'Healthy' purple tomato developed in Norwich not for sale in UK over GM restrictions

• Rob Setchell reports on the trans-Atlantic success for Norwich's home-grown purple tomatoes

A nutrient-rich purple tomato developed by British scientists, which could help improve health, is proving a hit in the United States - but cannot be sold in the UK.

The genetically modified (GM) fruit created at the John Innes Centre in Norwich has received regulatory approval in America.

It has proved so successful that seed sales have topped $200,000 in the first week, but because of tougher GM rules in Europe and the UK it cannot be sold on this side of the Atlantic.

Plant scientist Prof Cathie Martin initially received funding in 2003 to look at increasing the amount of healthy antioxidants in tomatoes.

After 20 years of research and experimentation she has developed a tomato that is high in antioxidants known as anthocyanins, which give the fruit its distinctive purple colour.

Tomato plants normally only make the antioxidant-rich purple pigment in their leaves.

"What we've done is we've been able to switch on the production of the purple pigment in the fruit," said Prof Martin.

"The purple colour is conferred by pigments called anthocyanins and these are good antioxidants.

"If you think about super-fruits like blueberries or blackberries, they're also purple and they're rich in these pigments."

They started selling the purple tomato fruits last year in America and had success at farmers' markets and high-end restaurants.

They have since started selling the seeds to home growers in the United States.

To create the purple tomato, Prof Martin said she put a piece of DNA into the cells of the plant which contain genes that switch on production of anthocyanins.

Because the plant is genetically modified, it is much more difficult for it to get regulatory approval in Europe and the UK, and the process could cost millions of pounds.

Despite this, Prof Martin is keen to take her case to Food Standards Agency to try and get the purple tomato approved for sale in the UK.

"I think it's really important that we improve the nutritional density of the foods that we eat," said Prof Martin.

"I personally think that doing it in tomatoes is great because it's already a little bag of goodness and we're just making it better."

Some remain cautious about genetically modified food.

"We think that GM foods are unnecessary, unwanted and unsafe," said Leonie Nimmo of GM Freeze.

"We already know what we need for a healthy and balanced diet and nature is more than capable of providing those things for us.

"The issues are around access, around poverty and around education in this country."

Prof Martin insists the purple tomato is safe to eat and will help people get more of the vitamins, minerals and fibre that comes from eating fresh fruit and vegetables.

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