A review article published in the journal Nutrients describes the impact of six popular diets on human health as well as planetary health. The health and environmental impacts of these diets have been compared in the review using carbon footprint databases and representative meal plans.
Study: Modern Diets and the Health of Our Planet: An Investigation into the Environmental Impacts of Food Choices. Image Credit: Matic Stojs Lomovsek / Shutterstock
Background
Generally, Americans choose dietary plans based on health benefits and ethical considerations. However, besides providing health benefits, dietary plans are known to impact planetary health significantly.
Carbon footprints are a well-known measure of planetary health. The carbon footprint of a given item or activity refers to the amount of greenhouse gases, especially carbon dioxide, emitted by that item or activity during a given period. The carbon footprint of a food item depends on its source and composition.
In the current review, the food choices of US residents were evaluated and compared in terms of their impacts on both human and planetary health. A total of six diets, including the Standard American, Mediterranean, vegan, paleo, keto, and climatarian diets, were compared using carbon footprint databases and representative meal plans.
Review outcomes
Based on the carbon footprint estimates, the six studied diets were categorized as either high- or low-emission. The high-emission category included the Standard American, keto, and paleo diets, and the low-emission category included the Mediterranean, vegan, and climatarian diets.
Regular consumption of red meat was identified as the primary determinant of high carbon footprints. A significant reduction in carbon footprints of the high-emission diets was observed upon replacing beef (red meat) with chicken or pork.
The lowest carbon footprint estimate was found in the vegan diet, as consumption of meat is completely prohibited in this diet. Similarly, Mediterranean and climatarian diets were associated with lower carbon footprints because of limited consumption of ruminant meat (cattle and sheep) and processed foods.
As discussed in the review, higher levels of carbon dioxide emissions during beef protein synthesis place the Standard American, keto, and paleo diets in the high-emission category. The environmental impact of ruminant meat is 20-100 times higher than that of plants. The environmental impact of other animal products, including milk, egg, chicken, pork, and seafood, is 2-25 times higher than that of plants.
Regarding environmental impact, ruminant meat contributes to 38% of methane emissions in the United States. Methane is a greenhouse gas with 28 times higher global warming potential than carbon dioxide.
The analysis of low-emission category diets in the review indicates that there is no need to eliminate meat consumption to make it environment-friendly completely. Reducing red meat consumption or replacing them with fish, turkey, or chicken is sufficient to reduce carbon footprint estimates of a high-emission diet.
The review also mentioned processed foods, which are common components of vegan and Standard American diets and have higher carbon footprints. However, processed meat's carbon footprints are lower than red meat's. The environmental impacts of processed foods can be reduced by modulating production methods.
The findings of this review highlight that diets with human health benefits appear to be healthier for the planet as well. Apart from adverse environmental impacts, high consumption of red meat is known to increase the risk of developing health adversities, including obesity, diabetes, cardiovascular diseases, and many other chronic diseases.
The dietary choice of US residents may vary among different age groups. For example, while elderly people focus more on the health benefits of a diet, young people stress more on its environmental impacts. However, some potential barriers against replacing meat with plant-based proteins include the taste of food, the sensory experience of eating meat, and the fear of developing a protein deficiency.
Significance
The review discusses the health and environmental impacts of six diets commonly consumed by US residents. While the Standard American, keto, and paleo diets have been categorized as high-carbon footprint diets, the Mediterranean, vegan, and climatarian diets have been found to have beneficial environmental impacts because of low carbon footprint estimates.
A high content of animal products, especially red meat, is believed to be responsible for high carbon footprints in the Standard American, keto, and paleo diets. In addition, a high-meat diet is also known to have negative health impacts. Thus, diets with health adversities are also likely to have environmental adversities.
Overall, the review suggests that moderate consumption of animal proteins and plenty of fruits and vegetables is the optimal diet choice in terms of promoting both human and planetary health.
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