Debate on sweetener safety and health effects continues with new research on weight loss support

27 Mar 2024 --- New research presented at the upcoming European Congress on Obesity (ECO 2024) on May 12–15 suggests that replacing sugar-sweetened F&B with low- or no-calorie-sweetened products can support weight management for at least one year after fast weight loss in adults. Meanwhile, experts question whether its outcomes are sufficient to confirm or disprove earlier research on the safety of low or no-calorie sweeteners and their effects on weight management.

The researchers conducted a year-long randomized controlled trial with overweight adults and children and adults with obesity. The new study also finds that consuming sweeteners and sweetener enhancers is linked to greater diet satisfaction, more positive mood, fewer cravings and a less explicit liking for sweet foods in adults. 

“Weight maintenance after weight loss is difficult to achieve, and our findings support the use of sweeteners and sweetener enhancers found in many foods and beverages worldwide as alternatives to sugar-sweetened products to help manage weight control in adults with overweight,” says trial lead author professor Anne Raben from the University of Copenhagen, Denmark. 

“The findings also provide important information to address potential adverse health effects controversies. Until now, safety data have generally come from animal studies using sweetener doses far above the usual human intake.” 

Study setup 
According to information shared by ECO 2024, researchers from the SWEET project — Sweeteners and sweetness enhancers: Prolonged effects on health, obesity and safety — recruited 341 adults with overweight or obesity and 38 overweight children for the trial. 

In the first two months, adults followed a low-energy diet to lose at least 5% of body weight, while children received advice to maintain their weight. In the next ten months, participants followed a healthy diet with less than 10% of energy from added sugar, with one group allowing for foods and drinks with sweeteners (the sweetener group), while the second group did not eat such products (the sugar group). 

The complete research results will be shared at the European Congress on Obesity in Venice, Italy (May 12–15).Commenting on this project design, Kevin McConway, emeritus professor of applied statistics at Open University, UK, asserts: “The results will say something directly only about maintaining weight loss, after quite rapid weight loss. What, if anything, this says about the use of non-sugar sweeteners for weight reduction in the first place isn’t clear.” 

He adds that since this scenario is unlike what happened in most of the studies reviewed by WHO, these new findings might add to what the WHO concluded but will likely not supersede it. 

The intake of sugar-rich F&B declined in both trial groups but significantly more in the sweetener group. Participants in this group who had lost 5% of their body weight at the program’s start were better able to maintain their weight loss. 

Adult participants in the sweetener group also had greater diet satisfaction when eating out, increased positive mood and lower craving for sweet food at six months than the sugar group. However, adults in the sugar group preferred sweet over savory foods at the six and twelve-month measurement points. The researchers found differences between the groups in reported physical activity or quality of life.

Replacing sugar-sweetened food and drinks with products containing low or no-calorie sweeteners did not impact eating behavior or physical activity for the participating children. However, the sweeteners did benefit kids with high levels of uncontrolled eating. 

Supporting sweetener safety? 
Last year, the WHO advised against non-sugar sweeteners for weight control based on a review of observational studies. At the same time, the WHO and FAO Joint Expert Committee on Food Additives (JECFA) confirmed the current acceptable daily intake level of aspartame. JECFA has called for additional research on the sweetener as it found limitations in the evidence of its impact on cancer and other health effects. 

After reviewing well-designed randomized controlled trials, US-based researchers concluded that low- and no-calorie sweeteners are safe and play a critical role in healthier eating habits because they reduce sugar and calorie intake. 

“The use of low-calorie sweeteners in weight management has been questioned, partly because of the link between their use and apparent weight gain in observational studies. However, it is becoming increasingly apparent that this is not the case in long-term studies,” says professor Jason Halford, one of the Sweet co-authors and president of the European Association for the Study of Obesity. 

Although the upcoming study results seem promising, McConway questions whether its results and trial length are sufficient to confirm or disprove the WHO’s findings. 

“The actual scenario it investigated is different from most of those reviewed by WHO, and what we know from the new trial about differences in disease risk isn’t very clear (and is barely discussed in the information we have so far). We might know more after the full results are published, but now, it’s too soon.”

Debate and research on the safety and health benefits of consuming low- or no-calorie sweeteners continues.Meanwhile, new research published in Circulation: Arrhythmia and Electrophysiology linked consumption of at least two liters of sugar-sweetened or artificially sweetened beverages weekly with a 20% higher risk of atrial fibrillation — an irregular and rapid heart rhythm — when adjusting to multiple variables. This association persisted after adjusting for genetic susceptibility to the condition. 

This study included 201,856 participants, with an average 9.9-year follow-up. 

Study limitations 
McConway notes that the negative associations found by the WHO were only found in observational studies after differences in sweetener use had gone on for some considerable time. He questions whether the length of the new trial to be shared at the European Congress on Obesity in Venice, Italy, was sufficient for associations with disease risk to show up. 

Moreover, he asserts that outcomes of safety testing used in the trial (impact on the gut microbiome) are not shared in the available abstract. At the same time, the risk markers for type 2 diabetes and cardiovascular disease did not differ between participants consuming non-sugar sweeteners and those who did not. 

The researchers note that the drop-out rate was more significant than estimated, as only 203 out of 341 initial participants completed the trial. 

“That might or might not be concerning,” comments McConway. “Details on why and when people dropped out might tell us something about how acceptable the different diets were, or whether some features of the intervention caused problems for some participants.”

Finally, the children’s results should be interpreted with caution as the trial involved a small number of participants. 

By Jolanda van Hal