A new study raises questions about glucosamine and Alzheimer’s disease—here’s what to know.
Reviewed by Dietitian Madeline Peck, RDN, CDN
Key Points
- A popular supplement, glucosamine, may contribute to Alzheimer’s disease progression.
- People with Alzheimer’s who took glucosamine saw a higher five-year death rate .
- These findings may help guide future treatments that target metabolic pathways.
Glucosamine, a popular over-the-counter supplement commonly used to alleviate joint pain, may contribute to Alzheimer’s disease progression, according to new research.
With millions of Americans taking glucosamine each year to provide relief from arthritis or common aches and pains, the findings from a recent study published in Nature Metabolism raise new questions about how this widely used supplement may interact with brain health, specifically in those who are already cognitively impaired.
Alzheimer’s disease is a complex neurodegenerative disorder characterized by progressive cognitive decline and memory loss. While researchers have identified many biological factors associated with Alzheimer’s, including metabolic changes in the brain, the underlying causes driving the disease remain unknown.
In this study, researchers focused on a specific metabolic process called glycosylation—the attachment of sugar molecules to proteins in the body—to better understand how it may contribute to Alzheimer’s disease progression. Because glucosamine plays a role in the metabolic pathway that supports glycosylation, researchers wanted to determine whether the supplement could influence brain changes linked to Alzheimer’s disease.
How Was the Study Conducted?
If you’re confused about how glucosamine relates to glycosylation, you’re not alone. It’s helpful to understand glycosylation first, which is a normal cellular process where sugar molecules get attached to proteins in the body. That process helps regulate how those proteins function and communicate with other cells. While glycosylation is normal, researchers in this study hypothesized that abnormal glycosylation may play a role in the progression of Alzheimer’s disease.
Glucosamine became a focus of this study because it’s an amino sugar that the body naturally produces and uses to build important structural molecules, including those molecules found in cartilage and connective tissues. This is why glucosamine supplements are commonly marketed to support joint health, and many adults take them regularly.
However, in this study, researchers were interested in a different role glucosamine may play in the body, as it can also enter a metabolic pathway that produces molecules involved in glycosylation. The researchers wanted to understand whether increasing glucosamine could influence glycosylation in the brain of an individual affected by Alzheimer’s disease.
To investigate this connection, researchers analyzed a range of samples. First, they studied electronic health record data from more than 65,000 people with cognitive impairment, including individuals with dementia and mild cognitive impairment. Amongst this sample, they compared people who took glucosamine with those who did not. Next, they analyzed brain tissue from mice with Alzheimer’s-like symptoms as well as postmortem human brain tissue from people who had Alzheimer’s disease to identify metabolic changes in the brain that may contribute to disease progression.
“Given that about 7.2 million Americans ages 65 and older live with Alzheimer’s disease, we estimated that many were also taking glucosamine for joint health,” Ramon Sun, Ph.D.one of the study’s authors, wrote in an article published in The Conversation. “We hypothesized that this sugar amine may be contributing to cognitive decline.”
What Did the Study Find?
Researchers found that individuals with Alzheimer’s disease who took glucosamine were 25% more likely to die within five years from Alzheimer’s progression than those who didn’t. They also found that people with mild cognitive impairment who took glucosamine were 25% more likely to progress fully to Alzheimer’s disease than those who did not take glucosamine.
To better understand why this might be happening, researchers turned to the mice with Alzheimer’s-like symptoms. They found that reducing abnormal glycosylation improved memory-related symptoms in the mice. Next, the researchers tested glucosamine in the mice. Because glucosamine can enter the metabolic pathway involved in glycosylation, they wanted to see what kind of effect increasing its availability would have. In the mice with Alzheimer’s-like symptoms, glucosamine increased abnormal glycosylation and worsened memory-related symptoms. However, healthy mice given glucosamine did not experience these changes. This suggests that the effect may only relate to brains already affected by Alzheimer’s disease.
While glycosylation is a normal process in which sugar molecules attach to proteins throughout the body, researchers found that in brains affected by Alzheimer’s, some proteins had abnormally high levels of these sugar molecules attached, a condition known as hyperglycosylation. They believe these abnormal changes may interfere with how proteins function, potentially contributing to memory loss and disease progression in those with Alzheimer’s.
How Does This Apply to Real Life?
While more research is needed, these findings suggest that glucosamine use may warrant caution in people with Alzheimer’s disease or mild cognitive impairment. That said, the researchers did not explicitly state that people should stop taking glucosamine based on this study alone. Instead, they emphasize the need for clinical trials and additional research before any changes to clinical recommendations are made.
Glucosamine is classified as a dietary supplement by the Food and Drug Administration, which means that it’s not as heavily regulated as a prescription medication, and anyone can purchase it over the counter. And while the supplement is considered safe and effective for joint health, it may be harmful for brain health in an individual who is already experiencing cognitive decline.
Beyond glucosamine, the study points to a promising new area of Alzheimer’s research. Rather than focusing only on amyloid-beta plaques and tau tangles—two abnormal protein deposits in the brain that serve as the main hallmarks of Alzheimer’s disease—these findings suggest that abnormal glycosylation may also play a role in disease progression.
Overall, the findings add to a growing body of research that metabolic changes may do more than just occur alongside Alzheimer’s disease, instead, they may actively contribute to how it develops and progresses. While these results aren’t enough to change clinical recommendations, they may be helpful in guiding future treatments that target metabolic pathways, like glycosylation.
Our Expert Take
This new study, published in Nature Metabolismraises important questions about glucosamine use in people with Alzheimer’s disease or mild cognitive impairment. That said, more research, especially clinical trials, is needed before experts can recommend that people stop taking glucosamine. In the meantime, individuals with Alzheimer’s disease or concerns about cognitive health should speak with a healthcare provider before starting or stopping any supplement, including glucosamine.
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