Do Unsaturated Fatty Acids Enhance Oxidative Stress?

Abstract: Only oxidized low density lipoproteins (LDL) are taken up by macrophages through the scavenger receptor leading to the formation of foam cells in the arterial wall. The fatty streaks formed may progress into complex arteriosclerotic lesions. Since long-chain fatty acids from the diet are readily incorporated into LDL, their resistance to oxidative modification has an impact on human health. Double bonds in fatty acids are highly reactive and therefore potentially subject to oxidative modification. Thus, LDL rich in polyunsaturated fatty acids have a high atherogenic potential. Vitamin E is the most important lipophilic antioxidant. Therefore, not only the number of double bonds in fatty acids of a dietary lipid determine its propensity to oxidation, but also the vitamin E content. To obtain an index for the stability against oxidation, the relative vitamin E content (number of relevant vitamin E molecules per 104 double bonds in the polyunsaturated fatty acids) has been calculated for the most frequently used dietary lipids. The in vitro stability agrees well with the shelf live of the respective oils and fats. The calculated in vivo stability yields a high value for olive oil, confirming that it is indeed suited for an «antiatherogenic» diet. For safflower oil and for salmon oil low values were found. This result can explain clinical studies in which an increase in oxidative processes has been found after high intake of these oils.In conclusion one can assume that a high intake of oils rich in polyunsaturated fatty acids may increase the oxidative stress and is. therefore, potentially harmful.

Keyword(s): Ateriosklerose

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