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 of oxidized lipid in human postprandial serum chylomicrons. After we fed subjects control corn oil containing low quantities of oxidized lipid, the levels of conjugated dienes in the chylomicron fraction were low (9.67+/-0.92 nmol/mu mol triglyceride), and no thiobarbituric acid-reactive substances (TBARS) could be detected. However, when subjects were fed a highly oxidized oil, the conjugated diene content in chylomicrons was increased 4.7-fold to 46+/-5.63 nmol/mu mol triglyceride, with 0.140+/-0.03 nmol TBARS/mu mol triglyceride. When subjects were fed medium-oxidized oil, the degree of oxidation of the chylomicron lipids was moderately increased (21.86+/-2.03 nmol conjugated dienes/mu mol triglyceride). Additionally, we found that chylomicrons isolated after ingestion of oxidized oil were more susceptible to CuSO4 oxidation than 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 are absorbed by the small intestine, incorporated into chylomicrons, and appear in the bloodstream, where they contribute to the total body pool of oxidized lipid.