These Two Unsuspecting Proteins May Predict Disability Years Later
Think about the things you do without giving them much thought.
Carrying groceries, getting up from a chair, or walking up a flight of stairs. Losing the ability to do these everyday tasks independently is one of the bigger concerns that comes with aging, but functional decline often happens gradually.
In a recent study1, researchers looked at whether changes inside the body could offer an earlier warning.
They focused on proteins in the blood, including two closely tied to kidney function and inflammation.
About the study
Researchers followed 230 adults ages 85 to 89 living in Kawasaki, Japan, as part of the Kawasaki Aging Well-being Project. None needed long-term care when the research began.
The team measured 29 proteins in their blood and tracked their health over the following years. They looked at who eventually received long-term care certification, which the researchers used as a measure of disability, as well as who died.
To see whether the patterns held up elsewhere, they also analyzed data from the InCHIANTI study, which followed adults in Italy for 15 years.
Two proteins were linked to higher disability risk
Two proteins stood out, beta-2-microglobulin (B2M) and cystatin C.
Both can provide information about kidney function because their levels tend to rise when the kidneys aren't filtering blood as effectively. Inflammation can also influence them.
People with higher B2M levels had a 35% higher risk of developing a disability, while those with higher cystatin C levels had a 42% higher risk of developing a disability.
The researchers then tested these associations in the broader Kawasaki cohort and the Italian group of adults ages 80 and older.
The relationship between the two proteins and disability risk remained, while some other associations from the initial analysis did not.
What this tells us about aging
B2M and cystatin C aren't necessarily causing disability.
Instead, they may work like other blood markers of aging, pointing to what's happening elsewhere in the body.
Kidney function naturally changes with age, but the kidneys do more than remove waste.
They help regulate fluid, electrolytes, blood pressure, and other processes that keep the body functioning normally.
Chronic inflammation can also affect multiple tissues and systems over time.
The researchers suggested that kidney dysfunction and inflammation may be part of the pathway behind functional decline in very old adults. Still, this was an observational study, so it can't show that higher levels of these proteins directly cause disability.
The findings don't mean someone with elevated B2M or cystatin C is destined to lose their independence.
They offer another piece of the puzzle for understanding why some people maintain physical function well into very old age.
How to support the systems behind the signal
You don't need to test these proteins yourself to take something useful from the research. Several everyday habits can support kidney, metabolic, and inflammatory health over time.
- Stay hydrated: Drinking enough fluids helps the kidneys clear waste efficiently, and heavy sweating or hot weather can leave you low on electrolytes.
- Keep sodium and ultra-processed foods in check: A balanced diet can support kidney and metabolic health.
- Move regularly: Physical activity supports metabolic health and helps regulate inflammation.
- Protect your sleep: Consistently poor sleep is associated with higher inflammation.
- Build strength: Resistance training helps preserve muscle and the physical capacity needed for everyday tasks, from carrying groceries to getting up from the floor.
These habits help maintain the physical capacity that supports independence as you get older.
The takeaway
Higher B2M and cystatin C levels were associated with greater disability risk in adults 85 and older.
The findings suggest that kidney function and inflammation may play a role in maintaining physical function later in life.