As many of you know, Stanford University researchers recently published results of a study comparing organically grown food with conventionally grown food. As you have likely seen, there were many resulting headlines throughout the news outlets:
Organic food hardly healthier, study suggests (CBSNews)
Why Organic Food May Not Be Healthier For You (NPR)
Stanford Scientists Cast Doubt on Advantages of Organic Meat and Produce (NYTimes)
Study questions how much better organic food is (AP)
Little evidence of health benefits from organic foods, Stanford study finds (Stanford School of Medicine)
There have been many individuals and companies quick to pounce on the study and suggest there are no advantages to growing organically. In addition, here is what one of the authors of the paper was quoted as saying:
"There isn't much difference between organic and conventional foods, if you're an adult and making a decision based solely on your health,” according to Dean Bravata, the senior author of the paper.
So you would think this settles it. Organically grown produce is no better than conventional produce, right? Just a waste of money… Well, let’s look at the actual conclusions from the study first.
The published conclusion of the study was the following:
“The published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods. Consumption of organic foods may reduce exposure to pesticide residues and antibiotic-resistant bacteria.”
So, basically the authors found that there was no nutritional difference in organic vs. conventional foods. However, organic foods have less pesticide exposure and less exposure to antibiotic-resistant bacteria. Isn’t that reason enough to choose organic foods? Many pesticides can have significant long-term health implications. That seems to be one of the top reasons consumers choose organically grown produce. It is certainly one of my top reasons.
In addition, the study does not address soil depletion or environmental effects. These are also reasons consumers choose organic produce. And it is a reason many growers have moved toward organic or more natural production.
To me, the study’s conclusion alone seems to favor organic production due to the lack of pesticide exposure, but I wanted to look at the study and the raw data the researchers were using. So, I read the study in depth and pulled up the raw data. Here is what I found:
- The researchers did not conduct any actual tests themselves, they selected existing scientific studies and completed a statistical analysis of the existing studies.
- The statistical method was decided among the researchers of which scientific studies to use and how to weight each methodology and results.
- The researchers looked at 223 studies of food. These were broken down into Fruits, Vegetables, Grains and Nuts, Oils, Meats, Poultry, Eggs, and Milk.
- The researchers used 17 studies in humans.
- Of the studies in humans only 1 of the 17 was longer than a year (2 years) the next longest was 278 days with the rest being less than 6months.
Without applying the same statistical methodology as the authors, there are some interesting points from the raw data presented (note: I did not read all the actual data from the studies that were examined and only looked at the summary of their reading of that data).
The data seems to clearly show the pesticide residue levels are much lower in organically grown produce.
With the exception of grain studies, many of the studies indicated more nutrients in organically produced foods. Some indicated there was no difference and only a few indicated conventionally grown produce had more nutrients. For some reason the studies of grains seemed to be more ambiguous and seemed to show more nutrients for conventionally grown crops in a number of instances.
To really do a more in-depth analysis it would be necessary to read all 223 studies and analyze each individually, but it does seem there are many issues with the study that would not lead to the conclusions found in the headlines. Personally, the study brought up more questions than it answered. Since it only compiled and analyzed other studies, there was nothing fresh about it. Much of the conclusions were left to their statistical interpretation, meaning which data they would include, how they would weight that data, etc. Another type of statistical analysis could come up with very different results.
The study will likely not change many attitudes toward organic growing. Nevertheless, it may have a positive effect since it seems to have opened up discussions about it and will likely draw others researchers out to show its limitations and perhaps complete more comprehensive studies.
Good Growing,
Graham Phillips
General Manager, BioOrganics