title: Importance of colonic support for energy absorption as small-bowel failure proceeds.
abstract: Digestive processes in the human colon are affected by the bacterial fermentation of malabsorbed carbohydrates and protein to short-chain fatty acids, which are absorbed and supply energy. Energy absorption was measured by assessing fecal bomb calorimetry in 148 patients with extremely different small-bowel lengths. Colectomy increased fecal loss of energy by 0.8 MJ/d and carbohydrate excretion fivefold in patients with a small-bowel length between normal and 150-200 cm. Patients with 100-150 cm small bowel, with and without a colon, excreted 1.3 +/- 0.3 and 4.7 +/- 0.5 MJ/d, respectively (P = 0.002), a difference of 3.4 MJ/d. Patients with < 100 cm small bowel excreted 3.1 +/- 0.4 and 8.0 +/- 1.3 MJ/d, respectively (P = 0.03), a difference of 4.9 MJ/d. Similar and highly significant differences were calculated by linear-regression analysis. Considerably less energy was excreted as carbohydrate than as fat in patients with preserved colonic function, probably because fermentation removed carbohydrate as absorbed short-chain fatty acids, whereas a comparable amount of energy was lost as carbohydrate and fat in patients without colonic function. The correlation between malabsorbed energy and small-bowel length was poor (r = -0.41) but increased when data for patients with and without a colon were separated (r = -0.56 and r = -0.58, respectively). Small-bowel length, however, was still an inaccurate measure of intestinal failure to absorb nutrient energy. In conclusion, colonic digestion may support energy supply with up to approximately 4.2 MJ/d as small-bowel failure proceeds, but it is of minor importance in patients with a small-bowel length > 200 cm or malabsorption < 2.1 MJ/d.
authors.affiliation: Department of Medicine A, Rigshospitale, University of Copenhagen, Denmark.
authors.forename: I
authors.initials: I
authors.lastname: Nordgaard
authors.forename: B S
authors.initials: BS
authors.lastname: Hansen
authors.forename: P B
authors.initials: PB
authors.lastname: Mortensen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003106:Colon / Q000378:metabolism* / Q000473:pathology; D004032:Diet; D004040:Dietary Carbohydrates / Q000378:metabolism; D004041:Dietary Fats / Q000378:metabolism; D002149:Energy Intake; D004734:Energy Metabolism; D005243:Feces; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D007410:Intestinal Diseases / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D007421:Intestine, Small / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000378:metabolism; D012778:Short Bowel Syndrome / Q000378:metabolism / Q000473:pathology; D014867:Water / Q000378:metabolism
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D014867:Water; D009584:Nitrogen