Provided is a carcinogenesis suppressing agent, cancer therapeutic agent, or agent for mitigating adverse reactions of anticancer agents, which is ingestible on a daily basis and with low prevalence of adverse reactions, comprising a reduced coenzyme Q as an active ingredient. The agents are useful as pharmaceuticals, cosmeceutical, cosmetics, foods such as functional foods (supplements, health aid foods, nutritional supplementary foods, nutrient-fortified foods, nutrient-adjusted foods, health beverages, foods for specified health uses, foods with nutrient function claims), animal drugs, animal feeds, or animal foods.
