Comparison between dodecanedioic acid and long-chain triglycerides as all energy source in liquid formula diets

Background: Dicarboxylic acids (DA) are water-soluble substances with high- energy density proposed as an alternative Lipid substrate-for nutrition pur poses. The aim of the present-study was to investigate the interaction betw een glucose and DA or long-chain triglyceride (LCT) metabolism after oral a dministration. Methods: two test meals containing either dodecanedioic acid (C12, the 12-atom DA) or LCT, together with glucose and amino acids, were each administered to five healthy volunteers. Tracer amounts of C-14-dodeca nedioic acid were added to the C12 meal to recover expired traced CO, and e stimate the minimum rate of C12 oxidation. Glucose, insulin, and C12 plasma levels were measured for 360 minutes after the test meal. Indirect calorim etry was performed for the duration of the study. Results: LCTs proved inef fective in promoting their own oxidation after oral administration. On the contrary, C12 was promptly oxidized, a minimum of 21.9% +/- 8.3% of the adm inistered amount giving rise to the recovered expired CO,. This difference in metabolic fate was reflected in a sparing effect on glucose: suprabasal respiratory quotient and suprabasal carbohydrate oxidation were significant ly (p < .05) lower under C12 administration than under LCT administration, with a difference of 0.024 +/- 0.015 in respiratory quotient (RQ) and a dif ference of 0.791 +/- 0.197 kJ/min in carbohydrate oxidation. Ln particular, carbohydrate oxidation increased by 54% over basal with LCT but only by 28 % with C12 administration. RQ increased over basal by 5.8% with LCT but onl y by 3.0% with C12 administration. Conclusions: These results show a fundam ental metabolic difference between conventional Lipids and DAs, which is th e basis for a possible role of DAs in clinical nutrition. The fate of spare d glucose is likely to be storage in glycogen form when dodecanedioic acid is made available as an energy source.