Intestinal Microbiota: The Forgotten Organ

Jun 22, 2015

Although your intestines are very good at digesting the food and drink you consume, it couldn’t do it on its own. To help your digestive system out, your intestines are home to around 100 trillion friendly microorganisms living in your body, collectively known as the microbiota. These microorganisms are nothing to worry about; they are mostly friendly and carry out useful functions. Because of the many ways they help the body out, many people refer to them as the bodies “forgotten organ”.



One of the most useful functions that our intestinal microbiota performs is helping us to digest all the food we eat and waste as little as possible. The bacteria not only help us to digest more food, but they often help us to digest food we wouldn’t be able to without them.

We get a lot of the energy that we use from carbohydrates, but the human body lacks the enzymes to properly digest many of these. Without the help of bacteria, humans would find it hard to digest starches, fibre, oligosaccharides (a sugar contained in beans) and lactose in lactose intolerant people.

As well as helping us to digest food, intestinal microorganisms can also synthesise the nutrients we need. Vitamin K, that we use to help blood clotting and the binding of calcium in bones, is produced by a certain type of intestinal bacteria. Evidence has shown that intestinal microbiota even enhance with the absorption and storage of lipids, which are essential to many bodily functions.


The useful functions of intestinal microbiota extend beyond digestion; another function is the aiding of our immune system in protecting us from harmful pathogens in the digestive systems. One of the ways that the microbiota does this is simply just being present in the intestines. By absorbing all of the nutrients they need, they leave little that can be used by harmful bacteria and this hinders their growth.

The microbiota isn’t present when you’re born, but microorganisms quickly start to populate the intestines in the first few months of a person’s life. By being present in the digestive system at this early age, it encourages the development of the immune system in this area and affects it in a way that is favourable to them and less favourable to harmful bacteria. The immune system continues to act in this way for the rest of the person’s life.

Other Beneficial Functions

Some studies have shown that intestinal microbiota can stop people from developing allergies to things that aren’t harmful to us. It was found that those who have an allergy, or later develop one, have a different composition of microbiota than other people, with a reduced amount of two specific bacteria. The theory surrounding this is that the microbiota is actually “training” the digestive system’s immune system to respond appropriately to these substances. People who do not have these bacteria in their guts in earlier life have an untrained immune system later on in life and are more likely to develop an allergy.

Changes in the Bacterial Composition

The composition of the bacteria in your intestines is very sensitive and can change with even the slightest change to your diet or lifestyle. Because they get the nutrients they need to survive from the food you eat, and the fact that different species of microorganisms use nutrients in different amounts, changing the food you eat can alter which species can survive the best.

People who are ill may have their microbiota altered as a result, especially if they need to use antibiotics. The antibiotics used to fight harmful bacteria may also affect the intestinal microbiota, which in turn may negatively affect the person’s health. Illnesses can also affect the intestinal microbiota if the person is eating less as a result and fewer nutrients are reaching the friendly bacteria.

If a persons’ intestinal microbiota is changed particularly severely, they may have to have a fecal transplant. This involves introducing the friendly microorganisms from a healthy person’s digestive system in order to return the microbiota composition to an ideal level.


Here at London Gastroenterology Centre, we’re experts on how a person’s digestive system should and shouldn’t be working and that’s why we can provide a whole range of excellent services and treatments, including endoscopic resection and private endoscopy in London. If you have seen a change in your bowel habits, have lost weight for no reason, or have any other concerns about your diet and would like to know more about our services then don’t hesitate to contact us on 020 7183 7965 and a member of our team will provide you will all the information you need.


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