January 3, 2017

expert reaction to commentary on diet drinks, sugary drinks and body weight

In a new review published in PLOS Medicine, the authors argue that sugar-free versions of drinks may be no better for weight loss or preventing weight gain than their full sugar counterparts, and they suggest artificially sweetened beverages should not be promoted as part of a healthy diet.

Prof. Naveed Sattar, Professor of Metabolic Medicine, University of Glasgow, said:

“I do not agree with the suggestion that diet drinks are no better than sugary drinks in terms of body weight.  Whilst I agree the evidence base in terms of proper trials comparing sugary drinks with diet drinks are lacking for real end-points like weight or heart disease, intuitively a drink which contains lots of calories (i.e. sugary drinks) versus one that contains few or no calories (i.e. diet drinks) must be worse for health given clear adverse effects on dental health and clear gain of calories and so weight gain potential.  To suggest otherwise would be irresponsible.

“As a practising physician, I would much rather my patients were able to take diet drinks than sugary drinks, but of course best of all would be water.  I do, however, agree that more robust trials in this area should be funded as otherwise we will always come back to these debates which simply cause confusion.”

Prof. Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London, said:

“This article is an opinion piece rather than a systematic review of the evidence.  It refutes a previously published systematic review that showed modest weight loss when full sugar drinks were replaced with artificially sweetened beverages because that review was industry funded, not on the basis of the scientific methods used.

“The authors also highlight that obesity and type 2 diabetes have been linked in observational studies with higher intakes of artificially sweetened beverages.  This does not prove causality as the authors admit.  The problem with drawing conclusions from observational studies is that the overweight or obese are more likely to buy low calorie beverages because they have been advised to do so for decades.  Although the effect of sugar replacement with artificial sweeteners on weight loss may be equivocal, when sugar is covertly replaced by artificial sweeteners in double blind studies there is clearly a benefit in terms of reducing weight gain.  There is no evidence to show that artificial sweeteners cause weight gain as the authors imply.

“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.”

Prof. Susan Jebb, Professor of Diet and Population Health, University of Oxford, said:

“This narrative review draws together a variety of evidence relating to artificially sweetened beverages (ASB).  It reasonably concludes that the evidence that they are specifically beneficial in controlling obesity is limited.  But it does not consider their use as a ‘harm reduction’ strategy – that is, whether or not they confer a specific benefit, there is evidence that they are better for health than a sugary alternative.  Sugar is a major risk factor for obesity, diabetes and dental caries.  As the authors show, the randomised controlled trials which are the best test of the effects of sugary drinks versus artificially sweetened drinks, either find no difference in weight or weight reductions for the group consuming artificially sweetened drinks.  Thus they provide no good evidence of health harms and some evidence of benefits when artificially sweetened drinks replace sugary alternatives.

“The article also considers the environmental impact of artificially sweetened drinks.  Since these products have no nutritional content it is not unreasonable to conclude that the inevitable environmental impact caused by the production, distribution and consumption of these products is unnecessary.  More research is needed on this aspect but it also needs to be put in the context of the environmental impact of the sugary alternative and other aspects of food production.  Focussing on artificially sweetened drinks risks detracting from the much more significant concerns relating to livestock in particular.

“For people seeking to manage their weight tap water is without question the best drink to choose, for health and the environment, but for many people who are used to drinking sugary drinks this will be too hard a change to make.  Artificially sweetened drinks are a step in the right direction to cut calories.”

* ‘Artificially sweetened beverages and the response to the global obesity crisis’ by Maria Carolina Borges et al. published in PLOS Medicine at 19:00 UK time on Tuesday 3 January 2017. 

Declared interests
Prof. Naveed Sattar: “No conflicts of interest.”

Prof. Tom Sanders: “Prof Tom Sanders is a Scientific Governor of the charity British Nutrition Foundation, member of the scientific advisory committee of the Natural Hydration Council (which promotes the drinking of water), and honorary Nutritional Director of the charity HEART UK. He is now emeritus but when he was doing research at King’s College London, the following applied:

Tom does not hold any grants or have any consultancies with companies involved in the production or marketing of sugar-sweetened drinks. In reference to previous funding to Tom’s institution: £4.5 million was donated to King’s College London by Tate & Lyle in 2006; this funding finished in 2011. This money was given to the College and was in recognition of the discovery of the artificial sweetener sucralose by Prof Hough at the Queen Elizabeth College (QEC), which merged with King’s College London. The Tate & Lyle grant paid for the Clinical Research Centre at St Thomas’ that is run by the Guy’s & St Thomas’ Trust, it was not used to fund research on sugar. Tate & Lyle sold their sugar interests to American Sugar so the brand Tate & Lyle still exists but it is no longer linked to the company Tate & Lyle PLC, which gave the money to King’s College London in 2006.

Tom also used to work for Ajinomoto on aspartame about 8 years ago.

Tom was a member of the FAO/WHO Joint Expert Committee that recommended that trans fatty acids be removed from the human food chain. Tom has previously acted as a member of the Global Dairy Platform Scientific Advisory Panel and Tom is a member of the Programme Advisory Committee of the Malaysian Palm Oil Board. In the past Tom has acted as a consultant to Archer Daniel Midland Company and received honoraria for meetings sponsored by Unilever PLC. Tom’s research on fats was funded by Public Health England/Food Standards Agency.”

Prof. Susan Jebb: “Prof Susan Jebb is employed by the University of Oxford and receives no personal funding from the food industry.  Susan Jebb is conducting research into the treatment of obesity, some of which include support from WeightWatchers, Slimming World and the Cambridge Weight Plan.  Susan was the independent Chair of the Public Health Responsibility Deal Food Network and was a science advisor to the Foresight obesity report. From 2007-10 she was the principal investigator for a research study funded by the food industry to investigate the potential for a functional beverage to help weight loss. The results of this work have been published: http://www.ncbi.nlm.nih.gov/pubmed/23920353.”