title: Conversion Percentage of Tryptophan to Nicotinamide is Higher in Rice Protein Diet than in Wheat Protein Diet in Rats.
abstract: We reported previously that the pellagragenic property of corn protein is not only low l-tryptophan concentration but also the lower conversion percentage of l-tryptophan to nicotinamide; the amino acid composition greatly affected the conversion percentage. The amino acid value of wheat protein is lower than that of rice protein. In the present study, we compare the conversion percentages of l-tryptophan to nicotinamide between wheat protein and rice protein diets in growing rats. The body weight gain for 28 days in rats fed with a 10% amino acid mixture diet with wheat protein was lower than that of rats fed with a 10% amino acid diet with rice protein (68.1 ± 1.6 g vs 108.4 ± 1.9 g; P < 0.05). The conversion percentage of l-tryptophan to nicotinamide was also lower for the wheat protein diet compared with the rice protein diet (1.44 ± 0.036% vs 2.84 ± 0.19%; P < 0.05). The addition of limiting amino acids (l-isoleucine, l-lysine, l-tryptophan, l-methionine, l-threonine) to the wheat protein diet improved growth and the conversion percentage. In conclusion, our result supports the thinking that the composition of amino acids affects the conversion ratio of l-tryptophan to nicotinamide.
authors: Department of Nutrition, School of Human Cultures, The University of Shiga Prefecture, Hikone, Shiga, Japan.
authors: Katsumi
authors: K
authors: Shibata
authors: Department of Nutrition, School of Human Cultures, The University of Shiga Prefecture, Hikone, Shiga, Japan.
authors: Tsutomu
authors: T
authors: Fukuwatari
authors: Department of Nutrition, School of Human Cultures, The University of Shiga Prefecture, Hikone, Shiga, Japan.
authors: Tomoyo
authors: T
authors: Kawamura
keywords: amino acid; nicotinamide; rice protein; tryptophan; wheat protein