Doenjang fermented for 24 mo exhibited a two- to three-fold increase in antitumor effects on sarcoma-180-injected mice and antimetastatic effects in colon 26-M 3.1 cells in mice compared with the 3- or 6-mo fermented doenjang. The 24-mo fermentation was the most effective in preventing cancer by decreasing tumor formation and increasing natural killer cell activity in spleens and glutathione S-transferase activity in livers of mice.
Many things about doenjang stay roughly the same during fermentation. This study shows that what’s increasing (bacteria, etc.) is responsible for the anti-cancer effect, which supports my umami hypothesis (that we need fermented foods or something similar to be healthy).
I make yogurt rather than buy it so that I can ferment it a long time (e.g., 24 hours in a yogurt machine). The yogurt I make is much sourer than commercial yogurt.