Effects of feeding tryptophan-limiting diets on the conversion ratio of tryptophan to niacin in rats.
We investigated the effects of feeding various types of nicotinic acid-free, tryptophan-limiting diets on the conversion ratio of tryptophan to niacin in rats. Various tryptophan-limiting diets were made by adding zein, gelatin, glycine, threonine, methionine, or glycine + threonine + methionine to a nicotinic acid-free, 9% casein diet. When the rats were fed with the tryptophan-limiting diets, the conversion ratio of tryptophan to niacin was markedly decreased. However, the ratio recovered after the addition of tryptophan to the tryptophan-limiting diets. These results clearly prove that the conversion was lowest when the rats were fed with the tryptophan-limiting diets. Therefore, we think that the pellagragenic factor of corn is simply due to a low content of tryptophan, but the adverse effect is due to a low conversion ratio of tryptophan to niacin.
Shibata
K
K
Department of Human Health Science, Faculty of Human Sciences, Osaka International University for Women, Japan.
Shimada
H
H
Kondo
T
T
D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D002364:Caseins / Q000494:pharmacology; D004032:Diet; D004435:Eating / Q000502:physiology; D005780:Gelatin / Q000494:pharmacology; D008099:Liver / Q000378:metabolism; D008297:Male; D009525:Niacin / Q000378:metabolism*; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000652:urine; D051381:Rats; D017208:Rats, Wistar; D014364:Tryptophan / Q000378:metabolism / Q000494:pharmacology*; D015430:Weight Gain / Q000502:physiology; D015028:Zein / Q000494:pharmacology
D000596:Amino Acids; D002364:Caseins; D009536:Niacinamide; D009525:Niacin; C016590:N(1)-methyl-4-pyridone-5-carboxamide; D014364:Tryptophan; D005780:Gelatin; D015028:Zein; C005211:N'-methyl-2-pyridone-5-carboxamide; C008472:N-methylnicotinamide