What we eat matters: Comparing environmental impact of different diets

In the last years, increasing attention has been paid to the impacts our food choices cause on the environment. Certainly, the foods and beverages we produce, choose and consume significantly contribute to our individual environmental footprint. This is not surprising considering that we use over half of the world’s habitable land for agriculture.

Multiple studies have shown the great contribution food production, processing, and distribution make to climate change, accounting for approximately 26% of global GHG emissions. However, agriculture activities have even a larger and more direct impact on habitat destruction, being one of the primary drivers of biodiversity loss. In fact, of 28,000 species evaluated to be threatened with extinction on the IUCN Red List, agriculture is listed as a threat for 24,000 of them.

But then, is there something we can do to reduce these impacts? Numerous studies indicate that we can find the solution in our dietary patterns, by reducing the consumption of meat and substituting it for plant-based alternatives.

Comparison of different diets’ environmental impact

In recent years, several studies have compared the environmental impact of different diet types in different countries and situations. Taking into consideration all phases of the food chain, one study published in Nature, analysed and compared three weekly well-balanced diets with equivalent energetic and nutrient content: one omnivorous, one vegetarian, and one vegan. In accordance with other study results, they found that from the three diets, omnivorous had the greatest environmental impact whereas vegan diets turned out to have the smallest environmental impact.

The impacts identified from omnivorous diets included eutrophication, land-use change, damage to respiration from inorganic chemical compounds, consumption of fossil fuels, and water consumption. For instance, beef production is by far the largest cause of tropical deforestation in the Amazon, accounting for at least 70 percent of all deforestation. Additionally, more rainforest is being converted to soybean plantations, much of which goes to feed the growing cattle population. An issue that involve us all. In Europe, for example, we only grow 20% of the proteins used to feed animals. The rest we import from other countries, contributing in many cases to deforestation.

Importantly, the same study concluded that chemical–conventional production methods, independently of the diet type, have a greater environmental impact than organic methods. Thus, a same diet type may have very distinct environmental impacts depending on which products we consume, and their production system. Another study in Italy, where researchers analysed the real diet of 153 adults, obtained similar results. In this case, vegetarian and vegan diets also represented a clear environmental advantage with respect to the omnivorous diet. However, plant-based diets with high intake of industrially highly-processed plant-based meat and dairy substitutes eliminated the environmental benefits of a vegan diet in comparison with a vegetarian choice.

What about diets nutritional quality?

A third study analysed the dietary patterns of seven European countries and measured their environmental impact as well as their nutritional quality. Interestingly, individuals with poor quality diets were also those with the highest impacts. Although there is no healthy food per se, but rather healthy diets and eating patterns, the study concluded that to achieve a low impact and good quality diet, the average population should decrease the amount of meat (−42%), sweets (−60%) and drinks (−37%) consumed. On the other hand, they should increase the consumption of fruits, vegetables (+60%), and cereals (+65%).

To summarise, we have the potential to improve simultaneously the quality of our diet and reduce its impacts by altering our eating patterns. A change in our eating habits may play an important role in the fight against some major current environmental problems.

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