Health: what’s behind fat addiction? | science and technology

Sugar and fat are two ingredients that are almost always present in addictive foods. Soft drinks, juices, candies or chocolate bars are loaded with sugar. Fast food menus depend on our appetite for fat to make their products appealing. The taste of these foods is important… but according to a new study published in Nature, there is more to it. A signaling system exists in humans, facilitating communication between the brain and the gut. This may help explain the urgency behind one of humanity’s major health problems.

“These results support the idea that there are two sensory inputs going to the brain: one encodes what we like and the other what we want. These two inputs work together. First, with the tongue, you recognize what you like…but then the stomach tells you what it needs,” says Charles Zuker, a Howard Hughes Medical Institute researcher and professor at Columbia University.

This split could explain, according to a 2020 sugar study, why drinks with artificial sweeteners fail to match the appeal produced by those with real sugar. In this study – also published in Nature – it was observed that even in mice whose sense of taste had been suppressed, the preference for sugar-containing drinks over artificially sweetened drinks was maintained.

In the case of fat, the team led by Zuker tested the mechanisms that determine food preferences, by providing two types of substances (dissolved in water) to laboratory mice: one had fat, while the other, although artificially sweetened, was not oily. Within two days, the mice showed a clear preference for oily, greasy water, even when the researchers genetically engineered them so they couldn’t taste the fat on their tongues. This proved that the desires of the gut could, in fact, trump the tongue.

María del Mar Malagón, president of the Spanish Obesity Society and a professor at the University of Cordoba, calls the new research “amazing”. For her, the most interesting aspect is that “the researchers were able to delimit the brain area that is activated during the consumption of fat, [which] is responsible for the appetite or preference for fat.

The researchers also identified specific neurons that transmit stimuli produced by fat to the brain when it reaches the stomach, as well as another group of neurons that inform the brain of the presence of sugars. In a study led by Mengton Li of the Howard Hughes Medical Institute, once signaling pathways in mice were identified, scientists were able to block them with a drug, thereby reducing the desire for fat.

Zuker, who explains that his job is to “understand the fundamental biological mechanisms behind our preferences”, believes that this knowledge can be useful in combating an epidemic of diabetes and obesity, which is a huge health problem in the world. ‘today.

“If you understand the circuit, maybe you can start modifying it with molecules that control its activity,” he points out, acknowledging that his team has already been in contact with the food industry to propose alternatives. that meet the demand for fat in the diet. intestine without causing negative side effects.

“There are two groups of people who can benefit from these interventions. One is made up of those who have clinical problems: in their case, it would be possible to intervene with a compound that allows [the brain and the gut] start to dissociate,” notes Zuker. “The second group is made up of general consumers. With them, the logic would work like in artificial sweeteners, the difference being that not only the tongue would have to be satisfied, but also the gut-brain circuitry.

“Conceptually, there may be a way to maintain the craving for sugar or fat, but without the excess calories.”

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