Nutritional quality of organic versus conventional fruits, vegetables, and grains.

OBJECTIVES To survey existing literature comparing nutrient content of organic and conventional crops using statistical methods to identify significant differences and trends in the data. DESIGN Published comparative measurements of organic and conventional nutrient content were entered into a database for calculation. For each organic-to-conventional comparison, a percent difference was calculated: (organic - conventional)/conventional x 100. For nutrients where there was adequate data, the Wilcoxon signed-rank test was used to identify significant differences in nutrient content as represented by the percent difference. Mean percent difference values were also calculated for each significant nutrient by study and by vegetable for the most frequently studied vegetables. The nutrient content of the daily vegetable intake was calculated for both an organic and conventional diet. RESULTS Organic crops contained significantly more vitamin C, iron, magnesium, and phosphorus and significantly less nitrates than conventional crops. There were nonsignificant trends showing less protein but of a better quality and a higher content of nutritionally significant minerals with lower amounts of some heavy metals in organic crops compared to conventional ones. CONCLUSIONS There appear to be genuine differences in the nutrient content of organic and conventional crops.

[1]  H. Vogtmann,et al.  Accumulation of Nitrates in Leafy Vegetables Grown Under Contrasting Agricultural Systems , 1984 .

[2]  Katrin Woese,et al.  A Comparison of Organically and Conventionally Grown Foods—Results of a Review of the Relevant Literature , 1997 .

[3]  H. Vogtmann,et al.  The Nitrate Content of Vegetable and Salad Crops Offered to the Consumer as from “Organic” or “Conventional” Production Systems , 1988 .

[4]  R. Naidu,et al.  Long-Term Changes in Cadmium Bioavailability in Soil , 1998 .

[5]  Urs Niggli,et al.  Effect of three farming systems (bio-dynamic, bio-organic, conventional) on yield and quality of beetroot (Beta vulgaris L. var. esculenta L.) in a seven year crop rotation , 1993 .

[6]  Karin Plochberger.  Feeding experiments. A criterion for quality estimation of biologically and conventionally produced foods , 1989 .

[7]  D. Lairon,et al.  Valeur nutritionnelle comparée des légumes obtenus par les méthodes de l'agriculture biologique ou de l'agriculture conventionnelle , 1984 .

[8]  R. Harwood,et al.  Organic Farming Research at the Rodale Research Center , 1984 .

[9]  T. Logan.  The Role of Organic Matter in Modern Agriculture , 1987 .

[10]  A. Mozafar.  Nitrogen fertilizers and the amount of vitamins in plants: a review , 1993 .

[11]  P. Warman,et al.  Yield, vitamin and mineral contents of organically and conventionally grown carrots and cabbage , 1997 .

[12]  Herbert H. Koepf,et al.  Environmentally sound agriculture: William Lockeretz (Editor). Selected Papers from the Fourth International Conference on the International Federation of Organic Agriculture Movements, Cambridge, MA 18–20 August 1982, Praeger, New York, 1983, 426 pp., tables and diagrams, ISBN 0-03-062863-6 , 1984 .

[13]  Werner Schuphan,et al.  Nutritional value of crops as influenced by organic and inorganic fertilizer treatments , 1974 .

[14]  L. Langner,et al.  The economic implications of organic farming , 1986 .

[15]  B. P. Klein,et al.  Ascorbic Acid and Vitamin A Activity in Selected Vegetables from Different Geographical Areas of the United States , 1982 .

[16]  J. Muthukannan,et al.  The Food Guide Pyramid , 1995 .

[17]  T. Nilsson.  YIELD, STORAGE ABILITY, QUALITY AND CHEMICAL COMPOSITION OF CARROT, CABBAGE AND LEEK AT CONVENTIONAL AND ORGANIC FERTILIZING , 1979 .

[18]  Yona Chen.  Organic Matter Reactions Involving Micronutrients in Soils and Their Effect on Plants , 1996 .

[19]  Y. Henis.  Soil microorganisms, soil organic matter and soil fertility , 1986 .

[20]  F. Bear,et al.  Variation in Mineral Composition of Vegetables , 1949 .

[21]  D. Lairon,et al.  Yield and content in nitrates, minerals and ascorbic acid of leeks and turnips grown under mineral or organic nitrogen fertilizations , 1987, Plant foods for human nutrition.

[22]  B. B. Desai,et al.  Effects of Agricultural Practices, Handling, Processing, and Storage on Vegetables , 1988 .

[23]  Y. Hadar.  The role of organic matter in the introduction of biofertilizers and biocontrol agents to soils , 1986 .

[24]  O. Meyer,et al.  Human Semen Quality in Relation to Dietary Pesticide Exposure and Organic Diet , 1999, Archives of environmental contamination and toxicology.

[25]  D. B. Kelly.  Congenital Occlusion of Choanae , 1939, British medical journal.

[26]  M. Miller,et al.  Vitamin and Mineral Contents of Carrot and Celeriac Grown under Mineral or Organic Fertilization , 1991 .

[27]  B. Kansal,et al.  Effect of different levels of nitrogen and farmyard manure on yield and quality of spinach (Spinacea oleracea L.) , 1981 .

[28]  C. Thoroughgood,et al.  Chemical evaluation of vegetables grown with conventional or organic soil amendments , 1976 .

[29]  J. Marbach,et al.  External qigong therapy for chronic orofacial pain. , 2002, Journal of alternative and complementary medicine.

[30]  Robert Sandy,et al.  Statistics for Business and Economics , 1989 .

[31]  A. Bendich.  Dietary reference intakes for vitamin C, vitamin E, selenium, and carotenoids institute of medicine washington, DC: National Academy Press, 2000 ISBN: 0-309-06935-1 , 2001 .

[32]  C. Coudray,et al.  Minerals and phytic acid interactions: is it a real problem for human nutrition? , 2002 .

[33]  H. Vogtmann,et al.  Effects of composted FYM and a compound fertiliser on yield and nitrate accumulation in three summer lettuce cultivars grown in an organic system , 1989 .

[34]  Comparison of chemical composition and taste of biodynamically and conventionally grown vegetables , 1981 .

[35]  Robert S. Harris,et al.  Nutritional Evaluation of Food Processing , 1988 .

[36]  A. Mayer.  Historical changes in the mineral content of fruits and vegetables , 1997 .

[37]  Y. Avnimelech,et al.  The Role of Organic Matter in Modern Agriculture , 1986, Developments in Plant and Soil Sciences.

[38]  N. Shier,et al.  A Comparison of crude protein, moisture, ash and crop yield between organic and conventionally grown wheat , 1984 .

[39]  its Panel on Folate,et al.  FOOD AND NUTRITION BOARD , 1998 .

[40]  D. Lairon,et al.  Effect of organic and mineral nitrogen fertilization on yield and nutritive value of butterhead lettuce , 1984 .

[41]  G. Shearer,et al.  Amino Acid Composition of Grain Protein of Maize Grown with and without Pesticides and Standard Commercial Fertilizers1 , 1981 .