Moderate food restriction suppresses the conversion of l-tryptophan to nicotinamide in weaning rats |
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Authors: | Katsumi Shibata Chifumi Nakata Tsutomu Fukuwatari |
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Institution: | 1. Department of Nutrition, School of Human Cultures, The University of Shiga Prefecture, Shiga, Japankshibata@shc.usp.ac.jp;3. Department of Nutrition, School of Human Cultures, The University of Shiga Prefecture, Shiga, Japan |
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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. |
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Keywords: | growth conversion calorie restriction nicotinamide tryptophan |
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