Gut Brain Circuit Driving Sugar Cravings

Sugar triggers specialized taste buds on the tongue and switches on a neurological pathway that begins in the gut according to recent research from the Howard Hughes Medical Institute published in the journal Nature. It was already known that sugar exerts a unique control over the brain, this study discovered a sugar sensing pathway that may help to explain why sugar is special and points to ways in which we might tame that insatiable craving for sugar. 

Signals from the intestines herald the arrival of sugar to the brain, triggering an appetite for more according to mice investigations conducted in this study; and the gut to brain pathway appears to be picky as it responds to sugar molecules but not artificial sweeteners or those found naturally in fruits.

"We need to separate the concepts of sweet and sugar," says Zuker, a neuroscientist at Columbia University. "Sweet is liking, sugar is wanting. This new work reveals the neural basis for sugar preference."

Sugar activates the brain’s reward system to make us feel good, but in the modern world that is laden with refined sugar this deeply ingrained appetite can cause havoc. In America the average annual sugar intake has increased from less than 10 pounds in the 1800s to over 100 pounds in this modern super sized society. This drastic increase does not come without costs as studies have linked excess sugar consumption to numerous health issues including most notably obesity and type 2 diabetes. 

By visualizing brain activity when rodents consumed sugar the path to the cNSY was determined by the team to begin in the linings of the intestines where a sensor molecule sparks signals that travel via the vagus nerve which provides a direct line of information to the brain. 

This gut to brain pathway appears to favor glucose and similar molecules, and will ignore most sweeteners as well as fructose. The researchers are now conducting additional studies to examine the connections between the gut brain circuit and other brain systems such as those that are involved in reward, feeding and emotions. 

"Uncovering this circuit helps explain how sugar directly impacts our brain to drive consumption," he says. "It also exposes new potential targets and opportunities for strategies to help curtail our insatiable appetite for sugar."