Homeopathy is simply an elaborate placebo. It is certainly not scientific, but it is worse than mere non-science: it is anti-science, and so should have no place in a University. In this series of posts I will explain why. In the first instalment I will describe the dilution problem, and the bizarre range of substances that homeopaths claim to have medicinal properties. In later posts I will consider the research evidence and evaluate the counterarguments that homeopaths use against their critics. But let's start with the basics...
The Dilution Problem
The probability that a homeopathic substance could have any effect (other than placebo) is vanishingly small. We can say this with some confidence because homeopathy contradicts at least two of the most solidly-established principles in biology and chemistry. The first is that larger amounts of a drug or toxin have larger effects. This is called the dose-response relationship, and it is an iron law of biomedicine. Ten paracetomols are more dangerous than two, just as ten pints of ale will get you drunker than two. There are no exceptions, except in the topsy-turvy world of the homeopath, where lower dilutions such as 3X can be bought over the counter and given to babies (e.g. for teething) whereas extremely high dilutions such as 200C are thought to be far too dangerous for this, and should only be prescribed by a trained practitioner.
For readers unfamiliar with homeopathic notation I will explain these dilutions. The "X" means that the original essence has been diluted one part in ten, and the number tells you how many times the dilution has been repeated. So 3X means that a one in ten dilution has been repeated three times, leaving a final concentration of one in a thousand, or 1x10E3. A "C" dilution is one in a hundred, so a 200C preparation would have a concentration of one in 1x10E400 (forgive me for not writing out the full number: a one followed by 400 zeroes). This brings me to the second basic principle that homeopathy flaunts: the Avogadro limit. Once the dilution process has passed 24X or 12C we can be pretty sure that no molecules of the original substance remain. According to the standard molecular model of Chemistry it is impossible for these dilutions to have any effect. At the lower dilutions yes, a 3X dilution will still contain a fair dose of the original essence, but most homeopathic preparations are taken way beyond the Avogadro limit: 30X and 30C are probably the most commonly used. To visualise a 30C dilution, imagine one molecule of an active ingredient being added to 10E60 molecules of diluent. What would this look like? We are not talking drop-in-a-swimming-pool or even drop-in-the-ocean here. 10E60 water molecules would make a sphere twenty-eight billion times larger than planet Earth.
Homeopaths are aware of the dilution problem, of course. However, they contend that it is irrelevant because of the way the dilutions are carried out. Between each step in the dilution process, the preparation is vigorously shaken (or "succussed") in order to transfer the "healing energies" of the solute into the diluent. This is obvious nonsense, and we will see later on that there is absolutely no evidence that succussion has any effect. But first, let's look in more detail at the range of substances homeopaths use to create these strange solutions.
Animal, Vegetable, Mineral?
At dilution levels beyond the Avogadro limit it makes no difference what the original essence was, but it is still worth spending a few moments considering the range of ingredients that homeopaths use. This provides another reason to be sceptical about the claims of homeopathy: the jaw-dropping silliness of the so-called remedies.
One common misconception about homeopathy is that it uses only natural substances, such as herbal essences and plant products like coffee or onions. Indeed, there are homeopaths who choose to specialise in such remedies, but for most practitioners the herbals are only a small part of their armoury. Another very important group of remedies are based on minerals, especially salts such as sodium chloride, magnesium phosphate and silicon dioxide, which you can buy in combination as a hayfever remedy. A third group of remedies are based on animal parts or products, such as duck liver, snake venom and even dog excrement. Fourthly, there are remedies known as “nosodes”, which are made from human disease products, such as pus, mucus, blood, faeces and scraps of tissue. Finally, there is a group of remedies known as “imponderables”, made from such things as electricity, thunderstorms or sunlight. There is even a remedy made from fragments of the Berlin Wall, used for those who feel oppressed, or who find themselves having to mediate between warring factions. I am not joking: homeopath Charles Wansbrough reports using Berlin Wall for patients who have “decided that their surrounding environment was hostile and suppressive and chose to create a ‘wall’ of fury that encircled their way of being”. Kees Dam was sceptical but decided to try a proving and was convinced:
“My ‘Berlin Wall’ was broken down when I trusted and believed my eyes seeing the effects of Berlin Wall as a homeopathic remedy”.Dam admits that the proving was not done blind, but does not think that to be a problem:
“I must honestly say that I never saw any difference in the quality of the proving depending on if the prover knew the remedy or not”.I hope it is clear that such thinking is closer to sympathetic magic or voodoo than it is to science. Some homeopaths agree, and remedies like Berlin Wall have proved divisive. George Vithoulkas launched a stinging attack in a speech in, appropriately, Berlin:
“If we teach our students to do or apply ridiculous things we will only reach the 'ridiculous', if we potentize the Berlin wall, or the National Anthem of France and we encourage our students to follow such nonsensical ideas, homeopathy will be identified with the ridiculous.”Quite.
Homeopaths select these "remedies" according to a principle known as the “Law of Similars”, or “Like cures like”. In 1790, the German physician Samuel Hahnemann noticed that cinchona bark, which contains quinine and had long been used as a malaria remedy, actually produced some of the symptoms of malaria when taken by a healthy person (namely himself). Unfortunately for homeopaths, it may be that Hahnemann’s reaction to the cinchona was in fact simply the result of an undiagnosed allergy. Nevertheless, it led him to wonder if a general principle of similarity could be used to discover new remedies, and to classify the chaotic muddle of herbal and mineral preparations that constituted the materia medica of the day. He therefore embarked on a series of experiments upon himself and others, to test for the pathological effects of various substances, including mercury, belladonna, tobacco and nux vomica. Family, friends, students and colleagues submitted themselves to these “provings”, and by 1796 he was convinced that homeopathy (“similar suffering”) was indeed the answer: a substance that causes particular symptoms in a healthy person can be used to cure those symptoms in a sick person. A few examples of the current uses of well-known substances should suffice to give the general idea: onions irritate the eyes and nose, and so may be given as a treatment for colds; coffee is a stimulant, and so can be used to treat insomnia; arsenic causes sickness and diarrhoea, and so is used for food poisoning, and so on.
Hahnemann intended his work on similars to be a refutation of the doctrine of signatures, which provided the basis for much of the medicine of the time. For Hahnemann, similarity was solely a matter of the effects a substance had, not (as in the doctrine of signatures) anything to do with its physical appearance or provenance. However, it is immediately clear from considering the range of substances described above that the doctrine of signatures quickly re-asserted itself, and that a major flaw in the method used in Hahnemann’s provings allowed this to happen (and has been perpetuated in almost all subsequent provings by others): his experiments were not done blind. In other words, he always knew exactly what his guinea pigs were taking, and probably they knew it too, and so his and their perceptions of any symptoms would inevitably have been coloured by the nature of the test and their existing knowledge of the substance. It is not therefore surprising that many ancient herbals resurfaced in homeopathy with similar functions based on appearance. Euphrasia, for example, re-appears as a homeopathic remedy for eye problems, just as it did under the doctrine of signatures owing to its supposed resemblance to a bloodshot eye. So as we have seen, nowadays virtually anything can be (and is) used as a homeopathic remedy, often based on nothing more that superficial resemblances or associations.
In this post I have explained three reasons to be highly sceptical of homeopathy: it defies the dose-response relationship, it ignores the Avogadro limit, and it uses a bizarre range of ingredients. Despite this, many homeopaths claim that there is good evidence that homeopathy does work. In the next instalment I will consider this evidence in more detail.