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素食主义是一种终身戒食肉、家禽、鱼、蛋等动物产品的行为规范，有时也戒食或不戒食奶制品和蜂蜜。遵循素食主义的原因通常是出于健康原因，或是出于对动物的爱，以及对动物权益的尊重等。
而近期的一项研究表明，素食对环境保护更为有利。
Pamela Martin is a geophysicist at the University of Chicago. She co-authored a 2009 study analyzing the environmental impact of an American diet based on meat versus a diet based on vegetables.
Pamela Martin: Right now the current mean American diet has 28% meat, but there's nothing to say that if we all cut back to 10% that we would suffer nutritionally. And yet the environment would benefit quite a bit from that.
Martin's study examined how much land a meat-based diet versus a vegetable-based diet would require to support Americans.
Pamela Martin: You need about four and a half times the amount of land to grow feed that you feed for cattle, versus using that land directly to grow food that we would directly consume.
Ultimately, Martin said, raising livestock requires more fertilizer and emits more greenhouse gases. These have environmental impacts.
Pamela Martin: We ought to be considering the health of the planet as well as the health of the people.
Martin believes a switch to a more vegetable-based American diet could have a positive impact on the environment.
Pamela Martin: I think the important consideration is to look at what's on your plate each night, and try to make some changes.
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