What to know about the safety of this popular supplement for arthritis
Researchers found that using glucosamine may be linked to accelerated progression and higher mortality in Alzheimer's disease and related dementias.
Author of the article:Washington Post
Washington Post
Richard Sima
Published Jul 24, 2026 • Last updated 21 hours ago • 5 minute read
Glucosamine
Photo by Mona Mäkelä /Adobe Stock
Glucosamine is a popular supplement that millions of American adults – an estimated 3.5 percent – use regularly for osteoarthritis and joint pain.
Until recently, studies seemed to indicate that the supplement was safe to use, even if its effectiveness on improving joint pain is slight, said Raquel Largo, a senior rheumatology researcher at the Jiménez Díaz Foundation in Madrid. “I think that there’s a lot of controversies regarding the real effect of glucosamine.”
But new research may be concerning to those who use it. A recent study published in Nature Metabolism adds a potential finding that people with Alzheimer’s or their caregivers may want to take into account when considering glucosamine, said Largo, who was not involved in the study. Researchers found that using glucosamine may be linked to accelerated progression and higher mortality in Alzheimer’s disease and related dementias.
Whether that is true or not – and many questions remain – the study does raise an important point: If people have any signs of dementia, “they really should be talking to a doctor about what they take and not take,” said Ramon Sun, an associate professor of biochemistry at the department of molecular and cellular biochemistry at the University of Florida and senior author of the study.
“There are so many things that we don’t know that will accelerate the disease or reduce the disease,” he added.
In the study, Sun and his colleagues analyzed clinical records from almost 25,000 patients diagnosed with Alzheimer’s disease and related dementias. The researchers found that patients who had documented use of glucosamine for at least a year after their diagnosis were 25 percent more likely to die in the next 10 years compared to patients who did not use glucosamine.
In contrast, using glucosamine did not increase mortality risk in patients with mild cognitive impairment, an intermediary stage between healthy aging and dementia. But using glucosamine was linked with a 25 percent higher chance of progressing from mild cognitive impairment to dementia.
The research did not look at healthy participants, but previous studies of glucosamine use in the general population did not demonstrate worsening of any disease, Largo said. (In fact, some research suggests glucosamine is linked to reduced cardiovascular and all-cause mortality, possibly because of reduced inflammation.)
When people take glucosamine, “the majority of it will come out as urine,” Sun said, “but there is a small percentage that will get into the cells and it becomes these sugar chains outside the cells. And that is universal. It’s the brain, the knee, the liver: It does it everywhere.”
These sugar chains, known as glycans, are attached to proteins and important for cellular function – and not just for energy. In the brain and nervous system, glycans are essential for neuroplasticity and proper neuronal communication. Too much or too little may not be good for brain function, Sun said.
When the researchers gave glucosamine to mice that carried Alzheimer’s disease-related genes, their social memory worsened and there were signs of increased glycans; this was not the case for mice without those genes that were given the supplement. Conversely, blocking an enzyme that synthesizes glycans improved the mice’s social memory.
But there are also major limitations to that study that call for additional research. The data linking glucosamine use and faster progression of dementia in humans is correlational and cannot show causation, and the researchers only accounted for sex, age and ethnicity as potential confounding factors that could explain the association, said Angela Zivkovic, a nutrition professor at the University of California at Davis who wasn’t involved in the study.
For example, people who take glucosamine because of joint pain may move less and be more physically frail, which is associated with higher dementia risk, Zivkovic said.
Researchers for the new study used a cutting-edge technique called spatial metabolomics to map out the amount of glycans in brains of Alzheimer’s patients as well as mice with Alzheimer’s-related genes, and they reported these brains had more glycans compared to healthy brains.
But the available techniques don’t make it possible to know if there is a general overabundance of glycans in the brain and how that is linked to dementia, Zivkovic said. “They used a really cool tool but applied it in a way that kind of missed a lot of the underlying biology.”
This kind of research is difficult to study because there are so many kinds of glycans that perform different functions.
“Glycomics is … sort of like the last frontier, and we have very little understanding of how it works,” Zivkovic said.
The evidence that glucosamine helps osteoarthritis pain is mixed at best, experts said.
Meta-analyses of previous studies tend to find that glucosamine has a “slight effect on pain” – when there was a statistical effect at all, Largo said.
Studies from larger, randomized controlled trials – the gold standard of biomedical research – find that glucosamine does not perform better than placebo.
“There is really no good double-blind placebo control study that shows that glucosamine is actually effective at minimizing joint pain,” Sun said. (The location of the osteoarthritis pain may matter; Largo said there is some research suggesting glucosamine may have a “moderate” effect on pain in the knee.)
Likewise, some studies suggest that glucosamine may help the structure of the joint, but the benefit is slight, Largo said.
As a result, many medical organizations do not recommend glucosamine for osteoarthritis patients.
Despite the lack of good evidence for glucosamine’s effectiveness, there is a reason the millions of osteoarthritis patients may still turn to it: There are few options for everyday pain or treatments to slow the progression of the disease.
NSAIDs (nonsteroidal anti-inflammatory drugs), such as aspirin and ibuprofen, are the only medications that are recommended. While they can be effective at controlling pain in the short-term, NSAIDs aren’t the best medications to use continuously. They come with their own risk of side effects and can be dangerous for older people or those with gastrointestinal problems, Largo said.
Funding for osteoarthritis research is low, despite the condition’s prevalence, because unlike cancer or dementia, for example, it does not kill you, at least directly, Largo said.
But osteoarthritis can not only lower quality of life; it can also cause people to move less, have problems working and increase risk for depression, cardiovascular issues and weight gain – which all impact longevity.
There needs to be additional research into the link between glucosamine and Alzheimer’s disease, experts say. “But the other side of the coin is: Is it worth it risking to take glucosamine, especially if it doesn’t really help with the joint pains at all?” Sun said.
Glucosamine is a popular supplement that millions of American adults - an estimated 3.5 percent - use regularly for osteoarthritis and joint pain.
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