According to a new study, a majority of adults arent sure how many portions of fruit and vegetables they should be eating. In 2003, the five-a-day campaign, based on a recommendation by the World Health Organisation (WHO), was launched in the UK to encourage individuals to eat five portions of fruit and vegetables a day.

However, despite this clear guidance, many people still arent reaching this target, as outlined in the new Health and Food Supplements Information Service (HSIS) report State of the Nation: Dietary Trends in the UK – 20 Years On.

The researchers based their investigation on the governments National Diet and Nutrition Survey and the Defra Family Food findings. They discovered that 16 years after the launch of the five-a-day campaign, 31 percent of adults aged between 19 and 64 are consuming their five a day. Just over a quarter of adults aged 65 and over are reaching the goal, while only eight percent of 11 to 18-year-olds are doing the same.

Dr Emma Derbyshire, a public health nutritionist and author of the study, said the findings are a "real cause for concern. Low intake of all these nutrients damages brain function and increases the risk for heart disease, bone disease and premature death. At the moment the message is still not getting through.”

According to the study, over the past 20 years the intake of a number of vitamins and minerals has been steadily decreasing.  The reporters also found that oily fish consumption has remained "consistently below optimal levels" over the past two decades, while intakes of fibre have remained below recommended levels.