EFFECT OF N-3 FATTY ACID-RICH FISH-OIL SUPPLEMENTATION ON THE OXIDATION OF LOW-DENSITY LIPOPROTEINS

This study was aimed at determining the effect of fish oil supplementa tion on copper catalyzed oxidation of low density lipoproteins (LDL) f rom nine hypertriglyceridemic human subjects. A rapid headspace gas ch romatographic method was used to measure the volatile oxidation produc ts from LDL. Propanal and hexanal were the major volatile products for med in the oxidation of n-3 and n-6 polyunsaturated fatty acids (PUFA) , respectively. Fish oil supplementation resulted in a significant inc rease in propanal formation from 3.7 to 13.4 nmol/mL LDL (P < 0.01); i t also resulted in small decreases in pentanal formation from 14.7 to 11.4 nmol/mL LDL and in hexanal formation from 138 to 108 nmol/mL LDL (P < 0.05). The changes in peroxidation products paralleled the change s in LDL composition, which showed a significant increase in n-3 PUFA from 3.2 to 14.6% (P < 0.01) and a decrease in n-6 PUFA from 43.7 to 3 5.0% (P < 0.05). Propanal formation was highly and significantly corre lated with n-3 PUFA content (r = 0.950, P < 0.001). Since total volati les remained unchanged, this indicated that the two groups of LDL samp les did not differ in overall oxidative susceptibility. Although fish oil intake did not alter the oxidative susceptibility of LDL, the chem ically modified LDL particles generated a distinct pattern of volatile oxidation products that reflected changes in their fatty acid composi tion.