No change in spontaneous mutation frequency or specificity in dietary restricted mice

It is well known that dietary restricted rodents live longer and are generally healthier than their ad libitum fed counterparts, with fewer tumors. Additionally, while dietary restriction appears to reduce the frequency of chemically induced mutation in laboratory animals, relatively little is known regarding the effect of dietary restriction on spontaneous mutational events. Although spontaneous mutation rates are generally low compared with chemically induced events, spontaneous mutations accumulate in most tissues over the lifetime of the animal and are therefore expected to contribute significantly to spontaneous neoplasia. It is generally presumed that dietary restriction results in less oxidative damage and a lowering of the mutation frequency. Here we report the results of dietary restriction on mutation frequency and specificity in lacI transgenic mice aged 6 and 12 months. Unexpectedly, no changes were observed in either the frequency or specificity of mutation in dietary restricted mice, compared with ad libitum controls. We therefore conclude that dietary restriction appears to have no appreciable effect on spontaneous mutation, at least in chromosomal DNA.