Lipid metabolism in experimental animals

Publications are scarce in the way in chich metabolic processes are affecte d by the ingestion of heated fats used to prepare food. Similarly, studies measuring metabolic effects of the consumption on fried food are poorly kno wn The purpose of this presentation is to summarize information on frying f ats and frying foods upon lipid metabolism in experimental animals. Food co nsumption is equivalent or even higher when oils or the fat content of fryi ng foods are poorly alterated decreasing their acceptability when their alt eration degree increase. After 4hr. experiment the digestibility and absorp tion coefficients of a single dosis of thermooxidized oils were significant ly decreased in rats, however the digestive utilization of frying thermooxi dized oils included in diets showed very little change in comparison with u nused oils by feeding trials on rats. Feeding rats different frying fats in duced a slight hypercholesterolemic effect being the magnitude of this effe ct related to the linoleic decrease in diet produced by frying. However HDL , the main rat-cholesterol carrier, also increased, thus the serum choleste rol/HDL-cholesterol ratio did not change. Results suggest that rats fed fry ing fats adapt their lipoprotein metabolism increasing the number of HDL pa rticles. Deep fat frying deeply changed the far, acid composition of foods, being possible to increase their n-9 or n-6 fatty acid and to decrease the saturated fatty acid contents by frying. When olive oil-and sunflower oil- fried sardines were used as the only protein and fat sources of rats-diets in order to prevent the dietary hypercholesterolemia it was provided that b oth fried-sardine diets showed a powerful check effect on the cholesterol r aising effect induced by dietary cholesterol. The negative effect of feedin g rats cholesterol plus bovine bile to induce hyperdholesterolemia on some cell-damage markers such as lactate dehydrogenase, transaminases, alkaline phosphatase, was significantly check when olive oil- or sunflower oil-fired sardines were used in rats. However, gamma-glutamyltransferase increased w hen diets containing fried sardines from oils used several times for frying were consumed. In conclusion frying appears to be an useful tool to modify the fatty acid composition of food and the lipoprotein metabolism of consu mers, however this culinary procedure has to be gently done to avoid high l evel of potential toxic compounds.