A diet that promotes plant-based protein to help the environment now has a more humane argument: It can reduce your risk of dying from many major diseases.
“This wasn’t just a cause of death. It was across the board,” said Walter Willett, professor of epidemiology and nutrition at the Harvard TH Chan School of Public Health.
Willett co-authored a new study examining the Planetary Health Diet (PHD) and its effects on mortality, which he helped develop in 2019 as part of the EAT-Lancet Commission. The diet recommends plant-based proteins such as nuts and legumes, and consumption of more fruits and vegetables, as well as healthy, unsaturated fats, while reducing animal-based protein sources and added sugars.
The new study, published in the peer-reviewed American Journal of Clinical Nutrition, looked at decades of dietary data from more than 200,000 healthcare professionals in the United States. Participants’ eating habits were scored on how close they were to the Planetary Health Diet. The closer they eat to people with a PhD (for example, eating more nuts and less red meat), the greater the benefit.
“All the major causes of death rates were lower,” Willett said, “including heart disease, cancer, neurodegenerative conditions such as Alzheimer’s disease, Parkinson’s disease, and strong benefits to humans. [respiratory] death.”
Willett also noted that the top 10 percent of participants who followed the diet saw a 30 percent lower risk of dying from all causes.
Mortality data were obtained from more than 54,000 participants who died during the study period.
Certain foods were associated with lower risk
Kathryn Bradbury, a senior research fellow at the University of Auckland’s School of Population Health, described the research as comprehensive and said it also took external factors into account.
“They also looked at other things people were doing in terms of exercise and smoking habits,” says Bradbury, who was not involved in the research. He highlighted certain foods that had more impact in the study.
“If you ate a lot of whole grains, a lot of nuts and healthy fats like olive oil and sunflower oil, those were the most important things in terms of reducing your risk of death,” Bradbury told CBC News from Auckland.
He added that reducing red meat was also important in his analysis.
make changes
For Toronto-based chef, author and food activist Joshna Maharaj, the work is both obvious and important.
“This is beautiful, basic, fundamental wisdom,” Maharaj said, calling it more academic support for what sustainability advocates have been talking about for a long time.
But he also emphasized that it’s not just about cutting back on certain foods like red meat, it’s about growing food more organically.
“There is an ecological way to consume meat,” Maharaj said. “You can eat less and pay more, but raising and eating animals can be part of a working system.”
Maharaj says current meat production is industrial and environmentally damaging, both because of the chemicals used and the land used to support factory farming.
Can you tell the difference between domestic production and grocery imports? Test your food knowledge with Samira Mohyeddin, host of the CBC Radio series Unforked, and Toronto chef and author Joshna Maharaj.
He says Canadians looking to make a change can start by looking into their refrigerators and learning about their own consumption patterns.
“Don’t worry about making a magical change,” Maharaj said.
License plates and policies
The good news for Canadians is that the country’s 2019 revised food guide already encourages more plant-based protein as well as limiting processed foods and sugary drinks.
“Canada’s food guide is largely consistent with a sustainable dietary model,” says Benoît Lamarche, scientific director of Laval University’s NUTRISS center and author of a recent paper comparing the guide to PhD.
But there is still a challenge in how to deliver the ideal plate of food to people. For example, Canada’s food guide shows a neat quarter devoted to general proteins and tells people how much protein and what kind of protein.
“We need protein, but total protein is not a good indicator of how healthy we are eating,” Lamarche said. “The source of the protein is a better indicator of the quality of our diet.”
Lamarche emphasized that a sustainable diet should go beyond just eating healthy, but also consider affordability, cultural appropriateness, and whether it is actually good for the environment.
Can a diet really save the planet?
The new study also found that adhering to PHD led to a lower environmental impact, based on calculations that foods on this diet would emit fewer greenhouse gases and require less water, fertilizer and cropland.
“That’s a huge number because it means that we can actually allow some of our cropland to return to forest… which will certainly help stabilize the global climate situation,” Willett told CBC News from Cambridge, Massachusetts.
Climate change, largely caused by the burning of fossil fuels, is also exacerbated by agricultural emissions, including methane, a shorter-lived but more potent greenhouse gas. A negative feedback loop emerges as food production is threatened by drought and other extreme weather events, amplifying and prolonging climate change.
An estimated 80 percent of the planet’s agricultural land is used to graze and grow fodder for livestock, according to Our World in Data’s analysis of UN figures.
“If everyone at the population level reduced their intake of animal-sourced food, it would be much more efficient because we would use that land to grow plant products that we would eat directly,” Bradbury said.
Willett says it’s urgent to address our food’s impact on the climate.
“It’s scary and unique because it’s not linear, it’s accelerating. And we’re reaching tipping points of no return.”