It’s not uncommon for people to crave sweet foods. After all, sugar is what our bodies use for fuel. New research suggests that a mechanism in the brain might compel us to seek out foods high in glucose, and that finding could lead to better ways of treating obesity.
Glucose is a component of carbohydrates and is used in cells throughout the body, and it is the main energy source of energy used by brain cells.
A group of researchers in the United Kingdom hypothesized that an enzyme called glucokinase might play some part in our desire for consuming glucose. The enzyme serves to sense glucose in the liver and pancreas, but it is also present in the hypothalamus, a part of the brain that regulates a variety of vital functions including food intake.
It’s long been theorized that glucose-rich foods would not have been as easily found in the past, leading to an innate mechanism to seek them out in preference to others. With that in mind, the researchers devised an experiment using rats, which, like humans, have been found to consume glucose in preference to other foods. The scientists found that when the animals haven’t eaten for 24 hours, the activity of glucokinase in a part of the hypothalamus that controls appetite increased significantly.
In the experiment, the rats were given access to both a glucose solution and their regular “chow” diet of food pellets. The researchers used a virus in one group to increase the activity of glucokinase in the hypothalamus, causing those rats to consume more glucose than chow. The scientist noted that when glucokinase activity was decreased, the rats consumed less glucose.
The results, the researchers say, suggest that there may be a mechanism in the hypothalamus that can detect how much glucose is reaching the brain, triggering a hunger for carbohydrates when animals it detects there isn’t enough present there.
The study is believed to be the first of its kind to identify a mechanism in the brain that responds to a specific nutrient, rather than to a shortfall in overall energy intake.
One implication is that the types of nutrients we consume could be at least as important as the number of calories we consume. This, in turn, might mean it is possible to cut down on cravings for glucose-rich foods and beverages by changes in diet. Because glucokinase levels vary from person to person, however, there may be no one-size-fits-all formula.
- Syed Hussain, Errol Richardson, Yue Ma, Christopher Holton, Ivan De Backer, Niki Buckley, Waljit Dhillo, Gavin Bewick, Shuai Zhang, David Carling, Steve Bloom, James Gardiner. Glucokinase activity in the arcuate nucleus regulates glucose intake. Journal of Clinical Investigation, 2014; DOI: 10.1172/JCI77172