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The trouble with herbals

October 6th, 2007 by Ben Goldacre in herbal remedies, bad science |

Ben Goldacre
The Guardian
Saturday October 6 2007

The news this week that herbal remedies can be ineffective or dangerous is boring: but come with me on a journey through time (time… time…) to the origins of medicine.

Herbs contain bioactive compounds. That’s why they can be effective, but it’s also why they can have side effects (some will inactivate your contraceptive pill, others will cause renal failure). Huge numbers of bioactive compounds extracted or derived from plants are used today in medical practice, including even common stuff like aspirin. There is little difference between herbal medicine and medicine in terms of what is used, only in how.

Digoxin in foxglove is very good at treating atrial fibrillation, a common kind of irregular heart movement. Unfortunately the dose range is very narrow, so it’s really quite easy to kill your patient. From the moment of its discovery, pharmacologists worked hard to standardise the dose.

They started with standardised preparations of the plant, but this proved dangerously inconsistent, because the quantity of the active component in foxglove was so variable, so new strategies were developed: standardised preparations of each batch of plant were tested in animals first, to work out how potent they were, and so on. Eventually we worked out how to extract the digitalis, and it could be weighed out.

Now people do careful studies of large numbers of patients on digoxin to see which dose is most beneficial, to understand how it works, and careful monitoring of side effects takes place, from individual clinicians writing about their concerns in medical journals all the way up to the yellow card system, where doctors and even patients can send in their concerns to the MHRA, however trivial or unproven they may be.

This process of enquiry, and standardisation, and testing, and verification, and negative findings, and dismissal of ineffective methods, and more, is one of the great developments in medical and intellectual history. Many people were disappointed along the way, as their ideas and theories were proved to be unfounded. Digoxin pills and foxglove both contain the same ingredient, but it is how they are managed and handed over that differs.

Until a herbal practitioner can show that giving a whole plant instead of an extract really is better, they’re making stuff up when they make those claims. Similarly, until they can show that using herbs at such low doses that they have no measurable effect is somehow beneficial, beyond the placebo (and placebo is great by the way) then they’re shooting with the stars.

But there are structural problems in the way that herbalists work: they have failed – over millennia – to collectivise, so they do not work together on research, but rather as independent commercial traders. They do not move to university settings, where the culture of critical self-appraisal might infect them, and possibly extinguish them too, if their ideas don’t stand up.

And where alternative therapists do move into universities, they wall themselves off from the most valuable influences. CAM therapists don’t rub shoulders with colleagues from other disciplines, who could share ideas and insights with them, and move ideas forward, or help brush the bad ones aside. The alternative medicine university courses I have approached have simply, flatly, refused to tell me the most basic things, like what they teach and how.

It’s because of this culture, not funding, that the “research” on herbal remedies is inadequate. Huge numbers of “trials” are produced, at great expense, but the trials are inept, they are not “fair tests”, they have inadequate “blinding” and “randomisation”, positive results alone are “cherry-picked”, and worse.

An inept trial, bound by design to give a false positive result, costs just as much as a fair test of a treatment. And these problems are endemic: one study looked at the entire cannon of research on traditional Chinese medicine, and found 1100 papers: not one single trial published in China, in the entire history of research into traditional treatments, had ever found a test treatment to be ineffective. Not a single one.

Herbal pills contain bioactive compounds which can have real effects, but it is these differences of style, not content, that divide alternative therapies from medicine: and it will ever be the same.