A survey by Cancer Research UK, involving more than 4,000 men and women, found that while residents of the south, East Anglia and Wales tend to eat reasonably well compared to the national average, only 17 per cent of people in Northern Ireland get their 'five a day'.
Commenting on the figures, Charlene Shoneye, a specialist dietician at Weight Concern, said that the results are "a cause for concern".
"We know that eating a diet high in fruit and vegetables can reduce the risk of cancers, aid weight loss and help prevent obesity but we are still not eating enough," she claimed.
Ms Shoneye urged consumers to incorporate healthy lifestyle habits into their daily routine.
"For example, take a piece of fruit to work so that you have it with you for a snack. And remember that your fruit or vegetable portions can be fresh, frozen, dried or canned so it needn't be expensive," she advised.
As well as eating five portions of fruit and vegetables each day, consumers should eat plenty of starchy foods - such as rice, wholegrain breads and cereals - and maintain a low intake of fat, sugar and salt.