Most of us have experienced food cravings at some point, especially for unhealthy foods that are filled with fats and sugars. While the general assumption is that we crave such foods over their healthier alternatives because of the way they taste, new research is showing it could be because of our gut’s neural link.
Researchers at Columbia’s Zuckerman Institute found that the gut may play an outsized role in cravings for fatty foods. Their findings, recently published in Nature, could drive further research into the gut’s connection to food preferences and possibly lead to novel ways of fighting overeating, obesity and metabolic disorders.
“To control our insatiable desire for fat, science is showing us that the key conduit driving these cravings is a connection between the gut and the brain,” the paper’s lead author Mengtong Li, a postdoctoral researcher at the Zuckerman Institute’s Charles Zucker Lab said in a statement.
Li’s team identified a gut-brain circuit — and not taste — to be responsible for fat cravings in mice. They did this by offering the mice water containing some dissolved fats and observed over a couple of days that the mice had a strong preference for the water-containing fats.
Previous research from the lab had shown that while the tongue told the brain what it likes to eat, the gut was telling the brain what it wants.
To eliminate the role of taste in food preference in the latest experiment, the researchers genetically modified the mice to lose the ability to taste. When the experiment was repeated, the mice were still found to prefer the water that had the fat dissolved in it even though they could not taste the water laced with fat.
“Even though the animals could not taste fat, they were nevertheless driven to consume it,” said Dr Zuker, who is a professor of biochemistry, molecular biophysics and neuroscience at Columbia’s Vagelos College of Physicians and Surgeons.
The researchers also found a specific region in the brain that was activated driving the animal to prefer fat. They did this by measuring the brain activity of the rodents while they were feeding on fat.
Neurons in a specific brain region were activated after receiving signals from cells in the gut that sensed fat in the intestine. These results were interesting since this same brain region was implicated in sugar preference in a previous study the lab had conducted.
When they blocked the signals from these gut cells, the researchers observed that the mice lost their appetite for fat.
“The overconsumption of cheap, highly processed foods rich in sugar and fat is having a devastating impact on human health. The better understanding, we have of how food hijacks the biological machinery underlying taste and the brain-gut axis, the more opportunity we will have to intervene,” Dr Zuker said.
While a lot more research is required, including in larger animals and humans, to establish the efficacy of these newly discovered pathways, the research raises several questions as to how disorders such as obesity and diabetes are caused.
“It could even open the door to novel treatments for such disorders that the world is currently grappling with,” said Dr Scott Sternson, a professor of neuroscience at the University of California, San Diego who works extensively on how the brain controls appetite. He was not a part of the research team at Zucker Lab.
“The capability of researchers to control this desire may eventually lead to treatments that may help combat obesity by reducing consumption of high-calorie fatty foods.” Dr Sternson said in the statement.