Organic produce is better for you than ordinary food, a major European Union-funded study says.
Researchers looked at a variety of food, including tomatoes
The £12m four-year project, led by Newcastle University, found a general trend showing organic food contained more antioxidants and less fatty acids.
But researchers did admit the study showed some variations.
The findings call into question the current stance of the Food Standards Agency (FSA), which says there is no evidence that organic food is better.
Researchers grew fruit, vegetables and reared cattle on adjacent organic and non-organic sites across Europe, including a 725-acre farm attached to Newcastle University.
They found levels of antioxidants in milk from organic cattle were between 50% and 80% higher than normal milk.
Organic wheat, tomatoes, potatoes, cabbage, onions and lettuce had between 20% and 40% more nutrients.
But the study, which is yet to be published in a peer-reviewed journal, also showed there were significant variations.
Project co-ordinator Professor Carlo Leifert said: "We have shown there are more of certain nutritionally desirable compounds and less of the baddies in organic foods.
"Our research is now trying to find out where the difference between organic and conventional food comes from.
"What we're really interested in is finding out why there is so much variability with respect to the differences. What in the agricultural system gives a higher nutritional content and less of the baddies in the food?"
He said he hoped the findings would help farmers in organic to improve the quality of their produce.
Final results of the project are due to be published over the next 12 months.
The FSA, the body which provides advice and information on food, currently states: "Consumers may also choose to buy organic food because they believe that it is safer and more nutritious than other food.
"However, the balance of current scientific evidence does not support this view."
But officials are currently evaluating organic food for nutrient and non-nutrient content, with a report due to be published next year.
However, the Soil Association said the findings of the EU project showed the watchdog should change its stance.
A spokesman said: "The FSA has always been quite sceptical of organic food when there is no need to be. This study again shows that and I would hope they change their stance soon."