Dianthus Medical Blog Archive

The Green Party and homeopathy

One criticism that has often been levelled at the Green Party is that they are anti-science. It's my understanding that they are aware of that criticism and are keen to embrace a more scientific mindset, so I was very interested to listen to James O'Malley's interview with the new Green Party leader, Natalie Bennett, on today's Pod Delusion.

Sadly, I think they may have a way to go before they can shake off the anti-science reputation.

One of the questions James asked in this context was about Natalie's attitudes to homeopathy. Homeopathy is, as we all know, scientific nonsense, and yet the Green Party have form for supporting it: the Greens' only MP, Caroline Lucas, has supported a parliamentary Early Day Motion praising homeopathy (although to be fair, she did later withdraw her signature).

So I was pleased when, in response to James's question about homeopathy, Natalie started by saying that she realised that homeopathy was scientific nonsense (and yes, she did use the exact words "scientific nonsense"). However, after that, her scientific credentials started to go downhill. She then said that she felt that perhaps it still had a "very small and limited place" in the NHS, by virtue of its placebo effect.

Now, I'm not completely unsympathetic to the idea of using homeopathy for its placebo effect, as I've argued before (although oddly, no homeopath has ever agreed with me on this point as far as I know). However, there are 2 problems with this approach. The first is an ethical one: what does the clinician who uses homeopathy say to the patient? Either the clinician has to admit that it is a placebo, which may nullify the placebo effect, or has to pretend that it is an active treatment, which is dishonest and, to my mind at least, crosses an important line in medical ethics. This is not necessarily an insoluble problem, but it is certainly a tricky one. Interestingly, placebos have been found effective even when patients are told they are placebos in one study, although I'm not convinced that the explanation given to the patients in that study was completely honest.

Natalie did not suggest a solution to this ethical problem, although to be fair she wasn't asked about it in this interview, which had to cover many other topics as well. Natalie, if you're reading this, I would be really interested in your views on this ethical question via the comments form below.

The second problem is that using treatments in the NHS that have been found to be no more effective than placebo in numerous randomised controlled trials sets a bad precedent for the way in which the NHS respects scientific evidence. James did ask her directly about this problem. Her reply is worth reproducing in full:

for some conditions, and the problem is of course that medical trials are almost invariably funded by the pharmaceutical industry so these trials are never done, for some types of conditions and some circumstances, if you did a double-blind trial of homeopathy, because of the placebo effect, you might get a 30 or 40% cure or substantial improvement in condition rate, you might get better results than you get for lots of medicines, for certain kinds of conditions, but no-one's done those tests, and what you would be testing is placebo. But there's a problem and science needs to think a lot more about how we can take advantage of the placebo effect, because it's very powerful

Now, on one level, she's right: the placebo effect is very powerful, and we would indeed do well to learn how to make better use of it. However, the claim that double-blind trials of homeopathy are never done is rather odd. First, it's wildly and hopelessly untrue. A meta-analysis published in 1997 found 89 double-blind trials of homeopathy, and I dare say many more have been done since then. For Natalie to express opinions on homeopathy when she is apparently so completely unfamiliar with the literature is worrying.

But those trials were placebo controlled trials. Perhaps Natalie meant that there were no double-blind trials testing homeopathy against an ineffective treatment that isn't a placebo, so that the specific placebo effect of homeopathy could be investigated. Well, by definition, that's impossible. Either you test homeopathy against some sort of inert substance, in which case it's a placebo controlled trial such as those that have been done many times before, or you test it against no treatment, in which case it cannot be a double-blind trial, and would have little scientific validity.

In addition, the idea that you might get better results than for lots of medicines seems hard to justify. Conventional medicines benefit from the placebo effect too. True, it's possible that a conventional medicine might be actively harmful and perform worse than placebo, but something would have gone seriously wrong if such a drug were ever to be licensed.

There are some serious misconceptions in there, and for me, that reply provides pretty good evidence that the Green Party have a long way to go before they lose their anti-science reputation.

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