In my last post, I very briefly talked about the gut microbiome and the health issues you might experience when it loses its balance. Today, I’m going to give a more detailed introduction into the gut microbiome and how it helps the health and the normal functioning of our body.
Now, here’s a disclaimer before you start reading: I have included some scientific names of bacteria and bacterial groups in this post. While they might sound a bit ‘Sciencey’ if you come from a non-science background, these names will come in handy if you’re interested in learning gut health further.
Also, if you love to read about these topics in bit more detail, stay tuned, because I will be bringing more in-depth posts about the gut microbiota and how they can impact our health in the coming weeks.
So, what really is the gut microbiome?
As you might very well know, our bodies are full of microbes. We call them our ‘microbiota’. Most of these microbes live inside our gut and we call them our ‘gut microbiota’.
In general, our gut is home to more than 100 trillion (1014) microorganisms. Within the gut, a majority of these microbes live in the colon while the stomach and the small intestines also contain small numbers of bacteria. In fact, one gram of human poop in the colon contains more than 1011 microbial cells.
Microbiome vs microbiota: is there a difference?
In most articles, you might have seen the words ‘microbiome’ and ‘microbiota’ being used interchangeably. While they generally mean the same thing, scientifically, these two terms have slightly different definitions.
Microbiota are the groups of microorganisms found in a certain environment (eg: the gut).
Microbiome, on the other hand, includes all the microbes and their genetic material. In some scientific literature, this definition of microbiome includes the environment the microbes live in as well as the complex interactions between these microbes.
Which microbes are usually found in the gut microbiome? The microbial community in our gut is an assorted collection of bacteria, fungi, viruses, and other microbial groups (such as archaea). However, we mostly focus on bacteria as they are the most studied group of microorganisms within the gut environment. Researchers estimate that there are around 1000 different bacterial species in the human gut.
The composition—or the make-up—of these species inside our gut is an important factor that determines our health status.
There are 6 major bacterial groups (known as ‘bacterial phyla’) living in our gut:
- Bacillota (previously known as Firmicutes)
- Bacteroidota (previously known as Bacteroidetes)
- Actinobacteriota
- Pseudomonadota (previously known as Proteobacteria)
- Fusobacteria
- Verrucomicrobiota
Bacillota (Firmicutes) include genera such as Lactobacillus, Enterococcus, and Clostridium while Bacteroidota (Bacteroides) include bacterial groups such as Bacteroides and Prevotella. The well-known bacterial genus Bifidobacterium belongs to the phylum Actinobacteriota.
Where do these microbes come from?
Our gut microbiome starts to develop from the moment we’re born.
During birth, a baby picks up microbes from the mother’s body, especially from her skin and vaginal areas. In the first few weeks, the baby’s gut microbiome looks similar to the mother’s, but it quickly starts to change.
Over the first 3–4 years of life, the gut develops its own unique mix of microbes, almost like a personal fingerprint. This process is shaped by things like whether the baby is breastfed or formula-fed, how clean the environment is, if there are pets around, and whether antibiotics are used. These early years are important for building a strong and healthy gut microbiome that can support health throughout life.
Are these bacteria good or bad?
Your gut contains both friendly and harmful bacteria at the same time. In a healthy gut, there are more good bacteria than bad bacteria and those friendly microbes help keep the villains in check.
Apart from protecting us from the pathogenic microorganisms, these good bugs help us in a few other ways too.
- They help train our immune system.
- Fun fact: did you know that about 70-80% of our immune cells are found in our gut?
- They help the gut digest complex carbohydrates.
- They produce vitamins such as vitamin K and some B-complex vitamins.
- They help remove external chemicals (such as drugs, pesticides, and some other environmental pollutants) from the body.
How does the gut microbiota impact our health?
As I just said, good bacteria in your gut help you keep off pathogens, extract energy from food components that your body can’t normally digest, produce vitamins, and regulate metabolites in a way that affects your health.
They also produce several compounds—such as short-chain fatty acids (SCFA)—that play important roles in reducing inflammation and keeping the gut barrier intact.
As you can see, we can enjoy good health as long as we have healthy numbers of friendly bacteria in our gut. However, certain factors can interfere with this stability between good and bad bacteria, shifting the balance toward an unhealthy state. We call this state ‘dysbiosis’. These imbalances have been linked with various diseases such as Inflammatory bowel disease (IBD), obesity, diabetes, and mental health conditions such as anxiety and depression.
What disrupts the balance?
Research shows that several lifestyle-related factors such as the “Western Diet”, lack of exercise, stress, environmental toxins, and medication use can influence the balance between healthy and unhealthy bacteria in our gut.
Our genetic make-up and disease conditions also play essential parts in maintaining this balance.
Can you reverse dysbiosis and improve gut health?
Your gut microbiome will soon come back to its ‘normal’ state if these lifestyle stressors are short-lived. However, it might take a bit more effort to bring your gut microbiome back to a healthy state if exposed to long-term changes.
In some instances, you might even need medical intervention. So, if you’re feeling that there’s something wrong with your gut, your first step should be to get yourself checked up by your doctor.
Once you get your doctor’s OK, you can start by incorporating lifestyle changes such as eating healthy, exercising regularly, and limiting, or better yet, quitting smoking to help shift your microbiome toward a healthier composition.
I will be talking more in-depth about these lifestyle changes and how they help improve your gut microbiome in the coming posts.
In summary, the gut microbiome is important for our health, affecting how we digest food, our immune system, and even our mood. By eating well, staying active, and making healthy choices, we can support our gut bacteria and improve our overall well-being.
As we learn more about the gut’s role in health, taking care of it becomes a key part of living a healthier and happier life.
References
- Malard, F., Dore, J., Gaugler, B., & Mohty, M. (2021). Introduction to host microbiome symbiosis in health and disease. Mucosal Immunology, 14(3), 547-554.
- Cani, P. D. (2018). Human gut microbiome: hopes, threats and promises. Gut, 67(9), 1716-1725.
- Gorbach, S. L. (1996). Chapter 95: microbiology of the gastrointestinal tract. Medical Microbiology, 4th ed.(Baron, S. ed.), University of Texas Medical Branch at Galveston, Galveston. Retrieved from http://www. ncbi. nlm. nih. gov/books/NBK7670/# _ncbi_dlg_citbx_NBK7670.
- Gilbert, J. A., Blaser, M. J., Caporaso, J. G., Jansson, J. K., Lynch, S. V., & Knight, R. (2018). Current understanding of the human microbiome. Nature medicine, 24(4), 392-400.
- Van Hul, M., Cani, P. D., Petitfils, C., De Vos, W. M., Tilg, H., & El-Omar, E. M. (2024). What defines a healthy gut microbiome?. Gut, 73(11), 1893-1908.
- Derrien, M., Alvarez, A. S., & de Vos, W. M. (2019). The gut microbiota in the first decade of life. Trends in microbiology, 27(12), 997-1010.
- Malard, F., Dore, J., Gaugler, B., & Mohty, M. (2021). Introduction to host microbiome symbiosis in health and disease. Mucosal Immunology, 14(3), 547-554.
