September 23, 2013
Your Brain Knows The Difference Between Real Sugar And Substitutes
Brett Smith for redOrbit.com - Your Universe Online
While your tongue may be fooled into mistaking an artificial sweetener for real sugar, your brain knows the difference, according to new research published in The Journal of Physiology.The difference is how each sweetener affects the brain’s reward center, and sugar has been found to provide a bigger reward than artificial substitutes.
"The consumption of high-calorie beverages is a major contributor to weight gain and obesity, even after the introduction of artificial sweeteners to the market,” said Ivan de Araujo, who led the study at Yale University School of Medicine. “We believe that the discovery is important because it shows how physiological states may impact on our choices between sugars and sweeteners.”
"Specifically, it implies that humans frequently ingesting low-calorie sweet products in a state of hunger or exhaustion may be more likely to 'relapse' and choose high calorie alternatives in the future,” he added.
In the study, researchers looked at a particular brain signal that is necessary for determining the selection between sugars and sweeteners. This signal modulates dopamine levels – part of the brain’s reward pathway – and only occurs when sugar is metabolized into a form usable as cellular fuel.
The scientists put laboratory mice through a combination of behavioral tests involving various sweeteners and sugars while monitoring chemical responses in their brains for reward signaling. The team said their findings regarding the signaling response differences are likely to be found in humans as well.
"According to the data, when we apply substances that interfere with a critical step of the 'sugar-to-energy pathway', the interest of the animals in consuming artificial sweetener decreases significantly, along with important reductions in brain dopamine levels,” de Araujo said.
"This is verified by the fact that when hungry mice – who thus have low sugar levels – are given a choice between artificial sweeteners and sugars, they are more likely to completely switch their preferences towards sugars even if the artificial sweetener is much sweeter than the sugar solution,” he added.
"The results suggest that a 'happy medium' could be a solution; combining sweeteners with minimal amounts of sugar so that energy metabolism doesn't drop, while caloric intake is kept to a minimum,” de Araujo concluded.
Dietary impact aside, some people say they simply prefer the taste of artificially-sweetened, or diet, soda to sugar-sweetened soda and a new study published last week in the journal Gastroenterology found that carbonation can play a role in masking the distinct flavors of each type.
“The presence of carbonation produced an overall decrease in the neural processing of sweetness-related signals, especially from sucrose,” the study authors wrote. “CO2 reduced the neural processing of sucrose more than that of artificial sweeteners. These findings might be relevant to dietary interventions that include non-caloric beverages, whereas the combination of CO2 and sucrose might increase consumption of 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 study author Rosario Cuomo, an associate professor in the department of clinical medicine and surgery at Federico II University in Naples, Italy.
“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.”