Estimating impacts of plant-forward diets in Aotearoa New Zealand: Implications for health inequity

Background

Shifting populations to more plant-forward diets has demonstrated health and environmental co-benefits, but current predictive modelling approaches often define alternative scenarios far from actual intakes. This study investigated the health, cost, and environmental impacts of moderate plant-forward substitutions in the New Zealand (NZ) context, additionally examining impacts on health equity between Māori and non-Māori populations.

Methods

Baseline intakes came from the NZ Adult Nutrition Survey 2008/09. Alternative scenarios consisted of an NZ-adapted EAT-Lancet diet and progressive isocaloric plant-forward substitutions, determined by proportionally substituting core (defined as Australian GST-exempt) animal foods with core plant foods. Alternative scenarios were modelled through changes in dietary risk factors using a multi-state life table model built for the NZ population to determine Quality Adjusted Life Years (QALYs), healthcare costs, and carbon footprints. Impacts on health equity were assessed by setting background disease rates for the Māori population equal to those for the non-Māori population.

Results

The changes in food category intakes were less extreme in the proportional scenarios compared to the EAT-Lancet scenario. We found that the EAT-Lancet scenario resulted in 630 [95% uncertainty interval: 544, 719] QALYs per 1000 individuals over the life course, while the 100% scenario resulted in 330 [278, 383] QALYs. EAT-Lancet additionally saved the most over the population’s life course in healthcare costs ($81.1 [63.9, 99.1] billion 2018 NZD) and GHGEs (39% reduction in kgCO2eq compared to baseline). The health gains would be higher for the Māori population following plant-forward diet transitions (41 to 80% greater).

Conclusions

While EAT-Lanet had the largest impacts, moderate changes may still have beneficial effects at a population level. Sustainable dietary transitions should be leveraged to address systemic health inequities.

Key messages

• Results are in line with previous investigations in New Zealand and abroad, more plant-forward diets are beneficial for health and the environment.

• Sustainable dietary transitions may be able to reduce health inequities experienced between Māori and non-Māori populations.