Purple GM tomato 'high in antioxidants'

In collaboration with the Press Association

European scientists have developed a type of genetically modified tomato that is particularly high in antioxidants. When the tomatoes were fed to specially-bred 'cancer-prone' mice, the mice lived longer. The tomato plants, which have been engineered to contain two pigmentation genes from the snapdragon flower, are rich in anthocyanins - the same plant chemical found in blueberries - and have almost three times the number of antioxidants found in natural fruit, according to lead author Eugenio Butelli.

This makes them particularly useful for studying the health benefits of anthocyanins.

To study the effects of the tomatoes on cancer, the researchers fed one of three diets to mice which had been bred to lack the p53 gene - an important 'tumour suppressor' gene which guards cells against becoming cancerous.

The first was a standard diet; the second was a standard diet supplemented with powdered red tomatoes; and the third was a standard diet supplemented with powdered purple tomatoes.

The researchers found that mice fed on purple tomatoes had an average lifespan of 182 days, while those fed on the standard diet typically lived for just 142 days.

Marco Giorgio from the European Institute of Oncology commented: "We have not recorded significant differences between the first two groups. But mice fed with purple tomatoes showed a significant increase of lifespan."

He continued: "It is a pilot test, a preliminary study useful to validate the hypothesis of obtaining health benefits from diet supplementation with modified food.

"Although mice's lifespan has significantly increased once fed on purple tomatoes we still don't know how it works. It is not likely everything can be explained on antioxidants basis alone."

The findings, which are published in the journal Nature Biotechnology, are part of the FLORA European Project - a large research project designed to discover whether plant antioxidants could help to prevent diseases.

The next step of the project will be to work out the effects of the tomatoes on different kinds of tumours and to work out how the antioxidants have their protective effect against cancer.

FLORA project coordinator Professor Cathie Martin, from the John Innes Centre in Norwich, commented: "The study confirms the latest research trends arguing that we can obtain significant beneficial effects by simple changes in our daily diet.

"Most people do not eat five portions of fruits and vegetables a day, but they can get more benefit from those they do eat if common fruit and veg can be developed that are higher in bioactive compounds."

Dr Lara Bennett, science information officer at Cancer Research UK, said: "It's exciting to see new techniques that could potentially make healthy foods even better for us. But it's too early to say whether anthocyanins obtained through diet could help to reduce the risk of cancer.

"We do know that eating a healthy, balanced diet that is rich in fibre, fruit and vegetables - and low in red and processed meat - is an important way to reduce your cancer risk."