Research on homeopathy, a 200-year-old form of alternative medicine, is often biased to make it look more effective than it really is, according to a new study out this week. Homeopathy researchers routinely neglect to register the details of their clinical trials before they publish their results, and unregistered trials usually provide rosier results than registered ones, the study found. Over a third of registered homeopathy trials in the past two decades have also never been published, which can be a sign of burying unflattering findings.
Homeopathy was invented by German physician Samuel Hahnemann just around the turn of the 19th century. It’s claimed to work on a principle of “like treats like.” In practice, this means finding a substance known to cause similar symptoms as whatever illness a person is experiencing, then diluting it in water so thoroughly that essentially nothing of the original substance should even be present. This “memory” left behind in the water is supposed to unlock its therapeutic potential and can be given to someone as is (or sprinkled onto a sugar pill) to cure what ails them.
To be clear, homeopathy’s theory of medicine isn’t supported by modern science, nor are its purported benefits, and scientists routinely remind people of just that. Even if homeopathy’s underlying principles don’t pass the sniff test, though, it still has its fans and practitioners. Absurdly, homeopathic treatments can be found in big pharmacy chains like CVS. But because they fall under the same umbrella as dietary supplements in many countries, including the U.S., there’s often little regulation of these products or their claims.
Since homeopathic treatments aren’t as closely scrutinized as approved drugs, the authors of this new study note, the scientific literature is really the only way to know whether the products actually work. And perhaps unsurprisingly, the literature on homeopathy looks to be just as shoddy as the theory behind it.
Researchers in Austria and the U.S. looked at registries containing clinical trials of homeopathic treatments dating back to the early 2000s. Trial registration is an important but often optional part of ethical clinical research. By registering trials beforehand, other scientists can better double check the work for signs of research bias or even outright fraud. Researchers who veer off course and conduct analyses of their results that weren’t outlined in their registered plan, for instance, might do so because their first findings didn’t give them what they wanted. Similarly, scientists might register but never publish a study because the results weren’t what they hoped for.
These issues are sadly systemic throughout science, but the field of homeopathy seems to be an especially bad culprit, the researchers found. Since 2002, they found, 53% of published homeopathy trials were never registered, and about 38% of registered trials went unpublished. Unregistered trials also claimed to show larger treatment effects on average than did registered trials. But even when researchers did publish the results of registered trials, they changed the outcomes they were looking for from the original plan about a quarter of the time.
Any one of these things may not be so bad in isolation, but put together they’re exactly the recipe for inflating how effective homeopathic treatments look in the clinical trial literature.
“Overall, the findings suggest a concerning lack of scientific and ethical standards in the field of homeopathy and a high risk for reporting bias,” the scientists wrote in their paper, published Wednesday in the journal BMJ Evidence Based Medicine.
Again, this shouldn’t come as a surprise, given that nothing about homeopathy makes much sense. But journals still publish these studies, some countries still endorse its use (including during the pandemic), and plenty of people will buy homeopathic “medicine” at their local pharmacy without knowing any better. While these products are usually little more than a fancy placebo, they can sometimes be so poorly made that they actually contain the poison that was supposed to be diluted away—accidents that have landed people in the emergency room and likely led to a string of infant deaths in recent years.
Homeopathy is probably the clearest modern day example of junk medicine still around, and as this new research suggests, so too is the science meant to support it.