Analysing 343 studies into the compositional differences between organic and conventional crops, the team found that a switch to eating organic fruit, vegetable and cereals (and food made from them) would provide additional antioxidants equivalent to eating between 1-2 extra portions of fruit and vegetables a day.
The study, published in the British Journal of Nutrition, also shows significantly lower levels of toxic heavy metals in organic crops. Cadmium, which is one of only three metal contaminants along with lead and mercury for which the European Commission has set maximum permitted contamination levels in food, was found to be almost 50% lower in organic crops than those conventionally grown.
Newcastle University’s Professor Carlo Leifert, who led the study, said: “This study demonstrates that choosing food produced according to organic standards can lead to increased intake of nutritionally desirable antioxidants and reduced exposure to toxic heavy metals.
“This constitutes an important addition to the information currently available to consumers which, until now, has been confusing and in many cases is conflicting.”
This is the most extensive analysis of the nutrient content in organic vs conventionally produced foods ever undertaken, and is the result of a groundbreaking, new systematic literature review and meta-analysis by the international team.
The findings contradict those of a 2009 UK Food Standards Agency (FSA) commissioned study which found there were no substantial differences or significant nutritional benefits from organic food.
The FSA-commissioned study based its conclusions on only 46 publications covering crops, meat and dairy, while Newcastle-led meta-analysis is based on data from 343 peer-reviewed publications on composition difference between organic and conventional crops now available.
“The main difference between the two studies is time,” said Professor Leifert, who is professor of ecological agriculture at Newcastle University. “Research in this area has been slow to take off the ground and we have far more data available to us now than five years ago.”
The study, started under the European Sixth Framework Programme project QualityLowInputFood and completed later with funding from the Sheepdrove Trust, found that concentrations of antioxidants such as polyphenolics were between 18-69% higher in organically grown crops.
Numerous studies have linked antioxidants to a reduced risk of chronic diseases, including cardiovascular and neurodegenerative diseases and certain cancers.
Leifert added: “The organic vs non-organic debate has rumbled on for decades, but the evidence from this study is overwhelming: that organic food is high in antioxidants and lower in toxic metals and pesticides.
“This study should just be a starting point. We have shown without doubt there are composition differences between organic and conventional crops. Now there is an urgent need to carry out well-controlled human dietary intervention and cohort studies specifically designed to identify and quantify the health impacts of switching to organic food.”
Helen Browning, Soil Association chief executive, said: “The crucially important thing about this research is that it shatters the myth that how we farm does not affect the quality of the food we eat. The research found significant differences, due to the farming system, between organic and non-organic food.
“We know that people choose organic food because they believe it is better for them, as well as for wildlife, animal welfare and the environment, and this research backs up what people think about organic food.
“In other countries, there has long been much higher levels of support and acceptance of the benefits of organic food and farming. We hope these findings will bring the UK in line with the rest of Europe when it comes to attitudes to organic food and support for organic farming.”
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