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Could Taking a Popular Joint Supplement Be Risky for People With Dementia?
New research suggests glucosamine may have unexpected effects in people with mild to severe cognitive impairment
AARP (Igor Golovniov/SOPA Images/LightRocket via Getty Images, Getty Images)
Key takeaways
- A large study links regular glucosamine use to higher death risk in people with dementia.
- People with mild cognitive impairment taking the supplement were slightly more likely to develop dementia.
- The findings don’t prove cause, and factors like health and activity levels may play a role.
Like millions of Americans, you may be taking glucosamine for achy knees or even to prevent joint problems. It’s one of the most popular supplements worldwide: People spent more than $2.5 billion on glucosamine in 2025.
But recent research suggests there may be risks to its regular use among people experiencing mild cognitive impairment or who have various forms of dementia, including Alzheimer’s disease, Lewy body dementia, frontotemporal dementia and vascular dementia.
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In a study from the University of Florida reported in Nature Metabolism, people with dementia who used glucosamine for at least a year had an increased risk of death over 10 years. Glucosamine use also was associated with an increased risk of progression to dementia in people with mild cognitive impairment.
Alzheimer’s disease and other dementias affect more than 7 million people in the United States. Glucosamine is an over-the-counter supplement often taken for osteoarthritis, which affects about 33 million U.S. adults. As many as 1 in 4 older Americans take glucosamine for joint pain.
Some previous studies linked glucosamine supplements with a decreased risk of developing vascular dementia, while other studies have found no links between glucosamine and dementia.
In this new study, the researchers looked at the University of Florida Health systems’ electronic medical records from 2012 to 2024. They identified more than 24,400 people with Alzheimer’s disease and other dementias. About 8 percent of them took glucosamine for more than one year. Over 10 years, this group had a 25 percent higher risk of death, compared with people with dementia who did not take glucosamine.
Analysis of health records from nearly 42,000 people with mild cognitive impairment found that those who took glucosamine were slightly more likely to be diagnosed with dementia over 10 years, compared with people with mild cognitive impairment who did not take the supplement.
What does glucosamine do in the body?
Glucosamine is a key building block of cartilage, the shock-absorbing tissue in knees and other joints. Laboratory studies have shown that glucosamine has anti-inflammatory effects. It also can be used as a building block for a process called glycosylation, in which sugars tag, or attach to, protein and fat molecules. This process is crucial for brain cells, says study coauthor Ramon Sun, associate professor of biochemistry and molecular biology at the University of Florida. “These sugars coat the outside of cells, and they regulate pretty much everything: how a cell functions, how cells talk to each other and how they take up nutrients,” Sun says.
In separate lab experiments, the Florida researchers found higher concentrations of sugar tagging in the brains of people with dementia as well as mice engineered to have dementia, compared with healthy brains. The sugar tagging was more concentrated in brain regions involved in memory, suggesting it may contribute to memory loss and other symptoms of Alzheimer’s disease and other dementias.
The researchers also manipulated the sugar-tagging system in the mice engineered to have dementia. Mice given glucosamine for two weeks showed increased densities of sugar tags in their brain tissue and lower scores on a standard memory test. When researchers blocked an important pathway in the sugar-tagging system, the density of sugar tags decreased and memory scores improved.
The sugar tagging doesn’t appear to be related to the clumping brain proteins seen in Alzheimer’s disease, Sun says. “We could reduce glycosylation and improve memory [in mice], but we don’t touch the tau or amyloid-beta proteins,” which are hallmarks of Alzheimer’s.
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“You hear a lot about plaques and [protein] tangles,” says study coauthor Matthew Gentry. “But it’s not just plaques and tangles. There’s also a metabolic component that we’re just scratching the surface on,” adds Gentry, professor and chair of biochemistry and molecular biology at the University of Florida.
“A strength of this study is they investigated the same question using a variety of different methods — medical record data, human brain tissue, mouse studies,” says Dr. Heather Whitson, distinguished professor of neuroscience and director of the Duke Aging Center in Durham, North Carolina.
Still, Whitson says, the research does not show that glucosamine is the direct cause of the worsening dementia. People taking glucosamine may have had more pain and inflammation or generally worse health, she says, and those factors contributed to worse outcomes.
Other explanations for the glucosamine connection
People taking glucosamine also may have been less physically active due to joint pain or mobility limitations, says Dr. Gwenn Garden, codirector of the Duke/UNC Alzheimer’s Disease Research Center and chair of the UNC neurology department. “Glucosamine is typically used for people who have osteoarthritis and may have lower levels of physical activity because they’re dealing with joint pain, and we know that is a risk factor for more rapid decline,” she says. Future studies should explore this possibility, as well as other factors that may explain the results.
Sun envisions future research to test the effects of lifestyle interventions — such as physical activity and a healthy diet — on the sugar tagging process.
While Sun estimates as many as 1 million Americans with dementia may be taking glucosamine, professional organizations such as the American College of Rheumatology and the Arthritis Foundation recommend against taking glucosamine for osteoarthritis, stating a lack of evidence. Science-based interventions for joint pain include physical activity and weight loss, as well as medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids.
The Centers for Disease Control and Prevention recognizes more than 20 arthritis-appropriate evidence-based programs that have been shown to reduce arthritis pain and improve flexibility and independence.
“This is a great reminder that we need to talk to our doctors about the use of supplements,” says Juan Rodriguez, AARP’s vice president of brain health. “Physical activity, eating healthier, losing weight and managing other risk factors can improve both joint health and brain health.”
“The practical message is not one of fear; it’s one of awareness,” Gentry says. “People should be aware that supplements are biologically active, and we don’t know what all of them do.”
The key takeaways were created with the assistance of generative AI. An AARP editor reviewed and refined the content for accuracy and clarity.
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