Abstract
Lactulose is adisaccharide which fructose bounds to galactose by β-1, 4 linkage, and has a sweetness of about 60 percent that of confectionary sugar. Lactulose is also known as a growth factor for Bifidobacterium. The effect of lactulose on cariogenic factors of Streptococcus mutanswas studied using the methods previously described (Infect. Immun., 19, 444, 1978; Int. Dent. J., 32, 33, 1982). Lactulose was not utilized for the growth and lactic acid production of serotype a-g strains of S. mutans. It did not serve as a substrate for plaque formation and cellular aggregation of S. mutans (a-g), and insoluble glucan synthesis by glucosyltransferase from strains used. In the cellular adherence experiment using lactulose, heat killed cells of S. mutans (c, g) labelled with 3H and GTase, the amount of cells that adhered to the smooth surface was almost O. Further, lactulose inhibited sucrose-dependent insoluble glucan synthesis and cellular adherence. Antibiotic-suppressed SD rats infected with S. mutansstrain 6715 were fed a diet containing 26% lactulose or 26% sucrose for 68 days. A significantly (p≤0.01) lower caries score (mean±SE, 33.6±2.1) was observed in the rats fed a diet containing lactulose than in the controls (71.1±3.6). These results indicate that lactulose, in addition to being a sweetening agent and a growth factor for Bifidobacterium, may be of value in controlling human dental caries. Lactulose is freely used in food and drink in Japan, without legal regulation requiringthat it be indicated on the label.
