Glucosamine: Does it really help knee pain?

After salsa class last night, we were sitting around doing cooldown stretches when my dance instructor mentioned that his knees sometimes hurt from dancing too much. One of my other classmates then mentioned that there’s a supplement you can take to help deal with joint pain called Glucosamine. Apparently, a lot of the elderly people he works with swear by the effects of the supplement.

Glucosamine HCl is marketed as a supplement for treating knee pain, but does it work?
Glucosamine HCl is marketed as a supplement for treating knee pain, but does it work?

I didn’t add my two cents to the conversation because as a scientist, Glucosamine sounded like a glucose molecule with an amine group attached to it. The word glucose may sound familiar to you as one of the basic components of table sugar, which is composed of one glucose molecule and one fructose molecule. After some quick fact-checking online, I saw that glucosamine was indeed a glucose molecule with an amine group attached to it, as shown below:

The structures for glucose and glucosamine differ only by the group colored in red.
The structures for glucose and glucosamine differ only by the group colored in red.

So it wasn’t entirely clear to me how this would be treated differently from sugar in the body. Then I went to PubMed (a science article search engine) and did a little research on clinical studies that have been conducted with Glucosamine.

According to Percope de Andrade et al., glucosamine hydrochloride has no effect on pain management, although the sulfate formulation has a moderate effect.1 The research in this article was based on a search of the literature for trials, reviews, and original articles detailing studies on Glucosamine when distributed to patients. (The hydrochloride in the name is simply a chemical formula for Glucosamine that makes it work in the human body.)

On the other hand, Gallagher et al. suggest that glucosamine may have a positive impact on protecting joint cartilage from decay and delay osteoarthritis progression.2 However, it seems that the effects are generally small and require taking the supplement on a more long-term basis.3

“This review supports the use of both oral glucosamine and chondroitin sulfate as structure-modifying, ‘chondroprotective’ drugs in patients suffering from [osteoarthritis] of the knee.”

– Gallagher et al., 2014

What does this mean?

Basically, this means that there isn’t enough evidence for or against the argument, and that more research is needed on the topic. However, extra poking around on the internet has informed me that there are generally few negative effects associated with taking the supplement (but please do not take my advice as a replacement for professional medical advice from your doctor). Still, it seems that the statistical significance is minimal at best, and that the supplement acts like a placebo.

Am I going to tell my salsa friends about my discoveries? Probably not. The placebo effect is a pretty effective thing, and if it helps them continue hobbies that they find fun, then I think the overall positive impact on their lives is worth keeping a little secret :).

– The Scientist Next Door

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