The billions of bacteria that live in our guts could be influencing our food choices, according to a new study. A new study by researchers at the University of Pittsburgh suggests that gut microbes may trigger food-seeking behaviors that contain certain nutrients. In this study, the researchers found that mice bred to have no microbiome but later colonized with the gut microbiomes of different animals showed significant variations in their eating behaviors.
The authors believe that gut bacteria could affect our food choices and cravings by influencing the availability of essential amino acids. The decisions we make about what we eat may not just come from our brains. The mechanisms that determine our food choices could be traced back to the evolutionary processes of gut microbes.
For decades, scientists have wondered if the intestinal flora is at the origin of food urges. However, no one had ever directly tested the hypothesis on animals larger than a fruit fly Trusted source. Dr. Kevin Kohl and Dr. Brian Trevelline of the University of Pittsburgh, Pennsylvania, explored this possibility with germ-free mice. Dr. Kohl is an Assistant Professor in the Department of Biology at the Kenneth P. Dietrich School of Arts and Sciences at the University of Pittsburgh.
Their research showed that mice given various types of microbiota voluntarily changed their food preferences. This work shows that animals with different compositions of gut microbes choose different types of diets. This study is published in the journal Proceedings of the National Academy of Sciences.
Microbes and amino acids
Microbes play a role in the manufacture of nutrients. Animals need a series of essential amino acids to survive. But the microbes that live inside our intestines need to grow and have some of those same nutrients or make nutrients that the human body or the animal body can recognize. For example, they make these essential amino acids and then they are released into the gut where they can be absorbed by the host. Additionally, microbes could also be broken down and digested to release nutrients. The microbes present in the intestine contributed beneficially to many processes, including synthesizing the nutrients needed by humans and supplementing their diets. This study also shows that some of these molecules can enter the host’s bloodstream and affect its behavior.
The researchers collected microbes from three species of wild rodents with different natural diets. They gave these microbial “cocktails” to 30 mice designed without gut microbiota. Mice in each group began to select foods rich in significantly different macronutrients. Mice whose microbes came from herbivorous wild rodents chose a diet with a higher protein-to-carbohydrate (P:C) ratio. Those whose microbes came from carnivorous and omnivorous rodents chose a diet with a lower P:C ratio.
The role of tryptophan
Tryptophan, an essential amino acid, is a precursor to serotonin, a neurotransmitter. Scientists believe that this hormone can regulate diet choice.
Mice with different microbiota also had varying levels of tryptophan in their blood before choosing different diets. Mice with higher amounts of tryptophan also had more microbes capable of producing this amino acid in their intestines. Tryptophan is just one of many chemical messengers that communicate with the gut and the brain. This experiment reveals how tryptophan could directly affect daily eating behavior.
The limitations of the study
As intriguing as the results are, it may be too soon to blame gut flora for all food cravings. This groundbreaking research provides only a glimpse of how microbes can interact with animal hosts. She did not compare the influence of microbes with other factors.
Other questions to explore
The question of whether the microbes present in our food influence food cravings is “to be studied in the future”, the authors conclude. Our microbiomes are constantly influenced by our environment, our lifestyles, and the animals and other people we interact with. All of this has the potential to influence our microbiota. But whether this produces meaningful behavioral consequences is still an open question at this point.
The gut microbiome influences host diet selection behavior
* Presse Santé strives to transmit medical knowledge in a language accessible to all. In NO CASE can the information given replace medical advice.