Skeptoid PodcastSkeptoid on Facebook   Skeptoid on Twitter   Skeptoid on Stitcher   iTunes   Google Play

Members Portal

Store

 

Get a Free Book

 

SKEPTOID BLOG:

4 out of 5 Fruit Flies Recommend Organic Fruit

by Stephen Propatier

March 27, 2013

Share Tweet Reddit

Donate Since the Stanford meta-analysis indicated that there is no nutritional difference between organic and conventionally grown produce. There has been a avalanche of mediocre and poor scientific papers trying to prove otherwise. These papers have a recurring theme, hormesis. My definition hormesis=plant homeopathy. Hormesis research is churned out weekly. A recent study was making the headlines. It was so ridiculous that I had to address it.

Dr. Johannes Bauer at Southern Methodist University, with the assistance of a high school student, did a study feeding identical strains of fruit flies conventionally farmed, and organic fruit. This study"Organically Grown Food Provides Health Benefits to Drosophila melanogaster", concluded that there is a definable health benefit/nutrition benefit to consuming organic produce. This is inconsistent with prior research. It is consistent with other poor methodological research promoting organic farming. It was published in the Journal of the Public Library of Science, or PLoS one. PloS one has demonstrated a pattern of publishing weak organic research. That pattern is very favorable to "the belief system" of organic proponents. This alone doesn't invalidate this research. It does indicate to me that their peer review process requires some refinement. I have included the principal investigator's You-Tube video. It effectively encapsulates his conclusions. Is organic food healthier? As you might surmise, I do not agree.

I will quickly try to encapsulate the highlights of this research. Abstract"Fruit flies were raised on a diets consisting of extracts of either conventionally or organically raised produce (bananas, potatoes, raisins, soy beans). Flies were then subjected to a variety of tests designed to assess overall fly health. Flies raised on diets made from organically grown produce had greater fertility and longevity. On certain food sources, greater activity and greater stress resistance was additionally observed, suggesting that organic food bestows positive effects on fly health. Our data show that Drosophila can be used as a convenient model system to experimentally test potential health effects of dietary components. Using this system, we provide evidence that organically raised food may provide animals with tangible benefits to overall health. ". This was the resulting conclusion. "Our data suggest that organic foods provide improved health outcomes. The reason for this effect remains unclear. In an attempt to investigate the molecular mechanism for these improved health effects, we measured the levels of insulin in flies raised on organic foods. ." and "Several studies have shown that organic food contains higher levels of essential nutrients, such as an increase in total protein content and unsaturated fatty acids in dairy products [4], or an increase in antioxidants in spinach [33], tomatoes [6] or bell peppers [34]. Organic food has furthermore been shown to contain lower levels of nitrates [33], which may explain some of the improved health characteristics of Drosophila raised on organic foods. Interestingly, organic foods have been demonstrated to contain elevated levels of polyphenols [4][6]. Polyphenols are organic compounds produced by many plants to fight diseases. However, polyphenols have beneficial health effects on animals, possibly through a mechanism such as xenohormesis[35]. The xenohormesis hypothesis postulates that the stress-related accumulation of certain plant molecules, such as polyphenols, may be sufficient to elicit a hormetic response in animals consuming those plants. Therefore, decreased pesticide and fungizide applications in organic farming may induce plants to upregulate production of their own defense and stress systems, which in turn could elicit beneficial xenohormetic responses upon consumption by animals."

As I have written in a previous post . I find the whole concept of Xenohormesis, to be implausible, and wholly unsupported by the chemical testing. Despite claims that stress produces a nutritionally superior product. There have been no tests, nor well structured studies, that demonstrate a detectable difference between organic and conventional produce. There are multitudes of poorly structured studies who try to show a nutritional benefit. I have found these studies to be small, lacking in controls, and without blinding.

Hormesis(Xenohormesis) appears only in poorly structured studies. It invariably has a tiny effect. The effect is consistent with statistical noise. It disappears with good methodology. There is no replication of any of these studies or the effects. My opinion...This pattern of research findings is consistent with normal variation, not true effect.

There is one proven difference between organic and conventional produce. Organic produce has less pesticide residue than conventional produce. The pesticide levels found on conventional produce is insignificant for humans. Organic proponents regularly deride pesticide residue as dangerous. This is not true. Toxicity is all about dose. All substances are safe at a low enough dose and dangerous at a high enough dose. Residue may be insignificant for humans, not for tiny insects. The biologist at Southern Methodist University did not control for this significant variable. This variable is extremely important when you make a definitive statement about the nutrition level of food for insects.

In traditionally grown produce there are conventional pesticides present. It is not a level that is dangerous to us. This is because we are a large mammal. Safe levels for us are dramatically different than safe for a tiny insect. Fruit is treated with pesticides whose specific purpose is to slow the growth and disrupt the lifecycle of Fruit Flies. Additionally traditionally grown produce will be selected to be specifically resistant to fruit flies. Organic farming by definition does not do this.

Not controlling for this variable invalidates the conclusion. It is a far more plausible conclusion that conventional produce is more toxic to fruit flies. Pesticide residue is a probable origin for the marked difference in fly longevity, fertility, and stress. Although the pesticide residue is probably insignificant for a mammal of our size. This residue would not be inconsequential to a tiny insect. Especially a pesticide that is specifically designed to be lethal for fruit flies.

Confirming nutritional superiority from organic fruit without considering other variables in the food is a science fail. A simple gas chromatograph may have provided them with useful information about the two feeding extracts. Especially pesticide levels. Pesticide is not the only factor ignored just the biggest.

This study lacks the scientific rigor necessary to cast doubt on the Stanford meta-analysis. To borrow a skeptoid saying, a stack of cow pies, no matter how big, does not constitute evidence.

I am very happy that this high school student was able to get her experiment published in a journal. I think this study would've have been a winner of the high school science fair. In my opinion it's not worthy of publication in a science journal. Certainly not proof of Xenohormesis.

I am still waiting for compelling evidence to change my opinion that organically produced food is simply marketing, not nutrition science.

by Stephen Propatier

Share Tweet Reddit

@Skeptoid Media, a 501(c)(3) nonprofit

 

 

 

Donate