Sustainable diets for the future: Can we contribute to reducing greenhouse gas emissions by eating a healthy diet?

BACKGROUND: Food systems account for 18-20% of UK annual greenhouse gas emissions (GHGEs). Recommendations for improving food choices to reduce GHGEs must be balanced against dietary requirements for health. OBJECTIVE: We assessed whether a reduction in GHGEs can be achieved while meeting dietary requirements for health. DESIGN: A database was created that linked nutrient composition and GHGE data for 82 food groups. Linear programming was used iteratively to produce a diet that met the dietary requirements of an adult woman (19-50 y old) while minimizing GHGEs. Acceptability constraints were added to the model to include foods commonly consumed in the United Kingdom in sensible quantities. A sample menu was created to ensure that the quantities and types of food generated from the model could be combined into a realistic 7-d diet. Reductions in GHGEs of the diets were set against 1990 emission values. RESULTS: The first model, without any acceptability constraints, produced a 90% reduction in GHGEs but included only 7 food items, all in unrealistic quantities. The addition of acceptability constraints gave a more realistic diet with 52 foods but reduced GHGEs by a lesser amount of 36%. This diet included meat products but in smaller amounts than in the current diet. The retail cost of the diet was comparable to the average UK expenditure on food. CONCLUSION: A sustainable diet that meets dietary requirements for health with lower GHGEs can be achieved without eliminating meat or dairy products or increasing the cost to the consumer.

Developing a timeline for evaluating public health nutrition policy interventions. What are the outcomes and when should we expect to see them?

OBJECTIVE: To develop a timeline for evaluating public health nutrition policy interventions. DESIGN: Concept mapping, a stakeholder-driven approach for developing an evaluation framework to estimate the 'time to impact' for policy interventions. The Schools (Health Promotion and Nutrition) (Scotland) Act 2007 was used as the model to develop the evaluation timeline as it had typical characteristics of government policy. Concept mapping requires stakeholders to generate a list of the potential outcomes, sort and rate the outcomes. Multidimensional scaling and hierarchical cluster data analysis were used to develop an anticipated timeline to impact for the policy. SETTING: United Kingdom. SUBJECTS: One hundred and eleven stakeholders representing nutrition, public health, medicine, education and catering in a range of sectors: research, policy, local government, National Health Service and schools. RESULTS: Eighty-five possible outcomes were identified and grouped into thirteen clusters describing higher-level themes (e.g. long-term health, food literacy, economics, behaviour, diet, education). Negative and unintended consequences were anticipated relatively soon after implementation of the policy, whereas positive outcomes (e.g. dietary changes, health benefits) were thought likely to take longer to emerge. Stakeholders responsible for implementing the legislation anticipated that it would take longer to observe changes than those from policy or research. CONCLUSIONS: Developing an anticipated timeline provides a realistic framework upon which to base an outcome evaluation for policy interventions and identifies positive and negative outcomes as well as considering possible unintended consequences. It offers benefit to both policy makers and researchers in mapping the progress expected towards long-term health goals and outcomes.