We admit to being confused by the latest research study on organic foods from the Stanford Center for Health Policy and Center for Primary Care and Outcomes at Stanford University. We are puzzled, first of all, by the appearance of this study in the Annals of Internal Medicine. We typically expect to see research studies in this journal addressing issues like disease treatment, public health screening, and quality of care. In fact, beginning with its inaugural issue in 1927, we are not aware of the Annals ever publishing a study focused on the topic of organic food until now.
We were also puzzled by the opening two sentences of this research study:
"Between 1997 and 2010, U.S. sales of organic foods increased from $3.6 to $26.7 billion (1, 2). Although prices vary, consumers can pay up to twice as much for organic than conventional foods (3—5)."
In a research study entitled "Are Organic Foods Safer or Healthier Than Conventional Alternatives?" we don't understand the decision to begin the study content with information about price. Unless the study authors intended to address the health and safety of organic food purchases for a family's weekly food budget, their decision to launch the study with price information seems at odds with the basic principles of research. (As a side note, if the Stanford researchers were going to conduct research on organic food pricing, it would not have been appropriate for them to rely on a 2008 column in a Friday edition of the New York Times newspaper and USDA data limited to seven foods - milk, eggs, rice, carrots, salad mix, spinach, and strawberries - even though these are the reference citations that the authors provided for their price information. Organic foods can cost up to twice as much as conventional foods. But what consumers find in real life in the supermarket is a much more varied situation than is implied by this "up to twice as much" statement.)
So before reading any actual data, we found ourselves puzzled by the researchers' opening two sentences, and by this journal's selection of the study for publication.
In terms of the actual data, it's important to recognize that no new data was gathered by the Stanford research team, which relied on statistical meta-analysis of previously collected data. This point is important, because we've seen more than ten statistical meta-analyses of organic food data over the past decade or so, and the vast majority of these meta-analyses have found nutritional benefits from organic production in at least a handful of nutrient areas. In the organics section of our website, we describe the overall nutrient benefits of organics as falling into the range of 5-20% percent.
We also explain why this percentage is not higher. For example, we point out that soil quality varies greatly from region to region, and many differences in soil quality cannot be overridden by organic farming practices. We further point out that organic is not the same as sustainable, and that organic foods are not required to be locally grown, grown in their native region, grown in a seasonally appropriate way, or grown in soil that meets specific nutrient standards. Given this context, 5-20% greater overall nutrient benefits from organic versus convention foods makes sense to us, and it seems like a good thing.
This 5-20% range also seems to fit with the data presented by these Stanford researchers. When they looked at nutrient comparisons between organic and non-organic foods, these researchers focused on 14 different nutrients, and came up with the following results:
Study comparisons favoring organic foods: 199
Study comparisons favoring conventional foods: 133
In other words, these Stanford researchers discovered that 199/332 comparisons (60%) favored organic foods, and 133/332 (40%) favored conventional foods, making organic foods were 20% more likely to compare favorably with conventional foods. While this conclusion is not the same as a conclusion of 20% greater nutrient content in organic foods, it is a finding in favor of organic foods with respect to their nutrient content and it is a finding consistent with other meta-analyses that we have seen.
Many consumers purchase organic foods to decrease their risk of pesticide exposure. In this context, we were encouraged to see the findings of the Stanford team. Detectable pesticide residues were found in only 213 out of 3,041 organic produce samples (7%). By comparison, detectable pesticide residues were found in 40,567 out of 106,755 conventional produce samples (38%). One possible conclusion from this information would be a 30% decreased risk of contamination in organic produce. From our perspective, this finding is good news for purchasers or organic produce.
Some consumers purchase organic foods with the hope of lowering their exposure to unwanted micro-organisms (for example, potential illness-causing bacteria) in food. In this context, the Stanford researchers came up with mixed findings. They noted that 7% of organic produce samples and 6% of conventional produce samples were found to contain E. coli bacteria; 67% of organic chicken samples and 64% of conventional chicken samples were found to contain Campylobacter bacteria; and 65% of organic pork samples and 49% of conventional pork samples were found to contain E. coli bacteria. Overall, the study authors found that differences in contamination were statistically insignificant. Interestingly, they did find that bacteria found in organic chicken and pork were 35% less likely to be resistant to the antibiotic medication, ampicillin. From our perspective, decreased exposure to antibiotic-resistant bacteria through selection of organic chicken and pork is a welcomed finding in this study and perhaps related to decreased exposure of chicken and pigs to antibiotics during organic production. At the same time, we are not encouraged to find such similar levels of overall bacterial contamination of organic food and conventional foods.
study—favorable nutrient comparisons 60% of the time for organic foods; a 30% decreased risk of pesticide contamination in organic foods; and similar levels of bacterial contamination in organic and conventional foods, with 35% less risk of finding antibiotic-resistant bacteria in organic chicken and pork—confirm the benefits of choosing organic foods from our perspective. When coupled with the prohibited use of irradiation, genetic engineering, and sewage sludge in all organically grown foods, we believe that these study findings add to the evidence showing organic foods to be worthwhile and to provide is with measurable benefits.
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