Comparison between dietary monounsaturated and polyunsaturated fatty acids as regards diet-related diseases

We have studied the effects of dietary fatty acid (FA) composition on lipids and lipoproteins, platelet function and other hemostatic variables as well as on the endogenous formation of DNA adducts of malonaldehyde (MA) in healthy subjects in controlled dietary experiments. The FAs studied were monounsaturated oleic acid (OA, 18:1 n-9), n-6-polyunsaturated linoleic acid (LA, 18:2 n-6), n-3 polyunsaturated alpha-linolenic acid (ALA, 18:3 n-3), and two long-chain, n-3 polyunsaturated FAs, eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3). The results indicated that a high OA and high LA diet had comparable effects on lipids and lipoproteins when they replaced saturated FAs in a diet. Furthermore, the effect of ALA did not differ from that of LA in this respect. Both diets also similarly increased in vitro platelet aggregation when compared with high saturated FA baseline diet. In another study the effect of LA and ALA on platelet function was studied. In this study ALA decreased in vitro platelet aggregation when compared with LA. When ALA was compared with EPA + DHA it was found that platelet function and some coagulation and fibrinolysis parameters were mainly affected in a similar manner by ALA and EPA + DHA treatments. The high LA diet increased the levels of DNA adducts of MA when compared with the effect of the high OA diet. Our findings indicate that the interpretation of the effect of diet, dietary fat or a specific FA on the development of chronic disease is extremely complex.