Artificial sweeteners are everywhere, but the jury is still out on whether these chemicals are harmless. Also called non-nutritive sweeteners, these can be synthetic – such as saccharin and aspartame – or naturally derived, such as steviol, which comes from the Stevia plant. To date, the U.S. Food and Drug Administration has approved six types of artificial and two types of natural non-nutritive sweeteners for use in food.

人造甜味剂随处可见，但这些化学物质是否无害仍有待观察。它们也被称为无营养甜味剂，可以是人工合成的，如糖精和阿斯巴甜，也可以是天然提取的，如甜菊糖醇，它来自甜菊叶植物。迄今为止，美国食品和药物管理局已经批准了六种人工甜味剂和两种天然无营养甜味剂用于食品。

That’s been great news for those working hard to curb their sugar consumption. Aspartame, for example, is found in more than 6,000 foods worldwide, and about 5,000-5,500 tons are consumed every year in the United States alone.

这对那些努力控制糖摄入量的人来说是个好消息。以阿斯巴甜为例，全世界有6000多种食品中含有阿斯巴甜，仅在美国每年该类食品就有5000 - 5500吨。

The American Diabetes Association — the most well-respected professional group focusing on diabetes — officially recommends diet soda as an alternative to sugar-sweetened beverages. To date, seven U.S. municipalities have imposed a sugary beverage tax to discourage consumption.

美国糖尿病协会（The American Diabetes Association）——最受尊敬的糖尿病专业团体——正式推荐无糖汽水作为含糖饮料的替代品。到目前为止，美国已有七个城市开始征收含糖饮料税，以抑制消费。

However, recent medical studies suggest that policymakers eager to implement a soda tax may also want to include diet drinks because these sweeteners may be contributing to chronic diabetes and cardiovascular diseases as well.

然而，最近的医学研究表明，渴望征收碳酸饮料税的政策制定者可能也想把无糖饮料纳入其中，因为这些甜味剂可能也会导致慢性糖尿病和心血管疾病。

Why are these sweeteners calorie-free?

为什么这些甜味剂不含热量?

The key to these virtually calorie-free sweeteners is that they are not broken down during digestion into natural sugars like glucose, fructose and galactose, which are then either used for energy or converted into fat.

这些几乎不含卡路里的甜味剂的关键在于，它们不会在消化过程中分解成葡萄糖、果糖和半乳糖等天然糖，这些糖要么用作能量，要么转化为脂肪。

Non-nutritive sweeteners have different byproducts that are not converted into calories. Aspartame, for example, undergoes a different metabolic process that doesn’t yield simple sugars. Others such as saccharin and sucralose are not broken down at all, but instead are absorbed directly into the bloodstream and excreted in the urine.

无营养的甜味剂有不同的副产品，它们不会转化为卡路里。例如，阿斯巴甜经历了一个不同的代谢过程，不产生单糖。其他的如糖精和三氯蔗糖根本没有被分解，而是直接被吸收到血液中，并随尿液排出。

Theoretically, these sweeteners should be a “better” choice than sugar for diabetics. Glucose stimulates release of insulin, a hormone that regulates blood sugar levels. Type 2 diabetes occurs when the body no longer responds as well to insulin as it should, leading to higher levels of glucose in the blood that damages the nerves, kidneys, blood vessels and heart. Since non-nutritive sweeteners aren’t actually sugar, they should sidestep this problem.

理论上，对于糖尿病患者来说，这些甜味剂应该是比糖更好的选择。葡萄糖刺激胰岛素，一种调节血糖水平的激素，释放。当身体对胰岛素的反应不正常时，就会发生2型糖尿病，导致血液中葡萄糖含量升高，损害神经、肾脏、血管和心脏。既然无营养的甜味剂实际上不是糖，他们就应该回避。

Artificial sweeteners, your brain and your microbiome

人工甜味剂，你的大脑和你的微生物群

However, there is growing evidence over the last decade that these sweeteners can alter healthy metabolic processes in other ways, specifically in the gut.

然而，在过去的十年里，越来越多的证据表明，这些甜味剂可以以其他方式改变健康的代谢过程，特别是在肠道内。

Long-term use of these sweeteners has been associated with a higher risk of Type 2 diabetes. Sweeteners, such as saccharin, have been shown to change the type and function of the gut microbiome, the community of microorganisms that live in the intestine. Aspartame decreases the activity of a gut enzyme that is normally protective against Type 2 diabetes. Furthermore, this response may be exacerbated by the “mismatch” between the body perceiving something as tasting sweet and the expected associated calories. The greater the discrepancy between the sweetness and actual caloric content, the greater the metabolic dysregulation.

长期使用这些甜味剂会增加患2型糖尿病的风险。糖精等甜味剂已被证明会改变肠道微生物群落的类型和功能。阿斯巴甜会降低一种肠道酶的活性，而这种酶通常对2型糖尿病有保护作用。此外，身体感知到的甜味与预期的卡路里之间的“不匹配”可能会加剧这种反应。甜味和实际卡路里含量之间的差异越大，新陈代谢就越容易失调。

High-intensity sweeteners allowed for use in food in the United States 

Sweeteners have also been shown to change brain activity associated with eating sweet foods. A functional MRI exam, which studies brain activity by measuring blood flow, has shown that sucralose, compared to regular sugar, decreases activity in the amygdala, a part of the brain involved with taste perception and the experience of eating.

甜味剂也被证明会改变与吃甜食有关的大脑活动。一项通过测量血流量来研究大脑活动的功能性核磁共振(MRI)检查显示，与普通的糖相比，三氯蔗糖会降低杏仁核的活动，而杏仁核是大脑中与味觉和进食体验相关的部分。

Another study revealed that longer-term and higher diet soda consumption are linked to lower activity in the brain’s “caudate head,” a region that mediates the reward pathway and is necessary for generating a feeling of satisfaction. Researchers have hypothesized that this decreased activity could lead a diet soda drinker to compensate for the lack of pleasure they now derive from the food by increasing their consumption of all foods, not just soda.

另一项研究显示，长期饮用或饮用更多的无糖汽水与大脑“尾状核”的活动减少有关。“尾状核”是调节奖赏途径的区域，是产生满足感的必要区域。研究人员假设，这种活动的减少可能会导致饮用无糖汽水的人通过增加所有食物的摄入量，而不仅仅是汽水，来弥补他们从食物中获得的快感的减少。

Together these cellular and brain studies may explain why people who consume sweeteners still have a higher risk of obesity than individuals who don’t consume these products.

这些细胞和大脑的研究可以解释为什么吃甜味剂的人仍然比不吃这些产品的人有更高的肥胖风险。

As this debate on the pros and cons of these sugar substitutes rages on, we must view these behavioral studies with a grain of salt (or sugar) because many diet soda drinkers — or any health-conscious individual who consumes zero-calorie sweeteners — already has the risk factors for obesity, diabetes, hypertension or heart disease. Those who are already overweight or obese may turn toward low-calorie drinks, making it look as though the diet sodas are causing their weight gain.

当关于这些糖替代品利弊的争论愈演愈烈时，我们必须对这些行为研究持保留态度(或持糖态度)，因为很多喝无糖饮料者——或任何有健康意识的人消耗零卡路里的甜味剂——已经有肥胖的风险因素，糖尿病、高血压或心脏病。那些已经超重或肥胖的人可能会转向低卡路里的饮料，但看起来好像是无糖汽水导致了他们的体重增加。

This same group may also be less likely to moderate their consumption. For example, those people may think that having a diet soda multiple times a week is much healthier than drinking one case of soda with sugar.

这群人不太可能节制他们的饮食。例如，这些人可能认为一周喝几次无糖汽水比喝一箱加糖汽水更健康。

Obesity in 2016

These findings signal that consumers and health practitioners all need to check our assumptions about the health benefits of these products. Sweeteners are everywhere, from beverages to salad dressing, from cookies to yogurt, and we must recognize that there is no guarantee that these chemicals won’t increase the burden of metabolic diseases in the future.

这些发现表明，消费者和健康从业者都需要检查我们对这些产品健康益处的假设。甜味剂无处不在，从饮料到沙拉酱，从饼干到酸奶，我们必须认识到，不能保证这些化学物质不会在未来增加代谢疾病的负担。