I have previously asked “What’s Woo Worth?“. My earlier post looked at the profits to be made from herbal medicine, homeopathy and supplements. This post takes a quick look at the evidence for the same categories of woo.
The evidence for alternative medicine is slim-to-none. That’s why it’s alternative. If a treatment worked (i.e., “was demonstrated to have curative properties in properly controlled Double Blind trials”) then it would cease to be alternative and would simply become medicine. Richard Dawkins made this point in his introduction to John Diamond’s Snake Oil. Dawkins wrote that:
Scientific medicine is defined as the set of practices which submit themselves to being tested. Alternative medicine is defined as that set of practices which cannot be tested, refuse to be tested or consistently fail tests.
Apart from the Journals Of Alternative Medicine (covered here by Dr Aust), there have been plenty of trials of alternative treatments such as homeopathy published in respectable journals indexed on PubMed.
Homeopathy’s problem is that it consistently fails tests. I looked for systematic reviews of homeopathy on PubMed [by searching for ‘homeopathy “systematic review”‘] and found three hits on the first page with free full text available. The first was a “systematic review of the quality of homeopathic clinical trials”. This review found that 59 studies met the inclusion criteria only 29% used a placebo control and 86% failed to consider potentially confounding variables. The second was “a systematic review of how homeopathy is represented in conventional and CAM peer reviewed journals”, that compared 46 articles (26 from CAM journals and 20 from conventional journals). This review noted in the results section that “of those in conventional journals, 69% (18/26) reported negative findings compared with only 30% (6/20) of CAM journals reporting negative findings”. The authors concluded that this finding indicated that “these results suggest a publication bias against homeopathy exists in mainstream journals”. Having read Dr Aust’s post (and bearing in mind that the first systematic review I looked at found that only 29% of 59 trials used a placebo control), I’m not sure that the authors chose the most likely explanation – isn’t it more likely that there were flaws in the trials published in CAM journals? The third full-text systematic review on the first results page (there were two more on the second and final page – but one was a review of treatments for a specific disease and one was a systematic review of a specific remedy) was “a systematic review of systematic reviews of homeopathy” by Edzard Ernst. Ernst found that the reviews:
failed to provide strong evidence in favour of homeopathy. In particular, there was no condition which responds convincingly better to homeopathic treatment than to placebo or other control interventions. Similarly, there was no homeopathic remedy that was demonstrated to yield clinical effects that are convincingly different from placebo. It is concluded that the best clinical evidence for homeopathy available to date does not warrant positive recommendations for its use in clinical practice.
Ben Goldacre’s piece on homeopathy “follows a trail of fudged statistics, bogus surveys and widespread self-deception” (and, handily, includes the references for five meta-analyses of homeopathy).
Herbal medicine, of course actually contains active ingredients and so at least there is a chance that there may be some effect above that of placebo (unlike in homeopathy). Of course, along with any intended effects there may also be unintended side-effects. There are different types of herbal medicine – individualised and standardised. There is a systematic review of individualised herbal medicine by Guo, Canter and Ernst. Their conclusions were that:
Individualised herbal medicine, as practised in European medical herbalism, Chinese herbal medicine and Ayurvedic herbal medicine, has a very sparse evidence base and there is no convincing evidence that it is effective in any indication. Because of the high potential for adverse events and negative herb–herb and herb–drug interactions, this lack of evidence for effectiveness means that its use cannot be recommended.
On PubMed, I found three free full-text articles by searching for the terms “herbal medicine” and “systematic reviews”. One compared treatments for IBS and found that Chinese herbal medicine required further study. The strongest evidence for efficacy was shown for smooth muscle relaxants in patients with abdominal pain as the predominant symptom. IBS review – PDF. There was a review of herbal medicines for asthma in Thorax (to sign in you need to do that one-time, free registration thing). No definitive evidence for any of the herbal preparations emerged. There was also a review of “herbal medicines for the treatment of COPD” and according to the authors: insufficient data are currently available for any specific herbal remedy; the overall methodological quality of the studies is low and only one trial used a referenced symptomatic benefit measure. [The authors note that the European Agency for the Evaluation of Medicinal Products recommended using both FEV1 and a measure of symptomatic benefit as a combined primary outcome]
What about supplements? Well, there’s plenty of evidence for vitamin and mineral supplements when it comes to preventing disease. As long as it’s deficiency diseases we’re talking about*. Any other claims that supplements prevent (or treat) disease are probably a load of nutribollocks. Supplements aren’t classed as medicines, they’re classed as food – so the manufacturers and retailers aren’t allowed to make medicinal claims for them. Nutritionists, however, are. According to one, food is better medicine than drugs. Happily, the Food Standards Agency has an Expert Group on Vitamins and Minerals (EVM). So there is a handy collection of information on vitamins and minerals here. There is a ‘movement’ in the field of alternative medicine that advocates high dose supplements and calls this approach “orthomolecular medicine” (try it in a Quacksafe search for “orthomolecular medicine“). Patrick Holford‘s book The Optimum Nutrition Bible included something called “Optimum Daily Allowances” (ODAs) and the ODA for Vitamin A was listed as being 2500µg. The ODA for Iron was 20mg. The EVM Safe Upper Levels for long-term supplementation of these nutrients are 1500µg and 17mg respectively. Patrick – are you sure your optimum daily allowances are, um, optimum? The EVM produced a 360-page PDF evaluating the evidence. Holford wrote a popular book. The EVM includes Professors, Dietitians, Lecturers and Physicians. Holford is a media nutritionist. His only qualification in nutrition appears to be an honorary diploma from the institute he founded and was a director of. 1984-1998 Director ION; 1995 DipION honorary diploma in nutritional therapy. More here and lots more here. An annotated PDF of Patrick Holford’s CV is available.
*RDAs were formulated with the aim of preventing deficiency diseases. RDAs are set to meet the needs of 97 to 98% of healthy people and humans should be able to obtain sufficient amounts of vitamins and thereby prevent deficiency diseases by eating a healthy, balanced diet.