Contrary to popular opinion, nutritionists at the University of Newcastle upon Tyne found that most people's diets get healthier from childhood to young adulthood.
However, the research, published in the journal Appetite (42, pp 255-263), also discovered that many people perceive barriers to healthy eating, including a lack of free time, work patterns and even negative influence from family members.
While a third of people, mainly men, felt their partners had a positive influence on their diet, 10 per cent, mainly women, indicated their partners' influence was negative.
A third of participants blamed a busy lifestyle as a reason for not being able to prepare 'healthy meals', often because they believed fruit and vegetables needed time for preparation and cooking. These people were more likely to have smaller intakes in fruit and vegetables over the 20 years than those who did not say a lack of time had influenced their diet.
However, it was perceived lack of time, rather than actual free time, that influenced people's food choices.
For the study, the Newcastle University research team examined the food consumption of 200 schoolchildren aged 11-12 years old and revisited the same people 20 years later in their early thirties. On both occasions, participants kept detailed food diaries and were also questioned about their diets and the perceived influences on food intake. Researchers then analysed the two sets of results.
Lead author Amelia Lake said the findings suggested that although general healthy eating messages were getting through to most people, they also needed to be more carefully targeted to reach individuals who believe their lifestyle still prevents them from eating well.
Schemes such as the Government's 'Five a Day' project, which recommends that each person eats five portions of fruit or vegetables per day, need to be combined with advice specifically tailored to individuals, perhaps in consultations with doctors and nurses.
However, Lake, a researcher with Newcastle University's Human Nutrition Research Centre, noted that the reasons for dietary patterns and change were complex.
"A lot depends on people's individual coping mechanisms and attitude to life. A lack of time is not necessarily the reason for people not attempting to eat healthily. Some working adults are inspired to make a healthy meal in the evenings, while somebody with the same amount of time on their hands would feel under pressure and be inclined to send out for a takeaway."
"These results suggest that the diet is really up to the individual and their personality, and that general health messages are not necessarily enough when a variety of factors are working to prevent people from eating healthily," she explained.
"Diet needs to be taken more seriously. Home has a major impact on what children and adults eat, schools and workplaces and health care professionals have a role to play. Despite all the healthy eating messages that abound, it's still easier to go to a local shop and buy a chocolate bar rather than a piece of fruit," she added.