title: Moderate food restriction suppresses the conversion of L-tryptophan to nicotinamide in weaning rats.
abstract: Calorie restriction leads to a change in the metabolism of nutrients. Nicotinamide is biosynthesized from L-tryptophan. We attempted to determine the effects of food restriction on the biosynthesis of nicotinamide from L-tryptophan. Weaning male rats were fed a conventional chemically defined diet without preformed niacin for 63 d. However, the food intake was restricted to 80 and 65% of the intake of the ad libitum-fed control group of rats. The 24-h urine samples were periodically collected, and the urinary excretion of nicotinamide and its catabolites was measured. The conversion percentages were lower in both restricted groups than in the ad libitum-fed control group during the experimental period (control group, 1.37 ± 0.24%; 80%-restricted group, 0.20 ± 0.04%; 65%-restricted group, 0.15 ± 0.02%; control vs. restricted groups, p < 0.01). Food restriction, even at mild level, suppressed the conversion of L-tryptophan to nicotinamide when compared to the ad libitum-fed control group.
authors.affiliation: a Department of Nutrition, School of Human Cultures , The University of Shiga Prefecture , Shiga , Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Shibata
authors.forename: Chifumi
authors.initials: C
authors.lastname: Nakata
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Fukuwatari
mesh_terms: D000818:Animals; D004032:Diet; D004435:Eating / Q000502:physiology*; D008297:Male; D009525:Niacin / Q000008:administration & dosage; D009536:Niacinamide / Q000378:metabolism*; D051381:Rats; D014364:Tryptophan / Q000378:metabolism*; D014886:Weaning
chemical_list: D009536:Niacinamide; D009525:Niacin; D014364:Tryptophan
keywords: calorie restriction; conversion; growth; nicotinamide; tryptophan