Prof Tim Lang, said that consumers are baffled by conflicting advice about food. He said that governments should set up an independent body of experts to integrate information on all aspects of food′s impact, including how healthy it is, its environmental effects and the social consequences of the way it is produced.

He acknowledged that this would be an extremely complex task, but said that consumers wanted reliable information. "The classical approach to this is to let prices and the consumer decide. But health and environment, justice and equity are all surely reasonable and decent aspirations," Lang said, "We need a food system to improve standards across a variety of equally important fronts."

He hoped that his proposed "omni-standards" would help consumers to navigate contradictory information. For example, the nutritional evidence for eating fish is very strong and that governments advocates eating two portions of fish a week. However fish stocks are in crisis and overfishing is having a significant ecological impact. "Which evidence do I listen to and shape my behaviour by?" he said.

Similarly, green beans from Kenya are good for you and if they are Fair Trade they may help the local economy where they are grown. However, he said each green bean stem has 4 litres of embedded water and they must be transported thousands of miles.Lang said that at present, scientists and NGOs often focussed on only one part of the problem. "Actually we are part of the problem. We′ve got to come together and start piecing information together," he said.

Communicating the information to consumers will not be easy, but he said packaging could have basic data in the form of a graphical representation of a food′s social, health and environmental footprint. More information could be made available via interactive screens in the supermarket or online.

Lang acknowledged that the practicalities of putting together a panel of experts to formulate the standards would be fraught with difficulty. One issue would be whether NGOs should be included directly.

"If I was off the record and there weren′t microphones here I would say something more interesting," he said. "I think there are very interesting tensions within government I will say very tightly – very interesting nuances between the various departmental chief scientists of their various positions."