Effects of fat and carbohydrate meals on colonic motor response.
BACKGROUND
Ingestion of a meal stimulates colonic motility. It is unclear whether the nutrient composition of a meal affects colonic motor response.


OBJECTIVE
To investigate and compare the effects of a predominantly fat or carbohydrate meal on colonic motility.


METHODS
In 18 healthy subjects, ambulatory colonic manometry was performed by placing a six sensor, solid state probe from the mid-transverse colon to the rectum. In a randomised, crossover design, 10 and 27 hours after probe placement, subjects received 4.18 MJ meals containing 60% calories from fat or carbohydrate sources. Preprandial and postprandial pressure activity and motor patterns were evaluated.


RESULTS
Both meals induced phasic activity with a greater area under the curve (p<0.03) in the first postprandial hour, compared with the control period. Fat induced motor activity persisted longer (p<0.05) than that of the carbohydrate meal, but the onset of motor response was slower (p<0.001). Although both meals induced more (p<0.001) propagating pressure waves, only the fat meal induced more (p<0.05) simultaneous and retrograde waves. After both meals, 50% of subjects exhibited high amplitude (more than 103 mm Hg), prolonged duration (more than 13 seconds) propagating waves. Both meals induced greater activity (p<0.05) in the transverse/descending colon than in the rectosigmoid colon.


CONCLUSIONS
Carbohydrate meals induce colonic motor response, but the effects are short lived when compared with fat meals. The prolonged, segmental, and retrograde phasic activity induced by the fat meal may delay colon transit. Thus meal composition influences colonic motor response.
Rao
S S
SS
Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA.
Kavelock
R
R
Beaty
J
J
Ackerson
K
K
Stumbo
P
P
D000328:Adult; D019540:Area Under Curve; D003106:Colon / Q000502:physiology*; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D005772:Gastrointestinal Transit; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D019518:Postprandial Period
D004040:Dietary Carbohydrates; D004041:Dietary Fats