Effect of grape pomace on alimentary hypercholesterolemia and chemically induced colon carcinogenesis in rats

The effect of dietary cellulose (5 or 15%) and dried powdered grape pomace (15%) on the development of hypercholesterolemia and colon carcinoma was st udied in male Wistar rats. Hypercholesterolemia was induced by the diet sup plemented with 0.3% of cholesterol and 0.55% of bile salts while colon carc inoma was induced by s. c. treatment with dimethyihydrazine (20 mg/kg, 12 d oses in one-week intervals). Fiber content in grape pomace was 67 g/100 g o f dry matter 10.3% of which was in water soluble form. 14 weeks after the a pplication of dimethylhydrazine, serum cholesterol level decreased by 38-48 % in animals fed grape pomace diet when compared to cellulose diets. Increa sed amount of cellulose in the diet showed no hypocholesterolemic effect. D ecrease of serum cholesterol in animals fed by grape pomace could be attrib uted mainly to low-density- and very-low-density lipoproteins although the changes in cholesterol distribution in lipoproteins were not statistically significant. A significant reduction (by almost 40%) was observed for chole sterol levels in aorta and for triacylglycerol levels in serum. Compared to cellulose diets, grape pomace diet reduced conjugated diene content in pla sma, erythrocytes and liver by 30-60% and it significantly increased catala se activity in erythrocytes and colon. When compared to 15% cellulose diet, an increase in superoxide dismutase activity was observed in liver while g lutathione peroxidase activities in liver and colon were reduced. Increased cellulose and grape pomace in the diet had similar effects (significant re duction by about 30%) on the incidence of medium aberrant crypt foci (4-6 f oci). However, the effect of high cellulose was more pronounced considering the total development of all crypt types (30% and 15% for high cellulose a nd grape pomace, respectively). Grape pomace and high cellulose diets showe d similar effect on the incidence and total Volume of tumours. On the other hand, the lowest average number of tumours was observed for 15% cellulose diet and the highest number for grape pomace diet.