Excerpts from ADA Position Paper
Excerpts from “Position of the American Dietetic Association: Food and Nutrition Professionals Can Implement Practices to Conserve Natural Resources and Support Ecological Sustainability,” Journal of the American Dietetic Association, 2007; 107(6): 1033–43.
Overall, animal protein production requires 25 kcal for each kilocalorie produced as food. Grain protein production requires only 2.2 kcal per food kilocalorie. The kind of animal protein also makes a difference. For example, for each food calorie produced, broiler chicken production requires 4 kcal, turkey requires 10 kcal, milk and pork both require 14 kcal, eggs require 39 kcal, beef 40 kcal, and lamb 57 kcal. Energy inputs depend on the livestock feed (ie, grain versus pasture). When livestock are pasture fed, energy costs can be reduced by half (57).
Food choices have a significant effect on the quantity of land needed for food production. In a comparison of environmental impacts of different protein choices, researchers found that meat protein required more land to produce than vegetable protein by a factor ranging from 6 to 17. In addition, meat protein production required approximately 26 times more water than vegetable protein on rain-fed lands, and production of vegetable proteins was 2.5 to 50 times more energy efficient than meat production, depending on the intensity of agricultural practices (63). It is important to note that environmental resource conservation associated with plant-based diets is diminished when foodstuffs are transported long distances. For example, local, organically produced meat may have a lower environmental impact than transported produce (63). Livestock grazed on indigenous grasslands (eg, grass-fed beef) is an example of a sustainable agricultural system because external inputs are minimized (64).
57. Pimental D, Pimental M. Sustainability of meat-based and plant-based diets and the environment. Am J Clin Nutr. 2003;78(suppl):660S–663S.
63. Reijinders L, Soret S. Quantification of the environmental impact of different dietary protein choices. Am J Clin Nutr. 2003;78(suppl):664S–668S.
64. Heitschmidt RK, Short RE, Grings EE. Ecosystems, sustainability and animal agriculture. J Anim Sci. 1996;74:1395–1405.