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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):1033-1043.
Excerpt: "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.
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