A popular over-the-counter supplement taken by countless older adults to help boost joint health could be tied to faster Alzheimer's progression, according to new research.
Study Findings
The University of Florida team behind the study say people with early memory problems who reported using glucosamine were more likely to go on to develop dementia than those who didn't take it. The findings, published in the journal Nature Metabolism, do not prove the supplement causes dementia. But they do raise a red flag and point to a suspect pathway in the brain's chemistry that might speed up the disease in some people.
Experts stress this is an association, not a final verdict - and no one should bin their tablets without speaking to their GP or specialist first.
What Did the Study Find?
Researchers used AI to comb through health records from 2012 to 2024, focusing on people diagnosed with either Alzheimer's and related dementias or mild cognitive impairment (MCI), which is often an early warning sign. Glucosamine use was fairly common: roughly 8% of patients in both groups reported taking it.
After adjusting for age, sex and other factors, the team found those with MCI who took glucosamine had a 25% higher chance of later developing dementia than non-users. Among people already living with dementia, glucosamine use was linked to a 25% higher risk of death during the study period. That pattern wasn't observed in the MCI group, suggesting that the supplement's effects may differ depending on how far the disease has progressed.
What Could Be Happening in the Brain?
The researchers homed in on a metabolic pathway that decorates proteins with complex sugar structures - think of them as tiny 'tags' that help proteins fold properly, travel to the right place in cells and do their jobs. In Alzheimer's, the team found signs that this sugar-tagging system is cranked up too high.
Glucosamine - being a sugar-related molecule that can cross the blood-brain barrier - can feed into the same pathway. In mouse experiments designed to mimic aspects of Alzheimer's, giving glucosamine boosted the attachment of sugar tags inside cells. The mice then performed worse on tests of social memory, which measures the ability to recognise and remember other individuals.
When scientists dialled down that sugar-tagging activity chemically, memory scores improved. And in human brain tissue from people with Alzheimer's, the researchers saw much higher levels of these sugar attachments compared to healthy controls. Put together, it suggests this isn't just a side-effect of the disease - it may be actively helping to drive it.
Should You Stop Taking Glucosamine?
The study does not prove glucosamine causes dementia, and it won't apply to everyone in the same way. If you take glucosamine for your joints, speak to your GP before stopping. They can look at your full health picture, including memory symptoms, other medicines and your reasons for taking the supplement.
If you've been advised to take glucosamine and have no memory concerns, your clinician may suggest carrying on while the evidence is reviewed.
