title: Stability of plasma fatty acids at -20 degrees C and its relationship to antioxidants.
abstract: The fatty acid composition of cholesteryl esters (CE), triglycerides (TG) and phospholipids (PL) was analysed with gas chromatography before and after 3 years' storage of EDTA plasmas at -20 degrees C. In the three lipid fractions the proportion of polyunsaturated fatty acids (PUFA) with 3 or more double bonds decreased by 14% to 46%, while the proportions of saturated and monounsaturated fatty acids and also of linoleate (18:2 omega 6) showed an increasing trend. The changes tended to be relatively greatest in TG and smallest in PL. The initial concentration of vitamin A correlated negatively with reductions of all 20- to 22-carbon PUFA in CE and with that of arachidonate (20:4 omega 6) and docosahexaenoate (22:6 omega 3) in TG. The change in CE-18:2 omega 6 tended to be inversely correlated with vitamin A. The initial concentration of beta-carotene and the change in CE- and TG-18:3 omega 3 and CE-22:6 omega 3 showed also inverse correlations. Vitamin C, alpha-tocopherol and selenium had only occasional and mostly insignificant associations with the fatty acid alterations. In freshly analysed samples the concentration of vitamin A correlated negatively with the percentage of 18:2 omega 6 in plasma CE, TG and PL and with that of 20:4 omega 6 in platelets, and beta-carotene and alpha-tocopherol had positive correlations with 18:2 omega 6 in most plasma lipid fractions and platelets. Vitamin C and selenium correlated positively with 22:6 omega 3 in plasma, and selenium also with that in platelets.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000097:blood; D001792:Blood Platelets / Q000378:metabolism; D002338:Carotenoids / Q000097:blood; D002788:Cholesterol Esters / Q000097:blood; D005227:Fatty Acids / Q000097:blood*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D010743:Phospholipids / Q000097:blood; D012643:Selenium / Q000097:blood; D014280:Triglycerides / Q000097:blood; D014801:Vitamin A / Q000097:blood; D014810:Vitamin E / Q000097:blood; D019207:beta Carotene
chemical_list: D000975:Antioxidants; D002788:Cholesterol Esters; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D010743:Phospholipids; D014280:Triglycerides; D019207:beta Carotene; D014801:Vitamin A; D014810:Vitamin E; D002338:Carotenoids; D012643:Selenium; D001205:Ascorbic Acid