THE AMINO ACID CYSTEINE MAY HELP THE GUT HEAL ITSELF New research from MIT has identified a single amino acid that enhances the gut’s ability to repair itself — the first evidence that one nutrient alone can drive this kind of regenerative response. In this mechanistic study, researchers tested all twenty amino acids and found one that stood out. It activated immune cells in the intestinal lining to release interleukin-22 (IL-22), a signaling molecule that stimulates stem cells responsible for r