Believe it or not, our body houses millions upon trillions of tiny, microscopic beings! They are found both inside and outside the body. These are composed of lots of different species of bacteria, fungi, and viruses. These microscopic beings are generally known as microbes. As a whole, they are collectively called a microbiota. The collection of their genes is called a microbiome. When they generally inhabit a part of the body, they get to be called as such. Thus, the gut microbiome is a collection of the genomes of the big group of microbes located in the digestive system.
There are different types of microbes for any given part of the body, both inside and out. In the case of the gut, there are about a hundred trillion of these microorganisms existing in the digestive tract. The digestive system is said to have more than 1000 species of bacteria which can generate more than 3 million genes. This is about 150 times more than a human’s genes! The microbiota can also weigh up to 5 pounds collectively. They are heavy for microscopic beings, right?
In the gut, about a third of the microorganisms are the same from one human being to another. However, two thirds of the microorganisms are unique for every person. This is why the microbiome in your gut is unique to you as a person. With this said, the different types of microorganisms and their amounts all influence a human body differently in their own way. This led scientists and researchers to study about how the gut microbiome affects our body’s functions and overall health. These gut microbes maintain a balance in our digestive system. Surprisingly, they also affect the other parts of the body and influence the health of a person as a whole. In general, the gut microbiota has a significant effect on many processes occurring in the gastrointestinal tract, like nutrient absorption, mineral absorption, production of fatty acids, and synthesis of different vitamins, enzymes, and amino acids.
One of the processes done by the gut microorganisms is fermentation. Fermentation byproducts are good to a certain degree. Some examples of fermentation byproducts are propionate, acetate, and butyrate. They actually help with enhancing the epithelial cell barrier integrity, help with immunomodulation, provide energy for the epithelial cells, and even provide some degree of protection against pathogens.
Non-pathogenic microbes, or the good bacteria in simpler terms, keep the pathogenic and opportunistic microbes in check. There is homeostasis in the number of microbes present per species, and a lot of environmental factors can disrupt the homeostasis. Altered gut microbiota can change the environment. This can lead to disruption of the gut barrier and other processes. This is called gut microbiome dysbiosis. When dysbiosis happens, there are side effects to all parts of the body. The kidney, liver, skin, immune system, and even brain is compromised. The person involved also is more likely to develop symptoms and diseases.
It has been shown that having gut microbiome dysbiosis can produce toxins that are deadly to the body. These toxins are caused by too much fermentation of some compounds. Since the dysbiosis already compromises the gut barrier, these toxins are able to leave the gut and go to the general circulation. With this, it can travel to all parts of the body. These toxins have been implicated in the development of chronic kidney disease and even cardiovascular disease.
The gut microbiome seemingly has a role in guiding the function of the body’s central nervous and immune systems. That is why researchers have studied their interactions. They have found that there exists a microbiome-gut-brain axis. This is made possible by signals going back and forth the two systems. It has been shown that there are microbes that cause more anxiety-like and depression-like symptoms in people. When these microbes are eliminated, people tend to have less anxiety and depression. Gut inflammation can be caused by antibodies against a certain microbe from the species Saccharomyces. This has been shown to present in people with schizophrenia, psychosis, and bipolar disorder.
The gut microbiome also has a pathway for the skin. It is called the gut-skin axis and there appears to be a modulatory effect from the gut to the skin. Some gut microbes and its products facilitate an anti-inflammatory response on the skin, thereby reducing pimples, rosacea, and other inflammatory conditions.
Research shows that children who have less diversity in the kinds of microbes found in their gut microbiota are more prone to food sensitivities and allergies like in peanut butter, egg, and milk. Having less good bacteria also makes a person more prone to be overweight or obese. Particularly, having the species of Christensenellaceae would make a person more likely to have a low bodily weight. In these cases, more diversity is better!
There have also been studies linking gut microbes to cancer. Some have proposed that certain types of bacteria, especially bad bacteria, can heighten your chance of developing cancer. Scientists have been trying to link specific species of bacteria to the development of lymphoma, stomach cancer, and colorectal cancer. However, like said earlier, more diversity of bacteria types in the gut is better. Two studies have had similar results on cancer therapy administered to mice. Mice with more diversity in their gut microbiota were more likely to respond to chemotherapy and immunotherapy compared to those which had less diversity.
In essence, maintaining a healthy gut microbiota is key to not developing disorders or complications in the body. You can do this by having a good diet and having a healthy lifestyle. Diet has been shown to have a critical role in shaping the gut microbiota. Diet can also change the microbiota’s ability in regulating and producing bioactive metabolites, like bile acids and short chain fatty acids and their metabolisms. These control the pH levels in the gut, the emulsification of fat, the activation of pathways, and regulation of other processes.