Common Joint Supplement Glucosamine Linked to Accelerated Alzheimer’s Progression

Researchers at the University of Florida have identified a concerning association between glucosamine, a widely used over-the-counter supplement for joint pain, and an increased risk of rapid progression from mild cognitive impairment (MCI) to dementia. The findings, published in Nature Metabolism, suggest that disrupted metabolism may play a critical role in the advancement of Alzheimer’s disease and related dementias.

Mild cognitive impairment is characterized by memory or thinking deficits that exceed normal aging expectations but do not significantly disrupt daily functioning. The study’s authors warn that millions of Americans living with Alzheimer’s or related conditions may be inadvertently worsening their prognosis through routine supplement use.

Senior author Ramon Sun, Ph.D., director of the Center for Advanced Spatial Biomolecule Research and associate director for innovation at UF’s McKnight Brain Institute, highlighted the scale of the issue. “In the United States, there are about 7 million people living with Alzheimer’s and millions more with related dementias such as Lewy body or frontotemporal dementia,” Sun said. “A lot of these people actively take an over-the-counter supplement that could be making their disease progression worse.”

To investigate the potential link, the research team conducted a large retrospective analysis of deidentified electronic health records from UF Health, spanning from 2012 to 2024. Utilizing artificial intelligence, they examined patients diagnosed with Alzheimer’s disease and related dementias (ADRD) or MCI. Approximately 8% of participants in both groups reported using glucosamine, including 1,896 individuals with ADRD and 2,750 with MCI.

After adjusting for demographic factors such as age and sex, the analysis revealed that glucosamine users were 25% more likely to progress from MCI to dementia. Among patients who already had an ADRD diagnosis, glucosamine use was also associated with a 25% higher mortality risk. Notably, this mortality correlation was not observed in the MCI group, indicating the supplement may exert a stronger detrimental effect once dementia is fully established.

Matt Gentry, Ph.D., chair of UF’s Department of Biochemistry and Molecular Biology and a co-author of the study, emphasized the preliminary nature of the results. “The electronic health record data are very provocative,” Gentry said. “While it’s an association and not proof of causality, it does raise an important clinical question that now deserves much more attention.”

Beyond statistical associations, the researchers explored a biological mechanism to explain the link. They focused on a metabolic pathway involving glycosylation, a process where sugar structures are attached to proteins. While this is a normal cellular function, the team found evidence that it becomes excessively active in Alzheimer’s disease.

Glucosamine, a sugar-related molecule derived from sources such as shellfish shells or corn, can cross the blood-brain barrier. Once in the brain, it enters biochemical pathways that construct these complex sugar structures. The study suggests that the Alzheimer’s-affected brain is particularly vulnerable to this overactivity.

To validate these findings, the team conducted experiments using genetically modified mouse models of Alzheimer’s. Mice treated with glucosamine showed significantly increased sugar attachment to proteins and exhibited worse deficits in social memory compared to controls. However, when the researchers suppressed this sugar-tagging process with chemical treatments, memory performance improved, suggesting a direct role for excessive glycosylation in cognitive decline.

Further supporting this mechanism, the researchers examined human brain tissue from the UF Neuromedicine Brain and Tissue Bank. Specimens from Alzheimer’s patients displayed significantly higher levels of sugar attachment than those from healthy controls.

“Proteins are the cell’s molecular machines, and many of them need sugar tags added in just the right way to fold correctly, travel to the right place and do their jobs,” Gentry explained. “What we found in Alzheimer’s is that this sugar-tagging system appears to be overactive. The Alzheimer’s brain is adding too many of these sugar structures, and this seems to contribute to the disease rather than protect against it.”

The study also utilized a spatial technology developed in Sun’s laboratory, allowing the team to map thousands of molecules involved in metabolic processes. This approach provided detailed insights into the intricate pathways driving the observed changes.

Sun noted that addressing metabolic defects could complement existing research focused on amyloid beta plaques and tau tangles, the hallmark physical abnormalities of Alzheimer’s. “Our results suggest that altered metabolism is a significant contributor to Alzheimer’s progression and, in addition, addressing the metabolic defect could be an important complement to approaches focused on Alzheimer’s plaques and tangles,” he said.

Despite the compelling evidence, the researchers caution that these results are preliminary. The observational nature of the health record analysis means causality has not been established, and other factors unrelated to glucosamine may contribute to the outcomes. The team stresses that a controlled human clinical trial is necessary to determine whether glucosamine directly accelerates Alzheimer’s progression and to identify which patient populations may be most at risk before any changes to supplement guidelines are recommended.