Effect of fatty acid structure on esterification by the small intestine in vitro

¹ Division of Gastroenterology and Nutrition Laboratory, Department of Medicine, The Mount Sinai Hospital, New York City

The effect of chain length and degree of unsaturation of fatty acids (FA) on in vitro esterification by slices of hamster small intestine was observed in a medium containing C¹⁴-labeled FA. After incubation, lipids were extracted and separated and the radioactivity in the esterified lipids was measured. Comparative experiments, in which results were expressed as per cent of substrate esterified per 100 mg tissue, indicate that for saturated FA, maximal esterification occurred with myristic acid, 14 carbons. As chain length was either increased or decreased, percentage esterification decreased. FA with 8 carbons or less were only minimally esterified. Among 18-carbon FA, two unsaturated bonds significantly decreased percentage esterification, although one unsaturated bond did not. These results suggest that, at least in vitro, the small bowel esterifies FA at varying rates depending upon chain length and degree of unsaturation. These differences are in the same direction as differences in absorption and partition of FA in vivo previously reported by others.