When artificial sweeteners hit the American market in the 1950s, food manufacturers made a big statement: They could satisfy America’s sweet tooth without the negative health effects (and calories) of sugar.
Today, artificial sweeteners and other sugar substitutes have become ubiquitous in the food supply, appearing in a multitude of products including diet soda, sliced bread and low-sugar yogurt, not to mention your morning coffee.
But questions about sugar substitutes have been raised for decades, with scientists and public health officials suggesting that they, too, may carry some health risks.
Research on how sugar substitutes affect our bodies is preliminary, complex, and sometimes contradictory.
“They haven’t been studied as much as they should be in humans,” said Dr. Dariush Mozaffarian, a cardiologist and director of the Food is Medicine Institute at Tufts University.
This leaves us with many questions about how to assess their potential benefits and risks. Here’s what we know.
What is a sugar substitute?
This term refers to a range of substances that taste sweet but don’t provide the calories of sugar. They are sometimes hundreds or even tens of thousands of times sweeter than sugar, so you only need a small amount to get your fill of sugar.
They are used to sweeten many “sugar-free” and “diet” foods and beverages, including energy drinks, chewing gum, candy, baked goods, and frozen desserts. Many are also sold as stand-alone products, in powder or liquid form.
Sugar substitutes are classified according to their manufacturing method:
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Artificial sweeteners Artificial sweeteners are synthetic food additives that are 200 to 20,000 times sweeter than table sugar, according to the Food and Drug Administration. Since the 1970s, the agency has approved six: aspartame (sold under the brand names NutraSweet and Equal), sucralose (Splenda), saccharin (Sweet’N Low), acesulfame potassium (Sweet One, Sunett), neotame (Newtame) and advantame.
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Plant and fruit based sweeteners Natural sweeteners are made from the leaves or fruits of certain plants and are at least 100 times sweeter than sugar, according to the FDA. They include extracts of the stevia plant (Truvia, Pure Via, Enliten) and monk fruit. Thaumatin, a less common low-calorie sweetener sold under the brand name Talin, is made from the West African katemfe fruit. The FDA generally recognizes these sweeteners as safe, so manufacturers can add them to foods and beverages.
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Sugar alcoholsSorbitols, which are neither sugars nor alcohols, are a type of carbohydrate that tastes sweet but contains fewer calories (and carbohydrates) than sugar. They go by names like sorbitol, xylitol, mannitol, and erythritol and are found naturally in some fruits and vegetables like pineapple, prunes, and mushrooms. The ones used in packaged goods are synthetically produced and approved by the FDA for use as sugar substitutes.
What are the potential benefits and risks?
Some evidence shows that if you regularly drink sugary drinks like soda and sweetened tea, switching to diet versions may help you lose some weight, as long as you don’t consume more calories from other sources, said Maya Vadiveloo, an associate professor of nutrition at the University of Rhode Island.
In a 2022 study of 12 randomized clinical trials, most lasting six months or less, researchers concluded that replacing sugary drinks with low-calorie or no-calorie sugary drinks could lead to some weight loss — about two to three pounds, on average — in adults who are overweight or obese and have (or are at risk for) diabetes.
Dr. Karl Nadolsky, an endocrinologist and clinical assistant professor at Michigan State University’s College of Human Medicine, said he’s seen this weight loss, and often more, in many of his patients when they switch to diet drinks.
But long-term studies of sugar substitutes have found no weight-loss benefits, and even some harmful effects. That’s why the World Health Organization recommended in 2023 that people avoid using sugar substitutes to control their weight or improve their health, citing research that links them to increased risks of health problems such as type 2 diabetes, cardiovascular disease, obesity and premature death.
The sugar alcohols erythritol and xylitol have also been linked to an increased risk of heart attack and stroke.
It’s hard to draw firm conclusions from studies of diet and health. This type of research is observational, meaning it can link sugar substitute consumption to certain health effects, but it can’t prove cause and effect, said Valisa E. Hedrick, an associate professor of nutrition at Virginia Tech. It’s possible that diet soda drinkers are simply less healthy, she said. Or perhaps other ingredients in the food or drink are responsible for the harmful effects.
Many scientists have tried to account for these limitations and still found consistent links between sweeteners and health problems, said Dr. Jim Krieger, professor emeritus at the University of Washington School of Public Health.
But to fully resolve these cause-and-effect issues, scientists would need to design studies that directly measure the long-term impact of sugar substitutes on human health, said Marion Nestle, professor emeritus of nutrition, food studies and public health at New York University. And that research is nearly impossible to do. “You can’t lock people up long enough to give them this artificial sweetener or that artificial sweetener and see what happens,” she said.
However, some (but not all) well-controlled animal studies and small human experiments, which can establish cause-and-effect links, have shown clues about how certain sweeteners might lead to health problems, Dr. Krieger said. Some research has shown that sugar alcohols can increase the risk of blood clotting, and therefore the risk of heart attack and stroke, and that other sugar substitutes can alter the gut microbiome and impair blood sugar control.
Takeaways
According to Dr. Eran Elinav, an immunologist and microbiome researcher at the Weizmann Institute of Science in Israel who has studied sugar substitutes, there is enough research on the topic to warrant further study. In the meantime, “the jury is still out” on whether they are dangerous, he added, or whether some sugar substitutes are safer than others.
On the other hand, too much sugar is undeniably bad for your health, Dr. Elinav said, with research linking it to increased risks of type 2 diabetes, heart disease and obesity. The American Heart Association recommends that women consume no more than 25 grams of sugar per day and men no more than 36 grams per day. A 12-ounce can of Coca-Cola contains 39 grams of sugar.
Given these known dangers, it’s best to choose artificially sweetened beverages like diet soda over regular drinks if you drink them every day, Dr. Mozaffarian said. But, he added, the goal is to minimize your consumption of both products over the long term.
Dr. Vadiveloo agrees and suggests ways to gradually reduce added sugars and sugar substitutes in your diet.
To cut down on regular or diet soda, you can try sweetened sparkling water with a small amount of fruit juice, she suggested; or instead of buying sweetened yogurt, try topping plain yogurt with fruit and a little honey.
A few years ago, Dr. Vadiveloo took her coffee with Splenda, but she gradually reduced the amount she used. “Now I take my coffee with milk, and I don’t miss the sweetness,” she says.