Long chain polyunsaturated fatty acids may account for higher low-density lipoprotein oxidation susceptibility in Lithuanian compared to Swedish men.

ABSTRACT

OBJECTIVES: Mortality in coronary heart disease among middle-aged men is four times higher in Lithuania than in Sweden. Traditional risk factors cannot account for this difference. We earlier reported that low-density lipoprotein (LDL) in Lithuanian men showed a lower resistance to oxidation, measured as LDL lag time during copper oxidation, than that in Swedish men. Serum concentrations of several fat-soluble antioxidant vitamins were lower among Lithuanian men. The aim of this study was to investigate whether differences in LDL fatty acid composition could account for the difference in LDL oxidation susceptibility between men in the two countries. METHODS: This cross-sectional study included randomly selected healthy 50-year-old men from Vilnius, Lithuania (n=50) and Linköping, Sweden (n=50). Main outcome measures were fatty acids in LDL, phospholipid (PL) and cholesterol ester (CE) fractions of LDL and LDL oxidation susceptibility. RESULTS: The mean proportions of PL 205n3 (eicosapentaenoic acid, EPA) were higher in Vilnius men (2.09 +/- 1.05 vs. 1.53 +/- 0.58%, p= 0.004). LDL lag time was shorter in Vilnius men, mean +/- SD (75.4 +/- 13.6 vs. 89.5 +/- 13.1 mins, p<0.0001) than in Linköping men. Mean serum gamma-tocopherol was lower in Vilnius men (0.07 +/- 0.05 vs. 0.12 +/- 0.04 microg/mmol, p<0.0001) but alpha-tocopherol did not differ. In a multiple regression analysis controlled for city, high PL-EPA, low alpha-tocopherol, and high plasma triglycerides significantly contributed to a short LDL lag time, r2=0.53. CONCLUSIONS: Fat quality, i.e. poly unsaturated fatty acids, especially LDL-EPA, plasma triglycerides and antioxidative vitamins may partly account for the increased LDL oxidation susceptibility found in Vilnius men compared with Linköping men.