An essential component of many soft drinks, carbonation, could affect the way we perceive the sweet tastes of such drinks – and could help to ‘disguise’ zero-calorie sweeteners as sugar.
Led by Dr Rosario Cuomo from "Federico II" University, Italy, the research team used functional magnetic resonance imaging (fMRI) to investigate the effects of carbonation on brain processing of sweet stimuli, which they suggest has relevance to studies of food selection and satiety.
They found that the presence of carbonation produced an overall decrease in the neural processing of sweetness-related signals in general, but noted that processing was especially reduced for sugars such as sucrose.
"This study proves that the right combination of carbonation and artificial sweeteners can leave the sweet taste of diet drinks indistinguishable from normal drinks," said Cuomo.
"Tricking the brain about the type of sweet could be advantageous to weight loss - it facilitates the consumption of low-calorie drinks because their taste is perceived as pleasant as the sugary, calorie-laden drink."
However, the team noted that there is also a downside to this effect; the combination of carbonation and sugar could stimulate increased sugar and food consumption since the brain perceives less sugar intake and energy balance is impaired.
Writing in Gastroenterology, the team investigated the interference between carbon dioxide (CO2) and the perception of sweetness, and the differential effects of CO2 on sucrose and artificial sweeteners (aspartame-acesulfame [As-Ac], a common combination used in diet beverages) by monitoring the changes in regional brain activity using fMRI.
“Our data suggest that CO2 modulates the perception of sweetness, reducing the global neural processing of sweetness,” said the authors – who noted that carbonation reduced processing of sucrose more than of As-Ac.
“The reduced discrimination between sucrose and As-Ac induced by CO2 would promote the consumption of low-calorie beverages and would converge with CO2-induced gastric distention in limiting caloric intake,” they said.
“This piece of information is of utmost importance for designing carbonated beverages and is relevant to the regulation of caloric intake.”
Published online ahead of print, doi: 10.1053/j.gastro.2013.05.041
“Effect of Carbonation on Brain Processing of Sweet Stimuli in Humans”
Authors: Francesco Di Salle, Elena Cantone, Maria Flavia Savarese, et al