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Study says organic food offers few advantages


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POSTED: Monday, August 03, 2009

People have many reasons for choosing organic foods. Some people may be most concerned with environmental sustainability, preservation of the soil quality of farm land, or avoidance of pesticide exposure. Other consumers may select organic foods expecting these foods to provide greater nutritional value.

Question: Are organic foods more nutritious than their less expensive conventional counterparts?

Answer: A study scheduled to appear in the September issue of the American Journal of Clinical Nutrition provides the most comprehensive published answer at this time. This report indicates that there is little difference in the nutrient content of organic foods compared to conventional foods.

Q: How did the researchers evaluate the nutritional value of the organic and conventional foods?

A: Researchers at the London School of Hygiene & Tropical Medicine conducted a comprehensive review and evaluation of the scientific literature on this topic. After a very thorough search of the scientific literature for high quality studies that provided acceptable data on the nutrient content of organic and conventional foods, the researchers identified 55 studies published between 1958 and 2008 that met their quality criteria for comparing organic and conventional crops for nutrient content.

Q: What nutrients were evaluated in the study?

A: For several nutrients, there were not enough studies published to make valid comparisons. However, they were able to determine that there were no significant differences between organic and conventional foods in the content of vitamin C, magnesium, calcium, potassium, zinc, copper and phenolic compounds. Phenolic compounds include many of the so-called phytochemicals such as flavonoids and tannins.

A few things were different for organic produce. Conventional foods were slightly higher in nitrogen, which is an estimate of the protein content of foods. Organic foods on average were slightly higher in phosphorus and acidity. Phosphorus is an essential mineral that is usually plentiful in the diet. Acidity is typically greater in produce that is less mature when harvested.

There were only 10 studies of animal-source foods that met the quality requirements for use in comparing organic to conventional foods and only total fat and mineral content comparisons were reported. No differences were found for these two components of animal foods.

Q: What did the researchers conclude?

A: They stated that the small nutritional differences they found between organically and conventionally produced foods were “;... unlikely to be of public health relevance”; and that they found no evidence to support the selection of organically produced foods for nutritional reasons. Since the number of high quality research publications was limited, the researchers emphasized the need for more well designed studies on this topic.

Based on this comprehensive study, those who cannot afford organic foods can rest assured that they are obtaining comparable amounts of key essential nutrients from more affordable conventional fare.

 

Joannie Dobbs, Ph.D., C.N.S. and Alan Titchenal, Ph.D., C.N.S. are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa. Dobbs also works with University Health Services.