Male Wistar rats were shortly after weaning fed a semisynthetic diet containing 0.3 % cholesterol. Dimethylhydrazine was administered in three one-week intervals, 20 mg/kg of body weight. In a 8-week feeding experiment it was found that diets containing 15 % of dried powdered tomato and white grape pomace significantly reduced serum cholesterol levels (by 43 and 54 %, respecti- vely) when compared to a control diet with 15 % of cellulose. Reduction of total cholesterol could be attributed to a decrease of cholesterol in very-low-density and low-density lipoproteins which was accompanied by a simultaneous increase of cholesterol in high-density lipoproterins. The serum triacylglycerol level was significantly reduced only by grape pomace. Both pomace types reduced the plasma content of conjugated dienes by 35 and 48 % and stimulated superaxide dismutase activity in liver by 72 and 39 %. Neither tomato nor grape pomace affected the inciden- ce and characteristics of aberrant crypt foci in the colon.

        Key words: tomato and grape pomace – dimethylhydrazine – carcinogenesis – colon – lipoperoxida- tion