LAP3 and nutritional disorder: In otherwise healthy individuals, most of the plasma proteins that pass into the gastrointestinal tract are degraded into amino acids by gastric and pancreatic proteases and subsequently reabsorbed by brush border transporters.17 Severe iron deficiency could lead to deranged function of the gut epithelial barrier, or may interrupt the production or function of peptidases and amino acid transporters important in protein recirculation.