Should I choose a plant-based diet?

Many Canadians are reconsidering their dietary habits and choosing plant-based foods instead of animal products, for health, environmental, and ethical reasons. A national survey estimated that 850 000 Canadians already eat an entirely plant-based diet that contains no meat, fish, dairy, or eggs.[1] As more Canadians consider a shift in their diets, they may direct questions about plant-based eating to their physicians. Here are several key points concerning plant-based foods that all physicians should have at hand to discuss with their patients.

Health
Studies have shown that switching from animal protein to plant protein can significantly reduce cardiovascular disease and overall mortality while maintaining muscle mass and strength-building benefits.[2] In a recent large prospective cohort study, replacing 3% of calories from animal protein with plant protein was associated with a 10% lower risk of overall and cardiovascular mortality.[3] 

Nutrition
All diets, including those containing animal products, require careful planning to ensure optimal nutrition. Whole foods are generally healthier than highly processed foods. Plant-based foods, rich in dietary fiber and protective phytochemicals, can provide all essential nutrients, including iron, calcium, and amino acids (except for B12).[4] 

People eating a predominantly or completely plant-based diet must include an adequate amount of B12-fortified foods or supplements. Because B12 absorption is reduced in older adults, Health Canada recommends B12 supplementation for all adults over the age of 50 regardless of their level of meat consumption.[5]

Environmental and ethical considerations
Public and planetary health must be considered in our individual food choices. Because the climate impact of plant-based foods is estimated to be 10 to 50 times smaller than that of animal products, a switch to more plant-based foods is critical to addressing climate change.[6] The harms to animals, and risks of zoonotic infections, novel pandemics, and antibiotic resistance related to animal agriculture are also pressing concerns that need to be addressed.

Further guidance
Canada’s Food Guide and the Lancet Commission on healthy diets provide very useful references.[4,7] As health care professionals, we have a responsibility to model healthy and conscientious eating habits. Our individual actions can make a difference. “Food is the single strongest lever to optimize human health and environmental sustainability.”[7]
—Jan Hajek, MD
—Tushar Mehta, MD 
—David Jenkins, MD, PhD

References
1.    Statista. Number of consumers who are vegetarian or vegan in Canada in 2018. Accessed 22 February 2021. www.statista.com/statistics/954924/number-of-vegetarians-and-vegans-canada.
2.    Hevia-Larraín V, Gualano B, Longobardi I, et al. High-protein plant-based diet versus a protein-matched omnivorous diet to support resistance training adaptations: A comparison between habitual vegans and omnivores. Sports Med 2021. https://doi.org/10.1007/s40279-021-01434-9.
3.    Huang J, Liao LM, Weinstein SJ, et al. Association between plant and animal protein intake and overall and cause-specific mortality. JAMA Intern Med 2020;180:1173-1184. 
4.    Health Canada. Canada’s food guide 2019. Accessed 22 February 2021. https://food-guide.canada.ca/en.
5.    Health Canada. Dietary reference intakes. Accessed 22 February 2021. www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/di....
6.    Hayek MN, Harwatt H, Ripple WJ, Mueller ND. The carbon opportunity cost of animal-sourced food production on land. Nat Sustain 2021;4:21-24. 
7.    Willett W, Rockström J, Loken B, et al. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 2019;393(10170):447-492. 

This post has been peer reviewed by the BCMJ Editorial Board.

Dr Hajek is an infectious diseases doctor based at Vancouver General Hospital and a clinical assistant professor of medicine at the University of British Columbia. Dr Mehta practises emergency medicine in Toronto and works with a local health and education organization in Haiti (www.hephaiti.com). He is also a co-founder of the online resource www.PlantBasedData.org. Dr Jenkins is a professor of both nutritional sciences and medicine at the University of Toronto, and Canada research chair in nutrition and metabolism.