Growing older is inevitable, but what happens inside our cells as we age may be more complicated than scientists once believed.
New research reveals a striking difference between men and women: a cellular process that clears out damaged material appears to slow with age in certain male cells while remaining relatively stable in female cells.
Researchers at the Sanford Burnham Prebys Medical Discovery Institute published their findings in the journal Aging Cell on September 27, 2026.
At the center of the study is autophagy, the body’s natural cellular recycling process. Scientists have long examined how this process changes with age, often focusing on its presumed decline. But the new findings suggest that the story is not so straightforward.
The discovery matters because aging may affect this cellular process differently by sex and cell type, raising new questions about how scientists understand the changes happening inside our bodies over time.
A Longstanding Assumption Faces New Evidence
Researchers questioned whether cellular recycling consistently declines as humans age.
“We commonly see people cite this idea that autophagy declines with age, but the actual evidence for this in humans is very thin,” said Caroline Kumsta, PhD, senior author of the study.
Led by Tatiana Moreno, PhD, the research team examined several types of human cells, including skin fibroblasts, blood immune cells, and laboratory-generated neurons.
The analyses included skin fibroblasts from 44 donors, induced neurons from approximately 22 donors, and blood immune cells from approximately 23 donors. Some individuals contributed to more than one analysis.
Rather than assuming that aging affected these cells similarly, the researchers directly measured their recycling activity.
Men’s and Women’s Cells Showed Different Aging Patterns
The clearest differences emerged when researchers compared cellular activity by sex.
In skin fibroblasts from male donors, autophagy activity decreased with age. Female donor fibroblasts remained relatively stable.
Researchers observed another pattern in laboratory-generated neurons. Those produced from female donors showed increasing recycling activity with age, while male donor neurons did not demonstrate the same increase.
These results suggest that cellular responses to aging depend partly on biological sex and the specific type of cell being examined.
However, the findings do not establish that women age more slowly than men. The study measured particular cellular processes rather than overall aging rates.
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Related: 10 Dark Realities of Aging in America That Many Seniors Face in Silence
Greater Cellular Recycling Did Not Always Mean Better Physical Function
One unexpected finding was that higher recycling activity sometimes accompanied poorer physical performance in older adults.
Among participants aged 70 and older, researchers found that increased autophagy was associated with reduced physical function.
Higher activity in blood immune cells was associated with lower aerobic fitness and slower walking speed. Other cellular measurements related to grip strength, body mass index, and resting heart rate were examined, although not all associations were statistically significant.
The researchers also conducted a small exercise investigation involving five adults aged 77 to 88.
After completing a 12-week fall-prevention program, most participants showed reduced autophagy activity in blood immune cells alongside improved physical performance.
The pilot was too small to establish that exercise caused these changes or reversed cellular aging.
Why the Discovery Could Change Aging Research
The findings raise questions about how scientists measure cellular aging and evaluate potential interventions.
Researchers found that changes in genes associated with autophagy did not always match changes in actual recycling activity.
That distinction matters because measuring genetic activity alone may not accurately reveal how efficiently cells process and recycle material.
“Autophagy and aging are so much more nuanced than previously assumed,” Moreno said.
The research team is now pursuing larger investigations with collaborators at the University of California San Diego to understand better the relationship between exercise, cellular recycling, and physical function.
The study has not identified a treatment to slow aging. Its significance lies in challenging the idea that more cellular maintenance activity necessarily means better health.
As interest in longevity grows, the findings challenge the idea that cellular aging follows a predictable pattern.
Could understanding these differences between men’s and women’s cells eventually lead to more personalized approaches to healthy aging?
