HOW DO WE SOLVE THE SOFT DRINK PROBLEM?

I’ve just had the privilege of attending a meeting of the International Carbohydrate Quality Consortium in Kalamata Greece (lucky me!). This small group of experts is chaired by Walter Willett, Professor of Epidemiology and Nutrition at the Harvard School of Public Health, and Professor David Jenkins of the University of Toronto, who was one of the scientists responsible for conceiving the glycemic index. The Consortium is co-funded by the Nutrition Foundation of Italy, Toronto 3D Knowledge Synthesis and Clinical Trials Foundation and members of the food industry who have a keen interest in the latest research on carbohydrates and alternative sweeteners.

The second day focussed on sugars, polyols (sugar alcohols) and intense sweeteners. An enormous amount of effort is going into finding substitutes for added sugars and making sure that there are no unintended health consequences.

There are still some concerns about the long-term effects of intense sweeteners on health. A small, poorly designed study published in 2014 in Nature, with only 7 human participants, suggested that some intense sweeteners change the microbiome; while the findings have not been replicated by other researchers since, they have stuck in the minds of many. There are also many experts (including me!) that question their effectiveness for long-term weight management, the reason that most people consume them in the first place. Is there evidence that they are helpful?

Yes, according to the SWEET study published this month in Nature Metabolism. Michelle Pang, Anne Raben and colleagues recruited 341 adults with a Body Mass Index (BMI) over 25 kg/m2, and randomised them to consume either intensely sweetened products or avoid them entirely for 12 months. In the first 8 weeks, all participants consumed a low energy (Calorie/kilojoule) diet using total meal replacement products (e.g., Cambridge or Optifast) in order to lose substantial weight. On average they lost 10% of their body weight but the challenge was to maintain the weight loss over the coming 10 months. While most regained some weight, half the subjects were able to maintain 5% or more weight loss, more so if they had been in the group permitted to consume diet/no-sugar soft drinks. Their faecal flora also showed changes that were interpreted as helpful. Thus, intensely sweetened products are useful, at least for 12 months.

According to new meta-analyses presented at the meeting by Walter Willett there are no ill-effects of intense sweeteners in the three large prospective cohorts of North Americans that have been followed for more than 20 years. In contrast, there are increased relative risks of type 2 diabetes, obesity, cancer, cardiovascular disease and other chronic diseases associated with sugar sweetened beverages (SSBs). Interestingly, there appear to be no associations with solid sources of added or free sugars, such as lollies, candies, chocolate, cakes and cookies. This is an important and welcome finding! It begs the question of why sugars in the form of SSBs are unique in their ability to do harm?

In discussions at the meeting, we agreed that a typical serve (355 mL or 12 Fl Ounces) of full-strength (i.e., ~10% sugars) SSB delivers a large (average GL=29 (High)) and rapid blood glucose spike (average GI=75 (High)) that likely overwhelms the capacity of the body to cope. This large glucose hit could well damage the sensitive beta-cells of the pancreas responsible for insulin production. Afterall, it’s their job to monitor glucose levels. The end result of regular, frequent consumption of SSBs might be beta-cell damage, insulin resistance and hyperglycaemia after any source of available carbohydrate (as most are converted to glucose in the body). And insulin resistance makes weight gain easier.

Professor John Sievenpiper’s group also plans new analyses on what types of foods are replacing SSBs in the diet. For example, are we eating more starch that is highly gelatinised, causing another high glycemic spike? Assistant Professor Laura Chiavaroli showed that many reduced-sugar breakfast cereals have a higher GI than the sugar-containing cereal that they are designed to replace. The energy content is exactly the same as well as the micronutrient content. Children likely add honey or sugar to improve their taste, increasing overall energy intake. Only time will tell.

Around the world, many soft drink companies have re-formulated some of their soft drinks to reduce their sugar content, e.g. Schweppes flavoured mineral waters have about 5-6% sugars, half that of regular soft drinks. These changes have had real world benefits. For example, according to the findings of the most recent Australian National Nutrition and Physical Activity Survey (NNPAS 2023) published in September 2025, around 20% of Australians are drinking sugar-sweetened beverages on any given day and only 1 in 10 consume intensely (“artificially”) sweetened versions (see the figure, below). Australians are now meeting the guidelines of the World Health Organisation (WHO) for free sugars (<10% of energy) although they (WHO) do not currently recommend the use of non-sugar sweeteners as replacements.

But it’s not just their sugar content that may be a problem: SSBs are “empty calories” and make no contribution to micronutrient or phytonutrient intake. There is nothing in them to quench the oxidative stress caused by a high glycemic spike. In the coming year, my laboratory is planning to undertake studies to see if adding vitamin C and other antioxidants (e.g. those that occur naturally in fruit) might help reduce inflammatory responses that accompany glucose responses.

In the meantime, if you enjoy a regular soft drink, please drink slowly and in moderation, preferably with a meal. In my mind, they are safer than a beer or wine or a gin and tonic, especially for those in their reproductive years.

Read more:

1. International Carbohydrate Quality Consortium
2. Nutrition Foundation of Italy
3. Toronto 3D Knowledge Synthesis and Clinical Trials Foundation
4. Suez and Colleagues. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. 2014
5. Pang and colleagues. Effect of sweeteners and sweetness enhancers on weight management and gut microbiota composition in individuals with overweight or obesity: the SWEET study. Nature Metabolism, 2025.
6. Australian Bureau of Statistics. National Nutrition and Physical Activity Survey: Food and Nutrients. 2025.

Emeritus professor Jennie Brand-Miller held a Personal Chair in Human Nutrition in the Charles Perkins Centre and the School of Life and Environmental Sciences, at the University of Sydney until she retired in December 2022. She is recognised around the world for her work on carbohydrates and the glycemic index (or GI) of foods, with over 300 scientific publications. Her books about the glycemic index have been bestsellers and made the GI a household word.