No one knows yet whether glucosamine raises or lowers your risk of dementia. A 2026 University of Florida study linked the popular joint supplement to a 25 percent higher chance of sliding from mild memory problems into dementia, while two earlier UK studies, each of nearly 500,000 people, linked it to a lower dementia risk. All of these are links, not proof, and they looked at very different groups of people.
What did the new glucosamine study find?
The study, published in Nature Metabolism in June 2026, used artificial intelligence to review UF Health patient records from 2012 to 2024. It focused on people with mild cognitive impairment (MCI) or dementia. About 8 percent had glucosamine use on record: 2,750 people with MCI and 1,896 with dementia.
After adjusting for age, sex and demographics, glucosamine users with MCI were about 25 percent more likely to progress to dementia. Among people who already had dementia, glucosamine users had about a 25 percent higher risk of death. In the MCI group, there was no difference in deaths.
The team also proposed a reason. Brains from people who died with Alzheimer's had unusually high levels of sugar chains attached to proteins, which the researchers call hyperglycosylation. In mice bred to develop an Alzheimer's-like disease, glucosamine raised those sugar levels in the brain and worsened memory. In healthy mice, it didn't.
The researchers are careful about what this means. Co-author Matt Gentry called the finding "an association and not proof of causality." Senior author Ramon Sun described the results as preliminary and said they need to be tested in a human clinical trial.
Didn't earlier studies say glucosamine lowers dementia risk?
Yes, and that's why this story is complicated. Two large studies used the UK Biobank, which follows about half a million adults in the United Kingdom.
A 2022 study of 495,942 people, followed for a median of 11 years, found glucosamine users had a 13 percent lower risk of dementia after adjusting for other factors. The link held for vascular dementia but was not significant for Alzheimer's.
A 2023 study of 494,814 people found a 16 percent lower risk of dementia, including lower risks of Alzheimer's and vascular dementia. A genetic analysis pointed the same way.
About 1 in 5 people in these studies said they took glucosamine. Both teams cautioned that their data can't prove cause and effect, and the 2023 team said randomized trials are needed. They also flagged a catch: glucosamine use was self-reported once, with no details on dose or how long people took it. And people who take supplements may simply live healthier lives, which can make a supplement look better than it is.
Why do the glucosamine studies disagree?
There are a few likely reasons:
Different people. The UK studies tracked a broad group of adults to see who developed dementia. The Florida study looked only at people who already had memory problems or dementia.
A more vulnerable brain. The Florida team suggests glucosamine's effect may depend on context, with the Alzheimer's brain more vulnerable than a healthy one. That would fit their mouse results.
No trials yet. All of the human findings come from observational data. None can rule out that something else about glucosamine users explains the results.
Put simply, the earlier studies speak to adults without dementia, and the new one raises a question for people whose memory is already slipping.
Does glucosamine even work for joint pain?
The evidence is shaky. The NIH's National Center for Complementary and Integrative Health (NCCIH) says it's "still uncertain" whether glucosamine and chondroitin help knee osteoarthritis symptoms.
Expert groups disagree. The American College of Rheumatology/Arthritis Foundation and the Osteoarthritis Research Society International advise against glucosamine for knee arthritis. The American Academy of Orthopaedic Surgeons lists it among supplements that may help. A two-year US trial of 572 people found glucosamine and chondroitin did no better than placebo at slowing loss of joint space, and a 2008 study found glucosamine sulfate no better than placebo for hip arthritis.
In the US, glucosamine is sold as a dietary supplement, which the FDA does not approve before it's sold. In some other countries, certain forms are sold as prescription drugs.
Is glucosamine safe?
According to NCCIH, large studies haven't found major safety problems. But there are known cautions:
Blood thinners. Glucosamine and chondroitin have been linked to a higher risk of bleeding in people taking warfarin.
Blood sugar. Glucosamine may raise blood sugar in some people.
Shellfish allergy. Glucosamine may come from shellfish shells, so an allergic reaction is a concern.
Asthma and glaucoma. The Mayo Clinic notes glucosamine might worsen asthma and might raise eye pressure.
Pregnancy. Little is known about its safety during pregnancy or breastfeeding.
Common side effects include nausea, heartburn, diarrhea and constipation.
What should you do if you take glucosamine?
There's no reason to panic, and no reason to ignore it either. A few practical steps:
Make sure glucosamine is on the medication list your doctor and pharmacist see.
If you, or a parent you care for, have mild memory problems or dementia, ask the doctor whether glucosamine still makes sense. That's the group where the new warning sign showed up.
If you take it for knee pain, ask whether it's actually helping.
If you take warfarin or manage diabetes, check with your doctor before starting or stopping any supplement.
The bottom line
A 2026 study linked glucosamine to faster progression in people with mild memory problems, and to a higher risk of death in people with dementia.
Earlier UK studies of nearly 500,000 adults linked glucosamine to a lower dementia risk.
All of these human findings are links, not proof. None of the studies was a randomized trial.
Glucosamine's benefit for joint pain is uncertain, and it may interact with warfarin and raise blood sugar in some people.
If you or an aging parent takes it, especially with memory concerns, bring it up with your doctor.
More from Healthy Again
The Popular Joint Pill Tied to Dementia (Sept. 30, 2026)
Sources
Healthy, Again. is health news, not medical advice. Talk to your doctor before changing any medicine or supplement.