OXIDATIVE SUSCEPTIBILITY OF LOW-DENSITY-LIPOPROTEIN FROM RABBITS FED ATHEROGENIC DIETS CONTAINING COCONUT, PALM, OR SOYBEAN OILS

The oxidative susceptibilities of low density lipoproteins (LDL) isola ted from rabbits fed high-fat atherogenic diets containing coconut, pa lm, or soybean oils were investigated. New Zealand white rabbits were fed atherogenic semisynthetic diets containing 0.5% cholesterol and ei ther (i) 13% coconut oil and 2% corn oil (CNO), (ii) 15% refined, blea ched, and deodorized palm olein (RBDPO), (iii) 15% crude palm olein (C PO), (iv) 15% soybean oil (SO), or (v) 15% refined, bleached, and deod orized palm olein without cholesterol supplementation [RBDPO(wc)], for a period of twelve weeks. Total fatty acid compositions of the plasma and LDL were found to be modulated (but not too drastically) by the n ature of the dietary fats. Cholesterol supplementation significantly i ncreased the plasma level of vitamin E and effectively altered the pla sma composition of long-chain fatty acids in favor of increasing oleic acid. Oxidative susceptibilities of LDL samples were determined by Cu 2+-catalyzed oxidation which provide the lag times and lag-phase slope s. The plasma LDL from all palm oil diets [RBDPO, CPO, and RBDPO(wc)] were shown to be equally resistant to the oxidation, and the LDL from SO-fed rabbits were most susceptible, followed by the LDL from the CNO -fed rabbits. These results reflect a relationship between the oxidati ve susceptibility of LDL due to a combination of the levels of polyuns aturated fatty acids and vitamin E.