Apple favourably affects parameters of cholesterol metabolism and of anti-oxidative protection in cholesterol-fed rats

The effects of apples on lipid metabolism were studied on 40 male Wistar rats adapted to semi-purified diets containing 0.3% cholesterol. In the experimental 'apple' diet, a part of starch (15%) was replaced by lyophilized apple (Gala variety). In the control diet, 13% of carbohydrate was replaced by a mixture of fructose/glucose/saccharose to match the sugar supply from the apples. The lipid source was corn oil and the dietary supply of vitamin E was reduced to 1/3 of the recommended value. The rats were sampled after 21 days adaptation. The fibre supply of the apple diet was notably low (about 2%); nevertheless, there was a slight but significant cholesterol-lowering effect in plasma, as well as in liver where cholesterol esters accumulate with cholesterol diets. The lipoprotein profile was markedly altered in apple-fed rats: a reduction of cholesterol in the triglyceride rich lipoprotein (TGRLP) fraction, together with a rise in the HDL fraction; hence there was a favourable effect in a cardiovascular protection perspective. This was paralleled by effects of the apple on cholesterol apparent absorption, which was markedly depressed, whereas bile acid digestive balance was unaffected. In parallel, there was a positive effect of the apple diet on parameters of oxidative stress prevention: higher FRAP plasma levels than in controls, together with a reduced MDA excretion in urine. In conclusion, the present work indicates that a moderate supply of dessert apples elicits interesting effects on lipid and peroxidation parameters.