Almost a billion people in the world are starving. Malnutrition leads to a characteristically swollen belly, although until now scientists hadn’t uncovered the molecular reason why intestines become inflamed when the body doesn’t get enough dietary protein. Researchers studying an enzyme formerly identified as the key receptor for SARS virus infection were surprised to uncover a novel function for the protein. ACE2 (Angiotensin Converting Enzyme 2) helps control blood pressure, but recently was discovered to promote absorption of amino acids [digested protein products] in the gut, in particular tryptophan (visualised here with ultraviolet microscopy). Without this essential amino acid the types of bacteria in the bowels change. Diarrhoea and inflamed intestines soon result. Studies on mice with inflamed intestines showed that increasing dietary tryptophan relieved the swelling and returned gut bacteria to normal. Tryptophan supplements could herald a new future treatment for sufferers of inflammatory bowel disease.
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