Scientists discover a surprising paradox in how our cells age
Scientists have discovered that the body's cellular recycling system behaves very differently during aging than previously believed, with higher activity sometimes linked to worse physical health. A small study suggests that even gentle exercise could help restore more youthful cellular recycling patterns in older adults.
Key points
- New research challenges the idea that cellular recycling uniformly declines with age.
- Autophagy changes varied by cell type and by sex in the study.
- A small pilot study suggested gentle exercise may lower autophagy in older adults.
A new study from Sanford Burnham Prebys Medical Discovery Institute reports that autophagy, the cellular process that collects and breaks down damaged proteins and waste, does not simply decline with age as long assumed. The findings were published on September 27, 2026, in the journal Aging Cell.
Researchers collected blood and skin samples from volunteers aged 23 to 72 who reported no chronic medical conditions, and converted some skin cells into induced neurons to study three cell types. They analyzed RNA transcripts and also directly measured how quickly cells carried out autophagy.
Varying results by cell type and sex
The study found that autophagy activity changed in different directions depending on the cell type and the participant's sex. In skin cells from male participants, recycling activity decreased with age, while in female skin cells it remained relatively stable. Induced neurons from female participants showed an increase in autophagy with age.
The researchers also found that expression of autophagy-related genes did not reliably indicate actual recycling rates. Senior author Caroline Kumsta said the results show cellular recycling rates are altered differently with age in each cell type and differently by sex.
It is exciting to have this exercise intervention that may have a positive effect on autophagy and healthy aging
— Caroline Kumsta
Exercise and physical function
Among participants aged 70 and older, greater autophagy activity was associated with poorer physical function across all three cell types. In blood cells, higher autophagy was linked to lower aerobic fitness; in skin cells, to a higher BMI; and in induced neurons, to weaker grip strength, lower metabolism and a higher resting heart rate.
In a pilot study, five participants aged 77 to 88 completed a 12-week gentle exercise program focused on reducing fall risk. Preliminary results suggested exercise could lower autophagy activity in blood cells toward levels more typical of younger adults, and participants showed improvements in physical performance.
