Chemoprevention of cancers by miso and isoflavones

Abstract

Cancer is a genetic disease and numerous genetic changes have been disclosed in its developmental stages. Corresponding to those endogenous events, environmental factors including chemicals, oncogenic viruses, and radiation participate in the initiation, promotion, and progression stages. Furthermore, development of cancer is greatly influenced by nutritional factors such as from daily food consumption and the additives in these foods. Retinoids, vitamins, essence of tea, and vegetables are believed to be highly effective in chemoprevention of cancer. In this mini review, miso, a fermented soy product, and the purported active chemopreventative component of soybeans, isoflavones, were examined for their biological activity; 1) during recovery from radiation induced damage, and 2) as a possible chemopreventor of cancers. Thus far, promising results have been obtained for prevention of liver tumors in mice, breast tumors in rats, and intestinal tract tumors in rats. Since chemopreventors derived from natural foods are not cytotoxic, they need not be given to the recipients intermittently. Furthermore, we have found that a combination of tamoxifen with miso greatly reduced occurrence of mammary tumors in rats and therefore might be applicable to human cancers.