Along with providing constituents that inhibit the onset of cancer,
tofu also works to eliminate the oxygen radicals that can trigger cancer.

The number of deaths caused by cancer has been increasing year by year. By 1981, cancer was the number one cause of death in Japan. According to the Ministry of Health, Labor and Welfare figures, approximately 290,000 people die of cancer every year, and this figure accounts for approximately 30% of overall mortality.
When looking at the causes of death according to physical region, the main causes in men are, from the highest, lung cancer, stomach cancer, liver cancer, and colon cancer; while for women the main causes are stomach cancer, colon cancer, liver cancer, and lung cancer.

When comparing the Japanese to Europeans and Americans, the Japanese have a high incidence of stomach cancer and a low incidence of colon cancer, while Europeans and Americans have the opposite situation. However, in recent years the incidence of colon cancer among the Japanese has increased. A relationship between this increase and food has been suggested as the westernization of eating habits has resulted in increased meat consumption and decreased dietary fiber consumption.

Other than eating habits, the incidence of cancer, a lifestyle-related disease, has been attributed to other factors such as carcinogens, genetics, environment, smoking, drinking, lifestyle rhythm and stress, etc.

The occurrence of colon cancer is facilitated by carcinogens or toxins generated by bad bacteria in the gut that aggravate the colonic mucosa. Furthermore, as the colonic mucosa absorbs moisture to create stool of reasonable consistency and quantity, carcinogens and toxins are also absorbed along with this moisture, and this can trigger various other cancers.

Since bad bacteria thrives on animal proteins and fats, high meat diets increase the levels of toxins in the body and can consequently increase the risk of cancer. For this reason, a review of dietary habits is necessary for the prevention of cancer.

An epidemiological survey (multi-person long-term statistical observation survey) has clearly shown that the incidence of cancer in any particular geographical region decreases in inverse correlation to the amount of soybean foods eaten.

The increased efficacy of soybean constituents, such as isoflavones, saponin and selenium, etc, that coincides with decreased meat consumption due to high soybean consumption, is currently drawing attention.

People with high levels of body fat produce oxygen radicals more easily. These can consequently act as triggers that can facilitate the development of cancer. Tofu can help prevent cancer as its low energy contributes little to fat increase while its constituents act to eliminate oxygen radicals.