Journal of Homeopathy: wheat

According to ScienceDaily, the journal Homeopathy has published a 2-part special issue on the biological models of homeopathy. Being the obsessive quirk that I am, I decided to get ahold of this 2-part special issue of Homeopathy to see what all the fuss is about.

ScienceDaily says that:

The special issue makes an important contribution to this debate, by reviewing laboratory experiments with high dilutions. It includes reviews and new findings in biosystems, ranging from whole animal behavioral, intoxication and inflammation models through diseased and healthy plant models, to test tube experiments using isolated cells, cell cultures or enzymes.

The editor in chief concludes that -

"Throughout its 200 year history claims that homeopathy has 'real' (as opposed to placebo) effects have been hotly contested. Our special issue brings together a wide range of scientific work in biological systems, where there can be no placebo effect, showing that there are now several biological experiments which yield consistently positive results with homeopathic dilutions."

One of the first articles I looked at was an article on the effect of arsenic on wheat seedlings [1]. This article was a review of an experiment on wheat seedlings that had been replicated 17 times among 2 research groups. The experiment was like this: To test potentiated arsenic as a cure for arsenic poisoning, researchers first exposed wheat seedlings to a 1%, 1.2%, or 1.6% solution of arsenic. Then, they had three outcome groups: 1 treated with water, 1 treated with 45X potentized water, and one treated with a 45X potentation of 1% Arsenic. Then, they measured wheat shoot length as an outcome after 7 days.

So, here's what happened with the two research groups. The first lab group conducted the experiment, and said experiment resulted in a 24% increase in shoot growth as compared to the placebo. This was the expected outcome, as homeopathic arsenic is taken to be a remedy for arsenic poisoning. A different research team later replicated the experiment, only to find the opposite – they found that the arsenic group had a reduction in hoot length by -3%. Curious about this discrepancy, they performed the experiments again. They found no statistically significant effect. So, they performed a meta analysis of all of the seed data and found a 3.2% reduction in seed growth and an (apparently nonsignificant) trend in reduction of germination rates.

The authors report that these findings are puzzling, but the fact that there was any effect at all shows that homeopathy does something. Their conclusion is that treatment of arsenic poisoned wheat seeds with homeopathic arsenic leads to statistically significant, yet contrary, effects. Without going into huge amounts of detail, I can say that the authors did a fairly good job of eliminating other factors that might have contributed to their results. Regardless, the meta-analysis certainly did not show that homeopathic arsenic is an effective treatment for arsenic poisoning in wheat.

I think that the experiment producing both positive, negative, and no effects does not point to homeopathy having some kind of effect, but rather it illustrates that science is messy and inexact. A 3.2% difference in wheat shoot growth is barely noticeable. Their mean growth rate was between 29 and 65mm. When a meta analysis reveals a 3.2% difference between treatment groups, we're talking about a difference in wheat shoot measurements of 1-2mm.

Surprisingly, the researchers in this paper talked about effect size. Effect size, simply is a measure of the strength of the relationship between two variables. In scientific experiments, it is often useful to know not only whether an experiment has a statistically significant effect, but also the size of any observed effects. In other words, if we look at a group of 20 people in a treatment group and 20 people in a placebo group, there might be significant differences, even when those differences are essentially meaningless. What is really important is how much these groups are different or how big the differences are. It is always possible to show that there is significant difference between two groups, unless they are 100% Identical. The important part is to what degree groups are different. For this, you need to know the effect size. In this case, the effect size of a 3% difference between their wheat groups amounts to 0.04. Effect size for Cohen's d an effect size of 0.2 to 0.3 might be a "small" effect, around 0.5 a "medium" effect and 0.8 to infinity, a "large" effect. If a small effect is from 0.2-0.3, and the effect size of the experimenter's wheat growth is 0.04, then I would chalk up the differences to experimental noise. This difference in groups is immensely tiny.

I have to wonder why the experimenters chose only 7 days of germination instead of taking measurements at 14 days, and then at 28 days. I don't know if a 1-2mm difference in shoot length among groups will actually translate into any measureable effects of plant size as the plants grow, but since the authors of this paper did not comment on further growth after the 7 day period, one cannot make any claims either way. There are also about a million factors that can influence early seed growth. I admit only rudimentary knowledge of horticulture, but even if seeds are placed side by side in rows in a pan, there could be enough of a difference in lighting, soil temperature, air temperature, and carbon dioxide distribution to account for the small differences seen among groups, even if the groups are dispersed. One thing the experimenters did do was to look for statistically significant differences among shoot growth of 2 pans of seeds where the seeds were placed side-by side and subjected to otherwise identical growing situations. They didn't find any differences. Here is how they arranged the seeds:

The 90 envelopes of each cardboard box were grouped in 9 groups of ten seeds each. The 9 groups of each box were randomly allocated to 3 3 treatment groups with the aid of a computer generated randomization list. The list was prepared newly for each box and each experiment. Thus, in one box, ten seeds of the first group were followed by ten seeds of the second group, and so on (corresponding to the order in which they were planted).

There are other research papers on homeopathy for treatment of arsenic poisoning. One was a study conducted on mice [2] which produced positive results, but it was unblinded. There have been other studies conducted on humans, but I'll just say that the guys over at NESS tore those studies apart. I am unconvinced that this minute difference among plant seedlings will translate into a clinically meaningful effect with regard to using homeopathy as a treatment for disease (also noting that the tiny effect the researchers found in their meta-analysis was contrary to homeopathy, stunting shoot growth rather than increasing it) and the standards for validity of non-homeopathic remedies are much higher. Given all of the other research published on homeopathy which has shown that its effects are equivalent to placebo in humans, I have to wonder why researchers are backtracking into preliminary studies and then saying, "See? High dilutions do something… even if what it does is barely measurable and contrary to the law of similar" when we already have ample evidence that homeopathy is of little clinical use.

1. Lahnstein L, Binder M, Thurneysen T, Frei-Erb M, Betti L, Peruzzi M, Heusser P, Baumgartner S. Isopathic treatment effects of Arsenicum album 45x on wheat seedling growth – further reproduction trials. Homeopathy (2009) 98:198-207
   
2. Mallick P, Chakrabarti (Mallick) J, Bibhas G, Khuda-Bukhsh AR. Ameliorating Effect of Microdoses of a Potentized Homeopathic Drug, Arsencium Album, on Arsenic-Induced Toxicity in Mice. BMC Complementary and Alternative Medicine, (2003)3:7