Fact checked by Nick Blackmer
:max_bytes(150000):strip_icc():format(jpeg)/GettyImages-2228306373-d620f19d88ed44f8b6caa86bae621b4f.jpg "Close-up of an unrecognizable woman's hands holding a jar of capsules. Health concept.")
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- Glucosamine is a supplement marketed to relieve joint pain.
- Studies designed to test glucosamine’s efficacy have yielded mixed results.
- If you plan to take glucosamine, track your symptoms before and afterward to see if you notice a difference.
Supplements are more popular than ever, and one in particular has been in the spotlight recently: glucosamine. Millions of adults take it each year to improve joint health and relieve osteoarthritis symptoms, but a recent study found that the supplement may be linked to accelerated dementia in some people.
The finding isn’t necessarily a reason to stop taking glucosamine, experts say, but it does raise questions about whether its potential risks outweigh benefits. So how effective is glucosamine, anyway? Here’s what the science says.
What Is Glucosamine and What’s It Believed to Do?
Glucosamine is an amino sugar found naturally in the body that stimulates the formation and repair of cartilage, which cushions your joints. Because cartilage tends to break down with age and glucosamine isn’t found in meaningful amounts in food, many people turn to supplements hoping to boost joint health.
Manufacturers usually harvest glucosamine from shellfish or produce it in a laboratory before it hits store shelves, where it’s often paired with chondroitin sulfate—another substance found in cartilage—and sold as a tablet or capsule. Product labels claim that the supplements support joint health or improve comfort and mobility.
Are Glucosamine Supplements Effective?
Claudette Lajam, MD, an orthopedic surgeon at NYU Langone Orthopedic Center and professor of orthopedic surgery at the NYU Grossman School of Medicine, said she’s observed that the combination of glucosamine and chondroitin sulfate “seems to help some people who have arthritis.”
But while it may be helpful for some individuals, the scientific support for glucosamine’s benefits “is fairly weak at best,” said Nathan K. Endres, MD, an associate professor of orthopedics and rehabilitation at the University of Vermont Larner College of Medicine.
Only a small number of studies have investigated glucosamine's effects on joints other than the knee, with limited evidence that it improves pain or joint structure, according to the National Center for Complementary and Integrative Health. The bulk of the research, meanwhile, has centered on knee osteoarthritis, but results have been mixed.
A 2008 study found that, compared to placebo, glucosamine and chondroitin sulfate failed to produce a “clinically important difference” in joint space width, a measure of joint health, while a 2016 study suggested that a placebo was actually more effective than the supplements in reducing knee pain.
At the same time, a 2022 meta-analysis found that, compared with placebo, adults with knee osteoarthritis taking the supplement combination had a “statistically significant advantage” in a self-administered questionnaire commonly used to evaluate symptoms.
Still, “even in the studies that show some benefit,” Endres said, “it’s not like leaps and bounds [of difference].”
Is Glucosamine Safe?
While evidence for glucosamine’s effectiveness is thin, it’s generally considered safe for most people. Both experts noted that glucosamine is popular in part because its known side effects are relatively mild. They include headaches and gastrointestinal symptoms like nausea and constipation.
In a new study, researchers did find an association between glucosamine use and faster cognitive decline in people with mild cognitive symptoms, as well as a higher risk of death within five years for Alzheimer’s patients. However, the research showed only a link between glucosamine and these outcomes; it didn’t prove cause and effect.
People who move less, the population most likely to take glucosamine, are already at a higher risk of dementia, Lajam explained, so reduced mobility may be driving the association rather than the supplement itself. More research is needed to better understand the connection between glucosamine and dementia.
Still, glucosamine does come with some more established risks. It can increase the chances of bleeding in people taking the blood thinner warfarin, and combining glucosamine with acetaminophen may reduce the effectiveness of both.
Additionally, supplements like glucosamine are largely unregulated by the Food and Drug Administration. Because of this, Endres says, “you don't know exactly what you're buying” when it comes to exact ingredients and dosage. If you find a product that works for you, Lajam recommended sticking with it.
She also advised speaking with a doctor before taking glucosamine, and tracking your pain before trying the supplement and again after 30 days to help decide whether it’s worthwhile.
One side effect of glucosamine, she said, is that “it makes your wallet skinnier.” If you’re going to spend your money, “you want to make sure you’re spending money on something that’s going to help you.”
