Effects of dietary long-chain polyunsaturated fatty acids on plasma amino acids and indices of protein metabolism in infants: results from a randomized clinical trial.
OBJECTIVE
Previous studies in vitro and in animals in vivo found that alpha-linolenic acid (C18:3omega3) may enhance oxidative damage of essential amino acids. We investigated whether the addition of the long-chain polyunsaturated fatty acids (LCPUFA) arachidonate (C20:4omega-6; AA) and docosahexaenoate (C22:6-omega3; DHA) in the form of egg phospholipids to infant formula affects plasma amino acid concentrations and indices of protein metabolism in term infants.


METHODS
In a double-blind, randomized clinical trial, healthy infants were fed from 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, blood samples were obtained and analyzed for plasma amino acids by high-performance liquid chromatography and for plasma phospholipid fatty acid composition by gas chromatography.


RESULTS
At the age of 3 months, plasma threonine concentrations were significantly lower in infants receiving dietary LCPUFA than in controls (124 +/- 16 vs. 216 +/- 28 micromol/l, p < 0.05). Values of other plasma essential amino acids, total protein, albumin, creatinine and urea nitrogen did not differ between the two feeding groups throughout the study. At the age of 5 days, plasma phospholipid AA and DHA concentrations were inversely correlated with 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 related 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 has no adverse effects on infant plasma amino acid concentrations and indicators of protein metabolism. Nonetheless, the apparent interaction of LCPUFA with some amino acids in formula-fed infants warrants further investigation.
Decsi
T
T
Department of Pediatrics, University Medical School of Pécs, Hungary.
Burus
I
I
Koletzko
B
B
D000596:Amino Acids / Q000097:blood*; D016718:Arachidonic Acid / Q000008:administration & dosage / Q000494:pharmacology; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D004042:Dietary Fats, Unsaturated / Q000494:pharmacology*; D004281:Docosahexaenoic Acids / Q000008:administration & dosage / Q000494:pharmacology; D004311:Double-Blind Method; D005227:Fatty Acids / Q000097:blood; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D006801:Humans; D007225:Infant Food; D007231:Infant, Newborn; D010743:Phospholipids / Q000097:blood; D011506:Proteins / Q000378:metabolism*
D000596:Amino Acids; D004042:Dietary Fats, Unsaturated; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D010743:Phospholipids; D011506:Proteins; D004281:Docosahexaenoic Acids; D016718:Arachidonic Acid