Not just vitamins

Bill Pardee, Oneota Community Co-op Board Presidentspray

widely publicized study from a group of Stanford University physicians, clinicians, and medical students alleged that organic food is not “significantly more nutritious” compared to commercially produced food. The strong criticism of the assumptions and methods of that study by scientists and experts on nutrition have not been similarly publicized. The failures of the study fall into four groups: 1) the use of misleading assumptions, such as that vitamin content is a primary measure of health benefit; 2) the near neglect of the health risks to the public from contam­ination by pesticides, herbicides, and disease carrying germs; 3) the neglect of the harm done to farmers and the soil by the use of some chemicals; 4) a presentation of statistics in a way that is unconventional and misleading. Their failure to acknowledge that some scientists reviewing the same data have come to different conclusions. This summary response is based on a 12 page article by Charles Benbrook, Center for Sustaining Agriculture and Natural Resources at Washington State University and comments by Kamyar Enshayan, Director for the Center for Energy & Environmental Education, UNI.

The Stanford group reviewed about 200 papers from other authors, rather than doing any new research. That is a worthwhile activity if it is done carefully and thoroughly without bias. The study’s basic conclusion is that no studies demonstrate clinically significant health impact (which they don’t define) of organic food. They compare organic and conventional foods based on one or two significant vitamins and to a limited and misleading extent to pesticide contamination. Because food intake is only one part of health, clinical studies of the effects of nutrition are extremely difficult, costly and few have ever been performed. Children, pregnant women, and anyone with a diminished immune system are especially sensitive to nutrition, however. In addition to vitamins, nutrition includes fiber, anti-oxidants, minerals, phytochemicals and other elements whose effects are still poorly understood by science.

The Stanford study glossed over the numerous studies of the impact of organic food on pesticide exposure in school-age children. For example, in two studies in the Seattle area and a third in Atlanta, the children were placed on an organic diet. Within a couple days, metabolites of organophosphate pesticides disappeared from their urine. When they returned to a conventional diet, the organophosphate pesticide metabolites returned to their former levels. This was repeated several times with consistent results for the three different groups of children. Again, the Stanford study glossed over strong evidence that pre-natal exposure to these pesticides increases the risk of several neuro-developmental deficits, including autism, ADHD, and asthma.

Avoiding such pesticide exposure is a major reason many consumers choose organic foods. The contamination varies from one food to another. Foods with a thick shell or peel are less vulnerable. The Stanford study presented the results in an odd and misleading way. They compared the number of samples of conventional food with pesticide contamination (33% in one of their examples) with the number of organic samples with some contamination (5% in the same example). First, the number of samples is not a good measure of risk! The risk depends on what kind of pesticide (or how many kinds) and the quantity of pesticide present. Some conventional foods have been found with 10% of the samples showing eight different kinds of pesticide. When organic foods are contaminated, it is more likely trace contamination with a single pesticide.

However, the Stanford group went farther and called that example “28% less risk” by subtracting 5% from 33% to obtain 28%. Most people would notice that more than six times as many samples of the conventional food had pesticide contam­ination. Common statistical practice would summarize the difference as (33-5)/33=85% less incidence of exposure. In addition, Benbrook explains that most residues in organic food are much lower than in conventional food, as well as less likely, and multiple kinds of pesticide are rare in organic food but common in conventional produce.

In the last few years, we have seen numerous recalls of food contaminated by disease causing pathogens such as e-coli, salmonella and listeria. Mass production of food makes our food system more vulnerable to such public health risks, and many people believe those risks are less with organically produced food.

It is well understood that raising meat animals with regular use of antibiotics breeds antibiotic-resistant bacteria. Even if those bacteria are not transferred to the meat itself, those bacteria eventually reach the human population, reducing our ability to treat disease. Many people choose organic food to reduce that risk. In fact, the incidence of ampicillin resistant bacteria on chicken and pork was found to be 52% with conventional food and 18% on organic samples. Stanford called this “only” a 35% reduction, but most people would say the risk is about three times as high (3×18 =54).

Similarly, many people choose organic food to support a more sustainable agriculture – an agriculture with lower risks to agricultural workers. Kamyar Enshayan asks, “How would Iowans’ health improve if we did not apply 6 million pounds of atrazine, a known endocrine disruptor, and a very possible breast cancer carcinogen?  Would levels of ADHD among children go down if millions of pounds of known neurotoxins were not added to our food every year?   Would the rate of Parkinson’s disease in the Midwest (twice the national rate) go down if we went organic?”

In summary, the Stanford study used criteria that are either impossibly demanding (clinically significant health impact) or too limited (vitamin content) for comparison, largely neglected the effects of chemicals and germs, glossed over results that conflict with their conclusion, and presented statistics in a misleading way. If you’d like references to more detailed criticisms, please email me at