Question of trust in the organic food wars As a city boy, I have learnt to tread carefully through the organic farming debate, watching for what might stick to my boots. Big conventional food companies require scrutiny. But so do the champions of organic food. When Stanford University researchers said this month that they had found no strong evidence that organic foods were more nutritious than conventional ones, I expected that organic advocates such as the Soil Association would immediately try to rubbish their conclusions, as they did when a 2009 UK study reached similar results. The Soil Association, whose patron is Prince Charles, duly leapt in, declaring Stanford's "American study" to be "of limited application in Europe." The problem with this riposte is that most of the studies the Stanford article examined were from Europe. In their analysis, published in the Annals of Internal Medicine, the Stanford researchers looked at 17 studies of the effects of food on humans, of which 13 were from Europe, and at 223 studies of the nutritional qualities of food, of which 157 were from Europe. When I asked the Soil Association for an explanation, it apologised and said "our choice of wording was unclear." It said it was attempting to highlight that the Stanford project "excluded all papers not written in English, in a field of research where many published papers come from non-English scientists - in particular in Germany." All the papers are in English, but they come from a range of European countries, including Germany, Switzerland, the Netherlands, Denmark, Italy, Finland and Greece. What did the Stanford study find? First, that with two exceptions, organic food was no more nutritious than conventional. The two exceptions were milk - a few studies suggested that the organic variety might contain "significantly more" beneficial omega-3 fatty acids - and phosphorus, which was higher in organic than in conventional food. However, the latter didn't matter much, since only "near-total starvation" was likely to produce human phosphorus deficiency. The Stanford work did find two studies reporting "significantly lower urinary pesticide levels" in children on organic diets. However, there was little evidence that the higher level of pesticides in conventional food exceeded allowed limits. There was also a higher risk of finding bacteria resistant to antibiotics in conventional chicken and pork than in organic food. So there is ammunition for both sides. But I was still interested in another research programme: a European Union-funded study effort, involving more than 30 institutions. I first heard about this from Peter Melchett, the Soil Association's policy director, when the 2009 study, commissioned by the UK Food Standards Agency, came out. He asked why they hadn't waited a year or two for the EU study to be completed and I agreed with him. So what did that project, called the QualityLowInputFood (QLIF) study conclude? According to its website, it found that organic food production resulted in higher levels of nutritionally desirable compounds and lower levels of undesirable ones. It also found that "health claims for organic foods are not yet substantiated." These seemed to be contradictory outcomes, so I asked Carlo Leifert of Newcastle University, the original project leader, to explain. He said that, with one exception, the papers proving the nutritional benefits of organic food had not yet been published. The QLIF website also said that "productivity remains a weakness of organic food chains." What seemed like better energy efficiency and lower greenhouse gas emissions "partly melted away when calculated on a per ton basis." I reach three conclusions. First, although no one has been able to show organic food is more nutritious, I understand why people buy it, especially for their children. The authorities might regard pesticide levels in conventional food as safe but who knows the long-term effects? Second, the way to marry the high farming productivity needed to feed a growing world population and lower pesticide use may be genetically modified food. We should press ahead with research on the health and environmental effects. The Soil Association may object, but my third conclusion is that campaigners need to be asked the same hard questions as any business or government, particularly when they have trouble wording their press releases.