EFFECTS OF DIETARY LONG-CHAIN POLYUNSATURATED FATTY-ACIDS ON PLASMA AMINO-ACIDS AND INDEXES OF PROTEIN-METABOLISM IN INFANTS - RESULTS FROMA RANDOMIZED CLINICAL-TRIAL

Background/Aim: Previous studies in vitro and in animals in vivo found that alpha-linolenic acid (C18:3 omega 3) may enhance oxidative damag e of essential amino acids. We investigated whether the addition of th e long-chain polyunsaturated fatty acids (LCPUFA) arachidonate (C20:4 omega-6; AA) and docosahexaenoate (C22:6-omega 3; DHA) in the form of egg phospholipids to infant formula affects plasma amino acid concentr ations and indices of protein metabolism in term infants. Methods: In a double-blind, randomized clinical trial, healthy infants were fed fr om day 5 of life formula with or without preformed LCPUFA (n = 10 and 12, respectively). At the age of 5 days and 1, 2, 3 and 4 months, bloo d samples were obtained and analyzed for plasma amino acids by high-pe rformance liquid chromatography and for plasma phospholipid fatty acid composition by gas chromatography. Results: At the age of 3 months, p lasma threonine concentrations were significantly lower in infants rec eiving dietary LCPUFA than in controls (124 +/- 16 vs. 216 +/- 28 mu m ol/l, p < 0.05). Values of other plasma essential amino acids, total p rotein, albumin, creatinine and urea nitrogen did not differ between t he two feeding groups throughout the study. At the age of 5 days, plas ma phospholipid AA and DHA concentrations were inversely correlated wi th histidine concentrations (AA: r = -0.60, p = 0.01; DHA: r = -0.53, p < 0.05). At the age of 3 months, DHA concentrations were inversely r elated to plasma histidine, methionine and threonine concentrations (r = -0.66, -0.62, and -0.64, respectively, p < 0.05). Conclusions: The dietary LCPUFA supplementation of infant formula used in this study ha s no adverse effects on infant plasma amino acid concentrations and in dicators of protein metabolism. Nonetheless, the apparent interaction of LCPUFA with some amino acids in formula-fed infants warrants furthe r investigation.