Local context is a factor in sustainable and healthy diets

Local context is a factor in sustainable and healthy diets

December 13, 2018

Local context is a factor in sustainable and healthy diets

Which is the best diet? In middle- and high-income countries, the answer is a diet low on animal-source food; however, in low-income countries, it's a diet based on nutrient-dense foods, even if it means increasing the environmental impact. This is the result of a British study on over 150 food systems.

We are what we eat. And unbalanced diets, low in fruit, vegetable, nuts and wholegrain cereals, and high in transformed and red meat, are among the main causes of chronic diseases, especially diabetes, cardiovascular diseases and cancer. But the threat is not just to our health, we also must think of environmental sustainability. Agricultural production, especially fodder cultivation, has an 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.

International view

In recent years, a number of studies have suggested that diets low on animal-source foods are healthy diets and also have a low environmental impact. 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 on 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. 

Researchers then compared nine risk factors in connection with diet and weight (such as level of nutrients, diet-related mortality) with environmental impact (greenhouse gas emissions, but also land, water and pesticide use). The first set of 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, consisted of four energy-balanced dietary patterns: flexitarian, pescatarian, vegetarian, and vegan. The results took into account the intake of nutrients based on international recommendations and weight-related mortality. 


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. 


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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".


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