comparative effects of high carbohydrate and fat diets on brush border membrane enzymes, energy metabolism and antioxidant defense mechanisms in rat intestine and liver

Digestion, absorption and metabolism of foods are major functions of intestines as well as liver. variations in major food components such as carbohydrates, fats and proteins in the diet has been shown to produce negative effects on human health, leading to several diseases. effects of high carbohydrate diet and high fat diet on various serum parameters and enzymes of brush border membrane, carbohydrate metabolism and oxidative stress in small intestines and livers of rats were assessed. rats were fed with high carbohydrate diets and/or high fat diets for 28 d. serum glucose, cholesterol, inorganic phosphate (pi) and serum alkaline phosphatase increased differentially by high carbohydrate diets and high fat diets. the activity of brush border membrane enzymes, alkaline phosphatase and sucrose, increased; however, γ-glutamyl transferase decreased by high carbohydrate diet whereas alkaline phosphatase and γ-glutamyl transferase increased; however, sucrase decreased by high fat diet. the activities of metabolic enzymes except lactate dehydrogenase, which was profoundly increased by high carbohydrate diet., significantly decreased by high carbohydrate diet and high fat diet in small intestine. the activity of lactate, malate, glucose-6-phosphate dehydrogenases and nadp-malic enzyme significantly increased; however, glucose-6-phosphatase and fructose-6-phosphatase decreased in the liver by high carbohydrate diets. however, these decreased by high fat diets. the two diets increased oxidative stress as apparent by increased lipid peroxidation with decreased activity of superoxide dismutase and catalase in mucosal and liver homogenates. in conclusion, consumption of high carbohydrate and fat diets caused extensive alterations in mucosal brush border membrane and liver, disrupted metabolic activity and antioxidant defence mechanism differentially as indicated by the changes in associated enzymes and other parameters.