Katherine MacAlister wonders who we can trust when it comes to buying our greens . . .

It's hard to know which way to turn these days. Everything nice, tasty or exciting is invariably bad for you, leaving a motley collection of lentils, carrot juice and herbal tea to keep us fit, healthy and miserable.

We all know that cigarettes, alcohol, big fry ups, Mars bars in batter and a gallon of coffee a day have a detrimental effect on every part of our bodies, from our arteries to our waistlines.

But vegetables? How can eating vegetables be bad for you, especially organic, and why are they getting more expensive?

Organic mushrooms in Tesco were recently found to have high levels of e.coli. When the scare-mongering died down, scientists discovered that the mushrooms were entirely harmless. And now, claim campaign groups, consumers who buy organic produce from the supermarket - and boost the organic market by 40 per cent a year - are being exploited.

A Friends Of The Earth organic food survey has revealed widely varying prices and evidence of possible over-charging.

The FOE found that a pint of organic milk that should cost 26p, costs 35p in Iceland, 41p in Sainsbury's and Tesco, and 45p in Marks & Spencer.

"Our results suggest many consumers are being ripped off by the supermarket giants," says Sandra Bell of FOE.

The Iceland supermarket chain realised that the way forward was to create a niche for itself by investing in organic farming in Britain and selling organic produce at normal prices. A spokesman explains: "Our customers have told us they want us to make natural food a part of everyday eating, but like us, they don't believe they should have to pay inflated prices.

"This is why we're willing to put our money where our mouth is. It's our aim to stop organics being a niche market and make it accessible to all income groups."

The Co-Op and Asda look set to follow suit, creating a more competitive market for organic produce.

This, in turn, may hit the independent producers hard, who have avoided the supermarkets and have been doing very nicely selling their produce to local suppliers and from the farm gate. John Wilkins is one of these. He began organic meat farming in 1991 at Brillbury Hall Farm in Brill, and has watched the market increase over the years.

"Working with the supermarkets is like selling your soul to the devil," he says. "You are at their mercy after that.

"The supermarkets are keeping the people who would buy organics out of the market. People with young families, for example, often cannot afford it."

And he feels that the surge in farmers' markets is a direct backlash against the supermarkets' monopoly on pricing.

Ginny Stay, who runs a farm and box scheme with her husband Mark, in North Aston, is staying as far away from the supermarket giants as possible. "We aren't big enough yet but would never produce for a supermarket because many of them just take what they want and leave you with the rest," she explains.

As a result the Stays' produce is cheaper than the supermarket equivalent and is local into the bargain. But she is worried that Iceland's new approach will mean that the farmer, rather than the supermarket, will be expected to compensate for the reduced prices.

This is echoed by Serena Howard who runs an organic box scheme in Chipping Norton. She is worried that the news will mean shoppers won't appreciate that organic food does cost a bit more.

"These supermarket wars are very undignified and unhelpful and send out the wrong message to the growers, who are the ones who will suffer in the end.

"I think supermarkets should educate the public instead, to explain why organic food is more expensive," she says.

It seems that there is a happy medium to be reached, but whether the supermarkets will take this on board and lower their profits to a more reasonable level, remains to be seen.