Effects of Miso in Reducing Risk of Liver and Gastric Tumors in Experimental Animals

Summary

When intact male C3H or ²⁵²Cf neutron irradiated B6C3F1 mice were fed on a diet containing 10% miso for 13 months, the frequency and multiplicity of liver tumors were significantly reduced in both cases. In irradiated females only a tendency for a similar reduction was observed. B6C3F1 male mice i.p. injected once with diethylnitrosamine (DEN) at 15 days of age and exposed to neutrons at four weeks of age also demonstrated a significantly decreased multiplicity of liver tumors when given a diet supplemented with either 10% miso or 20ppm biochanin A (5,7-dihydroxy-4-methoxyisoflavone). In Sprague-Dawley (CD) rats treated with 100ppm N-methyl-N’ nitro-N-nitrosoguanidine (MNNG) for 16 weeks in their drinking water, the net incidence of gastric tumors per mg MNNG intake was reduced with a miso-supplemented diet. In addition, when six-week-old rats were given s.c. injections of azoxymethane (AOM, 15mg/kg body weight) once a week for three weeks, and fed on diets containing 5%, 10%, or 20% miso and 10ppm biochanin A from five weeks of age, the numbers of aberrant crypt foci four weeks after the first administration of AOM were decreased with increasing miso in a dose-dependent manner. The present results indicate that administration of a miso-supplemented diet may inhibit the development of liver and gastric tumors, as well as aberrant crypt foci, in experimental animals.