HealthNotes

Following the USDA’s Dietary Guidelines for Americans is good for your health, and, according to a large study, it may also be beneficial for the planet. The findings were published in the Proceedings of the National Academy of Sciences and compared the average diets of 37 middle- to high-income nations (64% of the world’s population) to their respective nationally recommended diets. Researchers gathered information about each nation’s recommended diet from national organizations responsible for dietary advice. Each nation’s actual average diet was taken from Food Balance Sheets–detailed reports on national food systems calculated by the UN’s Food and Agriculture Organization. Researchers then calculated greenhouse gas emissions, eutrophication (water pollution due to nutrient runoff), and land use resulting from each diet using a database of the environmental impacts of various product categories, including twelve food groups. After assessing the environmental impacts of each nation’s recommended and average diets, researchers determined that, compared with average diets:

• Recommended diets in high-income nations were associated with 13 to 24.8% lower greenhouse gas emissions, 9.8 to 21.3% less eutrophication, and 5.7 to 17.6% less land use. Of these reductions, approximately 54% were due to reduced calorie intakes and 46% were due to differences in intakes of specific foods.
• Recommended diets in upper middle-income nations were associated with reductions of 0.8 to 12.2% in greenhouse gas emissions, 7.7 to 19.4% in eutrophication, and 7.2 to 18.6% in land use.
• Recommended diets in lower middle-income nations were associated with increases of 12.4 to 17% in greenhouse gas emissions, 24.5 to 31.9% in eutrophication, and 8.8 to 14.8% in land use.

Higher animal product consumption largely explains the lower reductions–or even increases–in environmental damage associated with recommended diets of middle-income nations. Animal products account for a large proportion of all three aspects of environmental impact considered in this study: greenhouse gas emissions, eutrophication, and land use. Even with these increases, researchers found that if every nation adopted their respective recommended diet, the overall environmental impact would be positive. While large-scale dietary changes won’t happen overnight, gradually shifting our eating to align with national recommendations could help reduce our environmental footprint.

Source: Proceedings of the National Academy of Sciences