Turku sugar studies. VII. Principal biochemical findings on whole saliva and plaque

Plaque and whole saliva samples of the subjects of the Turku sugar studies were analyzed for several enzymes and biochemical compounds. Strict xylitol diet maintained throughout the study a 50% lower quantity of plaque than the sucrose of fructose diets. Decreased plaque and whole saliva lactate concentration, diminished activity of salivary amylase, and reduced hydrolysis rate of sucrose in plaque and whole saliva were observed in relation to xylitol consumption. The xylitol diet also reduced the ratio of glucose to proteins in plaque. On the other hand, increased activity in plaque of alpha- and beta-glycosidases (against p- and o-nitrophenyl derivatives), fucosidase and aspartate transaminase, as well as increased activity of proteinases and lactoperoxidase in saliva were found in connection with xylitol consumption. The fructose diet caused less clear differences when compared to sucrose, but the experiments indicated a selectivity of the effects of dietary carbohydrates on the biochemistry of whole saliva, plaque and salivary glands. The results contribute in explaining the cariostatic effects of xylitol and the lower coriogenicity of fructose when compared to sucrose.