Researchers found that switching to an organic diet would provide an antioxidant boost equivalent to one to two extra portions of fruit and vegetables a day.
The study, published in the British Journal of Nutrition, also found significantly lower quantities of harmful metals in organic crops.
Levels of highly toxic cadmium, which are restricted by the European Commission, were reduced by almost 50 per cent compared with conventionally grown plants.
Professor Carlo Leifert, who led the research, said: "This study demonstrates that choosing food produced according to organic standards can lead to increased intake of nutritionally desirable antioxidants and reduced exposure to toxic heavy metals.
"This constitutes an important addition to the information currently availwhich has been confusing and conflicting."