A systematic review of population and community dietary interventions to prevent cancer.

Diet is an important factor in the causation of cancer. Previous systematic reviews of one-to-one interventions to encourage dietary change have found that such interventions can achieve modest improvements in diet. However, such interventions are resource intensive and unlikely to be good value for money at a population level. Interventions that address groups, communities or whole populations may be less resource intensive and effect change in a wider population. We report a systematic review of such interventions. We set wide inclusion criteria, including before-and-after studies and studies with a non-randomized comparison group as well as randomized trials. We found eighteen studies based in the community, seventeen based on worksites, five based in churches and one based in a supermarket. Interventions which targeted fruit and vegetable intake were most likely to be successful, particularly in worksites and churches. There was also evidence of small positive effects on reducing fat intake in worksites and churches. Overall the community-based interventions showed little effect. The studies included in the present review were generally poorly reported. Dietary changes are reported in the relatively short-term studies reviewed here but may not be sustained in the long term. The effects that we have identified are small but the reach is potentially very wide, in some cases as wide as a whole country. The cost effectiveness of such strategies remains to be evaluated.