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Benefits of a healthy gut flora

You probably have come across the phrase ‘human microbiome’ at some point in your life but do you truly understand its meaning? Have you ever wondered about all those microscopic organisms that occupy your body, both on the inside and the outside? Our bodies are made of both human cells and bacteria that live in various parts of the human body including the gut, skin, and mainly- the colon. 

The human microbiome (total number of microorganisms in the human body) may weigh as much as 5 pounds (just over 2 kilograms).¹

“The number of microorganisms present in the human microbiota is thought to be slightly higher than that of human cells in the body, and some have classified the microbiome as an organ in its own right .” ²

As it turns out, only less than half of your body is human, the rest is made of microscopic colonists, like bacteria, viruses and fungi that affect your immunity, digestion, mood and many other aspects of your health. It would be ignorant to think that these tiny organisms don’t feature in our well-being since the number of them is so vast. 

“So to our 30 trillion human cells, we have on average about 39 trillion microbial cells. So by that measure, we’re only about 43% human.” ³

Rob Knight , director of the University of California San Diego Center for Microbiome Innovation

The term ‘microbiome’ refers to the group of microorganisms living in the environment, in this instance, the human body. Microbiota, however, describes microorganisms that occupy a specific habitat within it, for example, the gut. So in this article, we’re diving into the gut bacteria specifically, in other words- the gut microbiota.

The gut (gastrointestinal tract) is a long tube that connects the mouth with the stomach, large intestine and, at the end of the passage, the anal sphincter. 

Science nowadays is progressing at a rapid pace and we learn more and more about the role of the gut microbiota in maintaining health and preventing disease. These organisms have a greater impact on us than we tend to think, leading to either enhancement of one’s bodily functions or to their debilitation. Of course, the make-up of gut microbiota can be influenced by a number of factors such as diet, medications or stress. The imbalance of microbes, also called dysbiosis, has been linked to weight gain, high cholesterol, IBS (irritable bowel syndrome) and even depression. ⁴

Conversely, a healthy gut microbiota, that of a balanced number of both healthy and unhealthy microbes, carries a vast number of benefits and helps regulate many bodily processes. 

Let’s take a look at how your gut bacteria may impact your health:

1. It supports the immune system.

Healthy gut microbiota plays a crucial role in protection from infections and helps strengthen the immune system. It promotes resistance against harmful pathogens, which means that in the event of infection your body can fight them off more efficiently. On the contrary, an environment that doesn’t have enough good bacteria is ideal for the bad bacteria to thrive, which leads to dysbiosis (imbalance) of the gut microbiota. This may cause autoimmune conditions, such as thyroid problems and rheumatoid arthritis. It has also been studied that an imbalance of gut bacteria may be a contributing factor in chronic diseases, such as inflammatory bowel disease (IBD) and even autism and cancer. ⁵

According to NCBI (The National Center for Biotechnology Information) :

“[…] dysbiosis of the microbiota seems to be an important factor in determining whether the immune system contributes or protects against the initiation of cancer.” ⁶

The unhealthy ratio of good and bad gut bacteria has also been shown to decrease the efficacy of anticancer drugs, promoting resistance to chemotherapy. ⁷

2. It helps maintain a healthy weight.

Having a balanced gut flora has been linked to a healthy weight. Your microbiome is crucial for digesting and absorbing food and influences how nutrients are stored in your body. It also has an impact on energy expenditure and the metabolism of essential amino acids. The gut microbiota is also known to produce short-chain fatty acids, which are compounds that have the potential to reduce appetite, therefore, preventing obesity. They can reduce your risk of developing colorectal cancer too.

On the other hand, dysbiosis of the gut bacteria has been shown to lead to obesity and type 1 diabetes.

“There are data that suggest that the bacterial composition of gut microbiota differs between obese and lean individuals and that a Western-style diet which is high in fat and refined carbohydrates may promote increased intestinal bacteria linked to obesity.” ⁸

3. It contributes to good sleep.

The gut’s microorganisms are capable of communicating with the brain, sending and receiving various signals that influence your mood, stress level, appetite and so on. This connection is called the gut-brain axis and it appears that it may impact the quality of your sleep as well. Studies ⁹ suggested that alterations in the gut microbiome are associated with changes in the circadian rhythm, which is the 24-hour internal clock in our brain that controls the sleep-wake cycle. The same study also linked restricted sleep, for two consecutive nights, with the changes in the gut microbiome.

“[…] the gut microbiome exerts multidimensional influences on many, if not all, brain functions and, consequently, changes that occur in the microbiome are likely to affect the quality and quantity of sleep.” ¹⁰

4. It helps enhance mood and cognition.

Chemicals that play an important role in happiness, such as serotonin, are mainly produced in the digestive tract, with only 10% of them being produced in the brain. Researchers have also found that gut bacteria generate a number of neurotransmitters, such as GABA, dopamine and norepinephrine that affect feelings of stress, happiness or sadness. A healthy composition of gut microbiota may therefore contribute to better emotional stability, reducing depression, anxiety and other mental health conditions.  

Study ¹¹  performed on two groups of women, the first of which consumed (rich in good bacteria) fermented milk for four weeks, has revealed they had lower brain activity and therefore were calmer during the emotional task as opposed to the rest of the women. The group that did not consume fermented milk with probiotics showed hyperactivity in the brain during the same task. 

A healthy gut comprises a huge number of microorganisms, which existence benefits us in many ways. A balanced ratio of the good and bad bacteria in the gut is the key to maintaining a healthy weight, good sleep quality, emotional stability and immunity. You can improve your gut bacteria by implementing a diet rich in fibre, natural probiotics and plant-based foods.

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Research references

1. https://depts.washington.edu/ceeh/downloads/FF_Microbiome.pdf
2. https://www.americanpharmaceuticalreview.com/Featured-Articles/562548-The-Human-Microbiome-What-It-Is-Why-It-Is-Important-and-Opportunities-for-Microbiome-Based-Therapeutics/
3. https://www.voanews.com/a/research-estimates-we-are-only-about-43-percent-human/4932876.html
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5962619/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425030/
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4056765/
7. https://gut.bmj.com/content/69/10/1867
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5082693/
9. https://www.archbronconeumol.org/en-sleep-microbiome-a-two-way-relationship-articulo-S1579212918303586#bib0170
10. https://www.archbronconeumol.org/index.php?p=revista&tipo=pdf-simple&pii=S1579212918303586
11. https://pubmed.ncbi.nlm.nih.gov/23474283/