Inhibition of the development of tumors or leukemia in mice and rats after reduction of food intake. Possible implications for humans.

Recent data referring to the influence of a restricted diet on the incidence of radiation-induced tumors and leukemia in rats and mice are reviewed. The incidence of tumors developing in rats exposed to total-body gamma irradiation was reduced from 93% to 35% in female rats and from 59% to 7% in male rats after restriction of food intake. In a similar study carried out on mice, the incidence of leukemia in irradiated mice of both sexes was reduced from 50% to 4% after restriction of food intake. Radiation-induced leukemia in mice is caused by a transmissible virus activated by total-body gamma irradiation. In most of the animal species investigated thus far, tumors, leukemia, and lymphomas were found to be caused by transmissible viruses. It appears that activation of some of these latent viruses could be prevented by restriction of food intake. If the results of experiments carried out on mice and rats are extrapolated for humans, it would follow that all of us (particularly those who have had multiple cases of cancer or leukemia among family members) should aim at holding our weight below the limits considered normal for our age, sex, and height. This appears particularly important for persons that have been exposed to large doses of ionizing radiation.