Glucosamine Supplements and Dementia: New Research Raises Concerns
Nearly 59 million Americans have been diagnosed with arthritis, a condition that causes joint pain and stiffness. And that might actually be an undercount: A huge chunk of adults have joint pain but haven't received an official diagnosis. So it's not exactly surprising that plenty of people are turning to supplements like glucosamine to try to ease discomfort and protect their joints.
But new research might have you thinking twice before walking down the supplement aisle: Glucosamine may have ties to the progression of dementia, as a new study published in Nature Metabolism suggests. This could be particularly important, since glucosamine is "one of the most popular supplements among older adults," says Ramon C. Sun, Ph.D., study co-author and professor of Biochemistry and Molecular Biology at the University of Florida College of Medicine.
What did the study find?
The research relied on an analysis of patient health records, along with supporting data from studying mice and human brain tissue. For the first part, the researchers analyzed the health records of people who visited University of Florida Health facilities between 2012 and 2024, zeroing in on patients who were diagnosed with Alzheimer's disease and related dementias (ADRD) or mild cognitive impairment (MCI). Overall, 8% of patients in both groups reported using glucosamine, which translated to 1,896 people with ADRD and 2,750 people with MCI.
After crunching the numbers, the researchers discovered:
- People with mild cognitive impairment who took glucosamine were 25% more likely to progress to dementia.
- Those who already had Alzheimer's disease or related dementias and used glucosamine were 25% more likely to die during the 10-year analysis period.
From there, the researchers studied genetically modified mice and discovered that glucosamine increased a process called glycosylation, in which chains of certain sugars called glycans attach to proteins inside cells. It's an important process in the brain, since it plays a role in how neurons communicate; this in turn affects learning and memory.
The increase was associated with worse memory, and when the researchers suppressed that process, the mice's memory improved. Finally, the researchers looked at the brain tissue of people with Alzheimer's disease and discovered that they had higher levels of glycosylation than people without Alzheimer's disease.
Ultimately, the researchers concluded that the process of glycosylation—which is a normal part of functioning—becomes overactive when someone has Alzheimer's disease or related dementias. Then when you add in glucosamine, it seems to fuel the disease, according to Sun.
What is glucosamine?
Glucosamine helps your body make molecules called glycosaminoglycans, which are part of cartilage, the flexible tissue that protects your joints and bones, according to the National Center for Complementary and Integrative Health (NCCIH). In supplements, glucosamine is usually paired with chondroitin, another component found in cartilage.
Glucosamine (and the combo of glucosamine and chondroitin) supplements are commonly used to treat joint pain. An estimated 3.5% of Americans report taking glucosamine, per 2023 research.
What's behind this link?
The link between glucosamine and dementia is complicated but worth exploring. But it's important to stress this: The study did not prove that taking glucosamine causes dementia or causes the disease to progress. Instead, it found a link between taking glucosamine and faster disease progression, but didn't determine that the glucosamine itself was fueling this.
Still, there is a connection. Sun flags glycosylation as something to consider.
"Glycosylation is the process by which cells attach sugar chains to proteins, and it shapes how those proteins fold, travel, and function," he explains—basically, how the proteins work. During the study, Sun and his fellow researchers found more of these sugar chains in tissue of people with Alzheimer's than from people without the disease. "We call it hyperglycosylation," Sun says.
The researchers also spotted this in two different mouse models of Alzheimer's disease; they saw changes involving amyloid and tau, two proteins linked to the development of dementia.
"That suggests it may be a shared feature of the disease rather than a quirk of a single model," Sun says. "The key point is that a brain with dementia and a healthy brain are not the same biological environment, and glucosamine doesn't appear to behave the same way in both."
Ultimately, glucosamine feeds into the pathway the body uses to make those sugar chains, Sun says. "Normally, the pathway has a main checkpoint that controls how much material gets made," he explains. "Glucosamine from a supplement is known to enter after that checkpoint, so it may bypass normal regulatory controls."
What should you do?
Experts stress that more research is needed before any real-world recommendations can be drawn. If you're taking glucosamine supplements—especially if you have a family history of cognitive decline or have been diagnosed with mild cognitive impairment—it's advisable to consult your doctor.
Until more is known, it's wise to be cautious. Consider discussing alternative joint pain management options with your healthcare provider.
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