2015年托福阅读最新材料：“纯素食主义”的风险

　　近几年，素食主义悄然流行，越来越多的人加入了素食者的行列。不过，近日发布在自然母亲网络的一篇文章指出，纯素食也有潜在的健康风险，比如，纯素食者患肠癌的几率更高、骨矿物密度偏低，以及更容易缺乏维生素B12等等。营养专家表示，加入纯素食者行列意味着你要花更多的时间来规划饮食结构以保证各类营养摄入均衡。如果没有精力和时间详细规划，营养专家建议不妨做一个“弹性素食者”，即大部分时间吃素，偶尔吃点肉补充动物蛋白。

　　Thinking of giving up meat from your diet? The potential health benefits of a green diet are well established, but a story by the Mother Nature Network (MNN) says there are also some potential side effects and health risks associated with a vegetarian lifestyle.

　　Could low cholesterol kill you? A study by the Honolulu Heart Program found that elderly people with a "low cholesterol concentration" had a "significant association with mortality." In addition, a 2009 review published in the American Journal of Clinical Nutrition found that while vegetarians have an overall lower rate of cancer compared with meat eaters, vegetarians do have a 39 percent higher rate of colorectal cancer.

　　Other health concerns associated with vegetarianism cited by MNN included lower bone mineral density and lower levels of vitamin B12. However, the publishers of the bone density study said the "magnitude of the association is clinically insignificant," at just around 5 percent.

　　Going vegetarian appears to have gained popularity in recent years. A recent Yahoo Sports article even examined the diet of Mixed Martial Arts (MMA) fighter Jake Shields. Though much of the media's focus has been on a worldwide trend toward bigger diets, whether that's Pizza Hut offering strange fast food mashups or yet another customer at the Heart Attack Grill proving that there is truth in advertising.

　　The lesson in these potential risk-factors seems to be that if you're going to become a vegan or vegetarian, you'll need to spend more time planning your nutritional choices to help ensure a balanced intake of vitamins and other nutrients. Though if you don't have the time or inclination for such efforts, there may be another option. University of Idaho nutritionist Katie Minor says that a "flexitarian" diet may be a viable third way.

　　"Flexitarians are people who are vegetarian most of the time, but once in a while will consume an animal protein," Minor told MNN. "The more restrictive you are with your diet, the more you'll have to closely monitor what you're consuming and the more likely your need will be to supplement. Work with a registered dietician to make sure you're not at risk for dietary deficiencies."