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Is coffee a colonic stimulant?
S S Rao1, K Welcher, B Zimmerman
1Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, USA.
Background:
It is unclear if ingestion of coffee affects colonic function and if this effect is due to its caffeine content. We investigated the effects of coffee on colonic motor activity in healthy humans.
Methods:
We performed ambulatory colonic manometry by placing a six-sensor solid-state probe up to the mid-transverse colon in 12 healthy subjects. The following day, over a 10 h period, subjects received four stimuli: 240 ml of three drinks at 45 degrees C in random order: black Colombian coffee (150 mg caffeine), decaffeinated coffee or water and 1000 kcal meal. We analyzed the effects of each stimulant on colonic motor responses.
Results:
Caffeinated coffee, decaffeinated coffee and meal induced more activity in the colon with a greater area under the curve of pressure waves (P < 0.01) and a greater number of propagated contractions (P < 0.05) when compared with water. Caffeinated coffee, decaffeinated coffee and meal induced greater (P < 0.05) motor activity in the transverse/descending colon when compared with the rectosigmoid colon. The effects of decaffeinated coffee on colonic motility were not significantly different from those of water or caffeinated coffee and were lower (P < 0.05) than that of a meal.
Conclusion:
Caffeinated coffee stimulates colonic motor activity. Its magnitude is similar to a meal, 60% stronger than water and 23% stronger than decaffeinated coffee.