Me and My Microbiome

You might have heard that we are in fact more bacteria than human, or that our human cells are far outnumbered by bacterial cells. Whilst scientists debate the exact numbers, there is no doubt trillions of bacteria present in and on our bodies. How did they get there? What do they do? Can they be harmful? In this blog, we will explore the fascinating world of the human microbiome and hopefully answer any questions you might have about the bacteria that make us who we are. 


What is a Microbiome? 

Microorganisms, or microbes for short, are tiny living things such as bacteria, viruses and fungi. They live in and on our bodies, and form habitats we like to call microbiomes. Scientists study microbes and the interactions with their environment, to understand how they protect us from pathogens, help digestion and even regulate mood.  



Where Did These Microorganisms Come From? 

From the moment we are born, we are exposed to an abundance of bacteria. Babies first acquire these microorganisms from their mother’s birth canal during delivery, or from contact with their mother’s or nurse’s skin. A babies’ microbiome will rapidly change and develop overtime based on their surroundings and environment. This means the milk they consume, the food they eat or the pets they live with, will all shape and develop their microbiome. 


Where Do These Microorganisms Live in Our Bodies? 

The type of bacteria present will largely depend on the environment. For example, the harsh acidic conditions in the stomach will mean fewer bacteria can survive there, whereas the nutrient-rich environments in our mouth and gut are excellent areas for bacteria to thrive. Another example is the lack of oxygen in our gut. Here, lives a specific type of bacteria that can survive without oxygen. These are called anaerobes (“anna-robes”). In general, bacteria reside in the mouth, skin, and gut where a complex and diverse group of bacteria flourishes. 



What is the Role of Bacteria in the Body? 

Bacteria on our skin have many different roles that help keep us healthy. They work alongside our immune system to create a barrier against harmful pathogens. Some beneficial bacteria can even produce acid on our skin creating harsh conditions for harmful and invasive bacteria. Don’t worry, our skin is only mildly acidic, and we don’t even notice it!   


Similarly, bacteria in our gut produce fatty acids by breaking down fibres. These acids help keep the lining of our intestinal walls healthy, and the acidity also prevents harmful bacteria from colonising there. Bacteria in our gut also crucially produce vitamins such as vitamin K. 


Our diet has a great influence on our gut bacteria, for example, vegetarians will have a different gut microbiome to someone who eats more meat. Generally, a diverse and balanced microbiome with a variety of bacterial strains is optimal to maintaining a healthy gut. Some people take prebiotic supplements which are foods for our gut bacteria, as well as probiotics which are living beneficial bacteria. Foods such as yoghurt and pickles are packed with probiotics. 


How can Bacteria be Harmful to us? 

Whilst most bacteria in our body are commensal, meaning they are harmless, a lack of beneficial bacteria in our bodies, or infection by harmful bacteria, can cause problems. If you get a cut on your skin, bacteria that normally live on your skin can enter your bloodstream where they don’t belong, causing an infection and triggering your immune system. 


In the gut, when your body does not have enough good bacteria, harmful bacteria can thrive. An unhealthy gut is linked to a variety of health issues such as indigestion and even depression or anxiety, as the brain is linked to the gut through our body’s gut-brain axis. If the lining of our gut is too weak, it can also become leaky, this condition allows harmful bacteria to enter our bloodstream. 


If too much bacteria accumulates in the mouth, they can feed off the sugars in your teeth and produce acids that can cause tooth decay. This is why we need to brush our teeth to avoid harmful build-up of bacteria in our mouth.  


The Importance of Our Microbiome

The diverse species of bacteria in our bodies carry out a variety of roles and are crucial for keeping us healthy. A healthy microbiome is one that is diverse and comprises a variety of beneficial bacteria to protect us from harmful bacteria. Our interaction with the environment such as our diet, and the medication we take can all influence our microbiome. Imbalances in the normal microbiome, particularly in our gut, can lead to health complications. Currently, researchers are studying the different species of bacteria as well as their genes, to investigate their link to some common health conditions such as obesity and diabetes.