[Niacin efficiency in zein base diets].

Lots of growing or adult rats consume ad libitum diets based on zein (12 p. 100 of protein) (diets A), or on zein partially supplemented by lysine and tryptophan (= protein quality of maize) (diets B), or on zein supplemented by amino acids to fill its deficiencies totally (diets C). The diets contain 15 mg of niacine per kg. The diets A 1, B 1 and C 1 receive an addition of 10 mg of supplementary niacin. The efficiency is estimated by the amount of niacin and tryptophan in blood plasma and in liver. The niacin efficiency depends more on the protein quality - more precisely of the intake of tryptophan - than the intake of niacin: the hepatic concentrations of niacin are 120 mug with diet A and 210 mug with diet C in growing rats. These variations are identical to the evolution of intakes and of concentrations of liver nitrogen. The administration of a supplement of niacin (10 mg/kg) does not cause repercussion on the body niacine on the growing rat and provokes a very weak profit on the adult animal. In the dietsA (unsupplemented zein), only the tryptophan is an efficacious source of niacin. The niacin seems unable to increase the vitamin storage in the liver.