The effect of dietary restriction of varying duration on survival, tumor patterns, immune function, and body temperature in B10C3F1 female mice.

Seven groups of mice were maintained on different dietary programs varying with respect to restriction at various stages of life. Restriction was associated with less age-related decline in T-dependent immunological function and a slight but significant lowering of body temperature. The best mean and maximum survival and the lowest late-life mortality rate was found in the group restricted throughout life, but restriction during any part of the lifespan enhanced survival to some degree. The mean life spans of tumor-bearing animals tended to be greater in restricted than in nonrestricted groups, corresponding to an age-decelerating effect. Tumor frequency varied with the period of life during which restriction took place and was not always decreased in restricted animals. These latter results suggest that the mechanisms whereby dietary restriction influences the aging rate and tumor susceptibility may not be entirely identical.