgG, IgA, and IgM at concentrations 100-fold higher than mature milk, providing passive immune protection against enteric pathogens. Lactoferrin chelates iron required for bacterial replication, exerts direct antiviral activity against influenza and rotavirus, and modulates mucosal immune responses. Insulin-like growth factor 1 (IGF-1) and transforming growth factor beta (TGF-β) promote intestinal epithelial cell proliferation and repair — clinically relevant for athletes with exercise-induced gut permeability and individuals recovering from intestinal injury. Multiple randomised trials confirm bovine colostrum significantly reduces upper respiratory infections in athletes and supports intestinal barrier function.