Washington State University – The largest study of its kind has found that organic foods and crops have a suite of advantages over their conventional counterparts, including more antioxidants and fewer, less frequent pesticide residues.

The study looked at an unprecedented 343 peer-reviewed publications comparing the nutritional quality and safety of organic and conventional plant-based foods, including fruits, vegetables, and grains. The study team applied sophisticated meta-analysis techniques to quantify differences between organic and non-organic foods.

Most of the publications covered in the study looked at crops grown in the same area, on similar soils. This approach reduces other possible sources of variation in nutritional and safety parameters.

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The British Journal of Nutrition study was led by scientists at Newcastle University in the United Kingdom. In general, the team found that organic crops have several nutritional benefits that stem from the way the crops are produced. A plant on a conventionally managed field will typically have access to high levels of synthetic nitrogen, and will marshal the extra resources into producing sugars and starches. As a result, the harvested portion of the plant will often contain lower concentrations of other nutrients, including health-promoting antioxidants.

Without the synthetic chemical pesticides applied on conventional crops, organic plants also tend to produce more phenols and polyphenols to defend against pest attacks and related injuries. In people, phenols and polyphenols can help prevent diseases triggered or promoted by oxidative-damage like coronary heart disease, stroke and certain cancers.

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Overall, organic crops had 18 to 69 per cent higher concentrations of antioxidant compounds. The team concludes that consumers who switch to organic fruit, vegetables, and cereals would get 20 to 40 per cent more antioxidants. That’s the equivalent of about two extra portions of fruit and vegetables a day, with no increase in caloric intake.

While crops harvested from organically managed fields sometimes contain pesticide residues, the levels are usually tenfold to a hundredfold lower in organic food, compared to the corresponding, conventionally grown food.

“This study is telling a powerful story of how organic plant-based foods are nutritionally superior and deliver bona fide health benefits,” said Charles Benbrook, a Washington State University researcher and the lone American co-author of the paper.

In a surprising finding, the team concluded that conventional crops had roughly twice as much cadmium, a toxic heavy metal contaminant, as organic crops. The leading explanation is that certain fertilizers approved for use only on conventional farms somehow make cadmium more available to plant roots. A doubling of cadmium from food could push some individuals over safe daily intake levels.