Effect of Dietary Modifications on the Inhibition of Rat Caries by Sodium Metabisulfite

¹ National Institute of Dental Research, National Institutes of Health, Public Health Service, U.S. Department of Health, Education, and Welfare, Bethesda, Maryland

Supplementation of a cariogenic diet containing 0.3 per cent sodium metabisulfite with a full vitamin mixture had no effect on growth or on the inhibition of caries usually observed in the presence of this compound. There was also no effect when this diet or control diets were autoclaved before supplementation with the vitamin mixture.

There was little difference in the caries scores obtained when the agent was added to the diet for 1 day of each week, 1 week of each month, or for the first 2 weeks only. Average caries scores were reduced 42, 45, and 39 per cent, respectively, over untreated controls. This is compared with an 80 per cent reduction obtained when metabisulfite was fed for the full 90-day test period.

Bacteriologic sampling of the cecal contents of rats fed sodium metabisulfite in the diet revealed a 200-fold reduction in the lactobacillus population as compared with control rats. The coliform count was doubled, and the streptococcus count was halved in the experimental group. There was no apparent difference in the average cecal pH between the two groups, although there was considerable variation between individual samples in a group. Average free thiamin levels of the cecal contents in the metabisulfitefed group was reduced to half that of the control group.