Interrelationship of stearic acid content and triacylglycerol composition of lard, beef tallow and cocoa butter in rats.
We investigated modes whereby stearic acid (18:0) exerts a neutral or cholesterol-lowering effect using dietary fats which provided graded levels of 18:0 and distinct triacylglycerol (TAG) profiles. Male Sprague-Dawley rats (150-175 g) were fed diets containing 0.2% cholesterol and 16% fat from corn oil, or from 1% corn oil plus 15% lard (13.2% 18:0), beef tallow (19.2% 18:0) or cocoa butter (34.7% 18:0) for 3 wk, and then killed in a fasted or fed state. Chylomicron (CM) fatty acid profiles suggested reduced absorption of 18:0 with greater 18:0 intake. CM TAG profiles indicated a reduction or loss of two TAG species compared to the TAG profiles of the stearate-rich diets: 1-palmitoyl-2-oleoyl-3-stearoyl glycerol (POS) and 1,3-distearoyl-2-oleoyl glycerol (SOS). Hepatic total cholesterol concentrations were 54-77% lower (P < 0.01) in the cocoa butter-fed than the lard-and beef tallow-fed groups. The cocoa butter group showed a significantly lower ratio of high-density lipoprotein esterified/free cholesterol than all other groups. Hepatic stearoyl-CoA and oleoyl-CoA concentrations, the substrate and product for hepatic delta 9 desaturase, were not significantly different for corn oil-fed and cocoa butter-fed groups in spite of a large difference in 18:0 intake. These data suggest that the neutral or cholesterol-lowering effect of 18:0 is not due to hepatic conversion of stearic to oleic acid, and that POS and SOS are poorly absorbed from stearate-rich dietary fats.
Monsma
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CC
Department of Nutritional Sciences, University of Wisconsin, Madison 53706.
Ney
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DM
D000214:Acyl Coenzyme A / Q000032:analysis; D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001835:Body Weight; D002784:Cholesterol / Q000032:analysis; D004041:Dietary Fats / Q000494:pharmacology*; D004435:Eating; D005223:Fats / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D008075:Lipoproteins, HDL / Q000097:blood; D008099:Liver / Q000737:chemistry; D008297:Male; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000254:growth & development; D013229:Stearic Acids / Q000494:pharmacology*; D014280:Triglycerides / Q000032:analysis / Q000494:pharmacology*; D015430:Weight Gain
D000214:Acyl Coenzyme A; D000924:Anticholesteremic Agents; D004041:Dietary Fats; D005223:Fats; D005227:Fatty Acids; D008075:Lipoproteins, HDL; D013229:Stearic Acids; D014280:Triglycerides; C031183:stearic acid; C052387:cocoa butter; D002784:Cholesterol; C013698:tallow; C029310:lard