Antiatherogenic properties of lipid fractions of raw and fried fish

Numerous epidemiological studies have established the protective role of fish with respect to cardiovascular diseases. Platelet activation, thrombosis and inflammation are crucial phases of atheromatic plaque formation and platelet-activating factor (PAF) is a common mediator of these events which plays a pivotal role in atherogenesis. The presence of various lipids with PAF-like activity or PAF antagonists in various foodstuffs has been reported and may prove a valuable index of their nutritional value. Under this perspective the aggregatory properties of lipid fractions obtained from six of the most widely consumed fish (rainbow trout, golden trout, sea bass, herring, coley and plaice) were studied in either raw or fried samples. The total lipids were extracted and separated into neutral and polar lipid fractions. All fractions were tested for their ability to aggregate platelets or inhibit PAF-induced aggregation. The aggregatory properties of lipid fractions were dependent on the fish species. Frying led to fractions of reduced aggregatory activity probably due to the absorption of the frying medium, which contains PAF inhibitors. The aggregatory properties of total lipids were mainly attributed to polar lipids while the PAF antagonistic activities were attributed to neutral lipids. The biological activities of such fractions with respect to their aggregatory properties may explain, in part, the protective role of fish against cardiovascular diseases and determine their nutritional value.