The effect of long-term food restriction on tumours in rodents.

The effect of restricting food intake by approximately 20% was studied in rats and mice. Both species were fed as similar "natural" diet composed chiefly of cereals and bone meal. The duration of the rat study was 24 months, but mice were studied for their whole lifespan of 36 months. In the mice, restriction increased longevity, and in both species the incidence of tumours was reduced and the onset delayed. The effect upon the different types of tumour varied; some types appeared to be unaffected by restriction, but the most common types in each species, liver tumours in mice, pituitary, mammary and skin tumours in rats, were significantly reduced.