We Are Wired For Sugar

Norbert, when your tongue is enjoying your mouthful of ice cream, another body part may be tasting that tasty treat. When you say 'taste' what you really mean is 'sense'. There may be a whole other pathway to the brain toggling our sugar switch and it's in our gut. Scientists working with mice, found that when sugar enters the intestines, it binds to receptors that send signals up the vagal nerve to an area of the brain stem called cNST. The vagal nerve connects the gut to the brain. And only glucose triggers the signal, not other forms of sugar such as fructose in fruit or even artificial sweeteners. So, it's not the sugary taste that triggers the gut to brain pathway but the actual glucose molecule that the brain responds to. This makes sense since glucose is the building block of life.

Scientists in this study found that mice given sugar water and artificially sweetened water had at first liked both but quickly only drank from the sugar water. Then, when they bypassed the tongue and injected sugar into mice guts, the pathway was again stimulated. This study affirms the importance of glucose because this gut to brain pathway only activates the glucose-signaling after it's been ingested and absorbed. It also makes sure that animals identify, develop, and reinforce a strong preference for glucose containing foods. That explains why sugar substitutes have neither satisfied sugar cravings nor lowered sugar intake in America. Maybe this work will lead to healthier ways to satisfy our sugar cravings.