Assessing the Health and Environmental Benefits of a New Zealand Diet Optimised for Health and Climate Protection

Population diets have impacts on both human and planetary health. This research aims to optimise a New Zealand (NZ) version of the EAT-Lancet diet and to model the impact of this diet on population health if it was adopted in NZ. The optimisation methods used mathematical equations in Excel to ensure: population diets met the nutritional recommendations; diet-related greenhouse gas (GHG) emissions did not exceed the NZ GHG boundary; and diet costs did not exceed baseline costs of the average diet. The EAT-Lancet diet was also directly mapped onto the NZ adult nutrition survey food groups, as another estimate of a NZ EAT-Lancet diet. Both diets were modelled using a DIET multi-state life-table model to estimate lifetime impacts on quality adjusted life years (QALYs), ethnic health inequities and health system costs. The optimised diet differed greatly from baseline intake with large amounts of fruits and vegetables, some fish but no beef, lamb, pork or poultry. Modelling nationwide adoption of the NZ EAT-Lancet diets generated large health savings (approximately 1.4 million QALYs), and health system cost savings (around NZD 20 billion). A healthy, climate-friendly, cost-neutral diet is possible for NZ and, if adopted, could provide large health gain, cost savings and reductions in ethnic health inequities