Research shows little advantage in eating organic tomatoes.

Organically grown tomatoes contain higher levels of key micronutrients than do conventionally grown tomatoes, say French scientists. But while this might seem like a bit of tasty research for the organic movement to get its teeth into, its conclusions could be a little harder to swallow.

After three weeks eating either organic or non-organic tomato puree, people have similar levels of antioxidants in their blood, says Catherine Caris-Veyrat of the Institut National de la Recherche Agronomique in Avignon. Hers is the first study to provide a controlled comparison of the micronutrients contained in produce, and to track them all the way through to humans, says Caris-Veyrat. But there's no clear evidence that going organic is healthier than sticking with conventionally fertilised crops, she concludes.

Her team cultivated tomatoes under conventional and organic conditions. All other variables, such as climate, irrigation and mechanical crop protection were identical. Chemical analysis reveals that organic tomatoes have higher levels of antioxidants, such as vitamin C, carotenoids and polyphenols. Thus, organic farmers argue a health benefit since these micronutrients could reduce the incidence of certain cancers.

But this isn't necessarily the case. Over a period of three weeks, volunteers were given a daily dose of 100g of tomato puree made from either organically or conventionally grown tomatoes. At the end of this period, levels of antioxidants in their blood plasma had increased, but there was no significant difference between the two different methods of culture.

'It's difficult to say eat more organic or eat more conventional,' says Caris-Veyrat. On the basis of this research, the best advice is simply to eat more fruit and vegetables irrespective of whether organic or non-organic, she says.

However, Anthony Trewavas, professor of cell and molecular biology at the University of Edinburgh, UK, questions whether higher levels of antioxidants are necessarily beneficial. 'If your diet contains adequate vitamins A, C and E then additional antioxidants like lycopene are surplus to requirements and may even be damaging,' he says. 'We are a healthy population with increasing life expectancy and lowering cancer rates. Organic food is a foible for those with money to waste.'

Henry Nicholls