The recommendation comes after the introduction of the sugar tax on soft drinks in the UK, in which manufacturers are incentivised to reduce the sugar content of their beverages.
Under the Soft Drinks Industry Levy, sugar replacements such as stevia, aspartame and sucralose - which are cited in the WHO guidance - are not included, meaning manufacturers can reformulate their drinks with these sweeteners to avoid the levy.
Tax prevents obesity
A study published in the journal PLOS Medicine earlier this year suggested the tax may have prevented more than 5000 young British girls from becoming obese.
Researchers from the University of Cambridge found that the introduction of the levy in 2018 coincided with an 8 per cent fall in obesity levels among Year Six girls (aged 10-11). However, there was no significant link between the levy and obesity levels for Year Six boys.
Commenting on the new guidelines, Francesco Branca, WHO director for nutrition and food safety, said: “Replacing free sugars with NSS does not help with weight control in the long term. People need to consider other ways to reduce free sugars intake, such as consuming food with naturally occurring sugars, like fruit, or unsweetened food and beverages.
“NSS are not essential dietary factors and have no nutritional value. People should reduce the sweetness of the diet altogether, starting early in life, to improve their health.”
The recommendations apply to all people, except those with pre-existing diabetes.
Further research needed
The WHO review also says that further research is needed on the effects on children and pregnant women, with the latter possibly experiencing “unfavourable effects” after consuming sweeteners in relation to their babies’ birth weight.
Artificial sweeteners are deemed safe, but are not recommended as a simple swap for sugars in most dietary guidelines, experts say, including from the British Dietetic Association (BDA).
Dr Duane Mellor, registered dietitian and senior lecturer at Aston University, said the WHO report focused heavily on observational studies which can only show an association between artificial sweeteners and health outcomes, rather than clinical trials which are better at showing causal links.
“In the case of sweeteners, a number of trials have shown that they can help with weight control, whereas observational studies may not show an association between sweeteners and weight control,” Mellor said.
“The reason observational studies do not suggest a benefit from switching to sweeteners could be that people who are trying to lose weight may choose sweeteners so from only observing it might look like those who use sweeteners tend to be overweight – something called reverse causality.
“However, overall this report highlights that universal replacement of sugar with sweeteners is not necessarily ideal, as this alone is unlikely to improve diet quality and produce the necessary changes to control weight long term.”
Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London, said randomised controlled trials have shown that when sugar-sweetened drinks are replaced with artificially sweetened ones, they do prevent unhealthy weight gain in children.
“In my opinion this advice, which is based mainly on a null effect of artificial sweeteners on weight gain, is likely to cause a lot of confusion in the public health arena because the sugar levy in the UK has drinks manufacturers replacing some or all of the sugar with artificial sweeteners,” he said.
