Study links joint supplement glucosamine to increased dementia risk – experts explain if YOU need to be worried

A joint pain supplement taken by millions of Britons may be linked to an increased risk of dementia, a major new study suggests.

Researchers in the US found that glucosamine – commonly used to ease joint aches and pains – was associated with a 25 per cent higher risk of progressing from mild memory problems to Alzheimer’s disease.

The study, led by scientists at the University of Florida, also found the supplement was linked to a 25 per cent increase in risk of death among patients already living with dementia.

However, experts stress the findings do not prove the supplement causes dementia.

‘A lot of these people actively take an over-the-counter supplement that could be making their disease progression worse,’ said lead researcher Dr Ramon Sun.

Glucosamine is a naturally occurring amino sugar that serves as a building block for the cartilage and connective tissues in the body. It is one of the most popular supplements for osteoarthritis, particularly among older adults. 

Because of its widespread use, researchers investigated whether it could influence Alzheimer’s disease and related dementias.

The team analysed health records from 2012 to 2024, using artificial intelligence to identify patients with either mild cognitive impairment (MCI) – an early stage of memory decline – or dementia. They found that around 8 per cent of patients were taking glucosamine.

After adjusting for factors such as age and sex, those with MCI who used the supplement were significantly more likely to develop dementia. Among those who already had dementia, glucosamine use was also linked to a higher risk of death.

The study, published in Nature Metabolism, suggests the supplement may influence a key biological process involved in Alzheimer’s. Glucosamine can cross into the brain and feed into a pathway that adds sugar molecules to proteins.

Researchers found this pathway appears to be overactive in Alzheimer’s disease, potentially damaging brain cells. 

‘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,’ said co-author Dr Matt Gentry.

Experiments in mice supported this theory, showing glucosamine worsened memory problems – while blocking the pathway improved them.

Despite the findings, scientists are clear that the study shows only a link, not cause and effect. The research was observational, meaning it cannot prove that the supplement directly accelerates dementia.

‘While it’s an association and not proof of causality, it does raise an important clinical question,’ Dr Gentry said.

In the UK, glucosamine is typically sold as glucosamine sulphate or hydrochloride. However, its benefits are debated. 

The NHS and NICE do not routinely recommend glucosamine for osteoarthritis, with studies showing mixed results and generally modest pain relief at best.

While some trials suggest slight improvements in joint pain, others show little to no benefit – meaning many people may be taking it with limited upside.

Researchers say the findings add to growing evidence that metabolism plays a key role in Alzheimer’s disease. 

Further studies, including clinical trials, are needed to confirm whether glucosamine has a direct impact on brain health.