Could the gut microbiota influence our cravings for food? In order to test this hypothesis, a team of scientists at the University of Pittsburgh began experiments with mouse models.
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To conduct the experiment, American researchers selected three different types of rodents with very different diets. They then gave three different types of microorganism cocktails to groups of mice that had no intestinal microorganisms.
According to the group of rodents, food preferences differed from each other. For example, some groups had a particular desire for foods rich in certain nutrients. ” Our work shows that animals with different compositions of intestinal microbes choose different types of diets said Kevin Kohl, a professor in the Department of Biology at the University of Pittsburgh and co-author of the study.
The gut: “the second brain”
These results came as no surprise to researchers! In fact, the brain and intestines are in constant communication to regulate certain actions. For example, to send us a signal of hunger or satiety, or to indicate the need for certain nutrients. This communication takes place through certain molecules. The microorganisms present in our body can also intervene in the messages exchanged between the brain and the intestine.
In addition, researchers have found that certain molecules that already exist in our body, and that differ depending on the body, can also influence our eating behavior. Tryptophan, for example, is an amino acid that is converted to serotonin when it goes to the brain and can therefore cause a feeling of satiety and drowsiness. The researchers found that this amino acid was more present in some mice even before they were fed the cocktail of microorganisms. This excess tryptophan subsequently affected the feeding behavior of mice, favoring the desire to consume tryptophan-rich foods.
How can our microbiota influence our food cravings?
During the experiments, some of the mice also showed a voluntary search for different types of food according to the herbivorous or carnivorous diet of the latter. The researchers observed that discrepancies in food preferences were caused by several factors: the presence of different types of amino acids, intestinal morphology, and host bacterial metabolism.
Like tryptophan, other molecules could affect our cravings for food. ” There are probably dozens of signals that influence eating behavior on a daily basis. Tryptophan produced by microbes could be just one aspect of this said Brian Trevelline, a postdoctoral student and co-author of the study. ” What you ate the day before may be more important than the germs you have adds co-writer Kevin Kohl. The chain of “cause and effect” between the whole network of microorganisms that live in our body, and everything we are digesting, is colossal.
After decades of scientific speculation, this study is a first step in showing the impact of our gut microorganisms on our nutritional physiology and food cravings. Now it would be necessary to test this type of experiment in men and compare the results with data corresponding to different types of diets and molecules.
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Originally published on 04/27/2022