FCRN member Christian Reynolds uses linear programming to calculate diets that meet both health and greenhouse gas emission criteria while being affordable for different income groups in the UK. Generally, the optimised diets are higher in plant-based foods than diets consumed in the UK in 2013, although seafood is higher in the optimised diet than in 2013 diets.
The diets were calculated according to the following constraints: cost of the diet should not exceed a budget for each income group; diets should be nutritionally complete; in order to minimise deviation from existing diets, consumption of each food type should not be more than doubled compared to its 2013 consumption (except for oily fish, because 2013 consumption of oily fish was particularly low, at less than half of recommended levels); greenhouse gas emissions should be as low as possible given the other constraints.
The tables below shows the optimised diets compared to 2013 diets.
To model dietary changes required to shift the UK population to diets that meet dietary recommendations for health, have lower greenhouse gas emissions (GHGE) and are affordable for different income groups.
Linear programming was used to create diets that meet dietary requirements for health and reduced GHGE (57 and 80 % targets) by income quintile, taking account of food budgets and foods currently purchased, thereby keeping dietary change to a minimum.
Nutrient composition, GHGE and price data were mapped to 101 food groups in household food purchase data (UK Living Cost and Food Survey (2013), 5144 households).
Current diets of all income quintiles had similar total GHGE, but the source of GHGE differed by types of meat and amount of fruit and vegetables. It was possible to create diets with a 57 % reduction in GHGE that met dietary and cost restraints in all income groups. In the optimised diets, the food sources of GHGE differed by income group due to the cost and keeping the level of deviation from current diets to a minimum. Broadly, the changes needed were similar across all groups; reducing animal-based products and increasing plant-based foods but varied by specific foods.
Healthy and lower-GHGE diets could be created in all income quintiles but tailoring changes to income groups to minimise deviation may make dietary changes more achievable. Specific attention must be given to make interventions and policies appropriate for all income groups.
Reynolds, C.J., Horgan, G.W., Whybrow, S. and Macdiarmid, J.I., 2019. Healthy and sustainable diets that meet greenhouse gas emission reduction targets and are affordable for different income groups in the UK. Public health nutrition, pp.1-15.