The concentrations of fecal formate strongly correlated (r2 = 0.8655) with the level of keratin 8 (K8; control group 18.0–65.7 ug/ml, NEC group 90.7–176.0 ug/ml; recovery group 21.7–36.2 ug/ml) indicating the relationship between formate and severity of intestinal epithelial damage (Figure 4B). The gene discussed is KRT8; the disease is necrotizing enterocolitis.