EFSA’s Panel on Dietetic Products, Nutrition and Allergies (NDA) found the claim to be unsubstantiated despite Merck referencing, “studies in patients with osteoarthritis, in healthy subjects, in animals and in vitro”. Twelve of those studies were human intervention studies and there were 13 reviews.
But the Panel said the human studies which it favours did not provide a strong case that glucosamine could help joints in healthy people.
“The evidence provided by consensus opinions/reports from authoritative bodies indicates that normal cells and tissues are genetically (gene expression) and functionally different from osteoarthritic cells and tissues and therefore may respond differently to intervention with exogenous substances.”
“The Panel also notes that the evidence provided for the proposed mechanisms which would explain an effect of glucosamine on joint cartilage is weak,” it said.
“The Panel concludes that a cause and effect relationship has not been established between the consumption of glucosamine and maintenance of normal joint cartilage in individuals without osteoarthritis (OA).”
“The Panel considers that results from studies in subjects with OA relating to the treatment of symptoms of this disease (e.g. erosion of articular cartilage, and reduced function of joints) with glucosamine cannot be extrapolated to the target population.”
“Therefore, no scientific conclusions can be drawn from the studies on patients with OA for the substantiation of the claimed effect in subjects without OA.”
Glucosamine and chondroitin have both been rejected under the general function, article 13 claims register, and the opinions have already been cited by local agencies such as the advertising watchdog in the UK - the Advertising Standards Authority (ASA).
The NDA opinion can be found here.