Calorie restriction reduces the buildup of nuclear DNA mutations in mice, with variable effects across tissues and genomic regions

Cells constantly incur damage to nuclear DNA. Most damage is repaired quickly, but a small share of mutations accumulates over time. Researchers evaluated whether long-term calorie restriction (CR) affects the rate at which those somatic mutations build up across the genome in mice.

Researchers compared mice fed roughly 30% fewer calories than controls allowed to eat freely. They examined mutations across the full genome in multiple tissues, assessing both base substitutions (single-letter swaps) and insertion/deletion events (letters added or missing). The study reported changes in mutation burden across tissues and across regions of the genome.

• Calorie restriction reduced the overall level of mutations in several tissues. Both substitution mutations and insertion/deletion mutations were diminished to varying degrees depending on tissue and mutation type.

• Tissue differences were clear. Liver cells showed a larger reduction in accumulated mutations under calorie restriction than kidney or brain cells.

• The largest mutation reductions occurred in the least-active parts of the genome—regions with few expressed genes or genes not active in those cells. One interpretation offered is that active genomic regions already experience frequent repair, so reductions in damage affect inactive regions more noticeably.

The results show that lowering calorie intake in mice can slow the accumulation of certain classes of nuclear DNA mutations. That provides a molecular correlate for a long-standing observation: calorie restriction extends lifespan and alters many aging markers in multiple species.

Calorie restriction triggers broad metabolic and physiological changes. Improved DNA maintenance may be only one of many mechanisms by which CR affects aging and health. The study does not demonstrate that mutation accumulation is the dominant cause of aging in normal animals. It also does not establish that the same pattern or magnitude of benefit would appear in humans.

Why the genomic-region result matters

Active regions of the genome are frequently transcribed and often show more robust repair activity. If CR reduces the rate of damage uniformly, the additional benefit will be more visible in genomic regions that normally receive less repair attention. The finding that inactive regions gained the most relative reduction in mutations is consistent with that logic, but it does not identify the biochemical steps responsible.

For researchers: the study supports further work to dissect which aspects of CR (lower metabolic rate, altered signaling, stress responses, shifts in repair pathway activity) actually reduce mutation formation or improve repair. It also suggests measuring mutation burdens by tissue and genomic context when testing interventions.

For readers considering diet changes: the mouse data show a molecular effect of calorie restriction, but mice and humans differ, and long-term calorie restriction has trade-offs and risks in people. These results are relevant to understanding mechanisms of aging and to designing interventions that might reproduce the beneficial molecular effects without the downsides of severe long-term restriction.

Calorie restriction in mice resulted in lower accumulation of nuclear DNA substitutions and insertion-deletion mutations across multiple tissues, with the strongest effects in liver and in less-active genomic regions. The finding links an established longevity intervention to a measurable reduction in genomic damage, while leaving open how much that reduction contributes to aging outcomes compared with CR's many other effects.