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SKEPTOID BLOG:

Organic Nutrition Controversy Redux

by Stephen Propatier

February 27, 2013

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Donate Organic farming proponents have been in a little bit of a tailspin since Stanford published a review demonstrating no nutritional difference between organic and conventionally grown produce. This has generated some of the most passionate and amusing rhetoric about dietary pseudoscience that I have ever read. Time and time again I have heard nothing but special pleading about the findings of that research. This month I was not surprised to be confronted by another study proporting the nutritional benefits of organic farming. I was pleasantly stunned to see that it was fairly decent research demonstrating a measurable benefit to organic farming. One study doesn't make a consensus, and given my prior organic food post, I felt it is reasonable to address the findings of this new research.

A peer reviewed and free access journal PLOS or Public Library of Science published the article"The Impact of Organic Farming on Quality of Tomatoes Is Associated to Increased Oxidative Stress during Fruit Development". Immediately this article was adopted as a de-bunking for the findings of the Stanford organic food research. It was picked up by several beat writers as proof of the theoretical organic nutritional benefit. I have attached the PDF version of the study journal.pone.0056354. One of the better written articles was in the Pacific Standard. For once I am not going to knock the news reporting because I think it has been equitable.

This new research shows a measurable difference between organic and traditionally produced tomatoes. It is a fairly well structured and designed study. There are some deficits which I will get into, but the methodology is reasonably sound. The conclusions are fairly presented and the findings suggestive. Like all good science when we learn something new I am excited. I have not changed my overall opinion of organic farming. Namely that it is not a method of agriculture, rather it is a marketing term. Still unconventional methods can produce happy accidents and it is entirely likely that we may learn something helpful to enhance food production.

I will try to boil down the salient points of the the research. You must accept the fact that I have only a cursory knowledge of the procedures utilized. In the organic tomatoes there was a statistically significant increase in Vitamin C, Flavanoids and Phenolytic compounds. The conventional tomatoes were larger in size but had lower concentrations of these chemicals. The researchers argue that this is "more important" in a "non staple" product.

Findings showed specifically that several nutrients flavanoids, Natural Phenols and Vitamin C were more concentrated compared to the larger conventionally grown crops. Assuming that the statistical methods were sound, the results look promising. Based on this one study I am not yet ready to advise wholesale purchasing of organic tomatoes or closure of traditional farms. The answers here, as usual, are far more complex and interesting than the conclusions of the research.

The authors did an admiral job with methodology, but it could be better. They used identical breed crops selected from the same farm and grew them within 1.5 km of each other. They selected tomatoes at varying stages of growth from both crops. They used identical laboratory methods to size tomatoes and determine nutrient content. I would like to point out some methodological errors. Admittedly I am not a botanist, farmer or agriculturalist. I am simply pointing out basic scientific method flaws that jumped out at me. Ideally to determine if this crop has a distinct difference in cultivation products you would have to control the variables.

In my opinion these are the method failures. They should have used genetically identical plants IE: cultivated clones. They should have a structured and timed watering system to provide the closest similar watering conditions. It was a small number of plants and it is reasonable to separate them widely in one field to provide similar conditions. This may not be possible with organic crops. There were a low number of plants used, only 30. Thirty plants of one breed is a very small number to draw conclusions from. They used standard chemical fertilizer and animal manure. The manure should have been analysed so that the chemical fertilizer was as chemically similar as possible. Finally the tomatoes were hand collected not machine collected. This allowed researchers to select which tomatoes would be tested at each stage. Machine or blinded collection should have been used.

Overall, you have a small study with one breed of tomato that showed improved chemical nutrients over conventionally grown. There were reasonable methodological mistakes, but it still puts some doubt on the conclusions. There is not enough rigor to this study to say that "oxidative stress" is the only way that the benefit is achieved.

I do take issue with the assumptions surround the benefit of the nutrients themselves. The nutrient benefits of Phenolytic compounds has been roundly criticized as part of the greater debate of actual antioxidant benefits. Flavanoids utilizes the same theoretical antioxidant benefit. Despite the fact that there is good research indicating no particular action in humans and no benefit, advocates dismiss negative studies. Although we can all agree that more vitamin C is probably beneficial I am not convinced that this is offsetting the the smaller yield size. The smaller yield size is a negative for the nutritional benefits of fiber and other so called macro-nutrients.

I am not sufficiently swayed by this research. It needs to be duplicated in larger studies with better controls. If this is duplicated with a large better controlled study I would agree with the organic "Stress" hypothesis. I do not think that this research is good enough to dismiss the findings of the Stanford study.

I suspect that with better controls or larger numbers this nutrient effect will disappear. If it doesn't maybe we will be able to add a new twist to agriculture and keep the benefits and the bigger size.

My experience tells me that most likely ideologues will lock on to this study as "proof" that organic farming methods produce higher quality crops. It is also likely that this study will not be duplicated or refined in any way. Disappointing but not surprising

When you surrender knowledge to ideology and not science, you give up the opportunity to learn something new and exciting.

 

by Stephen Propatier

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