OXIDATION OF LOW-DENSITY LIPOPROTEINS - INTRAINDIVIDUAL VARIABILITY AND THE EFFECT OF DIETARY LINOLEATE SUPPLEMENTATION

Low-density lipoprotein (LDL) oxidation was measured in vitro to determine intraindividual variability and to relate oxidation to linoleic acid enrichment. Intraindividual variability was determined for eight subjects on 3 consecutive days after 14 d on a fixed diet. Coefficients of variation were 7.49 +/- 1.50%, 6.58 +/- 1.16%, and 4.58 +/- 0.77% for oxidation rate, lag time, and diene concentration, respectively. In the second study 12 normolipidemic men consumed a daily diet supplement containing 35 g linoleate-rich oil in one period and 35 g oleate-rich oil in the other period (2 X 3 wk crossover). LDL oxidized faster after the linoleate diet than after the oleate diet (xBAR +/- SE: 16.42 +/- 0.85 and 13.16 +/- 0.68 nmol diene . mg LDL protein-1 . min-1, respectively, P < 0.02) and produced more conjugated diene (416 +/- 12.60 and 379.29 +/- 11.06 nmol/mg protein, respectively, P < 0.05) in proportion to the increase in LDL linoleate (r = 0.698, P < 0.001 and r = 0.618, P < 0.01 for rate and diene concentration, respectively). Lag time before onset of oxidation was not significantly altered by the linoleate-rich diet.