This is Scientific American — 60-Second Science. I'm Julia Rosen.
Got a minute?
You know those nutrition guidelines the government issues every few years? It turns out that following them isn't just good for your health. It's good for the planet, too.
"What we found is that impacts vary across nations, but in the high-impact nations, in general, you can see that, if you follow a nationally recommended diet, despite the fact that these diets don't mention explicitly—or most of them don't explicitly mention—environmental impacts, that you are going to have lower environmental impacts due to that. So that's sort of fairly clear across all the high-income nations."
Paul Behrens, an environmental scientist at Leiden University in the Netherlands. The food we eat takes a big toll on the environment. A third of the ice-free land on Earth is used for agriculture, and according to some estimates, producing food accounts for roughly a fifth of all human-caused greenhouse gas emissions. Fertilizer runoff also leads to other problems, like the algae blooms in Lake Eerie and the Dead Zone in the Gulf of Mexico.
However, following dietary guidelines would reduce those impacts, especially in wealthy countries like the US. "Most of the reductions come from meat and dairy," which have an outsized impact on land use and pollution, and are a major source of greenhouse gases. (That's partly due to cow farts. Seriously.) Heeding recommendations would also mean eating fewer calories, since many people here eat more than they need.
Overall, in high-income countries, Behren's team estimates that following the rules could result in as much as a 17 percent reduction in land use, a 21 percent reduction in nutrient pollution, and a 25 percent drop in agricultural greenhouse gas emissions. Cutting down on how much food we waste—which is roughly a third in the U.S.—could help even more. The results are in the Proceedings of the National Academy of Sciences.
Of course, people are notoriously bad at following diets. But: "These nationally recommended guidelines do actually have a knock-on effect to other areas of policy making. So if I'm developing a new healthy-eating-for-schools program then that's going to be based off a lot of detail that I get from the nationally recommended guidelines. So while it might not necessarily be the case that people follow directly...they actually are quite influential on the preparation of other advice."
Seems that a smaller environmental footprint and a healthier lifestyle could go hand in hand.
Thanks for the minute for Scientific American — 60-Second Science. I'm Julia Rosen.
你知道政府每隔几年发布一次营养指南吗？事实表明，遵守营养指南不仅有益于你的健康 。而且对地球也有好处 。
“我们发现，营养指南在不同国家有不同影响，不过总体来说，在具高影响力的国家，如果遵循国家推荐的饮食，尽管国家没有明确提及这些饮食，或者大部分饮食没有明确提及，你对环境的影响也会因此而减少 。这在所有高收入国家相当明确 。”
荷兰莱顿大学的环境科学家保罗·贝伦斯说道 。我们所吃的食物对环境造成了严重的负面影响 。地球上三分之一的不冻土地用于农业，据估计，人类产生的温室气体排放约五分之一来自食品生产 。化肥残留物也会导致其他问题，比如伊利湖的藻华现象以及墨西哥湾的死亡区 。
而遵循膳食指南会减少这些影响，尤其是像美国这样的富有国家 。“减少的大部分是肉类和奶制品，”这两类食品对土地使用和污染有巨大的影响，同时也是温室气体的主要来源 。（这一定程度上是因为牛放屁 。真的 。）听从建议也意味着减少摄入的卡路里，因为这里的很多人吃得比他们需要的多 。
一般来说，贝伦斯的团队估计，在高收入国家，遵守这些原则可能会使土地使用减少17%，营养污染减少21%，农业温室气体排放量下降25% 。减少我们浪费的食物量会有更大的帮助，减少的食物量大概是美国食物量的三分之一 。这项研究结果发表在《美国国家科学院学报》上 。
当然，人们在遵循饮食习惯方面做得极差 。但是：“这些国家推荐的指南实际上会对其他领域的政策制定产生连锁反应 。因此，如果我正在规划新的“学校健康饮食”项目，我可能不会采用国家推荐指南上的大部分详细信息 。所以，虽然人们不必直接遵守饮食指南，但实际上这些指南在准备其它建议时有很大的影响力 。”
谢谢大家收听科学美国人——60秒科学 。我是朱莉娅·罗森 。
1. in general 总的来说；总体上来看；大体上；
例句：In general, it seems to work pretty well in suburbs and out in the country. But not in the cities.
一般来说，在郊区和农村似乎可以找到相当不错的工作 。但在城市就没这么好 。
2. account for （数量或比例上）占；
例句：These commodity funds account for almost two-thirds of the total, but funds investing foreign exchange reserves have been growing faster.
3. result in 导致；引起；造成；
例句：That will only result in an impulsive decision, which is often a bad one.
4. cut down on 削减；减少使用；
例句：We must cut down on the amount of material we use.