Specificity of the disaccharide effect in the rat

Male rats were starved and refed diets containing 40% disaccharides (maltose, trehalose, sucrose, turanose), trisaccharide (melezitose), starch, or the monosaccharide equivalents. Responses of hepatic glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME), fatty acid synthetase (FAS), and total liver lipid (TLL) or changes in concentration of portal blood total carbohydrate and fructose were determined following refeeding of the different carbohydrate diets. Maltose, trehalose, sucrose, and turanose refeeding resulted in G6PD and ME responses which were higher than the responses to their component monosaccharides (disaccharide effect). Starch refeeding decreased the responses of G6PD, ME, and FAS when compared to refeeding of glucose. Refeeding diets containing fructose (sucrose, turanose, melezitose, and monosaccharide equivalents containing fructose) increased the responses of G6PD, ME, FAS, and TLL. No correlation between portal blood carbohydrate concentration and hepatic enzyme levels could be demonstrated. It is concluded that readily digestible disaccharides produce an effect which is greater than the effect produced by their monosaccharide equivalents. If these disaccharide configurations are fed as part of a trisaccharide or polysaccharide, the disaccharide effect is no longer discernible.