Organic food is healthier than conventional produce and may be better at preventing cancer and heart disease, according to the biggest study of its kind.
In a finding that challenges official advice, 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 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.
The findings could help settle the long running debate over the health benefits of organic food.
A spokesman for the Food Standards Agency - which has come under fire for insisting that organic produce is no more healthier than conventional food - said it would review the latest study.
The findings come from Prof Carlo Leifert, an expert in organic food whose four year Newcastle University study is funded by the European Union and food companies.
He 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.
They found that levels of antioxidants in milk from organic cattle were between 50 and 80 per cent higher than conventional milk.
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.
He also believes there is enough evidence for the Food Standards Agency to change its advice on organic food and admits to being puzzled why the agency has not already done so.
"I wonder whether it's more to do with politics," he said.
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 study - which runs for another year - found that milk was more nutritious in the summer, when cattle are grazing fresh grass.
"If you feed a cow on grass you get better milk," he said.
"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."
The Soil Association, which has been embroiled in a decade long dispute with the FSA 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.
The reasons why organic food is popular vary. Some shoppers buy it for the taste, others to reduce exposure to chemicals.
Organic meat is popular among shoppers concerned about animal welfare.
The Food Standards Agency has ordered a review into its advice on organic food and health benefits. The results are expected in March.
"Until then the advice remains that there is no evidence that organic food has higher levels of nutrients than conventional food," a spokesman said.
The new study shows that organic milk has 60 to 80 per cent more nutrients in the summer than conventional milk, and 50 to 60 per cent more in the winter.
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.
from This Is London
