WHAT IS GLUCOSAMINE?
Have you had literally any form of issue with your joints? I’d be surprised if you haven’t heard of or had glucosamine sulphate suggested to you at any point.
Glucosamine is a supplement derived from shellfish. It’s present in most body tissues, with high concentrations in joints and cartilage and can be used to combat joint pain in both trained and non-trained individuals. The sulphate form is generally the most widely recommended for oral supplementation.
Studies have shown that supplementing glucosamine sulfate reduces the rate of collagen (joint tissue) degradation and symptoms of osteoarthritis (degeneration of joint cartilage and the underlying bone). Most research specifically looks at knee joint issues over any other joint so this may be a factor to take into account on a personal level when considering the efficacy of supplementing with glucosamine sulphate. It’s also worth pointing out that whilst glucosamine can slow the progression of osteoarthritis, it can’t cure it. It's thought that the mechanism of glucosamine hindering the rate of collagen degradation via interfering with inflammatory signaling underlies the effects observed with glucosamine.
Multiple studies have shown that glucosamine supplementation, in a dose-dependent manner with most effects at 3000mg, modifies a serum biomarker thought to be indicative of less collagen breakdown. Collagen synthesis doesn’t appear to be significantly affected - this links up with what was said above about glucosamine sulphate working to slow the progression of osteoarthritis, not undo or cure it. Collagen synthesis does technically occur when a cell is treated with high glucosamine concentrations, but this isn't practical with regards to oral supplementation in humans due to too low a dose reaching the blood.
These results have been observed in both high impact (football) and low impact (cycling) sports so may be more applicable to those of you reading this that participate primarily in strength sports.
Preliminary evidence suggested glucosamine supplementation could cause insulin resistance, however, follow up studies concluded that although there is some evidence for worsening glucose parameters in pre-diabetic groups, the majority of evidence suggests that there isn’t an adverse effect of supplemental glucosamine on insulin resistance in either healthy or pre-diabetic subjects (Simon et al., 2011).
The most commonly reported side effect of glucosamine supplementation is flatulence - if that’s no issue to you, you’re good to go! It has almost no other widely reported side effects.
Research has suggested that to supplement glucosamine, an effective method is to take 300 – 500 mg, three times a day, alongside food, for a total daily dose of 900 – 1,500 mg. The benefits of glucosamine are dose-dependent, and clinical studies that have used up to 2,000 – 3,000 mg a day, taken in several doses have reported beneficial results from this level of supplementation. As always - consult with a healthcare practitioner for an in-depth discussion regarding supplementation doses specific to you.
Most sources recommend supplementing with the glucosamine sulphate as opposed to any other form. Most research reports glucosamine HCl as ineffective at reducing joint pain and mitigating the effects of osteoarthritis, however, both glucosamine HCl and sulfate are hydrolyzed to form free glucosamine in the intestinal tract of humans following oral ingestion, but sulfate appears to have an apparent intestinal bioavailability of around 90% as opposed to free glucosamine's bioavailability of around 26% (Setnikar & Rovati, 2001). It goes without saying that we’d rather be ingesting the form with greater bioavailability - hence the recommendation of using the sulphate form.
TAKE HOME MESSAGE
Glucosamine sulphate may well be worth the investment if you’re experiencing joint pain, especially knee pain. It really does depend on the cause of the joint pain though. If it’s not linked to any of the processes like cartilage degradation that glucosamine sulphate works to curb, you’ll likely be better off addressing the issue via other means.
Following multiple meta analyses, there does appear to be a division between studies that are conducted independently (they tend to show promise, but less promising) and studies conducted by potential conflicts of interest (still positive, but more so than the independents). It isn’t clear whether these differences are due to the design of the studies or due to some researchers not publishing poor results, with both being possibilities.
Nagaoka, I., Tsuruta, A. and Yoshimura, M., 2019. Chondroprotective action of glucosamine, a chitosan monomer, on the joint health of athletes. International journal of biological macromolecules, 132, pp.795-800.
Reginster, J.Y., 2007. The efficacy of glucosamine sulfate in osteoarthritis: financial and nonfinancial conflict of interest.
Setnikar, I. and Rovati, L.C., 2001. Absorption, distribution, metabolism and excretion of glucosamine sulfate. Arzneimittelforschung, 51(09), pp.699-725.
Simon, R.R., Marks, V., Leeds, A.R. and Anderson, J.W., 2011. A comprehensive review of oral glucosamine use and effects on glucose metabolism in normal and diabetic individuals. Diabetes/metabolism research and reviews, 27(1), pp.14-27.
Vlad, S.C., LaValley, M.P., McAlindon, T.E. and Felson, D.T., 2007. Glucosamine for pain in osteoarthritis: why do trial results differ?. Arthritis & Rheumatism: Official Journal of the American College of Rheumatology, 56(7), pp.2267-2277.