Theories behind the effect of starch‑ and sucrose‑reduced diets on gastrointestinal symptoms in irritable bowel syndrome (Review)

Abstract

increased amounts of starch and sugar have been added to the diet in the Western world during the last decades. undigested carbohydrates lead to bacterial fermentation and gas production with diffusion of water, causing abdominal bloating, pain and diarrhea. Therefore, dietary advice is the first line of treatment of irritable bowel syndrome (IBS), a disease characterized by abdominal pain and altered bowel habits without any organic findings. recently, a diet with a reduction of starch and sucrose led to a marked effect on gastrointestinal (GI) symptoms. The mechanism is unknown, but three possible mechanisms are presented in the present review. First, functional variants of the enzyme sucrase-isomaltase (SI) have been described in IBS. A subgroup of patients with IBS may thus suffer from partial SI deficiency with reduced digestion of starch and sucrose. Second, fructose absorption is less efficient than glucose absorption, which may lead to a physiological fructose malabsorption when ingesting high amounts of sucrose. a third mechanism is that high-sugar diets causing hyperglycemia, hyperinsulinemia and weight gain have led to painful neuropathy in animal models; whereas, improved metabolic control in humans has led to improvement of neuropathy. Starch-and sucrose-reduced diets lead to decreased levels of c-peptide, insulin, gastric inhibitory peptide, leptin and weight reduction. These metabolic changes may reduce the excitability of the hypersensitive nervous system often found in IBS and, thereby, lead to the reduced symptoms found after the diet. in conclusion, further studies are needed to investigate the pathophysiology behind development of symptoms after starch and sucrose intake, and the mechanisms behind symptom relief after reduced intake. Contents1. introduction 2. Genetic variants of sucrase-isomaltase deficiency 3. Monosaccharide absorption in the small intestine 4. Gastrointestinal effects of monosaccharide absorption 5. effect of sugar-rich diets on the development of polyneuropathy 6. discussion

Gene variants of the SLC2A5 gene encoding GLUT5, the major fructose transporter, do not contribute to clinical presentation of acquired fructose malabsorption

“…The aim of the study, molecular analysis of SLC2A5 gene concerning gene variants associated with fructose malabsorption, was based on other studies showing the role of SNPs/mutations affecting the uptake/metabolism of related sugars. Variants including partial deficiency of sucrose-isomaltase were shown to be associated with IBS [ 35 ]. Analysis of UK biobank data revealed that gene variants in human ketohexokinase gene are associated with loss of function and resulting in the rare benign condition of fructosuria [ 36 ].…”

Gene Variants of the SLC2A5 Gene Encoding GLUT5, the Major Fructose Transporter, Do Not Contribute to Clinical Presentation of Acquired Fructose Malabsorption.

“…The aim of the study, molecular analysis of SLC2A5/GLUT5 gene concerning gene variants associated to fructose malabsorption, was based on other studies showing the role of SNPs/mutations affecting the uptake/metabolism of related sugars. Variants including partial de ciency of sucrose-isomaltase were shown to be associated with IBS (35). Analysis of UK biobank data revealed that gene variants in human ketohexokinase gene are associated with loss of function and resulting in the rare benign condition of fructosuria (36).…”

Extraintestinal manifestations in irritable bowel syndrome: A systematic review

“…103 Thus, the painful syndromes may depend on neuropathy secondary to disturbed homeostasis in the nerves and surrounding tissues. 98 Even if the extraintestinal manifestations are not primarily explained by genetic influences, there is evidence of a genetic component in the associations between IBS and extraintestinal symptoms. 67 The associations between IBS and extraintestinal manifestations in twins may depend on both genetic and environmental conditions.…”

“…Several animal models have shown that high intake of fat and/or sugar has led to hyperglycemia, insulin resistance, metabolic disturbances, and histopathological changes with nerve super excitability. 98 Recently, poor dietary habits have been described in IBS patients in several countries. 65,99–101 Vitamins and minerals act as cofactors in multiple processes in the cells.…”

“…103 Thus, the painful syndromes may depend on neuropathy secondary to disturbed homeostasis in the nerves and surrounding tissues. 98…”