Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses

By Marcin Baranski, Dominka Srednicka-Tober, Nikolaos Volakakis, Chris Seal, Roy Sanderson, Gavin B. Stewart, Charles Benbrook, Bruno Biavati, Emilia Markellou, Charilaos Giotis, Joanna Gromadzka-Ostrowska, Ewa Rembiałkowska, Krystyna Skwarło-Son, Raija Tahvonen, Dagmar Janovska, Urs Niggli, Philippe Nicot and Carlo Leifert

Published in the British Journal of Nutrition (available free of charge) on July 15, 2014

Abstract

Demand for organic foods is partially driven by consumers’ perceptions that they are more nutritious. However, scientific opinion is divided on whether there are significant nutritional differences between organic and non-organic foods, and two recent reviews have concluded that there are no differences. In the present study, we carried out meta-analyses based on 343 peer-reviewed publications that indicate statistically significant and meaningful differences in composition between organic and non-organic crops/crop-based foods. Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95 % CI 5, 33) %, 69 (95 % CI 13, 125) %, 28 (95 % CI 12, 44) %, 26 (95 % CI 3, 48) %, 50 (95 % CI 28, 72) % and 51 (95 % CI 17, 86) % higher, respectively.

Many of these compounds have previously been linked to a reduced risk of chronic diseases, including CVD and neurodegenerative diseases and certain cancers, in dietary intervention and epidemiological studies. Additionally, the frequency of occurrence of pesticide residues was found to be four times higher in conventional crops, which also contained significantly higher concentrations of the toxic metal Cd. Significant differences were also detected for some other (e.g. minerals and vitamins) compounds. There is evidence that higher antioxidant concentrations and lower Cd concentrations are linked to specific agronomic practices (e.g. non-use of mineral N and P fertilisers, respectively) prescribed in organic farming systems. In conclusion, organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than the non-organic comparators across regions and production seasons.

Resources

Key Media Coverage

Clear differences between organic and non-organic food, study finds

Organic food has more of the antioxidant compounds linked to better health and lower levels of toxic metals and pesticides, according to the most comprehensive scientific analysis to date…

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Study of Organic Crops Finds Fewer Pesticides and More Antioxidants

Adding fuel to the debates over the merits of organic food, a comprehensive review of earlier studies found substantially higher levels of antioxidants and lower levels of pesticides in organic fruits, vegetables and grains compared with conventionally grown produce…

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Organic foods are more nutritious, according to review of 343 studies

“The first and foremost message is people need to eat more fruits and vegetables,” Benbrook said…

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Are Organic Vegetables More Nutritious After All?

There may never be an end to arguments over whether organic food is more nutritious. But a new study is the most ambitious attempt so far to resolve the issue — and it concludes that organic fruit and vegetables offer a key benefit…

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Also listen to Dr. Benbrook discuss the paper on NPR.