COSTLY ORGANIC vegetables are no better for your health than those grown conventionally, a study has found.

A two-year experiment which involved scientists growing potatoes, carrots and onions under both organic and traditional conditions has found the health-giving properties of each are virtually identical.

The chemical compound in vegetables that fights cancer, heart disease and dementia was found to be present in virtually the same amounts in both types.

However, the Irish Organic Farmers and Growers Association last night said the study, which was carried out by environmental scientists in Denmark, was not relevant to organic production in Ireland.

The group insisted that organic food produced here is healthier because our soil is kept more fertile by rotating crops.

In the study, scientists at the University of Copenhagen cultivated a total of 72 plots of land, half using traditional farming methods, including treating them with pesticides, non-organic fertilisers and added nutrients.

The other half were farmed organically, under conditions recommended by various organic food organisations, which involved using natural aids such as manure instead of fertiliser.

The result showed little difference in the amount of the key compound, polyphenols, in either the onions or the carrots, though there was a slightly higher level in organic potatoes than in conventional ones.

Crops were grown at different times of year and in different parts of the country because factors like the type of soil, the difference in climate and attacks by pests play a major role in the amount of polyphenols produced by plants.

Although levels of polyphenols have been shown to protect against cancer cells in laboratory tests, it is still unclear whether these antioxidants have the same beneficial effects when taken into the body through food.

Last night, the Irish organic association said Danish organic farming was different.

Grace Maher, development officer at the association, said that unlike in Denmark, soil in Ireland is kept fertile by rotating crops.

“Crop rotation is an integral part of organic farming. It is essential to prevent the build-up of pests and disease in the soil, but it is also important as it means that nutrients are not continually being depleted from the soil. This means that nutrients are readily available in the soil for crops to absorb.

“This is an isolated study and our research has shown that the main reasons people buy organic food is that it is free from pesticides, free from GM materials. It also has high animal welfare standards and is climate friendly. We also believe that organic food is more nutritious,” she said.

She insisted that organic produce can be cheaper if consumers shop around.

“On the issue of cost, organic food is extremely cost competitive and fruit and vegetables bought in season are often cheaper than conventionally produced food, particularly if sourced directly from the producer.”

The latest study is published by the Journal of Agricultural and Food Chemistry.