EFFECT OF MISO (JAPANESE SOYBEAN PASTE) AND NACL ON DMBA-INDUCED RAT MAMMARY-TUMORS

An AIN-76A diet supplemented with miso (Japanese soybean paste) reduced the incidence (p = 0.05, Fishers exact test) and delayed the appearance (p = 0.04, log rank test) of dimethylbenzfa]anthracene (DMBA)-induced mammary adenocarcinomas in female Sprague-Dawley rats. A Nad-supplemented AIN-76 A diet (containing the same amount of Nad as in the miso-supplemented diet) also delayed the appearance of tumors (p = 0.02, log rank test) compared with the A IN-76A control diet. The miso- and Nad-supplemented diet treatment groups showed a trend toward a lower number of cancers per animal, a trend toward a higher number of benign tumors per animal, and a trend toward a lower growth rate of cancers compared with controls. However, no statistical differences in the total number of tumors per animal or growth rate of the cancers were observed in the miso, NaCl, and control groups. Both miso and NaCl supplementation resulted in increased water intake and urine output but no change in the growth of the animals. These data suggest that miso consumption may be a factor producing a lower breast cancer incidence in Japanese women. (Nutr Cancer 14, 103–109, 1990). © 1990, Taylor & Francis Group, LLC. All rights reserved.