The Marukome company calls itself “the leading miso manufacturing company in Japan.” As a corporate brochure says, “world-renowned Japanese longevity is deeply related to the traditional food of Japan.” Miso is probably the most traditional food of Japan, in the sense that the Japanese eat a lot of it per capita, far more per capita than people in any other country. They eat lots of fish, too, but that’s not unusual.
A corporate brochure for the Marukome company that I got at the recent Fancy Food Show makes many health claims for miso. Some involve the whole product. Two are interesting. 1. “Miso soup also helps prevent heart disease and diabetes.” This is vague, unfortunately. 2. “In 1981, researchers at Japan Cancer Center announced that miso soup lowers the risk of stomach cancer when consumed every day. Miso soup also lowers the risk of other cancers including liver cancer.” This sounds like a survey result: daily consumption of miso was associated with lower risk of various cancers. At least it is specific enough to check.
The brochure also makes health claims based on components: Vitamin B2, Vitamin B12, Vitamin E, “Enzyme”, Sabonin, etc. Each somehow improves health — for example, Vitamin B12 “reduces mental fatigue.” What interests me is that “improves immune function” isn’t on the list, nor does the list mention the microorganisms that grow in miso. Improves immune function I believe to be the main benefit of miso and the reason it reduces cancer. Judging by this brochure, you’d think this is a new idea in Japan, where lots of fermented foods are eaten. In Japan I met someone (a nurse) who said that perhaps a third of Japanese think that to be healthy you should eat fermented foods regularly. Perhaps the usual belief is that they improve digestion and better digestion somehow wards off cancer.