Both the number
of neoplasms per animal and the incidence of neoplasia are reduced by increasing the intake of soy sauce. The maximal
level of inhibition was observed at 20% soy sauce in
the diet. Exposure to nitrite neither enhances nor diminishes
the anticarcinogenic effects of soy sauce in the diet (data not
shown). They also found that soy sauce contains a substantial
antioxidative activity.