Aspartame, xylitol and friends.
Text: Yvonne VahlensieckSugar substitutes offer sweetness with fewer or no calories. But how do they affect metabolism? Researchers in Basel are studying their effects on blood sugar, satiety and insulin. Questions remain about their long-term effects on health.
Key takeaways
- Sugar alternatives differ in their chemical structure and effects on the body, so each needs to be assessed individually.
- Studies in Basel show that xylitol and erythritol stimulate satiety signals, challenging the idea that only calorie-containing nutrients can do so.
- Many alternatives compare favorably with sugar, but the health effects of regular, long-term consumption remain uncertain.
Chocolate makes us happy because the sugar it contains triggers the release of chemical messengers that stimulate the brain’s reward center. It is therefore no wonder we so often crave sweet foods.
However, high sugar intake contributes to weight gain and increases the risk of conditions such as cardiovascular disease, diabetes, fatty liver disease and cancer. This is why the WHO recommends that adults consume no more than 12 teaspoons of sugar per day, and, if possible, only about six. This is the equivalent of 50 and 25 grams, respectively.
“Ideally, people would consume as little added or free sugar as possible,” says Bettina Wölnerhanssen, a physician and researcher at Basel University and St. Clara Research Ltd., St. Clara Hospital in Basel. This includes table sugar as well as sugars in honey, syrups and fruit juices, but not naturally occurring sugars in whole fruits or unsweetened dairy products.
Are sugar substitutes safe?
For those who do not want to give up sweet-tasting foods altogether, various sugar alternatives are available that provide fewer or no calories and have little or no effect on blood sugar levels. These include artificial sweeteners such as aspartame, which is around 200 times sweeter than sugar, as well as sugar alcohols such as xylitol and erythritol, which also occur naturally in foods such as berries and vegetables. They have a similar sweetness to sugar.
Many sugar alternatives have a bad reputation. For example, they are thought to trigger food cravings and thereby promote weight gain. They are also said to cause abdominal discomfort or even increase cancer risk. However, some of these concerns are not supported by the available research or relate mainly to very high doses.
One example is aspartame, a sweetener used in many diet drinks. Although IARC, a WHO agency, classified it as “possibly carcinogenic to humans,” the actual risk depends strongly on the level of exposure. The European Food Safety Authority has established an acceptable daily intake (ADI) of 40 milligrams of aspartame per kilogram of body weight. An adult weighing 70 kilograms would therefore have to consume more than 14 cans, each containing 200 milligrams of aspartame, in one day to exceed the ADI. Similar levels have been established for other sweeteners, too.
Negative reports on harmful health effects are often based on an overinterpretation of study results, explains Anne Christin Meyer-Gerspach, a nutrition scientist and researcher at Basel University and St. Clara Research Ltd., St. Clara Hospital. “The findings often come from animal studies and have not been confirmed in controlled human intervention studies.”
Although there is currently no reason to class sweeteners as unsafe if consumed in normal quantities, some questions remain unanswered: “Each sugar alternative has a distinct chemical structure and therefore affects the body differently,” says Meyer-Gerspach. There is still very little data available for some of the newer substances.
The two researchers have managed to fill in some of these gaps over the last few years. In their studies, participants were given defined quantities of sugar alternatives or sugar. The team then measured and compared their effects on metabolic processes, such as satiety signaling or insulin secretion.
How xylitol and erythritol affect satiety
In recent years, the researchers have focused on xylitol and erythritol, sugar alcohols that have shown interesting properties in several metabolic studies. Like sugar, for example, they trigger the release of chemical messengers that stimulate the brain’s satiety center. “This challenges the common hypothesis that only energy-containing nutrients can trigger satiety-related signals,” says Meyer-Gerspach. A similarly strong satiety-related response has not yet been observed with artificial sweeteners.
Erythritol in particular has also proved to be well tolerated even at high doses, at least in a limited number of participants. However, larger quantities of sugar alcohols can have a laxative effect in some people.
Sugar vs. erythritol: Effects on adolescent metabolism
In a recent study that is yet to be published, the researchers investigated whether erythritol is also a suitable sugar substitute for adolescents. For five weeks, the participants consumed either 25 grams of sugar or 36 grams of erythritol per day, in addition to their normal diet. The higher erythritol dose accounted for its slightly lower sweetness.
“Even after such a short period, the group receiving sugar showed adverse changes in certain metabolic markers,” reports Wölnerhanssen. For example, fasting insulin levels increased significantly. In the long term, such effects could increase the risk of diabetes. This increase in insulin was not observed in the erythritol group. Participants in this group also consumed fewer calories overall during the study. The researchers interpret this as a sign that erythritol satisfies cravings for sweet foods.
“The results illustrate that adolescent metabolism is particularly sensitive to sugar,” says Wölnerhanssen. She therefore advises teenagers to reduce their sugar consumption in line with the WHO’s recommendation.
On balance, many sugar alternatives perform well in direct comparison with sugar. The researchers emphasize, however, that the health effects of regular, longer-term consumption may vary from substance to substance and have not yet been conclusively established. By contrast, the adverse health effects of sustained high sugar consumption have been demonstrated in numerous studies.
Bettina Wölnerhanssen is an adjunct professor and performs research at the Department of Clinical Research, University of Basel. She is co-head of the Metabolic and Gastroenterology Research Group at St. Clara Research Ltd., St. Clara Hospital.
Anne Christin Meyer-Gerspach holds an adjunct professorship at the University of Basel, is a research-group leader at the Department of Clinical Research and co-heads the Metabolic and Gastroenterology Research Group at St. Clara Research Ltd., St. Clara Hospital.
More articles in this issue of UNI NOVA (November 2026).