4.12 考研英语外刊阅读模拟试题【难度6.8】经济学人:甜、代糖与健康

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Section II Reading Comprehension 

Part A 

Directions: Read the following four texts. Answer the questions below each text by choosing A, B, C or D. Mark your answers on the ANSWER SHEET. 

Text 2

The promise of sugar substitutes is simple: found in everything from yogurts to toothpaste, they claim to let people gorge on sweet treats without piling on weight and the tooth decay caused by sugar-loving bacteria. Now a growing body of research is suggesting that these substances may have surprisingly bitter consequences.

Sugar substitutes are a mixed sachet. They include synthetic concoctions (such as aspartame, saccharin and sucralose) and substances derived from plants, including a family of carbohydrates known as sugar alcohols (such as erythritol, maltitol, sorbitol and xylitol) and stevia. Some strike the human tongue as hundreds of times sweeter than sugar, so are added in tiny amounts to foods and drinks. These small quantities, combined with the observation that many are excreted largely unchanged, has led to the assumption that they pass through the human body without affecting metabolism.

Things may not be so simple. In some randomised controlled trials (typically lasting 4-12 weeks) substituting other sweeteners for sugars did admittedly result in lower weight gain. But a number of large, long-term observational studies have found the opposite: people with higher consumption of sugar substitutes—some of whom may be using these to replace sugar in their diets—end up putting on more weight than those who consume the least. Other studies show that they also end up with higher rates of heart problems, diabetes and cancer than abstainers.

Proving causality through such observational studies is difficult, as it would involve accounting for all the ways in which people who eat lots of sugar substitutes are different from those who do not. It could be, for example, that some consumers of these sweeteners are people who are already at high risk for diabetes or heart disease and looking to eat more healthily. Even without a smoking gun, however, the overall body of research was concerning enough to prompt the World Health Organisation to issue, in 2023, precautionary advice against the use of sugar substitutes as a means to control weight or prevent chronic diseases. (The advice does not apply to people with diabetes.)

There are plenty of hypotheses concerning how sugar substitutes could be causing harm. Some of these substances have been found to activate the same harmful gut and metabolic signalling mechanisms as sugar, and some studies in mice suggest that they could be affecting the function of immune cells involved in preventing the growth of tumours. Emerging evidence also suggests that they can affect the relative abundance of various gut bacteria, potentially tipping the scales in favour of harmful species. There are lots of open questions to be answered regarding the safety of sugar substitutes, says Herbert Tilg from the Medical University of Innsbruck, in Austria, but these studies are raising the level of concern.

Avoiding the most worrisome sweeteners is easier said than done. Food and drink manufacturers often use several in parallel (often combining a substance that elicits instant sweetness with one that generates a lingering taste), which means regular consumers of pre-packaged snacks or carbonated, energy and protein drinks will find them hard to avoid. The prudent thing to do is eschew these products altogether. And if you are hankering after something sweet, the best choice is a piece of your favourite fruit.

附注：根据历年考研英语真题阅读题源外刊等，摘选最新文章，模拟仿真出题。

参考答案见以下。

Quick look: CBDAC

26.【正确答案】C
【解析】题型：事实细节题
定位： 第二段最后一句“These small quantities, combined with the observation that many are excreted largely unchanged, has led to the assumption that they pass through the human body without affecting metabolism.”（这些微小的数量，加上观察到许多代糖在排出体外时基本保持不变，使得人们假设它们穿过人体而不会影响新陈代谢。）
分析： 原文明确指出了人们产生这一假设的两个原因：一是摄入量极小（small quantities），二是它们大部分原样排出体外（excreted largely unchanged）。选项C“它们被微量摄入，并且在离开身体时基本保持原样（leave the body intact）”是对原文的精准同义替换。
干扰项：[A] 它们完全提取自天然植物，原文提到代糖既有合成的也有植物提取的，且这并非不影响代谢的原因；[B] 它们完全替代了日常饮食中有害的碳水化合物，属于无中生有；[D] 它们给人的味觉是糖的几百倍甜，这是它们被微量添加的原因，而非不影响代谢的直接原因。

27.【正确答案】B
【解析】题型：事实细节题
定位： 第三段第三、四句“But a number of large, long-term observational studies have found the opposite: people with higher consumption of sugar substitutes... end up putting on more weight... Other studies show that they also end up with higher rates of heart problems, diabetes and cancer than abstainers.”
分析： 原文指出，长期的大型观察性研究发现了与短期试验相反的结果：摄入更多代糖的人最终体重增加更多，且患心脏病、糖尿病和癌症的比例也高于不食用代糖的人。选项B“它们与更大的体重增加和更高的疾病发病率有关”准确概括了这些研究的发现。
干扰项：[A] 它们始终导致显著的短期体重减轻，这是短期随机对照试验（4-12周）的结果，而非长期观察性研究的结果；[C] 它们在引发蛀牙方面比真糖更糟糕，原文第一段指出代糖标榜自己能避免蛀牙，并未说它比真糖更糟；[D] 它们能有效逆转成年人的心脏病和糖尿病，与原文事实（引发更高发病率）完全相反。

28.【正确答案】D
【解析】题型：事实细节/推理题
定位： 第四段第三句“Even without a smoking gun, however, the overall body of research was concerning enough to prompt the World Health Organisation to issue, in 2023, precautionary advice against the use of sugar substitutes as a means to control weight or prevent chronic diseases.”
分析： 原文表明，尽管缺乏确凿的因果证据（smoking gun），但整体研究已经足够令人担忧，促使世卫组织在2023年发布预防性建议，反对使用代糖作为控制体重或预防慢性病的手段。选项D“有足够的担忧来不鼓励将它们用于控制体重”完美对应了世卫组织的建议动机和内容。
干扰项：[A] 甜味剂和癌症之间的因果关系已被严格证实，原文明确表示“证明因果关系是困难的（Proving causality... is difficult）”且“没有确凿证据（without a smoking gun）”；[B] 糖尿病患者应立即停止使用代糖，括号内明确指出“该建议不适用于糖尿病患者（does not apply to people with diabetes）”；[C] 观察性研究不再可靠，原文只是说观察性研究很难证明因果关系，并未全盘否定其在医疗指南中的可靠性。

29.【正确答案】A
【解析】题型：事实细节题
定位： 第五段第三句“Emerging evidence also suggests that they can affect the relative abundance of various gut bacteria, potentially tipping the scales in favour of harmful species.”
分析： 本段列举了代糖可能造成危害的几种假设机制。其中一项是新出现的证据表明，它们会影响各种肠道细菌的相对丰度，“可能会使天平向有害菌种倾斜（tipping the scales in favour of harmful species）”。选项A“破坏各种肠道细菌的健康平衡”准确传达了“tipping the scales”的含义。
干扰项：[B] 加速免疫细胞的快速繁殖，原文是说代糖可能会“影响免疫细胞的功能（affect the function of immune cells）”，从而阻碍抑制肿瘤生长，并未说加速繁殖；[C] 完全消除代谢信号机制，原文是说它们“激活（activate）”有害的代谢信号机制，而非消除；[D] 直接触发人类肿瘤的形成，原文提到的是在“老鼠（in mice）”身上的研究表明会影响预防肿瘤生长的免疫细胞功能，而非直接在人类身上触发肿瘤。

30.【正确答案】C
【解析】题型：观点推断题
定位： 第六段最后两句“The prudent thing to do is eschew these products altogether. And if you are hankering after something sweet, the best choice is a piece of your favourite fruit.”
分析： 作者在文章最后给出了最谨慎的建议：完全避开这些（含代糖的）产品。如果你渴望吃点甜的，“最好的选择是一块你最喜欢的水果（the best choice is a piece of your favourite fruit）”。选项C“选择天然水果而不是人工加甜的产品”是对作者最终建议的直接概括。
干扰项：[A] 混合合成成分和植物提取物，这是食品制造商的做法（第一句），不是作者的建议；[B] 仔细检查碳酸饮料和能量饮料的标签，作者的建议是“完全避开（eschew altogether）”，认为它们很难避免，而非仅仅查标签；[D] 严格适量食用预包装零食，作者的态度是避开它们，去吃水果，而非适量食用。

【词汇注释】

【参考译文】

糖替代品（代糖）的承诺很简单：从酸奶到牙膏，它们无处不在，声称能让人们尽情享用甜食，而不用担心体重增加和由嗜糖细菌引起的蛀牙。然而，越来越多的研究表明，这些物质可能会带来令人惊讶的“苦涩”后果。

代糖是一个成分复杂的混合包。它们包括人工合成的调制品（如阿斯巴甜、糖精和三氯蔗糖）以及从植物中提取的物质，其中包括被称为糖醇的一类碳水化合物（如赤藓糖醇、麦芽糖醇、山梨糖醇和木糖醇）以及甜叶菊。有些物质在人类舌头上产生的甜度是糖的数百倍，因此在食品和饮料中只需添加极少量。这些微小的数量，加上观察到许多代糖在排出体外时基本保持不变，使得人们假设它们穿过人体而不会影响新陈代谢。

事情可能没有那么简单。在一些随机对照试验中（通常持续4-12周），用其他甜味剂代替糖确实带来了较低的体重增加。但是，一些长期的大型观察性研究却发现了相反的情况：代糖消费量较高的人——其中一些人可能正用代糖来替代饮食中的糖分——最终的体重增加反而比极少消费代糖的人更多。其他研究表明，他们患心脏病、糖尿病和癌症的比例也高于不食用代糖的人。

通过这种观察性研究来证明因果关系是困难的，因为这需要解释那些吃大量代糖的人与不吃代糖的人之间所有的不同之处。例如，可能是因为这些甜味剂的一些消费者本身就是糖尿病或心脏病的高风险人群，他们正试图吃得更健康。然而，即使没有确凿的证据，整体的研究结果也足以引起关注，促使世界卫生组织在2023年发布预防性建议，反对使用代糖作为控制体重或预防慢性病的手段。（该建议不适用于糖尿病患者。）

关于代糖如何造成危害，有许多假设。研究发现，其中一些物质会激活与糖相同的有害肠道和代谢信号机制；一些在小鼠身上的研究表明，它们可能会影响参与防止肿瘤生长的免疫细胞的功能。新出现的证据还表明，它们会影响各种肠道细菌的相对丰度，可能会使天平向有害菌种倾斜。奥地利因斯布鲁克医科大学的赫伯特·蒂尔格（Herbert Tilg）表示，关于代糖的安全性还有很多悬而未决的问题需要解答，但这些研究正提升人们的担忧程度。

避开最令人担忧的甜味剂说起来容易做起来难。食品和饮料制造商经常同时使用几种甜味剂（通常将一种能产生瞬间甜味的物质与另一种能产生持久余味的物质结合使用），这意味着预包装零食或碳酸饮料、能量饮料和蛋白质饮料的经常消费者会发现很难避开它们。最谨慎的做法是完全避开这些产品。如果你渴望吃点甜的，最好的选择是一块你最喜欢的水果。

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