A new journal is needed. It should be titled The Journal of Obvious Results and Unwarranted and Spectacular Conclusions. The readers of ACSH's webpages have by now seen headlines that read "Organically grown foods higher in cancer-fighting chemicals than conventionally grown foods." Like souls in a Hollywood hell, forced to sit through a bad movie for eternity, we will undoubtedly be having this "finding" thrust at us ad infinitum, as we are in the case of this latest article meant to prove the superiority of "organic" food.
The press releases about the article tell us that the its "findings appear in the Feb. 26 print edition of the Journal of Agricultural and Food Chemistry, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society." So far, so good!
In the press release, we are told: "Fruits and veggies grown organically show significantly higher levels of cancer-fighting antioxidants than conventionally grown foods, according to a new study of corn, strawberries, and marionberries. The research suggests that pesticides and herbicides actually thwart the production of phenolics chemicals that act as a plant's natural defense and also happen to be good for our health."
What is strange is that the article implies that any naturally-produced plant chemicals must be good thing and the more the better. The authors would never make such a sweeping and unwarranted assumption about manmade chemicals, of courses, so why make it about plant chemicals?
Obvious Results
We have thus been provided with an article that would be perfect for an issue of The Journal of Obvious Results and Unwarranted and Spectacular Conclusions. What the article says is that plants in agriculture (or elsewhere) are attacked by a variety of insects and microorganisms (bacteria, fungi, and viruses) as well as rats, birds, and other creatures. Since plants can't run from predators, their main line of defense is to respond by producing toxins to ward them off.
Obvious result number one is the confirmation that the less agricultural plants are protected from predators, the more they produce toxins. This is not only obvious and already very well known but is clearly stated in the press release and the article (I downloaded it and read it) but it's not stated as clearly as it could be. The chemicals are not referred to as "toxins" by the writers but as "phenolics" and "antioxidants." The article itself refers to "secondary plant metabolites" and "secondary phenolic metabolites" that "play an important role in plant defense mechanisms." Fine, but imagine how quickly these same chemicals would be clearly labeled as "toxins" if they were created by some high-tech process. It reminds me of the anti-biotech propaganda that refers to the protein in Bt corn as "toxic" when it is put there through biotech and then refers to the same protein as harmless when it is in live, "natural" Bt microorganisms.
If these chemicals are so good for us when produced the "natural" way and if plants make more of them when threatened, an obvious policy move would be to release additional insects and other plant predators into "organic" agricultural fields to get even more "nutritious" food. Why hasn't someone thought of that before?
Well-Known Facts about Plants and Chemicals
For some time now, Bruce Ames and others have been arguing that the vast majority of the toxins we ingest are the natural products of plants themselves, a conclusion shared by two different National Academy of Science panel reports. One man's meat is another man's poison, and one organism's deadly toxin is another's nutritious protein. No one would deny that in the enormous range of plant toxins, some are beneficial to humans while others could well be harmful and even carcinogenic. In fact, a number of the naturally produced plant chemicals, including secondary plant metabolites, have been shown to be carcinogenic. If one goes back to Ames' 1983 article in Science (vol. 221, no. 4617:1256-64), "Dietary Carcinogens and Anticarcinogens," one finds that plants produce both carcinogens and anticarcinogens, and it is the balance between the two that determines whether a food is anti-carcinogenic.
Our proposed journal, The Journal of Obvious Results and Unwarranted and Spectacular Conclusions, should have a special section called "The Stacked Deck" for articles biased in the way that the organic study under examination was. There was no stated attempt to test for secondary metabolites except those that were considered beneficial. Even though it was clearly indicated that insect infestation was the likely cause of higher "phenolic" production, there was no stated attempt to test for the fungus or other microorganisms that the insects may have carried or the toxins that these organism produce. Nor was there any statement of bioavailability simply the announcement that it was in the plant.
I have no quarrel with the authors doing such research or the journal publishing their results, but both could have been more responsible in how they did it. The article and the press release should have clearly stated that this was at best only a partial finding and that a fuller account would require detailing the production of carcinogenic compounds (including those produced by the insect infestation) and the bioavailability of each type, not just anti-carcinogens. Some estimation of the costs and benefits to consumers, given the likely price of the plants in the marketplace, would also help. The authors call for "further studies" (and, to their credit, note that mundane factors such as fertilizer use can affect the nutrient and protein content of plants), but they limit their call for new research to a proposed look at "total phenolic" content.
Surprising Conclusions, to Say the Least
The conclusions being touted about the research particularly that plants creating more chemicals create health benefits for human consumers clearly win classification as "Unwarranted and Spectacular Conclusions," particularly when the opposite conclusion is a very real possibility, if tests were done for it. It would be interesting to learn why the editors of a reputable journal and the peer reviewers did not request some kind of brief statement indicating that only limited conclusions could be drawn from the article.
We will no doubt be seeing this article's conclusions show up as non-sequiturs at the end of many articles in the future. The "organic" folk will not let you forget them.
Thomas R. DeGregori is a member of the ACSH Board of Directors and the author of two recently published books, The Environment, Our Natural Resources, and Modern Technology (Ames: Iowa State Press, A Blackwell Scientific Publisher) and Bountiful Harvest: Technology, Food Safety, and the Environment (Washington, D.C.: Cato Institute).
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March 11, 2003 Kudos to the author for pointing out some of the flaws in this paper in a public forum. In one of the courses I teach at UGA, we have a pesticide and organic foods discussion session, where I present a balanced view of the issue for our students. I almost made a case study out of this article because it was so bad! Critical thinking and data interpretation are skills we hope to impart to our students, and this was a great opportunity to see how conclusions go beyond the data. One specific thing that should be mentioned about the study that I didn't see in your piece: there were no insecticides or fungicides used on the "conventional" produce, only herbicides. The premise of the article is that plants make these defensive compounds in response to insect/fungal attack. What they have shown, if anything at all, is that weed competition (presumed but not quantified!) also causes phenolic compound synthesis. Their choice of model system to study was flawed, their description of the study plots woefully inadequate, and the premise misleading! After serving four years as associate editor for the Journal of the American Society for Horticulrual Science, I can say with confidence that this paper could not have been published in any reputable agricultural journal. I am seriously considering writing to the Journal of Agricultural and Food Chemistry and letting them know what the agricultural scientists of the world think of the paper. Mark Rieger |
