Food for thought
Nature 511, 7509 (2014). doi:10.1038/511264a
Researchers investigating different farming practices should not have to pick sides.
Some debates run and run. Last month, an analysis found that a selection of organically farmed food contained, on average, higher concentrations of supposedly beneficial antioxidant compounds than food produced by conventional farming (M. Barański et al. Br. J. Nutr. http://doi.org/tqs; 2014).
This field is still relatively small and the quality of research can be variable. The analysis advances previous work, thoroughly evaluates the current situation and yields some results that warrant further investigation. Still, several prominent nutrition scientists have voiced valid criticisms of the paper’s method and statistical analysis (see go.nature.com/ikx15z), and have raised concerns over the scientific rigour of some of the primary research that it covers.
It is good to be thorough: the study examines all of the available evidence so far. But in a field in which research quality can be hit and miss, it can be better to be cautious. The authors would perhaps have generated more confidence in their results if they had been more selective. But such selection, inevitably, raises questions about how it is done.
Beyond the arguments about this specific study, which the authors have defended, lies a bigger issue. There are some fundamental questions that this type of research cannot answer, despite the way the results have been interpreted by the mainstream media as pointing to clear benefits of organic farming.
The study attempts to examine how different farming methods affect the nutritional quality of the product — an important question. There is plenty of room for improvement in the conventional farming system and in the nutritional quality of many people’s diets. So far, so good.
The paper also refers to the link between increased dietary concentrations of antioxidant compounds, such as phenolic acids and flavonols, and a reduced risk of chronic diseases — including some cancers. However, the evidence for such a link is mixed, and tentative at best. A more important question is not the level of antioxidants in organic or non-organic food, but how that contributes to health.
It is also not clear that organic farming practices are the cause of the observed higher concentrations of antioxidants. Research could help to determine, for example, whether organic crops — which are not treated with pesticides — release more phenolic compounds as a defence against pests and pathogens. Or perhaps the nitrogen fertilizers applied to conventional crops encourage growth rather than the production of such chemical defences.
This is a useful discussion, but difficult to have on neutral territory. Research on the different farming systems can often seem like a contest in which one practice is pitted against another and in which researchers must pick sides. Science should stay focused on the heart of the matter: the provision of more nutritious food for more people in a more sustainable way.