Mortality, greenhouse gas emissions and consumer cost impacts of combined diet and physical activity scenarios: a health impact assessment study

Objective: To quantify changes in mortality, greenhouse gas (GHG) emissions and consumer costs for physical activity and diet scenarios. Design: For the physical activity scenarios, all car trips from < 1 to < 8 miles long were progressively replaced with cycling. For the diet scenarios, the study population was assumed to increase fruit and vegetable (F&V) consumption by 1-5 portions of F&V per day, or to eat at least 5 portions per day. Health effects were modelled with the comparative risk assessment method. Consumer costs were based on fuel cost savings and average costs of F&V, and GHG emissions to fuel usage and F&V production. Setting: Working age population for England. Participants: Data from the Health Survey for England, National Travel Survey and National Diet and Nutrition Survey. Primary outcomes measured: Changes in premature deaths, consumer costs and GHG emissions stratified by age, gender and socioeconomic status (SES). Results: Premature deaths were reduced by between 75 and 7648 cases per year for the physical activity scenarios, and 3255 and 6187 cases per year for the diet scenarios. Mortality reductions were greater among people of medium and high SES in the physical activity scenarios, whereas people with lower SES benefited more in the diet scenarios. Similarly, transport fuel costs fell more for people of high SES, whereas diet costs increased most for the lowest SES group. Net GHG emissions decreased by between 0.2 and 10.6 million tons of carbon dioxide equivalent (MtCO2e) per year for the physical activity scenarios and increased by between 1.3 and 6.3 MtCO2e/year for the diet scenarios. Conclusions: Increasing F&V consumption offers the potential for large health benefits and reduces health inequalities. Replacing short car trips with cycling offers the potential for net benefits for health, GHG emissions and consumer costs.