A pound of grains has a smaller environmental cost than a pound of beef, but that overlooks a key factor — nutrient density. If you’re getting more vitamins and minerals out of a pound of grass-fed beef liver than a pound of white rice, maybe it’s not fair to compare the environmental impact of these foods by weight and calories alone. 

Monica Reinagel at Nutrition Data linked to a Swedish study looking at the environmental effects of milk, soft drinks, orange juice, beer, red wine, mineral water, soy milk and oat milk, while taking into account the nutrients in all those beverages. With this more nuanced method, unfortified semi-skimmed cow’s milk beats orange juice and soy milk, which tie for a distant second.

Fascinatingly, three of the four scientists who conducted this study are employees of the Swedish Dairy Association. I’m not sure who employs the fourth guy, but I’m assuming it’s not the Swedish Soft Drink Association, since sugar water scored the worst. Presumably those three ganged up and pressured the fourth guy into going along with the pro-dairy conclusion of the study.

Still, it’s an interesting angle on the animal products vs. environment debate. In the conclusion of the study, Annika Smedman, Helena Lindmark-Månsson, Adam Drewnowski and Anna-Karin Modin Edman explain why the issue deserves more research:

With increasing frequency, persons and institutions draw conclusions on dietary recommendations from a climate perspective without a comprehensive analysis of nutritional relevance. … A sustainable diet cannot be formulated based only on one or a few aspects but requires taking the complexity of many nutrients into consideration. …

[W]e propose that caution must be taken when suggesting changes in food consumption patterns as a means to reduce [greenhouse gas] emissions. Using a functional unit involving only [global warming potential] per kilogram of a food item may lead to the conclusion that vegetable alternatives are always better than those of animal origin.

To our knowledge, the nutrient density has not been taken explicitly into account previously when discussing climate impact of food choices. … It is thus important to use both knowledge in nutrition and climate to avoid simplistic and erroneous conclusions for food recommendations and dietary guidelines to mitigate climate change.