A one-hour active coping stressor reduces small bowel transit time in healthy young adults

To examine the effect of a prolonged active coping stressor on the transit of a substance from the mouth through small intestine in normal human volunteers. Method: Twelve healthy undergraduate males were administered 10 g of the nonabsorbable carbohydrate lactulose in two experimental sessions. In normal individuals, lactulose produces hydrogen gas upon exposure to bacteria residing in the colon. Repeated measurements of breath hydrogen were obtained for 2 hours. In one session, subjects rested quietly for the 2-hour period. In the other counterbalanced session, subjects avoided mild electric shocks by playing videogames for the first hour. Results: Stress produced a statistically and clinically significant reduction in mean transit time, from 79 to 55 minutes. The magnitude of stress-induced reduction in small bowel transit time was significantly correlated with change in an index of cardiac sympathetic activity, pulse transit time. Conclusions: A prolonged active coping stressor with minimal motor requirements produced a decrease in small bowel transit time comparable with that observed in several studies of the effects of physical exercise and in comparisons between normal controls and patients with diarrhea-predominant irritable bowel syndrome.