Sales of watercress surged at the weekend after claims the salad could fight cancer.

Britain's three big watercress producers - Vitacress, Bakkavör and Watercress Company - said sales through the multiples had jumped to summer levels after the media picked up on the publication of a new study into the health benefits of watercress.

"Demand for watercress has rocketed since the cancer research story," said one producer. "Some lines have seen a more than 100% increase and current volumes are at the levels we would expect to see at the height of the summer."

The study is the product of two years of research, funded by the Watercress Alliance, of which the big three producers are members. Scientists investigating the nutritional benefits of watercress found a daily portion of 85g of the vegetable significantly reduced DNA damage to blood cells - a trigger in the development of cancers. As well as cutting cell damage by nearly a quarter, researchers also found a high watercress diet boosted levels of critical antioxidants in the blood stream. Blood levels of lutein rose 100% and beta-carotein 33% in adults after eight weeks on a helping a day. The benefits were greatest among smokers.

Professor Ian Rowland, who led the research project at the University of Ulster, said the findings were highly significant.

"What makes this study unique is it involves people eating watercress in easily achievable amounts, to see what impact that might have on known bio-markers of cancer risk, such as DNA damage. Most studies to date have relied on tests conducted in test tubes or in animals, with chemicals derived from cruciferous vegetables."

The Watercress Alliance is planning to keep the story in the headlines with a series of PR stunts. The annual Watercress Fest on 13 May will drum home the research findings again, as will the Big Green Lunch in June, which is being held in aid of a cancer charity.