Sucrase isomaltase deficiency is a disorder that affects normal digestion and therefore the absorption of carbohydrates and leads to sucrose intolerance. Intolerance is described as clinical symptoms caused by sugar malabsorption (Scriver et al, 2001), in the case of sucrose intolerance it refers to the inability to digest and absorb sucrose, which leads to several abdominal symptoms. Although sucrase isomaltase deficiency is not a fatal condition, it can cause discomfort to sufferers and therefore dietary changes need to be made to avoid the symptoms caused by the deficiency. Carbohydrates account for about half of the energy humans get from food. The digestion and absorption of carbohydrates occurs through the brush organ which has an apical and basolateral membrane. Anchored to the brush border membrane are enzymes involved in the digestion of disaccharides (Silverthorn, 2010). Carbohydrates can only be absorbed as monosaccharides, which means that polysaccharide and disaccharide carbohydrates must first be hydrolyzed into monosaccharides. Carbohydrate digestion begins in saliva and the stomach where alpha-amylase hydrolyzes the alpha-1,4 glycosidic bonds between glucose molecules in starch, forming maltotriose, the disaccharide maltose and dextrin are made up of five to ten glucose molecules (Lim, 2007). The disaccharides sucrose and lactose come directly from food. There are four enzymes present on the brush border membrane responsible for hydrolyzing sucrose, lactose and starch products into monosaccharides so that they can be absorbed (Lieberman et al, 2007). These enzymes are known as glycosidases and include; glucoamylase, lactase, trehalase and sucrase isomaltase (Lieberman et al, 2007). Sucrase isomaltase...... middle of paper...... Biol Chem, Volume 281.Lieberman M, Marks A, Smith C. (2007). Marks' Essentials of Medical Biochemistry: A Clinical Approach. Philadelphia: Lippincott Williams & Wilkins. Pp 316-317.Ouwendijk J, Moolenaar C, Peters WJ, Hollenberg CP, Ginsel LA, Fransen J, et al. (1996). Identification of congenital sucrase-isomaltase deficiency of a substitution of glutamine for proline leading to a block of sucrase-isomaltase transport into the pre-Golgi compartment. J Clin Invest, volume 97. Lim M, Roach J. (2007). Metabolism and nutrition. 3rd ed. Edinburgh: Mosby. Pp 145Scriver, Charles R, Beaudet, Arthur L, Sly, William S, et al. (2001). The metabolic and molecular bases of hereditary diseases. 8th ed. London: McGraw-Hill. Pp 1634-1639.Silverthorn DU. (2010). Human physiology: an integrated approach. 5th ed. San Francisco, California; London: Pearson/Benjamin Cummings. pp 703-704.