Glucosamine is a compound naturally occurring in the human body and found in high concentrations in joints and cartilage. Glucosamine supplements are primarily used as a joint health supplement and are typically derived from shellfish. A few studies suggest glucosamine may provide minor cognitive benefits, though no clinical trials have tested whether glucosamine can prevent age-related cognitive decline or dementia. Glucosamine supplements are generally regarded as safe, though some drug interactions are known.
No clinical trials have tested whether glucosamine can prevent age-related cognitive decline or dementia.
Our search identified:
• 1 large observational study that examined the association between commonly prescribed drugs/supplements and cognitive function • A few preclinical studies on possible mechanisms of action
An observational study that included 482,766 participants from the UK reported that regular use of glucosamine was associated with better performance on reasoning and reaction time, but not on memory [1]. While encouraging, there are some limitations to this study. Because the data come from a cohort study and not a clinical trial, it is impossible to prove that glucosamine is responsible for the improvement in cognitive performance. Also, the data are based on self-reported medication use and no information on duration or dosage was collected.
In preclinical testing, glucosamine readily penetrated the blood-brain-barrier? and had a positive effect on ability to complete a cognitive task [2]. Glucosamine treatment also improved spatial memory and recognition memory in small mammals [3; 4]. There are several potential ways glucosamine may protect the brain. In small mammals and invertebrates, glucosamine promotes generation of mitochondria?, which power our cells [5]. Cell culture studies also suggest that glucosamine inhibits inflammation? [6; 7; 8].
No studies have reported whether glucosamine can improve cognitive function or slow decline in people with dementia.
Glucosamine is generally considered safe, though much of the safety data comes from studies in people with osteoarthritis. Several large meta-analyses of randomized controlled trials reported that glucosamine was as safe as placebo [9; 10; 11]. However, a clinical trial of patients with osteoarthritis reported that glucosamine treatment for three months increased intraocular pressure, the fluid pressure of the eye [12]. It is not yet clear if glucosamine treatment may affect glaucoma risk, or if glucosamine may be harmful in glaucoma patients.
Some drug interactions with glucosamine are known. Glucosamine should not be used if you take warfarin, anisindione, or dicumarol, as the combination may raise your risk of bruising and bleeding [13]. Glucosamine may also reduce the effectiveness of acetaminophen (Tylenol), certain chemotherapy drugs (doxorubicin, etoposide, and teniposide), and diabetes drugs (glimepiride, glyburide, insulin, pioglitazone, and rosiglitazone) [14]. Some glucosamine products also contain manganese, so excessive supplementation of such products may lead to manganese overdose.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Glucosamine supplements are available in capsule or tablet forms and are typically manufactured by processing shells of shrimp, lobsters, and crabs. Vegans/vegetarians and people with shellfish allergies may use glucosamine supplements derived from fungi (Aspergillus niger) or fermented corn [15]. Clinical studies have used daily doses ranging from 900 to 1,500 mg [9; 16]. Glucosamine sulfate appears to be superior to glucosamine hydrochloride, the latter of which was reported to be ineffective for osteoarthritis in clinical studies [17].
Information on dosing, safety, and drug interactions with glucosamine from the Mayo Clinic
Full scientific report (PDF) on Cognitive Vitality Reports