title: Effect of vitamin or amino acid supplementation on plasma free amino acid levels in South African Blacks.
abstract: The object of this study was to determine the effect of large oral doses of L-leucine, vitamin B1, vitamin B2, vitamin B6 or vitamin C, given over a period of days, on the plasma free amino acid levels and protein nutrition index values of South African Blacks on a maize diet. In addition, single loads of L-tryptophan or L-kynurenine were given before and after the above regimen of L-leucine or vitamin to determine the effect of tryptophan or kynurenine with and without the influence of these factors on the plasma free amino acid levels and protein nutrition index values. Vitamin C therapy or a single dose of L-tryptophan increased the total plasma free amino acid levels. L-leucine therapy or a single loading dose of L-tryptophan increased the protein nutrition index. Single loading doses of L-kynurenine decreased the protein nutrition index. The levels of non-essential amino acids in the plasma of Blacks were much higher than those of Whites, and consequently the protein nutrition index values were much lower.
mesh_terms: D001741:Black or African American; D000596:Amino Acids / Q000097:blood* / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D044383:Black People; D006801:Humans; D007737:Kynurenine / Q000494:pharmacology; D007930:Leucine / Q000494:pharmacology; D008297:Male; D011736:Pyridoxine / Q000494:pharmacology; D012256:Riboflavin / Q000494:pharmacology; D013019:South Africa; D013831:Thiamine / Q000494:pharmacology; D014364:Tryptophan / Q000494:pharmacology; D014803:Vitamin B Complex / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D014803:Vitamin B Complex; D007737:Kynurenine; D014364:Tryptophan; D007930:Leucine; D011736:Pyridoxine; D001205:Ascorbic Acid; D012256:Riboflavin; D013831:Thiamine