Caffeine in sugar-sweetened soft drinks may do more than provide a mild stimulant effect and may play a role in encouraging us to drink more sweetened beverages.
A commentary article by researchers from Deakin University’s Centre for Advanced Food Sciences, in the School of Exercise and Nutrition Sciences, published today in Food Quality and Preference, argues that caffeine in cola-style sugar-sweetened beverages is not just a flavouring ingredient but a “silent amplifier” of preference and intake.
Gathering evidence from sensory science, product formulation, caffeine pharmacology and consumer behaviour, the authors argue that while caffeine is bitter in water it can be difficult to detect in cola-style drinks where sweetness, acidity, carbonation and flavourings mask its bitterness.
Professor Russell Keast, from Deakin University’s Centre for Advanced Food Sciences, said the usual concern about the harmful effects of too much caffeine are less an issue than how it behaves when combined with sugar in popular beverages.
‘Caffeine is often thought of as a flavour ingredient or pick-me-up, but in cola-style sugary drinks its role may be more subtle,’ Professor Keast said.
‘Consumers may not consciously taste the caffeine, but it can encourage them to choose that caffeinated drink again. It’s not necessarily about drinking more in one sitting – it is about making the caffeinated drink more likely to be the one they reach for next time.’
The authors highlight three key lines of evidence in their commentary article.
First, psychophysical studies suggest that caffeine at commercial concentrations is not reliably detected in cola-style beverages, despite being bitter and detectable when mixed with plain water.
Second, caffeine’s post-ingestive effects — including effects on alertness, mood and reward-related signalling — may become associated with the overall flavour of the drink. Over repeated exposures, this may strengthen liking, repeat choice and habitual intake.
Third, previous research has shown that caffeinated sugar-sweetened beverages may be associated with slightly higher sugar formulations and the effects of the caffeine will increase overall sugar intake in consumers.
Professor Lynn Riddell, from Deakin University’s Faculty of Health, said the public health importance lies in the combination of caffeine, sugar and repeated consumption.
‘Sugary drinks are already a major source of added sugar in the diet,’ Professor Riddell said.
‘This commentary highlights that caffeine may increase sugar exposure in two ways: by supporting slightly sweeter formulations and by encouraging people to choose caffeinated sugary drinks over other beverage options.’
The authors say the findings have implications for beverage reformulation, nutrition labelling and dietary advice.
For product developers, the commentary suggests removing caffeine from cola-style drinks may allow sugar levels to be reduced without compromising flavour. But, if caffeine is retained in reduced-sugar products, researchers and industry should examine not only immediate taste enjoyment, but repeat use, consumption volume, substitution with other beverages and total energy intake over time.
The commentary also calls for more research into energy drinks, where caffeine is often present at higher concentrations and may be more perceptible as bitterness.
Professor Keast said this raises an important question for sensory and consumer science.
‘Energy drinks are a logical next step because caffeine is not invisible as it is in cola-style beverages,’ Professor Keast said.
‘The question is whether caffeine still mainly acts through reinforcement, or whether its bitterness becomes part of the learned sensory profile of the product. Coffee shows us that people can learn to like bitter caffeinated products, so energy drinks deserve closer attention.’
Professor Riddell said the research also reinforces the need for clear communication with consumers.
‘Consumers deserve to understand not just how much sugar is in a drink, but how other ingredients may be influencing their preference and intake,’ Professor Riddell said.
‘Caffeine labelling and dietary guidance should recognise that caffeine can be having an affect even when its taste is not obvious.’
The authors emphasise that the commentary does not argue that caffeine is harmful at typical beverage doses. Instead, it focuses on how caffeine may interact with sugar, sensory masking and learned behaviour to shape beverage choice over time.
About the article
Title: Caffeine in Sugar-Sweetened Beverages: A Silent Amplifier of Preference and Intake
Article type: Commentary
Journal: Food Quality and Preference
Authors: Dhoungsiri Sayompark, Lynn Riddell, Uracha Wanich, Erminio Monteleone, Penny Thew and Russell S. J. Keast
Media contact:
Pauline Braniff
Lead, Communications
Deakin University Media and Corporate Affairs
M: 0418 361 890
E: pauline.braniff@deakin.edu.au
www.deakin.edu.au
