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An independent systematic review of the available published literature was designed to determine the relevance to health of any differences in nutrients and other substances in organically and conventionally produced crops and livestock products. This review does not address contaminant content (such as herbicide, pesticide and fungicide residues) of organically and conventionally produced foodstuffs or the environmental impacts of organic and conventional agricultural practices.
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The review was commissioned to give consumers accurate information about their food, based on the most up-to-date science. This research had also been called for by the organic sector to review emerging research in this area.
Research Approach: <BR> This research was split into two separate parts, one of which looked at differences in nutrient levels and their significance, while the other looked at the health benefits of eating organic food.
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A systematic review was carried out of all papers published over the past 50 years that related to the nutrient content of, and health differences between, organic and conventional food. A total of 162 relevant published articles were identified. These all had an English abstract and were published in peer-reviewed journals from 1 January 1958 to 29 February 2008. Articles included in the review were assessed for study quality. A total of 55 met the pre-defined satisfactory quality criteria.
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A total of 3,558 comparisons of content of nutrients and other substances in organically and conventionally produced foodstuffs were extracted for analysis.
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Results and findings: <br>Analysis of all studies, independent of quality, showed no evidence of a difference between organically and conventionally produced crops for the following nutrients and other substances: vitamin C, calcium, phosphorus, potassium, total soluble solids, titratable acidity, copper, iron, nitrates, manganese, ash, specific proteins, sodium, plant non-digestible carbohydrates, â-carotene and sulphur.
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Significant differences were found in some minerals (nitrogen was higher in conventional crops; whereas phytochemicals, magnesium and zinc, and sugars were higher in organic crops).
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When analysis was restricted to satisfactory quality studies, significant differences were found only in nitrogen content (higher in conventional crops), phosphorus (higher in organic crops) and titratable acidity (higher in organic crops).
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Evidence was more limited for meat, dairy and eggs. When looking at all studies, independent of quality, no difference was detected between organically and conventionally produced livestock products for: saturated fatty acids, monounsaturated fatty acids (cis), n-6 polyunsaturated fatty acids, fats (unspecified), n-3 polyunsaturated fatty acids, nitrogen and ash.
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Significant differences were found in some fats, which were higher in organic livestock products.
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When analysis was restricted to satisfactory quality studies, significant differences were found only in nitrogen content (higher in organic livestock products).
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Based on the current evidence, the review suggests that organically and conventionally produced crops and livestock products are broadly comparable in their nutrient content. Where nutrients are higher in organic crops and livestock products, it is unlikely these differences are relevant to consumer health.
<P>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food Standards Agency Research webpage</a>.