Circle paper 3

Food System Sustainability Workshops
Rod MacRae

What is the role of the human diet in addressing food security, health and climate change at the same time?


Governments have traditionally focused on managing the food supply, paying only minimal attention to managing demand, and demand – supply coordination.  This is a limited approach, given that what people eat (and waste) has a major impact all the way along  food supply chains, and on environmental performance in the food system, morbidity, mortality and health care costs.  Equally significant, the dominant diets may be reducing opportunities for building resilience at the farm level.  Now referred to as sustainable diets, they have received much attention recently in the literature (Mason and Lang, 2017).


From a climate change mitigation and resilience perspective, on a population basis[1], diets should have the following characteristics relative to current consumption patterns (MacRae et al., 2013):

  • less animal product,
  • minimal processing,
  • sourcing closer to production and processing, using innovative distribution mechanisms
  • be based on more frequent but smaller shopping trips to reduce storage, refrigeration and waste,
  • fewer trips by car,
  • fewer supply chain actors between the farm and the eater,
  • more seasonal foods.

If the foods consumed are from ecological production systems (as described in paper 1), then the benefits are augmented.  The negative impacts of consuming significant quantities of animal product are somewhat mitigated if the meat, eggs and dairy are produced ecologically since, in general, these have a lower GHG footprint than products from conventional systems (Lynch et al., 2011). To meet improved population health objectives, most of us should be consuming more nuts, legumes, fruit, vegetables and whole grains, and these too should come, as much as possible, from ecological production systems.

Such dietary changes can improve farm resilience by supporting shifts to forages and perennial crops (hay, pasture, fruit and nut trees), legumes (ideally part of more complex crop rotations) and a wider range of vegetables that permit farmers to design vegetable operations to reduce climate and market vulnerabilities. In particular, nutritionists promote consumption of vegetables with more intense colours, which also opens up space for more heirloom varieties that typically are more resilient than the dominant commercial varieties. The domestic development of a minimally processed short – season fruit and vegetable market (for example, IQF berries) would allow farmers to expand production and extend the marketing season.  As consumption of animals is reduced and their diets are altered to be less in competition with human food, greater human consumption of rye, oats and barley maintains their important place in rotations.

Such dietary changes are often lower cost for consumers.  Although vegetables are typically more expensive, plant proteins are usually cheaper than animal proteins and reductions in tertiary processed foods, such as meal replacements, save money.  Legumes, in particular, rate well on an energy / cost ratio (Drewnowski and Barratt-Fornell, 2004). Some studies have shown how one can eat a largely ecologically produced diet at the same price as a conventional one, but this requires shifts in buying, cooking and food choices to achieve (MacRae et al., 2014).  Increased food skills are often required, which has implications for the way we teach food literacy (Jaffe and Gertler, 2006).


A worst case scenario comes with extensive and revolving crop failures associated with heat stress, drought and intensified pest pressures. Such failures could disrupt import flows, raise food prices or both (the recent California cauliflower story being a signal of such challenges).  With such possibilities, the pressure to build higher levels of domestic self-reliance increases.  In earlier periods, Canada was much more self – reliant in basic fruit and vegetables (our most significant imports from a nutritional perspective) than currently (TFPC, 1994), and would need to return to those levels to sustain population health in the face of a worst case. Currently, we import many foods during our own growing and storage seasons.  Ontario has an annual $20 billion deficit in its food trade, about half of it goods already grown, stored and processed in the province.  Production and processing of these could be expanded, with positive economic implications (ERL et al., 2015).  More seasonal eating could shift this ratio, with a focus on fresh Ontario product during the growing season, stored goods later, and the need for a more vibrant processing sector (Desjardins et al., 2010).  This runs contrary to recent realities, for example, the loss of tomato and peach processing capacity.

Shifting diets is a challenge, but it has been done before, during WWII.  Although conditions are very different today, there are lessons to be learned from the suite of instruments employed at that time (much more extensive than just rationing and Victory Gardens) to align consumption with supply, while assuring the nutritional health of the population (Britnell and Fowkes, 1962; Mosby, 2014).  A focus on sustainable diets remains an unexplored, but potentially significant, strategy to help the food system adapt to climate change (Mason and Lang, 2017).


Britnell, G.E. and Fowke, V.C. 1962. Canadian Agriculture in War and Peace: 1935-1950. Stanford U. Press, Stanford, CA.

Desjardins, E., R. MacRae and T. Schumilas.  2010. Meeting future population food needs with local production in Waterloo Region: linking food availability and optimal nutrition requirements.  Agriculture and Human Values 27(2):129-140

Drewnoski, A. and Barratt-Fornell, A. 2004. Do healthier diets cost more?  Nutrition Today 39:161-168.

Econometric Research Ltd., Harry Cummings and Associates and R.J. MacRae. 2015. Dollars and Sense: opportunities to strengthen Southern Ontario’s food system.  Greenbelt Foundation, McConnell Foundation and Metcalf Foundation, Toronto and Montreal

Jaffe, J. and Gertler, M. 2006.  Victual vicissitudes: consumer deskilling and the (gendered) transformation of food systems. Agriculture and Human Values 23:143-162.

Lynch, D., R. MacRae and R. C. Martin. 2011. The carbon and Global Warming Potential impacts of organic farming: does it have a significant role in an energy constrained world?  Sustainability 3:322-362.

MacRae, R.J., V. Cuddeford,  S.B. Young and M. Matsubuchi-Shaw. 2013. The food system and climate change: an exploration of emerging strategies to reduce GHG emissions in Canada. Agroecology and Sustainable Food Systems 37:933-963.

MacRae, R.J., D. Lynch and R.C. Martin. 2014. Will more organic food and farming solve food system problems?  Part II: Consumer, Economic and Community Issues. In: R.C. Martin and Rod MacRae (eds.). Managing Energy, Nutrients and Pests in Organic Field Crops. CRC Press, Boca Raton, FL. Pp. 333-362.

MacRae, R.J., A. Siu, M. Kohn, D. McCallum, M. Matsubuchi-Shaw, T. Hernandez Cervantes and D. Perreault. 2016. Doing better with what we’ve got: strategies to reduce food and resource waste in the Canadian food system.  Canadian Food Studies 3(2):145-215.

Mason, P. and Tim Lang.  2017. Sustainable Diets.  Routledge.

Mosby,  I.  2014. Food Will Win the War. UBC Press, Vancouver.

Toronto Food Policy Council. 1994. Health, wealth and the environment: the impacts of the CUSTA, GATT and NAFTA on Canadian food security.  Toronto Food Policy Council Discussion Paper #2, TFPC, Toronto. September.


[1] It is important to think about this at a population level because individuals and communities can be significantly different.  Many individuals and communities may not substantially change diets for reasons of health, culture, religion and commensality.