Colonic Energy Salvage in Chronic Pancreatic Exocrine Insufficiency

Abstract

Background: Chronic pancreatic exocrine insufficiency results in maldigestion. As a result, increased amounts of undigested nutrients reach the colon, providing more substrate for bacterial fermentation to produce short-chain fatty acids, which could therefore provide additional energy supplement. Methods: This study aimed to assess carbohydrate malabsorption in patients with chronic pancreatic exocrine insufficiency after ingestion of a standard diet and to calculate energy salvaged by colonic bacterial metabolism. A 72-hour stool collection was done on 10 adult patients receiving a 3-day standard diet containing 100 g fat, 329 g carbohydrate, and 154 g protein, and short-chain fatty acids, fat, carbohydrate, and nitrogen excretion were assessed. A breath hydrogen test after ingestion of 200 g (dry weight) cooked maize meal (test meal) and 10 g oral inulin (standard), respectively, was subsequently done on the patients and 15 healthy adult controls. Results: Breath hydrogen production after ingestion of maize meal and inulin, respectively, and calculated carbohydrate malabsorption were significantly greater in patients (21.4% ± 17%) than in controls (10.2 ± 1.4%; p < .05). Patients malabsorbed 70.4 g/d (281.6 kcal) carbohydrate in the standard diet. Total carbohydrate loss in stool amounted to 8.1 g/d (2.4%), and 62.3 g/d (19%) was hence salvaged as short-chain fatty acids for energy provision. Colonic bacterial fermentation therefore converted 88.5% of malabsorbed carbohydrate to short-chain fatty acids, 92.8% of which was absorbed and 7.2% excreted. This suggests that 10.2% of energy expenditure/requirement in these patients is derived from salvage of malabsorbed carbohydrate. Conclusions: Colonic bacterial metabolism is a significant source of energy salvage in patients with pancreatic enzyme deficiency.

Patients with pancreatic exocrine enzyme insufficiency often experience nutrient maldigestion. Maldigested nutrients may provide additional substrates for colonic bacterial fermentation. The study is an assessment of the contribution of colonic bacterial fermentation of malabsorbed carbohydrate to the total body energy requirements in these patients.