A new study by lead author Hiromitsu Watanabe, published in the journal of Toxicologic Pathology is titled, “Beneficial effects of Miso with reference to radiation injury, cancer and hypertension.”
More from the Abstract:
This review describes effects of miso with reference to prevention of radiation injury, cancer and hypertension with a twin focus on epidemiological and experimental evidence. Miso with a longer fermentation time increased crypt survival against radiation injury in mice. When evaluating different types of miso provided by different areas in Japan, miso fermented for a longer period increased the number of surviving crypts, and 180 days of fermentation was the most significant. Dietary administration of 180-day fermented miso inhibits the development of azoxymethane (AOM)-induced aberrant crypt foci (ACF) and rat colon cancers in F344 rats. Miso was also effective in suppression of lung tumors, breast tumors in rats and liver tumors in mice. The incidence of gastric tumors of groups of rats given NaCl was higher than those of the groups given miso fermented for longer periods. Moreover, the systolic blood pressure of the Dahl male rat on 2.3% NaCl was significantly increased but that of the SD rat was not. However, the blood pressures of the rats on a diet of miso or commercial control diet (MF) did not increase. Even though miso contains 2.3% NaCl, their blood pressures were as stable as those of rats fed commercial diet containing 0.3% salt. So we considered that sodium in miso might behave differently compared with NaCl alone. These biological effects might be caused by longer fermentation periods.
So, what is miso soup? The introduction from the study explains:
Miso (fermented soy bean paste), a traditional ingredient of the Japanese diet, is fermented from a mixture of soybeans with rice, wheat or oats and contains vitamins, microorganisms, salts, minerals, plant proteins, carbohydrates, and fat. Saponin inhibiting lipid peroxides, trypsin inhibitor, isoflavones, lecithin, colin, prostaglandin E and others are additional substances1. Miso is used on a daily basis as a flavor in soup and solid food in Japan and other parts of Asia and is an essential ingredient for Japanese cuisine. Even though there is no equivalent product in Western cooking, those who are familiar with miso have prized its almost unlimited versatility for cooking. For example, it can be used as bouillon, a rich meat stock in soups and stews2. It is considered to exert health-promoting benefits, relieving fatigue, regulating intestinal functions, aiding digestion, protecting against gastric ulcer, decreasing cholesterol and blood pressure, and preventing diseases associated with the lifestyles, like cancers.
Miso has been shown to be beneficial in treating radiation in Nagasaki and Chernobyl, according to the study. This is what prompted scientists to undertake new research. The older research is summarized as follows:
When the 2nd atomic bomb was dropped in Nagasaki on August 9th, 1945, physician Tatuichiro Akizuki, along with 20 employees, was taking care of 70 tuberculosis patients at “Uragami Daiichi Hospital” (St. Francis Hospital) about 1.4 km away from the hypocenter. However, these people including Dr. Akizuki did not have any acute radiation disease. Dr. Akizuki considered that this was the result of consuming cups of wakame miso soup (miso soup with garnish of wakame seaweed) every day4. Later, this was translated into English and became known in the West. In the Chernobyl of nuclear power plant accident on April 26, 1986, in the Ukraine, many Europeans consumed miso soup as a preventive measure for radiation diseases. Therefore, Dr. Akizuki can be considered to be the first person in Japan to point out radioprotective effects of miso for maintaining health.
Read more about Dr. Watanabe’s study with lab rats fed miso soup, click here.