Researchers have shown that fruit and vegetables contain up to 40 per cent more nutrients if they are grown without chemical fertilisers and pesticides.
The £12 million project spanning four years and partly funded by the European Union also found that organic milk contains 80 per cent more antioxidants -substances which reduce the risk of tumours and life threatening problems.
Organic produce also had higher levels of iron and zinc, vital nutrients lacking in many people's diets.
Prof Carlo Leifert who led the study said the health benefits were so striking that moving to organic food was the equivalent of eating an extra portion of fruit and vegetables every day.
"If you have just 20 per cent more antioxidants in every portion of vegetables, then it's simply a question of maths - eating four portion of organic fruit and vegetables is the equivalent to eating five portions of traditional fruit and vegetables," he said.
"Having said that, eating five portions of organic is even better still."
His team grew fruit and vegetables and reared cows on organic and non-organic sites on a 725 acre farm near at Newcastle University.
The new study shows that nutrient levels in organic milk are up 60 to 80 per cent more than conventional milk in summer, and 50 to 60 per cent more in the winter. In summer the cattle are grazing fresh grass.
"If you feed a cow on grass you get better milk," Prof Carlo Leifert pointed out.
"I suspect that because British cattle have so much grass in their diet that nutrient levels may be higher in conventional UK milk than in some imported organic milk."
Organic milk also has higher levels of vitamin E.
Organic cheese can have up to twice as many nutrients than conventional varieties.
Organic tomatoes, wheat, potatoes, cabbage, onions and wheat have 20 to 40 per cent more antioxidants than conventional fruit and vegetables.
Organic spinach and cabbage have been found to have more minerals.
Organic wheat, tomatoes, potatoes, cabbage, onions and lettuce had between 20 and 40 per cent more nutrients.
Although the study has yet to be published in a peer-reviewed journal, Prof Leifert is convinced the findings are sound.
The research suggests that organic fruit and vegetable is healthier because it uses more natural fertiliser such as clover and manure.
"Plants have evolved to get nutrients from organic matter, " he said.
"They need only a small amount early on in the year, and most in the summer. Yet with chemical fertiliser, they get most soon after planting and very little when they need it most."
The Soil Association, which has been embroiled in a decade long dispute with the Food Standards Agency over the health benefits of organic food, has welcomed the latest research.
There are few signs that the boom in organic food is ending. Sales are growing by 25 per cent each year and shoppers now spend around £2 billion a year on organic produce.