A widely used supplement taken by tens of millions of Americans for joint pain may be associated with faster progression toward Alzheimer's disease, according to a major new study from the University of Florida. Researchers found that people with mild cognitive impairment who reported taking glucosamine were 25% more likely to progress to full dementia than those who did not use the supplement. Among people already diagnosed with Alzheimer's, glucosamine use was also linked to a 25% higher risk of dying within five years.
The findings were published on June 9, 2026, in the journal Nature Metabolism and are drawing significant attention from doctors, researchers, and the millions of older Americans who take glucosamine daily.
However, the researchers are clear: this study does not prove that glucosamine causes Alzheimer's or speeds up its progression. What it shows is an association — a statistical link that warrants further investigation and, potentially, caution.
What Is Glucosamine and Why Do So Many People Take It?
Glucosamine is an amino sugar that the body naturally produces. It is also sold over the counter in capsule form as a remedy for joint pain and arthritis, particularly of the knees. More than 40 million Americans take it each year, making it one of the most popular dietary supplements in the country.
It is not considered an essential nutrient, and there is no recognized condition caused by glucosamine deficiency. Most people take it based on reports that it helps with joint comfort. Because it is sold as a supplement rather than a drug, it does not go through the same rigorous pre-market testing required of prescription medications.
For years, glucosamine has been generally regarded as safe. That makes this new research all the more striking.
How the Study Was Conducted
The University of Florida team used artificial intelligence to analyze more than a decade of deidentified health records from the UF Health system, covering the period from 2012 to 2024. The dataset included records from approximately 24,000 patients with Alzheimer's disease and related dementias and about 41,000 patients with mild cognitive impairment.
Researchers identified patients who reported taking glucosamine and compared their health outcomes to similar patients who did not. About 8% of both groups reported glucosamine use — representing 1,896 patients with dementia and 2,750 with mild cognitive impairment.
After controlling for age, sex, and other demographic factors, the analysis showed that glucosamine use was associated with a 25% higher likelihood of progression from mild cognitive impairment to dementia.
The team did not stop at health records. They also used advanced imaging technology to examine human brain tissue collected after death, and they studied mouse models of Alzheimer's disease. Their goal was to look for a biological reason that might explain the association they found in the data.
What they found was suggestive. Glucosamine, which can cross the blood-brain barrier, appeared to feed into a chemical process inside brain cells called protein glycosylation — the addition of sugar molecules to proteins. In the brains of people with Alzheimer's disease, this process is already overactive and is thought to contribute to the buildup of harmful proteins. Glucosamine, the researchers suggest, may be adding more fuel to an already disrupted process.
Study Limitations and What Remains Unknown
The researchers and outside scientists are quick to note several important limitations.
First, this is a retrospective observational study — meaning researchers looked backward at existing health records rather than running a controlled experiment. This type of study can identify associations but cannot prove causation. People who chose to take glucosamine may have differed from non-users in ways that the analysis could not fully account for, even after statistical adjustments.
Second, the health records used in the study came from a single hospital system in Florida. The patient population may not represent all Americans or people around the world.
Third, the study looked only at people who already had cognitive impairment or Alzheimer's disease. It does not tell us whether glucosamine poses any risk to healthy people with no signs of memory trouble.
The researchers say the findings are preliminary and will need to be confirmed in a proper clinical trial before any public health recommendations can be made.
What Should You Do with This Information?
The study's authors are not calling for people to immediately stop taking glucosamine. What they are urging is a conversation with a doctor — particularly for older adults who already have early signs of memory loss.
The finding is especially relevant given how commonly glucosamine is used by seniors, exactly the age group most at risk for cognitive decline. As the study's senior author, Dr. Ramon Sun, noted, millions of people with Alzheimer's and related dementias are actively taking a supplement that could potentially be affecting their disease progression.
For people without any cognitive concerns, this study does not provide enough evidence to justify alarm. But for anyone with a family history of Alzheimer's, existing memory difficulties, or a diagnosis of mild cognitive impairment, it may be worth discussing current supplement use with a healthcare provider.
As always, the safest approach to any supplement — especially one taken long term — is to periodically review whether it is still appropriate given your current health status.
Source: University of Florida / UF Health. Published in Nature Metabolism, June 9, 2026.
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