Millions of people take glucosamine for joint pain. However, a new study suggests the popular supplement may be linked to faster progression from mild cognitive impairment to dementia. While the research does not prove cause and effect, scientists say the findings warrant closer investigation.
Glucosamine has long been one of the world’s most popular supplements for aching joints. It is often sold over the counter and widely used by older adults. People commonly take it to ease symptoms of osteoarthritis and support joint health.
However, a new study from researchers at the University of Florida suggests the supplement could have an unexpected downside for people with cognitive impairment.
Published in Nature Metabolism, the research found that people with mild cognitive impairment (MCI) who reported taking glucosamine were more likely to progress to dementia than those who did not use the supplement. However, while the study does not prove that glucosamine causes Alzheimer’s disease, the findings raise important questions about whether the supplement may influence how the disease develops.
Study Findings
Researchers analysed de-identified electronic health records from UF Health collected between 2012 and 2024 using artificial intelligence.
The team examined thousands of patients diagnosed with either mild cognitive impairment or Alzheimer’s disease and related dementias (ADRD).
Among them, glucosamine use was relatively common. Nearly 1,900 patients with dementia and around 2,750 people with MCI reported taking the supplement. This represented approximately 8% of each group.
After adjusting for age, sex and demographic differences, researchers found that people taking glucosamine had a 25% higher likelihood of progressing from MCI to dementia.
The study also found that patients already living with Alzheimer’s disease or related dementias who took glucosamine had a 25% higher risk of death during the study period. This increased mortality was not observed among people with MCI alone.
Senior author Dr Ramon Sun said the findings deserve attention because glucosamine is so widely used.
“A lot of these people actively take an over-the-counter supplement that could be making their disease progression worse.”
Why Might Glucosamine Affect The Brain?
The researchers did not stop at analysing patient records. They also investigated what might be happening inside the brain.
Their experiments identified an overactive metabolic pathway involved in attaching sugar molecules to proteins, a biological process known as glycosylation. While glycosylation is essential for normal cell function, researchers found excessive activity in brains affected by Alzheimer’s disease.
Glucosamine is a naturally occurring sugar-related compound that can cross the blood-brain barrier. Once inside the brain, it may contribute to this sugar-tagging process.
The researchers believe that in an Alzheimer’s brain, where this pathway already appears overactive, additional glucosamine could potentially worsen the imbalance.
The findings suggest that abnormal metabolism may be an important driver of Alzheimer’s progression, alongside the well-known build-up of amyloid plaques and tau tangles.
Animal Experiments Supported The Findings
To better understand the biological mechanism, the team also studied genetically modified mice.
Researchers gave glucosamine to mice, which then developed increased sugar-tagging activity within brain cells and performed worse on tests measuring social memory. When researchers chemically reduced the excessive sugar-tagging process, the mice’s memory performance improved.
The scientists then examined donated human brain tissue from people with Alzheimer’s disease. Compared with healthy brain samples, Alzheimer’s brains showed substantially higher levels of the same sugar-processing activity identified in the mouse studies.
Together, these findings suggest the metabolic changes may actively contribute to disease progression rather than simply being a consequence of Alzheimer’s.
Should I Stop Taking Glucosamine For My Joint Health?
This was an observational study, which meant that it found an association rather than proving that glucosamine directly causes faster cognitive decline. Additionally, other factors that the medical records did not capture may have influenced the results.
For most people taking glucosamine for joint pain, there is currently no recommendation to stop the supplement based on this study alone. Instead, this study suggests that properly designed clinical trials are needed before healthcare professionals can confidently recommend changes to glucosamine use.
However, individuals living with mild cognitive impairment, Alzheimer’s disease or other forms of dementia may wish to discuss their supplement use with their healthcare provider.
The findings also add to growing evidence that metabolism plays a much larger role in neurodegenerative diseases than previously thought. Understanding these pathways could eventually lead to new treatments that target Alzheimer’s disease beyond traditional approaches aimed at amyloid plaques and tau proteins.
