A supplement millions of older Americans reach for to help protect their joints may carry a hidden risk for people with dementia.
Recent research links glucosamine to faster cognitive decline and a higher chance of death, but only in those who already have dementia or mild cognitive impairment (MCI), respectively.
The finding comes from University of Florida neuroscientists, who published their study in the scientific journal Nature Metabolism. The team used artificial intelligence to comb through anonymized UF Health records from 2012 to 2024, analyzing more than 50,000 patients diagnosed with dementia or MCI. About 8% of both groups reported taking glucosamine.
After accounting for age, sex, and other factors known to influence MCI and dementia risk, the researchers found two significant associations between glucosamine use and dementia progression:
- Faster progression: Among people with mild cognitive impairment, glucosamine users were 25% more likely to progress to full dementia.
- Higher mortality: Among patients who already had dementia, glucosamine use was tied to a 25% increase in the risk of death.
That mortality risk didn’t show up in the MCI group, suggesting the supplement’s danger is greatest once dementia is established.
Glucosamine can cross the blood-brain barrier, the protective filter between the body’s bloodstream and the brain. Once it crosses the barrier, it can feed into metabolic pathways that add sugar molecules to proteins. In the brains of people with Alzheimer’s, that process is already in overdrive, and glucosamine could add to the problem.
Co-author Matt Gentry explains in a summary of the findings:
“Proteins are the cell’s molecular machines, and many of them need sugar tags added in just the right way to fold correctly, travel to the right place and do their jobs. What we found in Alzheimer’s is that this sugar-tagging system appears to be overactive. The Alzheimer’s brain is adding too many of these sugar structures, and this seems to contribute to the disease rather than protect against it.”
The researchers note that this is an association pulled from patient records, not proof that glucosamine causes decline. A controlled clinical trial is needed to confirm the findings.
Still, if you have a dementia or MCI diagnosis and take glucosamine, it’s worth talking to your doctor about alternatives. For healthy adults, the research offers no cause for alarm.
For more of our coverage on dementia, check out “This Cooking Oil May Lower Your Risk of Deadly Dementia” and “The Hidden Food Ingredient That Could Increase Your Dementia and Stroke Risk.”
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