Effects of excess intake of leucine and valine deficiency on tryptophan and niacin metabolites in humans.
Nineteen healthy humans (2 men and 17 women) served as experimental subjects in 4 experiments using diets having different levels of leucine and also a valine-deficient diet. The effect of an excess intake of leucine, with and without addition of vitamin B-6, and the effect of a deficiency of valine on urinary excretions of N1-methylnicotinamide, N1-methyl-2-pyridone-5-carboxamide, nicotinic acid, quinolinic acid, and 5-hydroxyindole acetic acid, and on the level of plasma amino acids were investigated. There was no effect of leucine on the excretion of these metabolites, but a marked decrease in the plasma (or serum) valine level was observed. The same decrease was seen when a valine-deficient diet was fed.
D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage / Q000097:blood; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007930:Leucine / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D009536:Niacinamide / Q000031:analogs & derivatives / Q000378:metabolism; D009539:Nicotinic Acids / Q000378:metabolism*; D009584:Nitrogen / Q000652:urine; D011728:Pyridones / Q000378:metabolism; D011736:Pyridoxine / Q000494:pharmacology; D011805:Quinolinic Acids / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism*; D014633:Valine / Q000097:blood / Q000172:deficiency*
D000596:Amino Acids; D009539:Nicotinic Acids; D011728:Pyridones; D011805:Quinolinic Acids; D009536:Niacinamide; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D007930:Leucine; D014633:Valine; D011736:Pyridoxine; D009584:Nitrogen