50% reduction in meat intake increases life expectancy and reduces dietary greenhouse gas emissions by 25%

Aim

In this paper the model is based on partial substitution of animal products with plant-based alternatives.

The paper aims to explore population-level outcomes of these changes on public health outcomes such as nutrient adequacy and life expectancy.

It aims to separate impacts of replacing meat or dairy with plant proteins on health, nutrition and climate outcomes within the context of the new Canada’s Food Guide (CFG) and Canadian self-selected diets.

Method

The study generated data from the 2015 Canadian Community Health Survey, comprising 13,612 adults.

Simulated scenarios help demonstrate the impact of hypothesised dietary changes of replacing portions of red or processed meat and dairy with plant-based protein alternatives.

25% and 50% reductions were selected to represent feasible dietary shifts.

Adherence to the CFG was also considered, using the Healthy Eating Index for Canada (HEFI-2019).

Key findings (350)

Key characteristics of observed dietary scenarios

In the observed Canadian diets there was an average intake of protein from red and processed meat intake of 69g a day alongside 231g dairy and 38g of plant proteins - predominantly consumed as legumes.

For all of these categories, males ate more than females.

Adherence to dietary guidance

When meat and dairy were substituted for plant-protein foods, adherence to CFG increased as determined by the healthy eating food index (HEFI-2019).

HEFI-19 score increased 14% when half of red and processed meat was substituted and by 12% when half of dairy was substituted.

Similar proportional gains were observed when one-quarter of these groups were replaced also.

Changes in nutrient intake

• Premenopausal females experienced notable reductions in iron inadequacy when dairy was substituted.

• Dairy makes a significant contribution to calcium and vitamin D intake, raising the need for supplementation when replaced. Notable decreases in calcium inadequacy were observed in older females.

• In dairy replacement scenarios there were also decreases in saturated fat with slight increases in free sugars.

These findings underscore the nuanced impacts of dietary substitutions on nutrient adequacy, influenced by factors like age, sex, and supplement intake.

Changes in health outcomes

Significant improvements in health outcomes with plant-based substitutions were observed as a result of reduced risk of chronic disease.

Replacing half of red and processed meat increased life expectancy by 8.7 months and replacing half of dairy increased by 7.6 months. This impact was particularly pronounced in males. Around 80% of this increase is attributed to increased plant-protein foods with the remaining 20% due to reductions in meat consumption.

Changes to diet-related GHGE

The observed Canadian diet released 3.99kg/CO2eq per person per day. Males release 1.5x more than females.

Diet-related GHGE decreased up to 25% when half of red and processed meat was replaced with plant-based proteins. 50% dairy substitution with alternatives had only a 5% reduction.

Conclusion

This research is largely theoretical at present but provides a framework to help overcome challenges in food system transformation.

The co-benefits for nutrition, health and climate from consuming more plant-based protein is clearly outlined as is the scale of impact depending on quantity and type of protein replaced.

The results also show important public health considerations when at scale and the imperative to consider particular sub-groups of the population such as the elderly.