Psychosocial predictors of dietary behaviour
For over two decades, epidemiological research has provided increasingly stronger evidence for a link between fruit and vegetable consumption and, cancer and heart disease. This has led health experts to recommend that people consume at least 5 servings of fruit and vegetables a day. In the UK, as in many European countries, the average consumption is approximately half the recommended level. Research has also shown that there are low levels of nutritional knowledge within the community, which might be one explanation for these low levels. The present studies examine the associations between cognitions and behaviour for intake of fruit and vegetables in two different populations, and then test the efficacy of a tailored intervention for changing eating behaviour, knowledge and attitudes in two randomised controlled studies. Two large studies were carried out in different samples of the population. The first study took place in a cancer screening setting with an older adult sample (n=1054), and showed that knowledge and attitudes were independent predictors of dietary behaviour. Data from the baseline survey were used to create a brief, personalised, tailored intervention designed to increase knowledge, improve attitudes and thereby modify behaviour. Results from the 6-week follow-up showed that the intervention was successful in improving nutritional knowledge, changing attitudes to fruit and increasing fruit and vegetable intake. Increases in intake were correlated both with increases in nutritional knowledge and positive change to attitudes. The second study was planned as a replication and extension of the first, with some improvements in measures and a more representative sample. It took place in a dental clinic setting (n=1846). Knowledge and attitudes were again shown to be independent predictors of fruit and vegetable intake, and variations in knowledge accounted for some of the demographic variations in intake. Subsequently a 3-group design was then used to test the effectiveness of the tailored intervention, comparing it this time to a general intervention and an untreated control group. The tailored intervention group produced significant changes in behaviour and knowledge compared to both the general intervention and control group, while the general intervention produced only significant increases to nutritional knowledge. The results suggest that tailored interventions can be a successful tool to use for changing knowledge and attitudes, and is more effective than a standard leaflet for everybody. Therefore it is important to consider the practicalities of using tailoring in the design of dietary interventions especially for improving fruit and vegetable intake which have previously been difficult to adjust. The two studies were limited by self-report measures of intake, and future work needs to consider incorporating some kind of objective validation. Also while medical settings proved feasible for carrying out interventions, participants were not representative of the general population, so any extrapolation to the general population must be cautious. Future research might examine setting effects for efficacy as well as feasibility. The recent developments in information technology could be used to assist future intervention studies in producing tailored interventions for larger groups of people.