Alzheimer's Risk: The Common Supplement You Need to Rethink

A supplement taken by millions of older adults to ease joint pain may accelerate the progression of Alzheimer's disease, according to new research from the University of Florida.

The study, published June 9 in Nature Metabolism, found that people already showing signs of mild cognitive impairment were 25 percent more likely to develop dementia if they were taking glucosamine in supplement form than those who did not use the pill.

Researchers also found that among patients already diagnosed with Alzheimer's disease and related dementias, glucosamine use was associated with a 25 percent increase in the risk of death.

A Neuropsychologist’s Take on the Findings

Dr. Jessica McCarthy, a New Jersey-based neuropsychologist specializing in dementia assessment and neurodegenerative disorders, spoke with Newsweek about the discovery.

"The study continues to build evidence towards the hypothesis that Alzheimer’s disease is not just a function of increased presence of amyloid plaques and tau proteins, but rather, it’s a combination of the aforementioned factors, along with metabolic dysfunction and inflammation," McCarthy said. "Because glucosamine crosses the blood brain barrier, it may worsen an already overactive metabolic pathway, facilitating a heightened risk of disease progression in people with mild cognitive impairment and mortality in people already diagnosed with Alzheimer's.

"Working backwards, sugar, in the form of glucose, doesn’t 'cause' Alzheimer’s, and completely eliminating carbohydrates isn’t the solution, either. The brain needs to decide when to utilize glucose to burn energy, and which to use in maintenance. In Alzheimer’s, it’s hypothesized that the brain has an issue with metabolic allocation, impacting inflammation."

She went on to say that as a neuropsychologist, her greatest concern following the report is people continuing to want to take shortcuts when it comes to their health in the form of over-the-counter pills and supplements.

"I'm not saying that supplements as a whole are problematic but taking supplements without understanding how they may interact with organ systems, pre-existing conditions, as well as other medications, can lead to problems, as this most recent study is suggesting," McCarthy said.

What Is Glucosamine?

Glucosamine is one of the most widely used dietary supplements in the U.S., sold over the counter and marketed primarily for joint pain and cartilage support as we age. Because it is used frequently by older adults—the same population most at risk for Alzheimer's disease—the University of Florida research team set out to examine whether the supplement could be influencing the course of neurological decline and its increase in recent years.

To do so, researchers used artificial intelligence to analyze anonymized patient health records from UF Health, collected between 2012 and 2024. They focused on two groups: patients diagnosed with Alzheimer's disease and related dementias, and those with mild cognitive impairment, a condition that can sometimes be a precursor to Alzheimer's.

Working with collaborators Yi Guo and Jiang Bian, the team identified 1,896 patients with dementia and 2,750 with mild cognitive impairment who reported taking glucosamine—approximately 8 percent of each group.

After adjusting for variables including age, sex, and demographics, the data showed a clear pattern: glucosamine users with mild cognitive impairment had significantly higher odds of progressing to dementia. The team also conducted advanced imaging studies of human brain tissue and used mouse models of Alzheimer's disease to look for biological mechanisms that might explain the association.

The researchers found evidence suggesting that glucosamine may interact with metabolic processes in the brain that are already disrupted in Alzheimer's patients. Notably, the increased mortality risk was only observed in patients who already had a dementia diagnosis, not in those with mild cognitive impairment—a finding the researchers say suggests the supplement's effects may vary depending on how far the disease has progressed.

What Should Glucosamine Users Do?

The researchers acknowledge that the findings are observational and that clinical trials will be needed to confirm them. Nevertheless, they say the work adds to a growing body of evidence pointing to metabolic dysfunction as a key driver of neurodegenerative disease.

"From a behavior modification and a modifiable risk factor to dementia standpoint, the research is robust on how we can improve both brain health and metabolic health," McCarthy said. "Exercising with moderate intensity at least three or four times a week at least 45 minutes at a time with a focus on building muscle mass, getting adequate sleep and prioritizing sleep hygiene, implementing a Mediterranean diet when it comes to nutrition, and taking your prescribed medications go an incredibly long way with regards to maintaining overall health and staving off some of these neurodegenerative processes.

"If you are interested in supplements, it's not something you should be doing independent of speaking with your medical team. We also know that a healthy and active brain is one that is stimulated, engaged intellectually and socially, fed well, and provided adequate time to rest. These areas have strong research support to help manage metabolic health and inflammation and should be the first line of defense when it comes to maintaining a healthy brain."