The British Medical Journal first reviewed the available evidence in 2000 and decided the jury was still out with an ‘inconclusive’ verdict with regards to how much glucosamine helps. Back then it was recommended with chondroitin.
Since then better quality studies have been performed, most notably the GAIT trial (or Glucosamine/Chondroitin Arthritis Intervention Trial) published in 2010. This large, well designed trial studied over 600 knees and researched the effects of glucosamine treatments on both pain and structural joint damage. It often surprizes people that these two are not the same or directly related to each other. People can have severe joint pain with minimal joint damage, or conversely advanced joint degeneration but minimal pain. There’s also been a further review by the BMJ in 2010.
So what do we know regarding glucosamine supplementation and what did the high quality GAIT trial find?
The Key Points
· The trial found no statistically significant benefits of taking glucosamine (in a range of protocols) for either pain or protecting against joint damage.
· The trial did show some benefits so glucosamine did have an effect it just did not reach a level of statistical significance that can give us good confidence that it makes a real difference. The things they did find out are:
· Glucosamine Sulfate has better current evidence of effect than Glucosamine Hydrochloride
· Dosage should be 1500mg per day (taken as separate doses of 500mg taken three times a day)
· No serious adverse events have been reported with glucosamine.
· However, mild and infrequent side-effects include stomach upsets, constipation, diarrhoea, headaches, rash, hair loss, and puffy eyelids. If you experience any then you should stop taking it.
· If you have a shellfish allergy this can be an issue as most glucosamine supplements are produced from shellfish. Non-shellfish versions are available.
· Overall glucosamine is considered to be medically safe. Long term effects are not known.
· People currently taking glucosamine and reporting benefit are not advised to necessarily stop taking it, however there is not strong enough evidence to recommend its use as a primary treatment.
· Glucosamine supplements often have a high salt content so if you have high blood pressure or diabetes you would be best to avoid it. The detrimental health effects of high salt intake have a high level of scientific evidence.
· If you are going to try taking glucosamine a 3 months trial course has been previously recommended to assess the effect. If it is helping then you need to continue taking it for continued benefits; if it is not helping then stop taking it at this point.
· Previous guidance used to suggest taking it with chondroitin. The more recent better quality trials conclude that taking glucosamine in combination like this may limit absorption as the compounds compete together for absorption. Glucosamine Sulfate should therefore be taken on its own without any other compounds added (eg. chondroitin, MSM). Effects in reducing pain in OA were evident in the first few months, whether this is maintained in the long term is not known.
· Glucosamine supplementation should not replace targeted physiotherapy and exercise which have a higher level of substantiated evidence for benefit. Physiotherapy improves pain for many people especially with mild and moderate osteoarthritis on x-ray findings.
· Supplement quality (i.e. glucosamine content) varies widely so if purchasing go for a good quality brand to reduce the chances of this. All non-licensed medicines (ie. supplements) tend to have this problem.
There’s been a meta-analysis of many studies in 2015 published in the Nature journal. It claimed significant effects for glucosamine with chondroitin. The issue with this? Many of the trials included were poorer quality than the GAIT trial and the improvement in pain was only 0.5 on a scale of 0 to 10. Hardly worth the expense and arguably insignificant.
Your Take Home Points
- Glucosamine may help in the overall management of osteoarthritic joints but the evidence quality is low compared to physiotherapy and rehab. Glucosamine may be no greater than placebo or have very small effects.
- Many evidence-based guidelines do not recommend glucosamine as first line management however people already taking glucosamine and reporting personal benefit are not advised to stop taking it as it is considered to be safe.
- A significant caveat is the long term effects of a high salt intake which the supplements contain.
Look after your joints and enjoy an active life. Don't skimp the rehab!