Small plant-based changes in the diet can reduce the carbon footprint by 25%

05 Mar 2024 --- Partially substituting animal protein foods with plant protein ones increases life expectancy and decreases greenhouse gas emission (GHG) by about 25%, according to the latest research by researchers from McGill University, Canada, in collaboration with the London School of Hygiene and Tropical Medicine, UK.

Another critical research finding indicates that the health benefits depend on the type of animal protein being replaced. However, while Canada’s updated Food Guide stresses the importance of plant-based proteins and a reduction of meat and dairy, it is mainly unclear whether these recommendations are practiced.

“Canadians, and individuals from other high-income nations, consume much more animal protein than plant protein foods. Therefore, there is dissonance between dietary guidance in Canada to consume more protein from plant sources and their actual consumption of plant protein foods,” Olivia Auclair, first author of the study and Ph.D. graduate in McGill’s Department of Animal Science, tells Nutrition Insight.

“We hope our findings influence consumers to make more conscious food choices and policymakers to facilitate the shift toward healthier and more sustainable diets.” 

Red meat, processed meat and dairy are significant diet-related greenhouse gas emission contributors in Canada. The current study found that this footprint drops by a quarter when individuals replace half of their intake with plant protein foods. Dairy reductions demonstrated GHG reductions of about 5%.

Seeding a climate-friendly diet
The study, published in Nature Food, used data from dietary records in a national nutrition survey and modeled partial replacements of red and processed meat or dairy with nuts, seeds, legumes, tofu, and fortified soy beverages against a combination of nutrition, health, and climate outcomes.

The researchers concluded that if half of the red and processed meat in an individual diet was replaced with plant proteins, the person could live approximately nine months longer because of a lowered risk of chronic disease. 

“Our findings show that we can achieve healthier and more sustainable diets by making simple partial substitutions of red and processed meat, particularly with plant protein foods. Some important considerations are consumers’ current dietary habits and their willingness to change,” Auclair explains. 

“Having worked with nutrition data from a nationally representative survey from 2015 allowed us to compare Canadians’ current dietary patterns with modeled partial replacement scenarios of animal- with plant protein foods.”

According to the researchers, climate modeling studies show that greenhouse gas emissions from the food system are on a trajectory that can preclude achievement of the Paris Agreement targets. Consumers are part of the global food system, making their dietary choices important in mitigating food system emissions. 

“Our findings show that making simple partial substitutions of up to 50% of red and processed meat with plant protein foods can lead to co-benefits among nutrition, health, and climate outcomes. These are likely more feasible for consumers to adopt than shifting to a completely plant-based dietary pattern or excluding certain food groups altogether,” says Auclair.The life expectancy of men doubled based on the projections of swapping out about 50% animal protein foods for plant protein foods. 

Meanwhile, the Health Council of the Netherlands presented an advisory report to the Dutch government recommending policy measures to guide the general population on adopting a plant-based diet. 

In addition, Amsterdam has become the first EU capital to endorse the call for a Plant Based Treaty to address food system impacts on the climate crisis, aiming to make the city a vegan capital. Implementing its plant-based plans, included in its Food Strategy 2024-2026 for healthy, fair and sustainable food, should start in early 2026 at the latest.

Projected life expectancy 
Data projections from the study show that the life expectancy of men doubles when they replace the protein types they consume. In contrast, partially replacing dairy with plant protein foods led to smaller gains in life expectancy and was accompanied by a trade-off — an increase in calcium inadequacy by up to 14%.

“Increasing the consumption of plant-based foods alongside reductions in red and processed meat would have considerable benefits for health and the environment and would involve relatively small changes in diets for most people in Canada,” says Patricia Eustachio Colombo, co-author and honorary research fellow at the London School of Hygiene and Tropical Medicine’s Centre on Climate Change & Planetary Health.

An important consideration on which the study’s recommendations are based is how feasible they are for consumers while having a solid foundation in science that accounts for synergies and trade-offs in three dimensions of sustainability — environment, human nutrition and health.

“Our study provides evidence that small, simple changes can go a long way for human and planetary health, but that the type of animal protein being replaced can lead to different (and not always beneficial) outcomes,” Auclair outlines. 

“It highlights the importance of assessing simple substitutions of animal- with plant-based protein foods that are more or less feasible for consumers to implement in their daily lives. We need to provide people with solutions that are within reach, or else they may not be willing to or able to make changes.” 

“The concepts of human and planetary health go hand-in-hand, and assessing one without the other would be painting an incomplete picture that could lead to misconceptions or inaccurate conclusions,” Auclair concludes.

Further to this, new research suggests that 100% plant-based eating is not necessarily the best route to a healthy population and planet. Meat, fish, eggs and dairy are highly nutrient-dense and could play an indispensable role in diets and a healthy ecosystem, particularly in low-income nations.

Last year, ProVeg Netherlands released its research findings with the Netherlands Nutrition Center (Voedingscentrum) about a broad spectrum of nutritional values in plant-based meat alternatives, including the critical markers salt and protein.

By Inga de Jong