A tomato that could help reduce the risk of developing cancer has gone on sale.

Tesco is launching a new Healthy Living variety of the fruit containing high levels of a chemical it claims is linked to a potential cancer risk reduction.

The tomato contains roughly a third more lycopene than other varieties sold on the vine. It is being grown by specialist growers Humber VHB in Runcton, near Chichester, and will be trialled first in Tesco stores in Sussex.

Lycopene is the pigment which gives tomatoes their red colour and is a powerful antioxidant also found in watermelons and pink grapefruit.

But customers will pay a hefty mark-up for the tomato, the benefits of which are scientifically unproven.

They are on sale in selected stores at £1.89 for a pack of four or five, while a normal pack of six Tesco tomatoes on the vine costs £1.08.

Prostate cancer is the most common type diagnosed in men in the UK and every year 10,000 men die from the disease.

Chris Hiley, head of policy and research for the Prostate Cancer Charity, said the effect of lycopene on prostate cancer had been subject to scientific studies.

He said: "Over recent years, prostate cancer researchers have repeatedly returned to questions about the role of lycopene in diet.

"We still can't come to a firm conclusion that the risk of prostate cancer is reduced by increasing lycopene intake but it is very clear that men should eat a varied and healthy diet and tomato and tomato-based products have a place in that."

Tesco's Healthy Living variety was naturally bred in Holland using different tomato types with high lycopene levels.

The lycopene is more easily absorbed into the bloodstream when the tomatoes are cooked with certain oils such as olive oil. The tomatoes may be the first in a succession of enhanced fruit and vegetables.

Dr David Hand, technical director of Humber VHB, said: "I think there are lots of supermarkets looking at superfoods and the health and well-being agenda, so it's very topical.

"The tomatoes are grown in exactly the same way we grow our normal types."

A spokeswoman for Tesco said the tomatoes were more expensive because they were part of a small production run.

The cost might go down if the line expanded.