Organic food 'better' for heart

A ten-year study comparing organic tomatoes with standard produce found almost double the level of flavonoids - a type of antioxidant. Writing in the Journal of Agricultural and Food Chemistry, the team said nitrogen in the soil may be the key. Dr Alyson Mitchell, a food chemist at the University of California, and colleagues measured the amount of two flavonoids - quercetin and kaempferol - in dried tomato samples that had been collected as part of a long-term study on agricultural methods.

They found that on average they were 79% and 97% higher respectively in the organic tomatoes than in the conventionally grown fruit. New Scientist magazine reported that the different levels of flavonoids in tomatoes are probably due to the absence of fertilizers in organic farming. Flavonoids are produced as a defense mechanism that can be triggered by nutrient deficiency, such as a lack of nitrogen in the soil. The inorganic nitrogen in conventional fertilizer is easily available to plants and so, the researchers suggests, the lower levels of flavonoids are probably caused by over-fertilization.

Soil Association policy director said: "We welcome the now rapidly growing body of evidence which shows significant differences between the nutritional composition of organic and non-organic food. "This is the second recent American study to find significant differences between organic and non-organic fruit. "These findings also confirm recent European research, which showed that organic tomatoes, peaches and processed apples all have higher nutritional quality than non-organic."

Steve - a compelling and well-structured study adds to the mounting data on organic versus conventional.