Studies on In Vivo Formation of Nitroso Compounds (VI)

Abstract

The relationship between dietary nitrate intake and nitrite detected in human saliva was studied with a basal diet and high nitrate diet. Nitrite contents in foodstuff and in saliva were determined colorimetrically by a diazo-coupling reaction with sulfanilamide and naphthylethylenediamine, and nitrate contents were determined as nitrite after conversion to nitrite by passing a cadmium column. Determinations of nitrite and nitrate in saliva were carried out at intervals of 1-2hr except at night.When 200g of salted Chinese cabbage was taken, the average concentrations of nitrite and nitrate in saliva increased to large quantities of 71.9 and 544.5ppm, however, in the case of basal diet, decreased to 12.2 and 76.5ppm, respectively.From these results, it should be concluded that the changes of nitrite and nitrate concentrations in human saliva depended upon those contents in the diets. Furthermore, when daily secretion volume of saliva was presumed as 1, 000ml, the total amount of nitrite in saliva were 7-28 times that of the diet ingested, and it was assumed that nitrite in saliva was formed in vivo by the reduction of nitrate. We can not give a clear explanation for this reduction mechanism yet, but nitrite in saliva might be produced by the action of micro-organisms in alimentary tract, perhaps in mouth.