Three portions of fruit and vegetables per day may be a sufficient amount to protect against heart disease, a small study has suggested.

The study, carried out by Dr Demosthenes Panagiotakos and colleagues at the University of Athens, questioned 848 people with heart disease and 1,078 healthy people about their eating habits, reported BBC News Online.

The results found that 43% of heart disease patients and 67% of healthy volunteers said they regularly ate fruit and vegetables. Most of these ate less than two portions per day.

Only 7% of the heart disease patients who regularly ate fruit and vegetables and 10% of the healthy volunteers who regularly ate fruit and vegetables said they ate more than 2.5 portions per day.

The researchers said that people who ate one to two potions of fruit and vegetables per day had a lower risk of developing heart disease than those who did not eat any. The level of risk fell with each additional portion eaten per day. Eating more than 2.5 portions per day was found to reduce the risk by around 70%.

However, the researchers said that the reduction in the risk of heart disease levelled off after this point.

The UK's Department of Health, however, backed its recommendation for five portions of fruit and vegetables to be eaten per day.

"The World Health Organisation and the UK Committee on the Medical Aspects of Food and Nutrition recommendations are based on epidemiological research that states we should consume at least 400g of fruit and vegetables a day - five portions.

"Large studies have shown that the more fruit and vegetables that is consumed the lower the risk of coronary heart disease," a spokeswoman for the department was quoted by the BBC as saying.