Increased excretion of a brain depressor amine in infantile coeliac disease and in healthy infants on a high protein milk diet.

Urinary excretion of piperidine, a heterocyclic pressor amine of gut bacterial origin and nicotine-like activity in the brain, has been estimated by a gas chromatography method in healthy men and women, in normal breast-fed and formula-fed infants and in infants with untreated coeliac disease. The excretion of piperidine cannot usually be detected during the first week of life. The amount present in urine increases upon weaning with higher excretion in formula-fed than in breast-fed infants at four to six months of age. When premature infants fed on human milk are weaned, the urinary content of piperidine rises from undetectable amounts to normal for age. The high content present in untreated coeliac disease may be responsible for the initial mental depression commonly seen in this disease and suggests that piperidine is one of the "auto-intoxicating" substances arising from the bacterial decomposition of protein postulated by Metchnikoff in 1903 but hitherto unidentified.