Is there any evidence that herbal medicines work?
Systematic reviews conducted by the Cochrane Collaboration are considered the ‘gold standard’ of medical research. They are incredibly stringent and methodical and only look at the highest quality clinical trials (randomised placebo-controlled clinical trials) – this means that some studies done on herbs, especially older studies, just don’t cut the mustard.
Talking of mustard, a big problem with getting high quality evidence for herbal medicine is that some herbs have very distinct tastes (like chilli, ginger or mint) so it is difficult to create a convincing placebo. Another problem is the limited funding available for testing plant extracts that cannot be patented into a sellable drug.
Herbs vary in their composition according to where they are grown, how and when they are picked, dried, stored etc, which causes variations in results from different studies. And, crucially, different people with the same condition tend to respond completely differently to the same herbal treatment.
It is often said in the media that there is ‘no evidence’ for herbal medicines. What this often means is that there is a lack of high quality evidence that meets all the requirements. It also means that there is no evidence that they don’t work, either.
This is a very good article written by a US herbalist on the subject, called ‘Herbal Medicine: How do we know it works?”