About this Article: This article describes a systematic literature review undertaken to examine the effectiveness of various community-based healthy diet and nutrition interventions. A discussion of interventions that have shown success, along with those that have shown no impact is presented along with recommendations for further research. Interventions involving behavioural change strategies, tailored nutrition education, weight management and incentives show promise.
About This Series: The É/Exchange working paper series is designed to facilitate sharing of results and to encourage discussion of concepts, practices, and policies in applied health. This series provides a way to disseminate well-written, but not yet published, reports of research. It is also a way to make research conducted by affiliated community members accessible to a wider readership. The series is co-sponsored by The Population Health Improvement Research Network (PHIRN), Réseau de recherche appliquée sur la santé des francophones de l'Ontario (RRASFO); and the Ontario Health Human Resources Research Network (OHHRRN).
As the incidence of chronic disease and pressure to allocate public funds effectively rise, so have political and societal pressures to ensure that efforts to improve population and public health are directed to proven programs and services. A recent systematic review by Dobbins and Tirilis sought to identify and summarize research findings on the effectiveness of community-based interventions on healthy diet and nutrition among various populations.
The review was limited to studies of strong methodological quality and the search for topic related literature indentified 33 such reviews, 17 of which were relevant to this topic. Interventions described in the literature include: improving diet, weight management, fruit and vegetable consumption, nutrition education, sodium reduction, cognitive/behavioural change strategies, lifestyle interventions, self-help interventions, and incentives.
A number of interventions were found to improve eating behaviours among their target populations:
- Adults who are exposed to cognitive or behavioural change strategies are more likely to change their eating behaviours than adults who are not. Effective interventions include self-monitoring combined with one other self-regulating intervention, intention formation, feedback on performance, goal setting and review of behavioural goals.
- Tailored nutrition education (delivered through e-mail and print) and community based interventions increase fruit and vegetable consumption among pre-school and school-aged children, and among adults when the intervention is implemented in a work-based setting. While the increase may not be enough for health effects, the most effective strategies provide clear messages about increasing fruit and vegetable consumption; incorporate behavioural theories and goals; provide a consistent framework for implementation and evaluation; provide longer, more intensive interventions rather than one or two contacts; actively involve influential people such as family members; and target those whose knowledge of fruit and vegetable intake is low.
- Tailored nutrition education is also associated with small decreases in fat intake.
- A weight loss/weight management intervention was shown to reduce Body Mass Index among individuals with pre-diabetes, while those not exposed to the intervention did not have the same reduction.
- Interventions targeted at weight loss (low fat or low calorie diets) are effective for adults in the short- to medium-term, particularly among those who are obese or who have high risk factors (e.g., pre-diabetes and chronic diseases), but do not appear to be maintained over the long term (five years).
- Incentives (e.g., monetary, provision of free food, price reductions on healthy food) to loose weight are effective in the short- to medium-term, while long term impacts have not yet been measured.
To some extent the results illustrate that many population health and public health programs are associated with benefit to various populations, particularly related to outcomes such as health eating.
Some differences in outcomes among various sub-populations were noted in the studies:
- There is some evidence to suggest that children from higher income families are more likely to practice healthier eating than children from lower income families and that White children consume fewer grams of fat than Black children, following an intervention. In addition, ethnic minority individuals were are likely to drop out of studies than White participants.
- Tailored nutrition education is associated with increased fruit and vegetable consumption among individuals with low income as well as among members of different ethnic groups, while such community based interventions have not been shown to change consumption among adults in the general population.
- Pregnant women, women of childbearing age and those with type 2 diabetes, exposed to healthy eating and obesity prevention interventions decrease their fat intake, increase their fibre intake and improve their carbohydrate consumption, compared to those who are not exposed to such interventions.
What does not work?
While the following types of interventions may be effective as an integral part of a broader strategy, little or no impact was noted for the following types of interventions on their own:
- Involving parents in an intervention to reduce fat intake among children and adolescents have shown mixed results.
- Generally speaking, behavioural diet and nutrition interventions aimed at reducing Body Mass Index or slowing BMI increases over time have not proven effective.
- Strategies focused on maintaining appropriate weight for age have not resulted in change.
- Omega 3 supplementation has not been associated with weight loss.
Population based interventions on community-based diet and nutrition has been indentified as a priority topic area for Ontario. This systematic review has identified some promising interventions for practitioners to consider along with some to discount.
Reference: Dobbins, M., Tirilis, D. Diet and Nutrition: A Synthesis of Review Evidence. An overview of systematic review evidence on the effectiveness of community-based interventions to promote healthy diet and nutrition. Exchange Working Paper Series, Fall 2011, PHIRNS1 Volume 1. University of Ottawa, Ottawa, Canada. Available at rrasp-phirn.ca.