A healthy and sustainable diet, to each their own

A healthy and sustainable diet, to each their own

July 24, 2020

A healthy and sustainable diet, to each their own

Which is the best diet? There is no single answer as it depends on several factors, above all a person's level of income and technological development. Without forgetting that changes also depend on the social structure and behavior of individuals and groups. 

Daily food choices have a huge impact on human health and on the health of the entire planet. While it is true to say that “we are what we eat” and that unbalanced diets are among the main risk factors for chronic diseases, including diabetes, cardiovascular diseases and cancer, we must also think of the environmental sustainability of our diet. Agricultural production, especially fodder cultivation, has a major environmental impact, because it covers almost 40% of the global surface, uses approximately 70% of water resources and is responsible for more or less a quarter of all greenhouse gas emissions, without mentioning river pollution caused by the use of fertilizers and pesticides.

A look around the world

In recent years, a number of studies have suggested that diets low in food from animal sources foods and rich in fruit, vegetables, nuts and whole grains are healthy diets, and also have a lower environmental impact. A concept summarized and described schematically in the Double Food and Environmental Pyramid developed by the Barilla Foundation and deepened by several studies that have launched the “planetary diet” concept, setting the limits beyond which food consumption is no longer sustainable. However, the majority of studies on sustainable diets have been carried out in high-income countries and the focus has not been on health, but on the greenhouse gas emissions generated by food production. 

A study published in The Lancet Planetary Health and conducted by researchers at the University of Oxford, included a detailed nutritional analysis of the typical diets in over 150 countries, with the objective of assessing the health differences of the various food systems. 

All sustainable diets were classified based on three different approaches to sustainability: diets based on environmental sustainability; diets based on food security and food for everyone and, lastly, diets built on the principles of public health, including vegetarian and vegan diets. 

Comparing nine risk factors connected to diet and weight (such as level of nutrients, diet-related mortality) with environmental impact (greenhouse gas emissions, but also land, water and pesticide use) researchers came to specific conclusions for each group. In particular, diets based on environmental sustainability, replaced 25-100% of animal-source foods with plant-based foods. The second set of diets, based on food security, reduced levels of underweight, overweight, and obesity by 25-100%. The third set, based on public health measures, consisted of four energy-balanced dietary patterns: flexitarian, pescatarian, vegetarian, and vegan. 

Vegetable is better

Results turned out as expected, but they strengthened with scientific rigor the recommendations of those involved in environmental and food sustainability. In fact, researches demonstrated that diets that rely mainly on plant-based foods considerably reduce the environmental impact of food production in middle- and high-income countries, improving the level of nutrient intake and reducing premature mortality. Paradoxically, in low-income countries, adopting a balanced diet would increase the demand for natural resources, but this is inevitable in order to provide everyone with enough locally-produced food. All over the world, the best combination of health benefits and environmental benefits is given by low greenhouse gas emissions diets. Health benefits are smaller (but present) in diets associated with lower fresh water use and moderate in diets that reduce pesticide and cropland use.


With the adoption of the various food systems, premature mortality is reduced in percentages ranging between 4 and 12%, depending on the scenario: in more than half of these cases the reduction is linked to an increased consumption of vegetables, a third to an increased consumption of fruit, a fifth is linked to a greater consumption of pulses and a tenth to the reduction of red meat consumption.

A sustainable and healthy diet is context specific

"Even if a worldwide strategy would lead to healthier diets, when assessing environmental impact, differences between the countries must be maintained", experts explain. "In particular, in low-income countries the environmental advantages of a healthy diet are not as marked, therefore, we need to take a case-by case approach. It is important to send the message that a one-size-fits-all sustainable and healthy diet does not exist. Diets must be based on the local context, also taking into account the technology investments required as a consequence of the population's change of diet", they add. 

Last but not least, the forces that can push people to change their diet must be taken into account. This is explained by the Austrian and German authors of an article recently published in Nature Sustainability which - studying in the consumption of meat and its impact in particular - analyzed the effect on the environment of a large number of possible food changes and identified the most important elements of behavior when people want to change course at the table. “Rather than drastic changes in small groups of people, changes are needed that affect a large part of the population,” the experts write, referring to the effect of dietary changes on the environmental footprint of food systems. “Even if 40 percent of the world's population became vegetarian, the environmental benefits would not fully emerge if the rest of the population continued to eat meat at current levels,” they explain.

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