Artificial sweeteners and other sugar substitutes are used in a wide range of foods and especially beverages to provide sweetness with fewer or no calories. The question is: are they safe? The short answer: it depends on the sweetener. Some appear to be safe, some are safe in moderation but may cause diarrhea or other gastrointestinal effects in larger quantities in some people, and others we recommend that people avoid, primarily because they may pose a slight risk of cancer.
One thing seems clear: you’re better off drinking beverages with sugar substitutes than you are consuming sugary drinks, which contribute to weight gain and are linked to a higher risk of heart disease, type 2 diabetes, and obesity, not to mention tooth decay. That said, try to avoid aspartame, which tops our list of risky artificial sweeteners and appears in such popular beverages as Diet Coke, Diet Pepsi, and Diet Dr. Pepper. Your best bet: water, whether plain, unsweetened flavored (e.g., JUST or Hint water), carbonated (e.g., Polar seltzer, LaCroix), or tap water dressed up with a slice of fruit, cucumber, or sprig of mint or other herbs.
If you consume diet drinks or artificial sweeteners, look for safer sweeteners. The artificial sweetener neotame, the natural "high-potency" sweeteners stevia leaf extract and thaumatin appear to be safer, as does erythritol, which occurs naturally in some fruits but is also manufactured for use as a sweetener. Avoid acesulfame potassium, aspartame, saccharin, and sucralose, which may pose a small risk of cancer.
Sugar alcohols (e.g., xylitol, sorbitol, erythritol) are another class of sugar-free (and booze-free) sweeteners. Some occur in plants, but they are typically manufactured. Most have about half as many calories as sugar, though erythritol has one-twentieth as many. They appear to be safer sweeteners, except that large amounts of most of them (except erythritol) may cause diarrhea or have laxative effects.
Allulose, a sugar metabolized differently than traditional sugars, has only 10% of the calories of regular sugar. It appears to be a safer sweetener, except that large amounts may lead to diarrhea or other gastrointestinal discomfort in some people.
Based on the available evidence, which is relatively limited, CSPI advises that children avoid no/low calorie sweeteners. The American Academy of Pediatrics concluded in 2019 that the long-term safety of no-calorie sweeteners in childhood has not been assessed in humans. In 2018, the American Heart Association concluded that it is prudent to advise against prolonged consumption of low-calorie sweetened beverages by children.
Can artificial sweeteners and other low-calorie sweeteners help you manage your weight? According to the Dietary Guidelines for Americans, replacing added sugars with low- and no-calorie sweeteners may reduce calorie intake in the short-term and aid in weight management, but questions remain about their effectiveness as a long-term weight management strategy.
See our comprehensive Chemical Cuisine ratings of more than 150 food ingredients and additives.