title: Increased conversion ratio of tryptophan to niacin in severe food restriction.
abstract: The effect of food restriction on the conversion ratio of tryptophan to niacin was investigated, because it is known that the conversion ratio is influenced by nutritional factors. A 20% casein diet was fed to rats ad libitum (control), 1/2 the food of the control. 1/4 the food of the control, or starved for 9 days, and urine samples were collected to measure the urinary excretion of such tryptophan metabolites as kynurenic acid, xanthurenic acid, and nicotinamide. The conversion ratio in the 1/2, 1/4, or starving group increased at day 1 of the experiment, but returned to the original value from day 2. Only in the starving group did the conversion ratio extremely increase from day 6 to day 9, being about 5-times higher than that of the original value on day 9. The possible mechanism by which the conversion ratio increased during food restriction is discussed.
authors.affiliation: Department of Human Health Science, Faculty of Human Sciences, Osaka International University for Women, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shibata
authors.forename: T
authors.initials: T
authors.lastname: Kondo
authors.forename: A
authors.initials: A
authors.lastname: Miki
mesh_terms: D000818:Animals; D005508:Food Deprivation / Q000502:physiology*; D007736:Kynurenic Acid / Q000652:urine; D008297:Male; D009525:Niacin / Q000378:metabolism*; D009536:Niacinamide / Q000031:analogs & derivatives / Q000652:urine; D051381:Rats; D017208:Rats, Wistar; D014364:Tryptophan / Q000378:metabolism*; D014977:Xanthurenates / Q000652:urine
chemical_list: D014977:Xanthurenates; D009536:Niacinamide; D009525:Niacin; C016590:N(1)-methyl-4-pyridone-5-carboxamide; C028330:xanthurenic acid; D014364:Tryptophan; C005211:N'-methyl-2-pyridone-5-carboxamide; D007736:Kynurenic Acid; C024058:N(1)-methylnicotinamide