Organic foods are up to 60 per cent higher in many antioxidants and have lower levels of a toxic metal, than conventionally grown crops, according to a UK study.

The study, published in the British Journal of Nutrition on July 15, is a meta-analysis of 342 peer reviewed publications on the compositional differences between organic and conventional crops.

The study is one of the largest and most comprehensive of its kind, but its authors have argued that there is not enough conclusive evidence that organic food is better for you.

The study's senior author, Professor Carlo Leifert from the Newcastle University school of Agriculture, Food and Rural Development, says there seemed to be some health benefits to organic food.

But he says more work needs to be done to measure the health effect of human consumption of organics.

"The fact that you find that composition differences, even for compounds that are linked to health benefits, doesn't mean that you can make a health claim to say that organic food is better for you," Professor Leifert said.

Professor Leifert says he found that on average, over all crops and in all geographic locations where studies were undertaken, antioxidants were higher in organic foods.

He says conventional foods were found to have a higher concentration of a toxic metal called cadmium and a higher frequency of pesticides.

Dr Ian Musgrove, a molecular pharmacologist and toxicologist at the University of Adelaide, says it is "yet another study that shows there is little difference in nutritional content" between organically and conventionally grown food.

"This study is consistent with a lot of other studies that have looked at the amount of nutrients in organic versus inorganic foods," Dr Musgrove said.

Dr Musgrove says there are some increases in certain antioxidant species, but in terms of overall nutritional value, there is not much to choose between the two.

"If you’re going to choose organic food, then there are no strong health reasons to choose organic food over conventionally grown food," Dr Musgrove said.