OXIDIZED LIPIDS IN THE DIET ARE A SOURCE OF OXIDIZED LIPID IN CHYLOMICRONS OF HUMAN SERUM

We examined whether oxidized lipids in the diet determine the levels o f oxidized lipid in human postprandial serum chylomicrons. After we fe d subjects control corn oil containing low quantities of oxidized lipi d, the levels of conjugated dienes in the chylomicron fraction were lo w (9.67+/-0.92 nmol/mu mol triglyceride), and no thiobarbituric acid-r eactive substances (TBARS) could be detected. However, when subjects w ere fed a highly oxidized oil, the conjugated diene content in chylomi crons was increased 4.7-fold to 46+/-5.63 nmol/mu mol triglyceride, wi th 0.140+/-0.03 nmol TBARS/mu mol triglyceride. When subjects were fed medium-oxidized oil, the degree of oxidation of the chylomicron lipid s was moderately increased (21.86+/-2.03 nmol conjugated dienes/mu mol triglyceride). Additionally, we found that chylomicrons isolated afte r ingestion of oxidized oil were more susceptible to CuSO4 oxidation t han chylomicrons isolated after ingestion of the control oil. The lag time for oxidation decreased from 4.30+/-0.40 to 3.24+/-0.51 hours (P< .05). These data demonstrate that in humans dietary oxidized lipids ar e absorbed by the small intestine, incorporated into chylomicrons, and appear in the bloodstream, where they contribute to the total body po ol of oxidized lipid.