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08 February 2011

The Evidence for Homeopathy is Homeopathic

When it comes to homeopathy, it seems that the more dilute the evidence, the stronger the belief in the remedy. Case in point, a recent conversation that Leslie Saunders and I had with a proponent of the nostrums on Facebook.

To avoid highlighting spelling mistakes (and for the sake of concision) I'll paraphrase some of the arguments made. But let me be clear: all of these arguments were made by one or more proponents of homeopathy. Please remember that: I'm not making any of this up.

Claim: Homeopathy doesn't work if you close your mind.

Leslie's Response: It also doesn't work in double-blind, placebo-controlled trials.

It's worth noting that it's very easy to perform a double-blind, placebo-controlled trial with an open mind.

This reminds me of the argument that the remedies require tailoring to the individual, which is impossible to do in a controlled environment. That's complete bollocks: all you have to do is have the consultation for every person in the trial, have the homeopaths prepare the nostrums, and then randomise participants to test or control groups. Swap out the remedies prepared for the control groups with placebo, and you're good to go! In fact, I'd be interested in having a third group that had their "specialised" remedies reassigned at random; I would wager that the results would be indistinguishable.

And if the remedies require tailoring to the individual, why does Boiron sell cookie-cutter remedies to the general public? I don't see you speaking out against the profitmongering of "Big Homeo".

And say what you will about "Big Pharma", aspirin will still get rid of your headache even if you don't keep an open mind. And speaking of aspirin...

Claim: Scientists don't even know how aspirin works, therefore knowing how something works isn't important in a therapeutic context!

Leslie's Response: Actually, scientists do know how aspirin works. Damaged and pain-causing cells produce cyclooxygenase-2, which in turn produces a prostaglandin. This chemical sends a message to the brain, signalling that a specific body part is in pain. Prostaglandin also causes the injured area to become inflamed. Aspirin adheres to the cyclooxygenase-2 and prevents it from producing prostaglandin, which in turn prevents some of the pain signals from reaching the brain. The lack of prostaglandin production also minimises inflammation.

I would add that even if we didn't have complete knowledge of the pharmacodynamics and pharmacokinetics of aspirin, we may easily posit plausible methods of action for the drug. Homeopathy fails the plausibility test.

Claim: More people have been killed by modern drugs over the last 3,000 years than have been killed by homeopathy.

Gem's Response: You're doing it wrong. That's like comparing the number of people killed in car accidents by seatbelts to the number of people killed in car accidents by not being in the car. Of course no one has died by taking homeopathic medicine—no one has been killed by rubbing their thumb and forefinger together attempting to cure their cancer, either—because it doesn't do anything!

This is a transparent fallacy of the perfect solution: medicine is imperfect, therefore we shouldn't use it.

Nitpick Alert: Homeopathy has not been around for 3,000 years (nor have "modern drugs"). Homeopathy was invented around 1796.

Claim: Science supports microdosing: it's called hormesis.

There are two obvious problems with this one. First, homeopathy doesn't involve micro-dosing: these aren't small doses of a toxic substance, they are literally nonexistent doses. Second, the principle of hormesis certainly does not apply to all substances, and so is not analogous to Hahnemann's ipse dixit "Law of Infinitesimals". Indeed, the hormesis dose-response model is still debated in the scientific literature.

Claim: Homeopathic remedies work in the spiritual plane, not in the physical plane.

No kidding.

Please demonstrate the existence of a "spiritual plane". Also, if the remedies do not work in the "physical plane", how are they useful for curing diseases in the "physical plane". Also, could you possibly get any more hand-wavy?

Claim: Homeopathy is energy medicine, which heals the "vital force" of the patient. This energy is called Chi by Chinese and Prana by Indian Ayurveda.

Oh goody, vitalism! Is homeopathy useful in balancing the four humours? Will it help realign my chakras?

Gem's Response: I would caution you that referencing medical beliefs and practices from times and places where the average life expectancy was roughly 30 years could be counter-productive.

Claim: Quantum physics says...

Go away.

Claim: No, seriously: quantum physics proves that water has memory!

Gem's Response: Water memory was proposed by French immunologist Jacques Benveniste, who also claimed that homeopathic remedies could be emailed to patients. Nature, the journal who published his findings on water memory, suspected him of fraud, and when they sent John Maddox, James Randi, and Walter Stewart to investigate, Benveniste's own team was unable to replicate his results. Experiments have shown that "water memory" lasts less than a picosecond. As for the appeal to quantum physics, that's a wild guess that is unsupported by any data.

Claim: Plenty of studies show evidence for efficacy.

Gem's Response: In such positive studies, as the controls are tightened, the effect size approaches zero. Anyone can cherry pick studies that support their own biases; this is why systematic reviews of the literature are important. Here are some such reviews:

From the Mayo Clinic:

The evidence from rigorous clinical trials of any type of therapeutic or preventive intervention testing homeopathy for childhood and adolescence ailments is not convincing enough for recommendations in any condition.

From the British Pharmacological Society:

The results of these re-analyses demonstrate that the more rigorous trials are associated with smaller effect sizes which, in turn, render the overall effect insignificant... Collectively these data do not provide sound evidence that homeopathic remedies are clinically different from placebos.

From the Lancet:

This finding is compatible with the notion that the clinical effects of homoeopathy are placebo effects.

The Response

The remainder of this account will be verbatim.

Homeopathic Proponent: if you have to be told what to think, thats your own fault,its worked for me and others so i dont need someone else to tell me yay or nay*

Gem: Yeah, because you're not subject to regression to the mean, confirmation bias, confusion between correlation and causation, mistaking the natural history of a disease for effects of a remedy, or any other cognitive bias that affects the rest of us.

In effect, what you're saying is that your personal experience trumps the data, that double- or triple-blind randomized controlled trials are irrelevant, and we need nothing more than anecdote to know that a particular intervention is effective.

That's not how science works: that's how magic works.

Homeopathic Proponent: lol that was a complete waste of time

Gem: For you, perhaps. You've demonstrated that evidence doesn't matter to you. Even if you're going to cling dogmatically to your position, it's possible that there are a few onlookers with open minds who might actually consider the evidence and change their positions.

Let's be fair: a skeptical takedown of homeopathy is like shooting fish in a barrel—or, to make the simile a little more apropos, like shooting the memory of fish in a barrel.

* Leslie pointed out that this was the rhetorical equivalent of saying (as Jay Novella might), "Oh yeah?"

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