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In contrast to World Health Organization (WHO) guideline, a newly published report from the UK’s Scientific Advisory Committee on Nutrition (SACN) states that non-sugar sweeteners (NSS) may help adults lose a small amount of weight in the short term.

SACN released its updated guideline in early April in response to the WHO guideline, published in 2023, which offers a conditional recommendation against the use of NSS to control body weight or reduce the risk for noncommunicable diseases, such as type 2 diabetes.

The WHO guideline defines NSS as “all synthetic and naturally occurring or modified non-nutritive sweeteners that are not classified as sugars.” Common examples include aspartame, sucralose, saccharin, and stevia.

What’s the Evidence?

The WHO recommendation is based on evidence — all described in the guideline as being of low or very low certainty — from a systematic review of randomized controlled trials (RCTs) and from prospective observational studies.

While some RCTs found NSS use could result in weight loss and lower body mass index (BMI), the studies were very short (mostly ≤ 3 months), varied widely in design, and typically didn’t assess the effect of substituting sugar with NSS, the WHO guidelines noted.

By contrast, the observational studies, which had follow-up of up to 10 years, indicated that higher NSS intake was associated with higher BMI and obesity risk, along with increased risk for type 2 diabetes and cardiovascular risks, the guidelines state.

Overall, the WHO concluded that the small amount of weight loss from NSS in short-term experimental settings may not be relevant to their long-term use in the real world.

The conditional nature of the recommendation indicates that the organization is less certain that policies dissuading use of NSS for weight loss would benefit all populations, so policymakers in various countries should discuss the recommendation before deciding whether to adopt it.

SACN’s Take on the Issue

The SACN report knocks the WHO’s conditional recommendation for giving greater weight to the observational cohort studies than it gave to RCTs. In its recommendation, the committee does the opposite and gives greater weight to “good quality RCTs, where available because these minimize the potential for bias and confounding.”

Prospective cohort studies are observational in nature, so “it is not possible to say that consumption of sweeteners caused weight gain,” a UK Department of Health and Social Care spokesperson told Medscape Medical News. “WHO acknowledged that this finding was based on low to very low certainty of evidence. Data from randomized controlled trials suggest that when sweeteners replace sugar in the diet, energy intake is reduced, therefore preventing weight gain.”

Nevertheless, because the evidence on NSS and health outcomes is inconsistent, SACN recommends minimizing NSS intake “on a precautionary basis,” she added. The report noted there may be some value in using NSS for older children and adults “to help reduce weight gain in the short to medium term, but it is not essential and is not the only option.”

For younger children, the committee recommends not giving drinks sweetened with sugar or NSS and giving them unsweetened food.

For older children and adults, SACN states that swapping sugars for NSS may help reduce sugar intake from foods and drinks, at least in the short term, but that the long-term goal is to limit both sugar and NSS intake.

WHO did not respond to requests for a comment.

Expert Reactions

The SACN recommendation “is not very different from previous advice,” noted Oliver Jones, professor of chemistry, RMIT University, Melbourne, Australia, in an expert commentary included with the report. “The advice from nutrition bodies is to have a balanced diet and avoid taking in too much sugar — for example, fruit drinks such as orange juice often have the same level of acidity and sugar as soft drinks, so it is best not to drink too much of them.”

SACN recommends against using too many NSS because they can lead to confusion about calorie intake and because weight management is a multifaceted issue that needs to be looked at holistically, he added.

The paucity of evidence to base recommendations on is notable, Jules Griffin, director of the Rowett Institute, University of Aberdeen, Aberdeen, Scotland, said in his commentary.

“Despite the large consumption of NSS drinks by parts of the population, we don’t have conclusive evidence of benefits or drawbacks on some pretty fundamental outcomes, including tooth decay, weight gain, and type 2 diabetes, with studies showing opposite outcomes.”

An Update on Processed Foods

SACN simultaneously released an update on processed foods and health. The report concludes that the association between higher consumption of processed and ultra-processed foods and adverse health outcomes is “concerning.”

However, “limitations in the available evidence meant that it was unclear whether these foods are inherently unhealthy due to processing or because a large majority of them are high in energy (calories), saturated fat, salt and/or free sugars,” the advisory committee wrote.

Overall, commented Hilda Mulrooney, a senior academic in Nutrition and Health, London Metropolitan University, London, England, “SACN advice remains consistent; to meet healthy eating recommendations for nutrients such as fiber, the diet should contain more whole grains, fruit and vegetables.”

An estimated 51%-68% energy intake in the UK diet comes from ultra-processed foods, she noted. “Given that many of these are also high in fat, salt, and sugar, the advice remains that intakes of these foods should be reduced,” she added.

Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.