Healthy Skepticism: Fruit Flies and Organic Food

As a self-styled scientific skeptic I often need to remind myself about confirmation bias. This is the very human tendency to seek out the evidence that confirms what we already believe and ignore evidence that disagrees with our existing opinions and beliefs. I had to remind myself of this earlier this week when I read about a well-conducted study that provides evidence that organically grown food may have some benefits over conventional foods. The evidence is not absolutely conclusive but it is compelling nonetheless.

Truthfully, I am not sold on the idea that the benefits of organically raised food extend anywhere beyond marketing. However, this has always been a tough topic for me to discuss because there are a lot of people whom I like and respect that swear by the “Organic” lifestyle. Furthermore a diet that is rich in vegetables and lean meats, whether organic or not, and low on foods that don’t have a lot of nutritional value other than calories, is likely to be a healthy diet.


The reason I think it is worth evaluating is that organically grown food is much more expensive the conventional food, making it inaccessible to many, which has public health implications. The elevated cost, at least in the U.S., is a result of the increased cost and labor involved in adhering to the USDAs guidelines for organic certification. In reality the criteria for displaying the Organic label differ worldwide, but typically for foods to be considered organic they need to be grown without synthetic pesticides, fertilizers, and without the routine use of antibiotics or growth hormones. Organic livestock needs to be fed organically grown feed (that meets the aforementioned standards) and be provided with access to the outdoors and the freedom to move about.

Whether there is an actual health benefit or not is, at this point, somewhat irrelevant from an industry perspective because clearly we believe it in the U.S.   According to the USDA , the Organic Food Industry has grown immensely over the last 15 years.  In 1997 the sales of Organic foodstuffs was $3.6 billion but by 2008 the market had boomed and sales increased to $21.1 billion.  It didn’t stop there, 2011 data from the Organic Trade Association placed the value of the organic food industry at $29 billion. I have no problem with an industry making money, that’s how the economy works; however when I see that much money involved I do tend to be very skeptical of that industry’s claims, particularly where health is concerned.

Organic trade association logo

So back to the article that tested my skepticism.  It was published by Chhabra and Colleagues and was an experiment that evaluated the benefits of an Organic diet on Drosophila Melanogaster fruit flies. Okay, so fruit flies are not human but they do have short lifespans and so make it easy to study the effects of various things on longevity among other things. Further, much of what we have learned about genetics and human physiology over the years began with research on Drosophila Melanogaster so they have been repeatedly validated as a good preliminary model for research on animal physiology. What the authors did was raise separate groups of fruit flies on either diets of conventionally grown bananas or bananas that were grown organically.

Drosophila melanogaster

They found  that  the flies on the organic diet lived for a longer period of time and had improved fertility. This is a significant finding. What is even more interesting about it is the study’s lead author Ria Chhabra was a high school student when this paper was published. According to Tara Parker-Pope who edits the Well Blog for the New York Times, Chhabra came up with the idea for this study after she heard her parents arguing about the worth of organic foods. Now while it’s true that one study such as this certainly can’t completely answer the question about the value of organic foods, Chhabra deserves many accolades for her scientific approach to the problem!

While Chhabra’s study is compelling,  the results can’t be directly translated to humans. In fact, there have been numerous studies done on the value of the organic food for humans and the results have been mixed. However, in a 2012 Meta-Analysis published by Smith-Spangler and colleagues that looked at health outcomes, nutrient levels, and contaminant levels, the authors concluded that the available published literature does not contain significant evidence that organic food is healthier than conventional food.

So despite some interesting evidence demonstrating the benefits of Organic Food on Drosophila Melanogaster (and despite my worries about confirmation bias) there still is, to my mind, not enough evidence to support the claims we often hear about Organic food. However,  there really is no harm to be done in consuming an organic diet if you can afford it, it is generally a healthy diet. Further, if you do eat organically raised livestock you can rest in the knowledge that these animals are likely to have lived a better life than their factory-farmed counterparts, which is, by itself, a worthwhile aim.

There is one vital caveat, however, and that is that for some very important crops, organic methods provide a smaller yield than conventional methods. Therefore if we mandate that businesses use organic processing methods, then we will likely drive up costs and potentially reduce access to food for a large number of people. As a consequence, our well-intentioned attempts at improving public health could end up having exactly the opposite affect.