The poll - which asked 997 adults about their eating habits - found that 49% only had one or two portions, even though research has shown that five can cut the risk of heart disease and cancer.

Overall, only 13% of men and 21% of women managed to meet this target, while 48% said they found it hard to meet the recommendations.

The survey also revealed regional variations, with southerners more likely to meet the target than those in the North.

Although 59% of people in the south west of England ate fewer than two portions a day, 23% of southerners overall managed to eat five, compared to only eight per cent of those living in Yorkshire and Humberside.

Cultural habits

Sarah Schenker, a nutrition scientist at the British Nutrition Foundation, said the low consumption of fruit and vegetables in the UK was caused by a focus on junk food.

Five portions should provide all necessary vitamins

"When you walk down the street, you're not bombarded with fruit and vegetables - you're bombarded with chocolate and snacks - even if you're just buying a newspaper," she told BBC News Online.

She said it could be difficult to achieve the recommended amounts.

"It's something you have to aspire to because it's not culturally habitual," she said.

"But if you look at the Continent, where it is culturally habitual, you can see lower levels of heart disease and cancer."

Health benefits

Differences in cultural attitudes were also likely to be behind the regional variations, she said, with Mediterranean-style diets influencing London and the South more heavily than the North.

And she explained why it was important to get the recommended amounts.

"Five portions of fruit and vegetables are considered essential to providing optimum levels of minerals and vitamins, including antioxidants - which have been shown to reduce disease," she said.

"Rather than thinking of how much of each vitamin or mineral you get each day, you can focus on the five portions, and if you include a variety of products you should be reaching optimum levels."

Campaign

A spokeswoman for the Cancer Research Campaign said the results were alarming but not surprising.

"We know that people are not eating enough fruit and vegetables and we know that eating more can reduce the risk of some cancers," she said.

"We need to do more to encourage people, especially children, to eat more fruit and vegetables.