The trouble with homeopathy
By RICHARD DAWKINS
Added: Wed, 24 Feb 2010 00:00:00 UTC
The British House of Commons Select Committee on Science and Technology has issued a report on homeopathy, recommending that "The Government should stop allowing the funding of homeopathy on the [National Health Service]."
The committee consists of 14 Members of Parliament, chaired by the Liberal Democrat Phil Willis, and including the estimable Dr Evan Harris, my own MP in Oxford, again Lib Dem, who is also championing Simon Singh in his libel defence against the British Chiropractic Association (see other threads on our website).
People who are otherwise sceptical of homeopathy sometimes defend it on the grounds that, purely as a placebo, it is effective. I shall not discuss this interesting claim, but the Select Committee does, and makes the further recommendation that âplacebos should not be routinely prescribed on the NHSâ. Further, "The funding of homeopathic hospitals—hospitals that specialise in the administration of placebos—should not continue, and NHS doctors should not refer patients to homeopaths."
I am impressed by the scientific intelligence shown by the Select Committee. It is reassuring to find that at least some of our MPs are scientifically literate. May I urge British readers of this site to write to their MP strongly supporting the Select Committee's recommendation. Perhaps send the link to the above website, and write even as little as a single sentence encouraging them to give full backing to the recommendations of the Select Committee. Here is where you can get the email address of your MP.
Since MPs may act only on behalf of their own constituents, it is important that you give your full address, even if you are contacting them by email.
Let me just add a few words about why I am personally convinced that homeopathy doesn't work.
The best way to test any proposed therapy is the Double-Blind placebo-Controlled Randomised Trial (DBCRT). Indeed, I think it is the only way that is completely foolproof. Unfortunately it is sometimes hard or impossible to do it in practice. For example, in the case of acupuncture it is difficult to imagine how patients can be shielded from knowing whether they are in the experimental or control group (how would you set about administering a dummy, or placebo needle-prick).
With homeopathy, however, that problem doesnât arise. Homeopathy is eminently eligible for, indeed vulnerable to, double blind testing. And even just thinking about how to do it immediately shows up the near-impossibility of homeopathy working. The point is that a central tenet of homeopathy is that the more dilute the âactiveâ ingredient, the more effective it is. For the allegedly most effective dosages, the dilution is so extreme that, in order to have any appreciable likelihood of ingesting even one molecule of the original âactiveâ ingredient, you would need to drink a volume equal to all the matter in the solar system. There is the further point that in ordinary tap water there would in any case be more than homeopathic traces of any random ingredient you care to name. It has been amusingly estimated that every pint of water you drink contains at least one molecule that passed through the bladder of Oliver Cromwell (surprising as this is, it follows from the fact that there are far more molecules in a pint than there are pints of water in the world).
It follows that there will be no reliable chemical difference between the experimental dose and the control dose. Therefore, if a DBCRT experiment revealed any difference in effectiveness, we would have a lot of explaining to do.
Homeopaths have been made aware of this problem, and their response is, to say the least, far-fetched. They agree that there is no chemical difference between the experimental and control doses. Abandoning chemistry, they put their trust in physics. During the dilution ('succussion') process, and before it becomes too dilute to exert any influence, the purportedly active ingredient is supposed to imprint a 'memory' of itself on the molecular structure of the water: a memory stored in the pattern with which the water molecules are arranged relative to one another. Never mind if we find this implausible, it is at least testable.
Without going to the trouble of trying to examine the structure of the water molecules directly, the following DBCRT experiment with real patients could, and I think should, be done. Indeed, if homeopathy has any clinical effectiveness at all, the following experiment should show it. We can worry about molecular memories and things like that afterwards, if the experiment gives a positive result. And thatâs a very big if.
Here's my experimental design.
- Take a large, predetermined number of patients, preferably who have presented themselves to homeopathic clinics and been rated suitable for treatment by homeopathic practitioners. They neednât all be suffering from the same complaint, although it will increase the resolving power of the experiment if they are. Every patient should be examined before the experiment begins, by homeopathic practitioners, the best the profession can come up with, who should write a report on the patient. For every patient, the practitioners should agree upon a prescription of what they consider the ideal homeopathic treatment. The prescriptions for the different patients need not be the same. Every patient is written a prescription of an ideal homeopathic remedy, personally chosen, individually tailored to that individual and for the relevant complain – so nobody can come along afterwards and allege that the treatment was not sufficiently âholisticâ, or did not take sufficient account of individual requirements.
- Randomly assign half the patients to the experimental group, and half to the control group. It is vitally important that nobody involved in the experiment should have any way of discovering which patients are experimental and which control: not the homeopathic practitioners, nor the patients, nor the nurses taking care of them, nor anybody involved in writing down the data. The choice should be determined at random by a computer, unknown to any human, and stored securely in the computer.
- For every one of the prescriptions written down for individual patients, professional homeopathic technicians (the best in the business) should make up the medication identically for the experimental and control cases, with an identical regime of succussion (successive dilution and shaking) with the single exception that the procedure for preparing the experimental doses begins with the purported active ingredient, while the control doses begin with the same volume of water. Apart from that, both must be made by the same regime of successive dilution and shaking. At all stages, the procedures should be carried out by fully trained and experienced homeopathic technicians, exactly as they normally would, but without knowledge of whether they are shaking the experimental or control dose on any one occasion.
- At the end of the succussion regime, the technicians bottle up the medications, and make them into pills or whatever would be the normal procedure. Then, as determined by the randomising procedure above, each patient is given either the experimental version of his/her own personal prescription or the control version of his/her own personal prescription. Still neither the patient nor anybody else knows which dose is experimental and which control. Treatment proceeds for as long as the homeopathic practitioner has prescribed.
- At the end of this time, all patients are re-examined by the same practitioners who examined them before the experiment, and judgment is written down as to whether the patient has improved, got worse, or stayed the same. That judgment, once written down, is securely sealed so that it cannot be tampered with after the codes are broken.
- The computer codes are now broken, and the results analysed by statisticians who are told only that this set of patients belong to 'Group A', and that set of patients belong to 'Group B'. If there is any statistically significant difference between the groups, the identities of 'Group A' and 'Group B' may now be divulged. My shirt is on there being no difference. Indeed, if there is a significant difference, and it is a repeatably verifiable effect, I will eat my shirt.
From time to time, experiments that sound a bit like the above have been done. Occasionally a difference has been reported. I find these results unconvincing, partly because the positive results are evanescent and unrepeatable, and also because, as far as I know, no experiment has ever been done with all the controls I have listed above in place. In particular, it is important that the control doses should be prepared by exactly the same succussion regime as the experimental doses. The control dose should certainly not be ordinary tap water, or distilled water. It must be shaken in exactly the same way as the experimental dose. Otherwise, one might suspect that shaking alone has some effect – perhaps aerating the water, although I donât need to specify the details. It is vitally important that the only difference between the two doses should be the presence or absence, at the beginning of the identical succussion regime, of the purported active ingredient.
It is even important not to make up a single stock supply of control dose, once and for all, to be used across the whole experiment. Even if the control dose is prepared by vigorous succussion, it will not do to make one big vat of control stuff. That would mean that the control patients have something in common with each other, whereas the experimental patients would not.
If the hopes of the homeopaths were realised, and if experiments as carefully controlled as this one reliably and repeatably showed that the extremely diluted homeopathic substances were effective, what should we conclude? Since there is no chemical difference between the doses, it would mean that a hitherto unknown principle of physics had been discovered. This is exceedingly unlikely, but not totally impossible. The homeopath who made such a stunning discovery should receive the Nobel Prize for Physics, as well as the Nobel Prize for Medicine. With such a holy grail in view, shouldnât homeopaths, if they really believe in their subject, be beavering away, night and day, in the laboratory to demonstrate the effect? And are they? No. They are much more interested in taking money off patients who believe in the treatment because – like any placebo – it sometimes seems to work.
The experiment I have proposed is not technically difficult, and it wouldnât cost very much money, as medical research goes. Prince Charles, whose backing of homeopathy has greatly helped it to achieve the degree of respectability that it enjoys in Britain, including NHS support, could easily afford to fund the research. He should do so. Nothing in the experiment I have described violates his preference for a âholisticâ approach to medicine. On the contrary, my design bends over backwards to accommodate it, even allowing the treatment prescribed to every patient to be uniquely tailored to that individual.
If homeopathy really worked, it should be easy and cheap to demonstrate it. The conclusion seems inescapable. More clearly and obviously than for any other 'alternative' therapy, homeopathy seems vanishingly unlikely to work. Not all homeopaths are charlatans; many of them are probably sincere, as are their patients. But until homeopathy is demonstrated to work (which it almost certainly will never be) it should not be supported by the NHS.
Please write to your MP, to sustain the momentum begun by the Select Committee.
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