Glucosamine Supplement Linked to Accelerated Alzheimer's Progression in New Study
Researchers found individuals with mild cognitive impairment taking the popular joint health supplement were 25% more likely to develop dementia.
A study published in Nature Metabolism suggests that glucosamine, a common supplement for joint health, may accelerate the progression from mild cognitive impairment to Alzheimer's disease. Researchers at the University of Florida analyzed medical records and examined laboratory mouse models and human brain tissue to investigate the compound's effects.
The study found that individuals with mild cognitive impairment who took glucosamine supplements were 25% more likely to progress to dementia compared to non-users. Among those who already had dementia, glucosamine users also showed a higher mortality rate.
Glucosamine is a naturally occurring compound that is a building block for cartilage, the connective tissue that cushions joints. It is concentrated in cartilage and contributes to its strength and elasticity. The primary reason people take glucosamine as a dietary supplement is to support aging joints.
According to senior author Ramon Sun, Ph.D., professor of biochemistry and molecular biology at the University of Florida, the body has a natural regulatory mechanism for producing sugar chains attached to proteins, a process called glycosylation. These sugar chains are essential for proteins to fold correctly, be transported within cells, and interact with other proteins.
Supplemental glucosamine bypasses the body's natural regulatory checkpoints. The study's findings on human brain tissue revealed an excess of these sugar chains on proteins in the brains of individuals with Alzheimer's disease. The researchers hypothesize that this overabundance may interfere with the function of proteins crucial for nerve cell communication.
Experiments with mice showed that while healthy mice given glucosamine did not exhibit an increase in these sugar chains or a decline in memory, mice with an Alzheimer's-like disease demonstrated an increase in sugar chains and worsened memory test performance after glucosamine administration.
The researchers noted limitations in their study, primarily relying on medical records which may not fully capture all supplements taken by participants. They acknowledged that over-the-counter supplements are not always documented, and records may not accurately reflect dosage, brand, or consistency of use.
"The finding should therefore be treated as a safety signal that warrants controlled human research, but it did not—could not—reach a conclusion that glucosamine causes Alzheimer’s disease," stated Neil Levin, senior nutrition education manager at Now, a manufacturer of glucosamine supplements.
The study focused on patients with dementia and mild cognitive impairment and did not examine cognitively healthy individuals. The researchers emphasized that the findings do not suggest that glucosamine poses a risk to those taking it solely for joint health. However, they recommend that individuals with a diagnosis of cognitive impairment or dementia who take glucosamine discuss its use with their doctor.
Future research, including well-designed, double-blind clinical trials, is needed to further evaluate the impact of glucosamine on cognitive decline in patients with dementia.