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SEPTEMBER 2003

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Comparative study of the effects of diets based on conventional and organic food

GRINDER-PEDERSEN et al. (2003) Effect of Diets Based on Foods from Conventional versus Organic Production on Intake and Excretion of Flavonoids and Markers of Antioxidative Defense in Humans; J. Agric. Food Chem. 51, p5671-5676.

16 healthy Danish people ate an identical 100% organic diet or 100% conventional diet for 3 weeks and had their urine tested before and afterwards. The diets were analysed for five flavonoids and the organic diet was found to contain significantly higher levels of the antioxidant quercetin, which was found in significantly higher concentrations in the urine of those eating the organic diet. The authors concluded that "the growing conditions of fruits and vegetables (conventional vs organic) affected the content of five selected flavonoids and resulted in differences in the urinary excretion of major dietary flavonoids."

Blood samples were also taken to measure antioxidant capacity of the blood with mixed results. Unfortunately they were taken after 12hr fasts, despite Serafini et al. (2002) showing that the effect of antioxidant-rich foods on the antioxidant capacity of the blood is transient and likely to have passed before the sampling after a 12 hour fast. No wonder then that the results were confused, and the authors acknowledged that "other factors may have affected this marker".

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