contribution of malabsorption to the reduction in net energy absorption after long-limb Roux-en-Y gastric bypass

• Published in: The American journal of clinical nutrition Vol. 92; no. 4; pp. 704 - 713
• Main Authors: Odstrcil, Elizabeth A, Martinez, Juan G, Santa Ana, Carol A, Xue, Beiqi, Schneider, Reva E, Steffer, Karen J, Porter, Jack L, Asplin, John, Kuhn, Joseph A, Fordtran, John S
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01-10-2010; American Society for Nutrition; American Society for Clinical Nutrition, Inc
• Subjects: Adult; bariatric surgery; Barium Sulfate - analysis; Biological and medical sciences; Body Mass Index; Body Size; carbohydrate intake; Diabetes Mellitus - epidemiology; Diet; diet-related diseases; Dietary Proteins - metabolism; Duodenum - anatomy & histology; Eating - physiology; Energy Intake; Energy Metabolism; fat intake; Feces - chemistry; Feeding. Feeding behavior; Female; Food; food intake; Fundamental and applied biological sciences. Psychology; Gastric Bypass - adverse effects; Gastric Bypass - methods; human diseases; human nutrition; Humans; Hydrogen - analysis; Intestinal Absorption; malabsorption; Malabsorption Syndromes - epidemiology; Malabsorption Syndromes - etiology; Malabsorption Syndromes - metabolism; Male; metabolizable energy; Middle Aged; Nitrogen - metabolism; nutrient intake; Nutrition; nutrition physiology; obesity; Obesity, Morbid - physiopathology; Obesity, Morbid - surgery; Organ Size; patients; protein intake; Respiratory Physiological Phenomena; Sorption; Stomach; Urinalysis; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Human; Stomach; Digestive system; Bypass; Intestinal malabsorption; Digestive diseases; Intestinal disease; Energy absorption
• ISSN: 0002-9165; 1938-3207
• DOI: 10.3945/ajcn.2010.29870

BACKGROUND: Roux-en-Y gastric bypass (RYGB) restricts food intake, and when the Roux limb is elongated to 150 cm, the procedure is believed to induce malabsorption. OBJECTIVE: Our objective was to measure total reduction in intestinal absorption of combustible energy after RYGB and the extent to which this was due to restriction of food intake or malabsorption of ingested macronutrients. DESIGN: Long-limb RYGB was performed in 9 severely obese patients. Dietary intake and intestinal absorption of fat, protein, carbohydrate, and combustible energy were measured before and at 2 intervals after bypass. By using coefficients of absorption to measure absorptive function, equations were developed to calculate the daily gram and kilocalorie quantities of ingested macronutrients that were not absorbed because of malabsorption or restricted food intake. RESULTS: Coefficients of fat absorption were 92 ± 1.3% before bypass, 72 ± 5.5% 5 mo after bypass, and 68 ± 8.7% 14 mo after bypass. There were no statistically significant effects of RYGB on protein or carbohydrate absorption coefficients, although protein coefficients decreased substantially in some patients. Five months after bypass, malabsorption reduced absorption of combustible energy by 124 ± 57 kcal/d, whereas restriction of food intake reduced energy absorption by 2062 ± 271 kcal/d. Fourteen months after bypass, malabsorption reduced energy absorption by 172 ± 60 kcal/d compared with 1418 ± 171 kcal/d caused by restricted food intake. CONCLUSION: On average, malabsorption accounted for [almost equal to]6% and 11% of the total reduction in combustible energy absorption at 5 and 14 mo, respectively, after this gastric bypass procedure.