Background on homeopathy and the controversy surrounding it from NCCAM director Stephen Straus, Harvard University's Tom Delbanco and David Eisenberg and medical historian James Whorton.

Professor of Medical History, University of Washington

Homeopathy is an approach to medicine that is very popular worldwide. It has become more popular in America in recent years, but it's still not as common here as it is in Europe and in Asia, especially in India. But the word "homeopathy" is derived from Greek root words meaning "like the disease," and it's an approach to healing that involves treating patients with drugs that duplicate the symptoms of the illness. So that if a patient finds himself complaining of headache and nausea and restlessness, the homeopath will find a drug that through experiments done by homeopathic practitioners has been found to produce those symptoms in healthy people. It's a form of like curing like.

Homeopathy is an interesting alternative system because for most of American history alternative medical history it was the most popular system; from the 1840s into the early 1900s homeopathy attracted more patients than any other alternative system. As recently as 1900 roughly ten percent of all the practitioners in America were homeopaths. That was maddening to allopathic doctors because homeopathy seemed to them to be the most impossible system of all, because its system of practice involved first of all administering drugs that were supposed to duplicate the symptoms of the disease and that didn't make any sense to allopathic doctors. But more than that, it seemed to be absolutely impossible because homeopaths insisted that for their drugs to be made effective they had to be carried through a special process, a preparation that involved passing them through serial dilutions of the order of one to a hundred.

The classic way of preparation of a homeopathic drug was to take one grain of the remedy, to grind it up with ninety-nine grains of milk sugar, lactose, and mix that very thoroughly to get a medicine to the first dilution and then of course if you took one grain of that mixture and you had mixed it thoroughly, you would have one one-hundredth of a grain of the starting drug. They would take one grain of the mixture, add it to another ninety-nine grains of lactose, grind that up, mix it to get a medicine to the second dilution, which means now if you take one grain of that you're going to have one ten-thousandth of a grain of the homeopathic drug. But they would then take a grain, carry it through a third dilution and ultimately this would be done until the thirtieth dilution was reached, which means you would have, I'm not sure what the word for this is but you would have one over ten to the sixtieth grains of the drug. And if you took a random grain from that thirtieth dilution you would not have a single molecule of the starting material. And so certainly from the allopathic perspective it couldn't exert any effect.

Homeopaths were convinced it did because the method had been discovered through experience by the system's founder, Samuel Hahnemann. He had found that, first of all, giving drugs that simulated the systems of the disease cured people. And then secondly he had found that the more he diluted those drugs, the more he broke them up through this preparation, the more effective they were and the fewer side effects there were. He couldn't explain it. He made some general suggestions about freeing the spiritual, or the "dynamism" was the word he used to indicate some sort of spiritual power, or an energy perhaps we might say today, from the drug; he believed you stripped it away as you ground it down and kept diluting it. But he would not have made a strong stand on that as his theory, he really wasn't that concerned about what was going on, it was simply the fact that clinical experience indicated to him that it worked, and it worked much more effectively than anything allopathic doctors were doing. So while allopathic medicine has been critical of all alternative systems historically, it's been more critical of homeopathy than any other because it's impossible to explain it in terms of conventional scientific theory.

But for much of American history it was the most popular system. It took away more patients than any other system and it was maddening in the 19th century in that homeopathy appealed particularly to the upper classes. It was disturbing to allopaths to see the more educated people in American society falling for homeopathy. And secondly, people with more money to pay higher fees were going to homeopaths. …

But the people who went to homeopaths were attracted to it for the same reason people are attracted to many alternative systems today, in that it gave spirit or some non-material entity, some vital force, some vital energy in the human body a place. Whereas allopathic medicine was already in the early 1800s walking down that path of reductionism, of accounting for everything in terms of chemistry and physics and essentially denying anything that couldn't be explained that way. So I think whether or not homeopathy works it fulfills a need in a lot of people to not be reduced to physiochemical machines and to feel that they there is some sort of healing power in their bodies that can be tapped into by a similar force. …

Has there been any conclusive evidence on whether homeopathy works?

… In 1994 there was an article published by Pediatrics, which is a mainstream medical journal, reporting a study done on childhood diarrhea in Nicaragua by a homeopath which demonstrated that children with diarrhea treated homeopathically fared better than those who were given the basic supportive nursing treatment. That article was initially turned down by the journal because one of the reviewers responded that even though it appeared to be a well designed study, he refused to believe that homeopathy could work until he could be provided with an adequate explanation of how it worked, something that made sense in terms of biomedical science. The other two reviewers were favorably impressed by it, but initially it was turned down on the grounds that homeopathy couldn't work, therefore it didn't. Eventually it was accepted, it was the first and I think still only homeopathic article to be accepted and published in an allopathic journal.

	Beth Israel Deaconess Hospital Boston; Professor, Harvard Medical School

You take a homeopathic medicine, you grind up a spider, you bathe the spider parts in water, you dilute the parts so far that there's not one molecule of spider left, you put that water on a pill and you say, swallow it, it's going to make you feel better. There's no way that potion of water plus inert pill is anything different from a placebo. And I don't care how many papers will come out and say, this is scientifically proven to be different. It's nonsense. …

... Some people will get better because people get better over time. Other people will swear it's terrific. Other people will be disappointed. What makes me mad is when people charge a lot of money for that... and say, "This is absolutely going to help and it's much better than a placebo." I think that's nonsense.

...I think if our hospital brought in a homeopath and put him or her on the staff, the doctors would go berserk, particularly if the hospital was giving that person resources which the doctor felt they should get themselves. I think some of the patients would be helped by that person, or would feel that way. How to weigh those facts in a time of shrinking resources is not easy.

Director, OSHER Institute, Harvard Medical School

Are there any therapies that are biologically impossible?

The favorite example of something that appears to be implausible is homeopathy...When you take a substance and you dilute it so many times that the chances are there's not a single molecule left, I personally do ask the question, what is in the water that is making a difference? That said, it's at least provocative that there are a large number of clinical trials that are controlled and randomized and double blind that make the argument and the suggestion that homeopathy may work... [There are] a hundred and thirteen randomized control trials across different clinical conditions suggesting that homeopathy may in fact be better than placebo.

Now, I don't take sides in this particular debate, but what fascinates me is the observation that here's a therapy with some evidence that it may work and you're left with a couple of thought provoking questions. One way to put it is either homeopathy works based on the clinical trials, or the randomized double-blind placebo-controlled trial as we know it has some problems. So that's a bit of an intellectual challenge. The flip side of it is, how could it work? What would be a plausible mechanism? It does not withstand this crucible of plausibility question. You can't make a plausible consistent argument as to how it could work.

...I see the case that says scientifically, chemically it can't work, therefore it doesn't work. Then again, I see the weight of the evidence and I say well, why do all these systematic reviews come out with the suggestion that homeopathy may be different from placebo? I turn it on its head and say, what can be learned from this about doing better controlled trials? Or conversely, what could we possibly do scientifically to create a theory that would substantiate homeopathy? To me it's the challenge... And I have yet to see a well-designed study that we could do. We've tried, we've imagined...We have yet to come up with a design that really will answer the question, does it work, yes or no, and how?

What has been suggested is just large observational studies exposing one group to homeopathy and one group to placebo. That seems to be insufficient to the challenge, because a challenge here is not just does the observation suggest it works, but give us a plausible mechanism as to how it may work...I mean part of science and part of the challenge of academic institutions is to understand the why and to predict the future and to use it to help people over time, that's what real knowledge is. We don't have that kind of knowledge yet for homeopathy.

	Director, National Center for Complementary and Alternative Medicine, National Institutes of Health

In your view, is homeopathy a plausible technique?

Homeopathy is a very important area for discussion because it is among the more challenging areas for research. Not because homeopathic practices are hard to study, it's because they're hard to believe. Belief is very important in everything we do in life, as well as in science. There is no biological plausibility [for homeopathy] or, at least, the hypotheses that exist today about homeopathy are not very strong ones.

If you dilute a substance to the point that there's not a single molecule of it left, it's hard to presume that it should be biologically active. Yet there are people who believe that it is and there are two centuries of claims that it is. Now it is easy to ask whether the treatment is beneficial. It's much harder to understand why it would be beneficial if it is. As I mentioned earlier, the advantage that acupuncture has is not only a lot of data of poor to moderate quality to say that it works, but some rational explanation as to how it would work in certain areas. Homeopathy doesn't have that luxury, and so our studies of homeopathy at this point or fairly small, exploratory studies.

Why would you study homeopathy at all?

There are homeopathic products for sale in the United States today. There are some that advertise in magazines and television for respiratory infections and for many other indications. In Western Europe, where there's a much longer tradition of accepting homeopathy (it is very mainstream in the United Kingdom), two entire hospitals of the national health service are dedicated to homeopathy.

The belief quotient - the sense that it works on the part of good, intelligent, thoughtful, individuals - raises it to the level of importance for us to ask whether it's correct or not. There are things that may be hard to study, but they're important to ask whether they're right or not.