The commentary piece highlighted a lack of evidence linking these drinks in preventing weight gain and could not recommended their consumption as part of a healthy diet.
Industry responded by calling the results 'unhelpful' at a time of rising rates of obesity.
Although there was no direct evidence for a role of ASBs in weight gain, there was concern over the drinks’ ability to stimulate sweet taste receptors.
Together with consumer knowledge of the drink’s low-calorie content, overconsumption of other food was likely thus contributing to obesity and type 2 diabetes.
Sugar reduction
The introduction of a sugar levy in countries such as the France and the UK has shifted the emphasis onto ASBs as one way of escaping the charge.
ASBs are not taxed or regulated to the same extent as sugar-sweetened beverages (SSB) possibly due to their perceived harmlessness, said the researchers.
This perception plays a big part in ASB sales, which account for approximately one-quarter of the soft drink market globally.
Investments in expanding drinks portfolios and shifting production to these products have become central in order to maintain this momentum.
Drinks giant Coca Cola already have its Diet Coke and Coca-Cola Zero versions available as have PepsiCo with its sugar-free Pepsi MAX brand.
From July of this year, Lucozade Ribena Suntory are to reformulate its drinks to contain less than 4.5g of total sugar per 100ml.
“A common perception, which may be influenced by industry marketing, is that because ‘diet’ drinks have no sugar, they must be healthier and aid weight loss when used as a substitute for full sugar versions,” said Professor Christopher Millett, senior investigator from Imperial’s School of Public Health,
“However we found no solid evidence to support this.”
Industry influence
The commentary, which also included researchers from the University of Sao Paulo and Federal University of Pelotas, went further by highlighting the influence the drinks’ industry had in collating and assessing evidence.
“The lack of solid evidence on the health effects of ASBs and the potential influence of bias from industry-funded studies should be taken seriously when discussing whether ASBs are adequate alternatives to SSBs,” said Dr Maria Carolina Borges, first author of the study from the Federal University of Pelotas.
Reaction: 'Extremely unhelpful'; 'unwarranted'
The British Soft Drinks Association director general, Gavin Partington, criticised the commentary piece saying that contrary to the claims made in the article scientific research showed that low calorie sweeteners, such as those found in diet drinks, helped consumers manage their weight as part of a calorie controlled diet.
“At a time when we are trying to encourage people to reduce their overall calorie intake it is extremely unhelpful that products which contain no sugar, let alone calories, are demonised without evidence.”
“It’s worth bearing in mind that the UK soft drinks sector is the only category in which sugar intake is consistently falling year on year – over 17% since 2012.”
Professor Tom Sanders, professor emeritus of Nutrition and Dietetics, King’s College London, commented that: “The conclusion that reduced sugar or sugar-free drinks should not be promoted or seen as part of a healthy diet seems unwarranted and likely to add to public confusion.”
After publication, the International Sweeteners Association (ISA) pointed to a 2016 review and meta-analysis that concluded the use of low calorie sweeteners could help reduce energy intake and thus could be helpful in weight loss.
The organisation also responded to the allegations that industry-sponsored research was more likely to report favourable results about diet drinks' influence on weight control. ISA reiterated previous comments made in reference to another 2016 study that also investigated this relationship.
Commenting on this study by Daniele Mandrioli et al, Professor Carlo La Vecchia, epidemiologist at the University of Milan, said: “The conclusions in the systematic review by Mandrioli et al raise concerns since they are based on a subjective evaluation of a few reviews that were classified as “favourable” or “unfavourable” on the basis of a questionable algorithm.”
"ISA strongly believes that the food industry support in research can contribute the most to advancing scientific evidence in nutrition science," added the organisation in a statement.
"We fully support a transparent relationship between scientists and industry funding and actively encourage full disclosure of all conflicts of interest."
Source: PLOS Medicine
Published online ahead of print: DOI:10.1371/journal.pmed.1002195
“Artificially Sweetened Beverages and the Response to the Global Obesity Crisis.”
Authors: Maria Carolina Borges et al