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.

糖替代品的承诺很简单：从酸奶到牙膏，各种产品中都有它们的身影，它们声称能让人们尽情享用甜食，却不会增加体重，也不会引发由嗜糖细菌导致的蛀牙。 如今，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。

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.

糖替代品是一包混合物。 它们包括合成混合物（如阿斯巴甜、糖精和三氯蔗糖）以及从植物中提取的物质，包括一类被称为糖醇的碳水化合物（如赤藓糖醇、麦芽糖醇、山梨糖醇和木糖醇）和甜菊糖苷。 有些糖替代品给人的甜味是糖的数百倍，因此只需在食品和饮料中添加极少量。 这些微小的剂量，再加上许多糖替代品在很大程度上未被改变就被排出体外的观察结果，让人们假设它们会穿过人体而不影响新陈代谢。

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.

事情可能没那么简单。 在一些随机对照试验（通常持续4至12周）中，用其他甜味剂替代糖确实能减少体重增加。 但一些大型长期观察研究发现的结果却恰恰相反：摄入糖替代品较多的人（其中一些人可能是为了在饮食中替代糖）最终比摄入最少的人体重增加得更多。 其他研究还表明，与不食用糖替代品的人相比，他们患心脏病、糖尿病和癌症的几率也更高。

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.)

要通过这类观察性研究证明因果关系很困难，因为这需要考虑到食用大量糖替代品的人与不食用的人之间的所有差异。 例如，这些甜味剂的一些消费者可能已经是糖尿病或心脏病的高危人群，他们希望吃得更健康。 然而，即使没有确凿的证据，整体研究结果也足以令人担忧，促使世界卫生组织在2023年发布建议，反对使用糖替代品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。）

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.

关于糖替代品如何造成危害，有许多假设。 已经发现，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，一些对小鼠的研究表明，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，可能会使有害菌种占据优势。 奥地利因斯布鲁克医科大学的赫伯特·蒂尔格表示，关于糖替代品的安全性，还有许多悬而未决的问题有待解答，但这些研究正在引发越来越多的担忧。

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.

避免食用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多种甜味剂（通常是将一种能立即产生甜味的物质与一种能产生持久口感的物质相结合），这意味着经常食用预包装零食或碳酸饮料、能量饮料和蛋白质饮料的人很难避免食用它们。 最明智的做法是彻底避开这些产品。 如果你想吃甜食，最好的选择是吃一块你最喜欢的水果。