Why do you always want to eat? You may be controlled by your gut bacteria!

Have you ever had this experience: you just finished dinner, go out for a walk, smell the aroma coming from the barbecue restaurant, and can't help but eat a few skewers.

Even though I had a full lunch, I could turn around and start afternoon tea, ordering cakes, milk tea, fruits, and fried chicken...

Why do you crave food all the time? It's not your fault. You may be being manipulated by your gut bacteria.

1

Gut bacteria talk directly to your brain, telling you to "eat, eat, eat"

Some time ago, in a new study published in the authoritative scientific journal Science, a team of scientists from the Pasteur Institute in France and other institutions revealed the mysterious connection between the brain and intestinal bacteria - the two can communicate directly. In the biological world, this can be said to be a dialogue that breaks dimensions.

Image source: Science magazine official website

In a mouse model, the researchers found that hypothalamic neurons can directly detect changes in intestinal bacterial activity and regulate physiological processes such as appetite and body temperature based on these changes.

Neurons in different areas of the mouse brain, especially the hypothalamus, express a Nod2 receptor, also known as a nucleotide oligomerization domain, which is a special intracellular protein that recognizes fragments of the cell wall of intestinal bacteria called mureins.

After the two come into contact, the electrical activity of neurons is inhibited, causing the brain to lose the ability to control processes such as food intake and body temperature. As a result, mice (especially elderly female individuals) gain weight and are more likely to develop type 2 diabetes.

Image source: gutmicrobiotaforhealth

The study expands our understanding of how gut bacteria can communicate directly with nerve cells and participate in the regulation of physiological processes such as our body temperature and appetite, a process that was previously thought to require the participation of immune cells.

In addition to "high-level" functions such as communicating with nerve cells, the "basic" functions of intestinal bacteria are also very powerful.

2

Intestinal bacteria are closely related to human health

Most people’s first impression of bacteria is that they are “bacteria that cause disease” and “must be eliminated as soon as possible”, but in fact there are “good guys” among bacteria.

There are hundreds of millions of bacteria living in the intestines, which are mainly divided into three categories: beneficial bacteria, opportunistic bacteria and pathogenic bacteria. Beneficial bacteria are the "good guys" among bacteria.

Various bacteria in the intestines, source: smithsonianmag

Beneficial bacteria are bacteria that are beneficial to human health. Bifidobacterium is a type of beneficial bacteria in the intestines. It is more common in the intestines of infants and less common in the intestines of the elderly. It can enhance immunity, adjust intestinal flora, and lower cholesterol.

Pathogenic bacteria, as the name implies, are bacteria that can cause human diseases. Fortunately, these bacteria are transient bacteria and have little chance of staying in the intestines for a long time. When the intestinal flora is ecologically balanced, these bacteria are few in number and generally will not cause illness in the human body.

Clostridium perfringens is one of these bacteria, which exists in the intestinal flora and also in feces. After contaminating meat food, it multiplies in large numbers and can release enterotoxins, causing vomiting and diarrhea in humans.

Opportunistic pathogens are like fence-sitters. They are usually well-behaved, but they will rebel under certain conditions, causing trouble in the intestines and making the body sick.

Enterococcus is a type of opportunistic pathogen that is widely present in the human intestine. Under the monitoring of the human immune mechanism, it is an honest and peaceful bacterium, but once it breaks through the control of the immune mechanism, it turns into a terrible demon and infects the human body.

The three types of bacteria exist in the intestines in different quantities and proportions, and are always in a dynamic balance with the host (that is, humans). This balance and stability plays a very important role in the physiological functions of the human body and has a profound impact on human health.

If the beneficial bacteria are "killed" or destroyed, the bacterial flora will be unbalanced, and pathogenic bacteria will take the opportunity to multiply rapidly, causing a series of health problems, such as enteritis, diarrhea, abdominal pain, vomiting and other gastrointestinal disease symptoms.

A large number of pathogenic bacteria can also produce toxic substances such as indole, hydrogen sulfide, and nitrosamines by decomposing food residues. These toxic substances can reach organs through the bloodstream and cause tissue and organ lesions.

3

Fecal microbiota transplants could help you regain your health

What if a person's intestinal flora is disordered and has already affected their health? You can transplant intestinal bacteria from others.

"Fecal microbiota transplantation" (FMT) is the process of transplanting functional flora from the feces of healthy people into the gastrointestinal tract of patients, rebuilding intestinal flora with normal functions, and treating intestinal and extra-intestinal diseases.

For example, various specific intestinal "difficult and complicated diseases": Clostridium difficile infection, inflammatory bowel disease, metabolic diseases, intestinal immune deficiency, intestinal allergies and other diseases.

The whole process is roughly as follows: using modern instruments and equipment in the laboratory, humanely separating and obtaining highly purified bacterial flora, and then injecting the quantified bacterial liquid into the patient's intestines through an endoscope or drainage tube. (Sending the contents of a healthy person's feces into one's own intestines)

The administration method is different for different conditions of patients. The fecal bacteria administration route is also divided into three routes: upper gastrointestinal tract (oral fecal bacteria capsules), middle gastrointestinal tract (nasogastric tube, gastroscope forceps hole, percutaneous endoscopic gastrostomy jejunal tube), and lower gastrointestinal tract (colonoscopy, enema, colostomy, and endoscopic intestinal catheterization).

Although this relatively new treatment method sounds a bit strange, it is effective. Currently, patients with severe Crohn's disease and intestinal fistulas have been treated with this method and their symptoms have been greatly relieved.

Therefore, if you want to eat delicious food, it is not enough to have good teeth. Please also take care of our intestinal flora and keep them in a dynamic balance so that we can enjoy the delicious food better.

References:

[1] Gabanyi, Ilana et al. “Bacterial sensing via neuronal Nod2 regulates appetite and body temperature.” Science (2022).

[2]Borja, et al. "Probiotics, gut microbiota, and their influence on host health and disease." Molecular Nutrition & Food Research (2017).

END

Reviewer: Wu Xinsheng, deputy chief physician of the Department of Gastroenterology, the 371st Hospital of the People’s Liberation Army.

Tadpole Musical Notation original article, please indicate the source when reprinting

Editor/Xiao Xitushuo