Excretion of Dicarboxylic and ω-1 Hydroxy Fatty Acids by Low Birth Weight Infants Fed with Medium-Chain Triglycerides

ABSTRACT. The effects of feeding a commercial formula containing increased amounts of medium-chain fatty acids on the urinary excretions of C6-C10 moncarboxylic, dicarboxylic, and ω- 1 hydroxy acids were studied in 13 growing preterm infants of mean birth weight 1.42 kg in a randomized double-blind cross-over clinical trial. Infants were allocated to two sequential feeding regimes of 5 days each, during the last 3 days of which urine was collected and analysed by gas-chromatography mass spectrometry. The two feeding regimes consisted of high energy and proteincontaining formulas specially designed for growing low birth weight infants. In one diet the triglyceride component consisted of 46% medium-chain (C8-C10) and 54% longchain fatty acid residues: in the other it consisted of 4% medium-chain and 96% fatty acid residues. The infants were randomized so that six infants were fed first with the medium-chain predominant formula and seven were fed first with the long-chain predominant formula. There were significant differences in the urinary excretions of octanoate, sebacate, suberate, adipate, 7-hydroxyoctanoate, and 5-hydroxyhexanoate; these substances appearing in much greater quantities in the urine during the period in which medium-chain triglycerides were predominant in the formula. The significance of this organic aciduria, which accounted for 0.7% of the dietary intake of medium-chain triglycerides, remains to be established.