The Devil in the Details

September 4, 2012
By Chuck Benbrook

A comprehensive paper on the nutritional quality and safety of conventional versus organic food was published in the September 4, 2012 issue of the Annals of Internal Medicine (Smith-Spangler et al., Vol. 157, Number 5: pages 349–369). The Stanford University Medical School team concluded that:

“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.”

Their analysis loosely supports these conclusions, but many devils lurk in the statistical details underlying this study’s findings. For details, see the technical review of the Stanford study.

The basic statistical indicators used by the Stanford team to compare the nutritional quality and safety of organic versus conventional food consistently understate the magnitude of the differences reported in high-quality, contemporary peer-reviewed studies.  In the case of pesticides and antibiotics, the indicator used—the percent of samples of organic food with a trait minus the percent of conventional samples affected—is not a valid indicator of human health risk.

The Stanford team did not consider extensive, high quality data from the USDA and Environmental Protection Agency (EPA) on pesticide residue levels, toxicity and dietary risk, as well as a persuasive body of literature on the role of agricultural antibiotic use in triggering the creation of new antibiotic resistant strains of bacteria, and the genes conferring resistance.

The team’s answer to the basic question “Is organic food more nutritious or safer?” is based on their judgment of whether published studies provide evidence of a clinically significant impact or improvement in health.  Yet few studies have been designed in a way that could isolate such impacts.

From my read of the same literature, the most significant, proven benefits of organic food and farming are: (1) a reduction in chemical-driven, epigenetic changes during fetal and childhood development, especially from pre-natal exposures to endocrine disrupting pesticides, (2) the markedly more healthy balance of omega-6 and -3 fatty acids in organic dairy products and meat, and (3) the virtual elimination of agriculture’s significant and ongoing contribution to the pool of antibiotic-resistant bacteria currently posing increasing threats to the treatment of human infectious disease.

The Stanford team’s study design precluded assessment of much of the evidence supporting these benefits, and hence their findings understate the health benefits that can follow a switch to a predominantly organic diet, organic farming methods, and the animal health-promoting practices common on organically managed livestock farms.

Over time, unbiased analysis coupled with modern-day science is likely to show with increasing clarity that growing and consuming organic food, especially in conjunction with healthy diets rich in fresh, whole foods, is one of the best health-promotion investments we can make today as individuals, families, and a society.

            Is Organic Food More Nutritious?

The Stanford team does not define empirically what it means by a food being “significantly more nutritious” than another food. In carefully designed studies comparing organic and conventional foods, organic farming leads to increases on the order of 10% to 30% in the levels of several nutrients, but not all.  Vitamin C, antioxidants, and phenolic acids tend to be higher in organic food about 60% to 80% of the time, while vitamin A and protein is higher in conventional food 50% to 80% of the time.

A team of plant and food scientists carried out a sophisticated meta-analysis of the “organic-versus-conventional food” nutrient-content literature. The team was led by Kirsten Brandt, a scientist at the Human Nutrition Research Center, Newcastle University in the United Kingdom.   Their analysis was published in Critical Reviews in Plant Sciences in 2011, under the title, “Agroecosystem Management and Nutritional Quality of Plant Foods: The Case of Organic Fruits and Vegetables” (Vol. 30: 177–197).

The Stanford paper cites this analysis but does not mention its findings, remark on the study’s scope and sophisticated methodology, nor acknowledge the major differences in the conclusions reached.

The Brandt et al. study both documents significant differences in favor of organically grown food and explains the basic farming system factors leading to the differences.  They conclude that increasing the amount of plant-available nitrogen, as typically occurs in conventional farming, “…reduces the accumulation of [plant] defense-related secondary metabolites and vitamin C, while the contents of secondary metabolites such as carotenes that are not involved in defense against diseases and pests may increase.”

This Stanford study raises more technical questions about analytical methods and metrics than it answers, and several of its “answers” are highly suspect.  Hopefully in the years ahead, improved methods under development in CSANR to compare food nutritional quality and safety will shed clearer light where now the shadows seem to be constantly shifting.

 

 

26 comments on “The Devil in the Details”

  1. Lynn Perrin BGS MPP said on September 4, 2012:

    If the Stanford research did not examine GMOs it is flawed. Here is a 2007 letter to Canadian and B.C. Ministers of Helath from Dr. John Blatherwick Chief Medical Health Officer Vancouver B.C. re his concerns re GMOs which are not in organic food http://justpoliticsinabbotsford.files.wordpress.com/2012/01/blatherwick-re-gmos.pdf

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  4. Chuck Benbrook said on September 5, 2012:

    To Lynn re GMOs — The U.S. government adopted a policy in the 1980s that assumes that if GM foods are “substantially equivalent” in terms of protein, calories, nutrient levels, etc they are no different than unmodified foods, and unlikely to pose any human health risks. Consistent with this policy, the gov’t has invested very little in independent, GE food health and safety studies. I suspect this is why the Stanford team did not pick up much in their literature searches, and decided to not address GMOs.

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  6. Rich Wallick said on September 5, 2012:

    There may be a fatal flaw in the meta-analysis in that, if the underlying studies reference USDA Organic from California as “organic,” than the studies are comparing conventional with conventional. It has been proven that, since 2000 to 2009, USDA Organic produce in California was produced using synthetic nitrogen. This means the produce is not “organic.” According to the USDA most all the USDA Organic produce from California does not meet the legal standards for, nor the definition of, “organic.” These documents were obtained through FOIA from the USDA: Case 3:10-cv-00754-AC Wallick v. U.S. Department of Agriculture. I can provide copies of the original USDA documents.

    As I do not have access to the actual meta-analysis, I can not determine how many studies used the fake organic but I would suspect there would be enough to invalidate most of the studies used for the meta-analysis and thus the meta-analysis itself.

    Sad to think that so many good scientists were unaware that they were engaging in junk science due to fraud on the part of the USDA and the growers, producers, and certifier in California.

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  8. foodallergysleuth said on September 6, 2012:

    Nicely stated and good analysis! My problem was that a scientific study would even use something as vague and not even quantifiable like “healthy” and “safer” as part of its title.

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  11. Niclas said on September 9, 2012:

    I have read the abstracts from the 298 studies cited in the meta-analysis. Virtually each one that measured vitamins and minerals in fruit and veggies found an advantage to organic.

    Furthermore there are only a handful studies regarding meat, (pork, chicken, rabbit, steer) and those studies are mostly investigating yield and not all includes nutrition data.

    Is it even science to make a conclusion on organic meats from five selected studies?

    • Chuck Benbrook said on September 28, 2012:

      Five studies on meat is clearly not enough, especially given the diversity of animal species, husbandry systems, and meat products. If there were five on the impacts of organic versus conventional dairy systems on omega 6:3 ratios and CLAs levels, some broader conclusions might emerge from five studies if their design was sound and findings reasonably consistent. In the pesticide part of the Stanford team’s meta-analysis, they identified only six multi-food studies. They varied greatly in quality, limits of detection, foods tested. Some were 20 years old, none were current, and only one addressed residues in food in the U.S. (a study I was a co-author on that focused on residue data from late 1990s through 2001 or 2002). As I said in my letter to the editor of “The Annals of Internal Medicine,” the Stanford team’s findings re pesticides are not only wrong mathematically, they are also essentially irrelevant to the presence and risks associated with pesticides in the contemporary U.S. food supply.

  12. Syd said on September 9, 2012:

    Another reason GE/GMO foods were not singled out/included is that they are actually owned by the companies that produce them as a patented product so those companies control all aspects of their use which very specifically denies any use for studies. The contracts for being able to grow these are stupendous and the penalties worse than fairy tale legends. The only approved use basically for these so-called “fuds” is for consumption. We cannot know how they actually affect us because they are private and we are not entitled to know even though our government which we pay for supports them and subsidizes them in atrocious amounts.

    Also, Cargill (another private company that does not have to disclose anything) is a big supporter of the GE/GMO lines and is also a main supporter of Standford.

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  15. Andrea Psoras said on September 10, 2012:

    the study was done in the UK using that food? Food in the UK and in the EU doesnt have near the gmo and those associated herbicides as US food. Meanwhile thank you to the reader who posted about Cargill supporting Stanford and that would distort or compromise the quality of the research and finds. Much appreciated.

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  17. Lana said on September 13, 2012:

    The study does not include indirect safety impacts of organic foods vs conventional foods. I.e. their definition of ‘safe’ clearly does not include environmental health. Indirect impacts of the production and use of pesticides and chemicals on water supplies are well documented, which have a serious knock-on effect on the health of humans nationwide and worldwide. Other indirect safety impacts include the link between agro-chemical usage and the loss of bees/pollinators, upon which the security of our whole food and farming system depends…

    • Chuck Benbrook said on September 28, 2012:

      Many people have criticized the Stanford team for impacts/aspects of organic farming and food quality that were left out of the study. On this point, they deserve a break, since even the job they took on was enormous, and one which they struggled to carry out in an appropriate way, as the many technical critiques of their methods have driven home. What bothers me about the study was that the stated findings in the paper were not well supported by their analysis, and they seemed determined to focus on certain “findings,” while ignoring large bodies of science in other disciplines that speak to whether organic food delivers health promoting benefits worthy of note. In a way, the Stanford team set up a straw man, testing the assertion that for any given patient, “Organic food can cure the common cold or reverse diabetes or prevent cancer,” and then shot it down by showing that the medical literature lacks case control studies and clinical trials demonstrating that this assertion is true. But this does not rule out the possibility that organic food and farming can help prevent the onset of disease, slow its progression, and supports normal pre-natal development across the U.S. population. The lack of evidence that organic food can cure a given patient, much like administering a course of drug treatment often does, should not be extended to also imply that consumption of organic food has no bearing or impact on the incidence, severity, or prevention of a number of health problems.

  18. jennifer said on September 27, 2012:

    nice article

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