A commonly-used over-the-counter supplement taken by millions of older adults to support joint health may be associated with accelerated Alzheimer's progression, new research indicates.
Scientists at the University of Florida behind the study discovered people experiencing early memory problems who reported taking glucosamine were more likely to develop dementia than those who didn't use it, according to Science Daily.
The research, published in the journal Nature Metabolism, doesn't prove that the supplement directly causes dementia. However, it does raise concerns and identifies a worrying pathway in the brain's chemistry that could potentially speed up the condition in some people.
Crucially, experts stress this represents an association rather than definitive proof - and nobody should throw away their tablets without first consulting their GP or specialist.
What did the study find?
Glucosamine is widely available in chemists and supermarkets for joint pain and stiffness. It's usually derived from shellfish shells or corn, with many people taking it daily in the hope of easing knee and hip issues.
The new analysis examined years of health records alongside experiments in mouse models and human brain tissue. Together, the evidence suggests glucosamine may contribute to a 'sugar-tagging' mechanism in the brain that's already disrupted in Alzheimer's - potentially worsening the situation.
Researchers utilised artificial intelligence to analyse health records spanning 2012 to 2024, focusing on individuals diagnosed with either Alzheimer's and related dementias or mild cognitive impairment (MCI), which commonly serves as an early indicator. Glucosamine usage was relatively prevalent: roughly 8% of patients in both groups reported taking it.
Having taken into account age, sex and other factors, the team found that those with MCI who used glucosamine had a 25% higher probability of subsequently developing dementia compared with non-users.
Amongst those already living with dementia, glucosamine usage was linked to a 25% increased risk of death throughout the study period. That pattern was not observed in the MCI group, suggesting that the supplement's effects may differ depending on the stage of the disease's progression.
What could be happening in the brain?
The researchers concentrated on a metabolic pathway that attaches complex sugar structures to proteins - imagine them as tiny 'labels' that help proteins fold correctly, travel to the right location within cells and carry out their functions. In Alzheimer's, the team found evidence that this sugar-tagging mechanism is functioning excessively.
Glucosamine - being a sugar-related compound capable of crossing the blood-brain barrier - can contribute to the same pathway. In mouse experiments designed to replicate aspects of Alzheimer's, administering glucosamine enhanced the attachment of sugar labels within cells.
The mice subsequently performed more poorly on assessments of social memory, which evaluates the capacity to recognise and recall other individuals. When researchers chemically reduced that sugar-tagging activity, memory scores showed marked improvement.
Examining human brain tissue from Alzheimer's patients, the team observed significantly elevated levels of these sugar attachments compared to those from healthy individuals. Taken together, this suggests the process is not merely a by-product of the disease - it may be actively contributing to its progression.
Should you stop taking glucosamine?
The research does not establish that glucosamine causes dementia, and it won't affect everyone identically. If you take glucosamine for your joints, consult your GP before discontinuing.
They can assess your complete health situation, including memory symptoms, other medications and your reasons for taking the supplement. If you've been recommended to take glucosamine and have no memory concerns, your clinician may advise continuing while the evidence is examined.
