The Stanford University Medical School researchers evaluated the findings of selected studies previously published in international peer-reviewed journals, posing the question: are organic products safer or healthier than conventional alternatives? Parameters examined in a wide variety of foods included nutrient levels, pesticide residues, microbial contaminants and the incidence of antibiotic-resistant bacterial strains. The findings of human nutrition studies were also analysed.
Smith-Spangler et al. (2012) state in summary that their comprehensive study yielded scant evidence that produce from organic agriculture has health benefits. The authors claim they found no clear evidence that consuming organic products offered any health benefits compared to conventionally produced foods, although the study findings show that organic foods reduce contamination from pesticide residues and that organically farmed chicken and pork can reduce exposure to antibiotic-resistant bacteria.
Stanford study has numerous flaws
Alberta Velimirov and Thomas Lindenthal (FiBL Austria) have given the Stanford study a closer look. Beside the discrepancies mentioned above, the two scientists found an array of serious flaws.
Just some of the flaws are listed here:
- The scant evidence of health benefits of organic produce that Smith-Spangler et al. (2012) claim to have found is inconsistent with the findings of other comparative meta-analyses, ignores the findings of basic research, and to an extent is the result of methodological shortcomings. In addition, the importance of randomly selected food quality parameters in relation to the whole system must not be taken out of context. Only a comprehensive interpretation that takes into account all sustainability parameters across the entire production chain can reflect the overall value of a food.
- Positive health impacts of organic produce referred to in the Findings section of the study by Smith-Spangler et al. (2012) are given no mention in either the Summary or in the press releases. Findings not mentioned in the Summary include the trend for organic produce to have higher levels of total phenols, higher levels of beneficial fatty acids in organic cow’s milk, a beneficial fatty acid profile in breast milk if the mother consumes a predominantly organic diet, and lower levels of the mycotoxin deoxynivalenol in cereals.
- Smith-Spangler et al. (2012) acknowledge that the risk of contamination with pesticide residues and antibiotic-resistant bacteria is lower in the case of organic produce. The authors use an unusual metric that presents the level of risk as 30% lower, although this figure would be 81% if conventional statistical methods were used.
- Even this clear finding with regard to substantially lower pesticide residues in organic products is qualified by the authors of the Stanford study by noting that in both production systems (organic and conventional) the risk of levels exceeding allowable limits is relatively low. The key point, however, is that in reality no individual residue occurs in isolation. The interactions between several substances are key. Discussions in the EU have therefore focused for some time on how to better assess residue interactions (such as interactions between various pesticides).
- Human nutrition research is not only expensive; it is also, and more importantly, very difficult to conduct. Aside from the difficulties involved in conducting the sort of long-term research that would be required to identify clinically relevant differences, human health depends on a whole range of influences. Short-term switching of dietary habits, as analysed in the Stanford study, delivers no clinically relevant results.
- In addition to human studies, research on animal nutrition is vital in order to explore the impact of consuming organic products over longer observation periods on genetically identical animal populations. The Stanford study completely ignores animal feeding experiments that have proven the positive impacts of organic products in terms of fertility, juvenile mortality and immune function.
- A study very similar to the Stanford study, published by renowned researchers at Newcastle University in the UK (Brandt et al. 2011), was ignored. This study, which evidences the benefits of organic products much more clearly, was published just one day after the Stanford study. It must have been known to the Stanford authors via precursor publications.
Upon detailed analysis, Lindenthal und Velimirov conclude that the Stanford study lacks rigour and gives a superficial and in some instances unjustifiable interpretation of results. It also frequently displays a fundamental lack of understanding of relevant systemic relationships.
What is needed: Research that improves organic practice
The Stanford study is methodologically flawed and hampers the continued improvement of organic farming. Many comparative studies that have been conducted in the past are equally unconstructive, as is the type of media coverage such studies receive. What is rather needed is a concerted research effort within the organic system. Given the advanced level of knowledge that already exists on the benefits of organic production and its development potential, scarce research resources need to be targeted towards its continued development. This would help to expand organic production and the availability of organic products. Alongside health benefits, this would have many positive environmental and socio-economic impacts in support of sustainable development.
(This text contains excerpts from the opinion paper by Thomas Lindenthal and Alberta Velimirov. The full response to the Stanford study is available for download.).
Further information
- Contact FiBL: Thomas Lindenthal and Alberta Velimirov
- Download: Opinion on Stanford Study (118.6 KB)