TGF-β1 and TGF-β2 in breast milk have protective effects on intestinal epithelial cells in premature infants, which can enhance the proliferation ability of intestinal epithelial cells, enhance the expression of tight junction proteins, such as ZO-1, maintain intestinal mucosal barrier function, and downsize NEC (19, 20). Here, TGFB1 is linked to necrotizing enterocolitis.