Effect of L-tryptophan on fasting intestinal motility and intestinal transit time in the human

Since previous experiments in dogs suggested L-tryptophan to disturb the migrating motor complex (MMC) we set out to study its effects in man. In six healthy volunteers intraduodenal instillation of 50 mmol L-tryptophan did not disrupt the interdigestive motility pattern. In comparison to saline L-tryptophan caused a brief and local increase of motor activity in the upper small bowel. There was no change in small bowel transit time. The oral intake of 560 kcal liquid formula diet produced a typical digestive pattern for 160-209 min. The increase and the maximum of serum gastrin levels did not correspond to the changes of motor activity.