With Glucosamine Studies, It Pays to Read the Fine Print

As many of you reading this know, I’m a skeptic when it comes to glucosamine supplements for treating knee pain. Of course my usual disclaimer applies: If it works for you, go ahead and keep taking it. I don’t think the supplements are actually harmful (unless you’re diabetic). For most people, the only damage will occur in the region of their wallet.

Occasionally a clinical study on glucosamine will catch my eye. Here’s one with an impressive headline: “Glucosamine-containing supplement improves locomotor functions in subjects with knee pain – a pilot study of gait analysis.”

First, let’s get right to the researchers’ exciting conclusion:

Our data based on gait analysis using a motion capture system suggest that supplements [containing glucosamine] can increase walking speed through increased stride length and increased force of kicking from the ground during steps, and these improvements may be associated mainly with alleviated knee pain and direct effects on muscle.

Well, this certainly sounds good. But one odd thing you’ll note if you look closely at this study. There didn’t seem to be a control group. In fact, the researchers make a damning admission near the end of their article:

There are some limitations to the present study. First, it was conducted as an open label study.

Hmm. An “open label study.” What the heck is that? Well, the gold standard would be a double-blind study. In such a clinical trial, the patients don't know whether they are receiving real glucosamine or a placebo. What’s more, the “double blind” means that the researchers don't know whether they are evaluating subjects who have taken glucosamine or a placebo.

So in other words, in a figurative sense, it’s like the subjects and the researchers are both wearing blindfolds until the very end. This ensures no placebo effect for patients and also that researchers won’t be swayed when they evaluate the results, because they happen to personally believe, or not believe, in the efficacy of glucosamine.

So what would be the opposite of a double-blind study? A study where both researchers and patients know who's taking the medicine that’s supposed to improve their joint health – thus fairly effectively polluting the integrity of the results? Well, that would be – you guessed it – an open label study.

Well, if the researchers weren’t at all conflicted, this still might work. Maybe. Maybe? Ah well so much for that. Four of the authors, it turns out, work for Suntory Wellness, which made the glucosamine supplement used in the trial.

Now you’re probably wondering: Who would publish such a conflicted study?

The article appeared in a publication of Dove Press, an “open-access” publisher that has taken some heat before for its business practices and has been tarred as a “predatory” open-access scholarly publisher. Such publishers “are predatory because their mission is not to promote, preserve, and make available scholarship; instead, their mission is to exploit the author-pays, open-access model for their own profit.”

I think the very fact this study includes FOUR authors who work for the company that makes the supplement being tested, and was “open label,” should be enough to send any smart knee-pain sufferer running in the other direction. Remember to read the fine print!