One day, when geography professor Evan Fraser and I were looking at a figure which showed the proportion of different food groups we need to eat as a healthy diet by Harvard Healthy Eating Plate (HHEP) model, a question came to mind: Is there any study about whether there is enough fruit and vegetables (F&V) produced to adopt the HHEP diet and what would be the environmental consequences of adopting such a diet?

Harvard Healthy Eating Plate guidelines: 50% of the plate should consist of F&V

HHEP advises that a dinner plate should consist of 50% of F&V, 25% of grains and the remaining 25% should be proteins, fats, and dairy. To answer our question, we started to explore what other nutritional guidelines across the globe are recommending for us to be healthy. Some of them, such as Food and Agricultural Organisation (FAO) and United States Department of Agriculture (USDA), recommend eating at least 2350 kilocalories/person/day. Other guidelines such as the Canadian Food Guide (CFG) also suggested the number of required servings of different food groups.

F&V production is much less than we should be eating

After seeing various nutrition recommendations, we were wondering what the global agricultural production or availability looks like. Production data is available in terms of mass or kilocalories. This brought another curiosity to mind; about how we calculate the number of servings of food needed to be eaten as per the HHEP and compare this with our current production. But, if we convert mass or kilocalories into the number of servings, would we have enough servings of each food group as per the HHEP recommendation? The answer is no.

In order to feed everyone according to the HHEP’s guidelines, global agriculture would have to produce 15 servings of F&V per person per day. However, according to 2011 FAO data, just 5 servings were being produced. The calculation also shows a smaller shortfall in protein production, with 3 servings per person per day produced, compared to the 5 recommended by the HHEP. However, other food groups such as oil and fat, sugar, milk and grains, were being grossly overproduced.

Following this mismatch between overproduction of some food groups and underproduction of others, an immediate question came to mind: What would the land use and greenhouse gas impact be if we were to adopt the HHEP diet today and in the future? As we found out, the world’s agriculture producers are not growing enough F&V to feed the global population a healthy diet. But we also found that we need to increase protein production too, and in that case, we would need extra land to use for agriculture to feed the growing population. If the agricultural industry immediately corrected its imbalances and shifted its production priorities to align with the HHEP, a new problem would emerge. It would free up 51 million hectares of arable land globally, but the total amount of land used for agriculture (includes pasture land as well) would jump by 407 million hectares. Greenhouse gas emissions would also rise as a result. Therefore growing more F&V should be accompanied by reduced reliance on livestock in order to keep the global food supply sustainable. The question can be raised again, how?

Best pathway: a significant increase in F&V production with a shift away from animal proteins

To explore the possibility in this context, we calculated the ratio of existing animal based protein to plant-based protein. Currently, globally, 84% of protein is from animal sources and only 16% protein is from plant sources. Then we explored the amount of the land used to produce this amount of animal and plant protein.

At present, 103 million ha of arable land and 1092 million ha of pasture land is used for the production of 84% animal protein and about 36 million ha of arable land is used for the production of 16% plant protein. So adopting HHEP diet would not help to develop a sustainable food system. We cannot imagine an agroecosystem without animals in it, because animals play a role in cycling nutrients in the environment and preserving the quality of certain types of land. The best path forward would couple a significant increase in F&V production with a shift away from animal protein. In this context, we made a scenario analysis of required arable and pasture land for today and the future if we adopt 20% protein from animal sources and 80% protein from plant sources. We found that currently we would need 675 million ha of land and in 2050 we would need 813 million ha of land to produce the total protein servings which is even less than the amount of land that is currently being used for producing our proteins.

So in conclusion, if we want to move forward to feed the future, to be healthier without increasing the amount of land that agriculture uses, we both have to shift to a Harvard Healthy Eating Plate model and shift our protein consumption away from livestock-based to plant-based.

Based on: KC KB, Dias GM, Veeramani A, Swanton CJ, Fraser D, et al. (2018) When too much isn’t enough: Does current food production meet global nutritional
needs?. PLOS ONE 13(10): e0205683.