Factors Affecting Digestibility of Fatty Acids in the Rat

Abstract

Triolein, trilinolein and trierucin were more completely digested than the corresponding non-esterified fatty acids. Palmitic and stearic acids were very poorly digested either as triglycerides or as free acids. When diets containing oleic, linoleic, eicosenoic or erucic acids were fed, the neutral ether extract of the feces contained large amounts of calcium and phosphorus. This also occurred with trierucin but not with other triglycerides, saturated fatty acids or nervonic acid. The calcium content of the diet was found to play an important role in determining the digestibility of fatty acids. This should be considered in preparing synthetic diets because commonly-used salt mixtures cover a wide range of calcium concentrations. The digestibility of erucic acid appeared to improve as the protein level in the diet was increased. The addition of desiccated thyroid or of thiouracil did not affect the digestibility although the totalamount of fatty acid ingested was much greater in the former case. The digestibility of erucic acid seemed to be lower in old than in young rats.