Keywords: Organic food, Nutritional quality of organic food, Toxicological quality of organic food, Comparisons between organic and conventional food, Chemical composition of food.

Valid nutritional and toxicological quality comparisons between organic and conventionally grown foodstuffs require that the plants be cultivated in similar soils, under similar climatic conditions, be sampled at the same time and pre-treated similarly and analyzed by accredited laboratories employing validated methods. In terms of foods of animal origin, animals would have to have been fed on plants meeting the above production criteria. Although there are almost 200 published papers dealing with this subject, very few studies, particularly with regard to foods of animal origin, meet the above criteria.

Moreover, the number of samples in studies are usually inadequate to allow valid statistical comparisons. Thus, in terms of most nutrients and contaminants, no consistent trend of differences can be established in chemical quality between organic and traditionally grown foods. However, despite the heterogeneity of the material and research methodology, certain differences in chemical quality between conventionally grown foods and those produced by organic farming can be identified.

The clearest difference appears to be the higher protein, nitrogen and nitrate contents of conventionally grown plants compared with those cultivated organically.

Dr Jorma Kumpulainen, MTT, Agrifood Research, Finland

20 pages, 4 figures, 10 tables, 39 refs.