It’s one of those things we hardly talk about. If we have to, at the doctor’s for instance, it is with an awkward feeling. But our faeces and everything that goes with it are very important. The gut has become one of the hottest topics in scientific research. And it turns out that what is going on inside, is crucial to our health and wellbeing.
We are not alone. Humans are colonised by many microorganisms. They reside on or within human tissue and bio fluids, such as the skin, the lungs, saliva, mammary glands, and seminal fluid. Some of these residents just co-exist, others have a mutualistic relationship with their human host, and there are those that can harm us.
The largest numbers of bacteria and the greatest number of species live in our stomach and intestines. This complex community of microorganisms is called our gastrointestinal microbiota or gut flora. Not only human digestive tract contains a gut flora, but that of other animals as well.
These microorganisms take in food, digest it, extract and absorb energy and nutrients, and expel remaining waste as faeces and urine. Bacteria make up sixty percent of dry mass of faeces. Thus faeces are an ideal source to test the health of one’s gut flora.
The human gut flora consists of trillions of bacteria and over one thousand distinct bacterial species. It is established at about one to two years after birth. Considerable variability exists in gut bacteria in healthy people. Generally, the gut flora doesn’t change much in a person. Change can come about in stressful situations, when we change our diet or when our overall health changes. These changes concern not only the amount of bacteria, but also the number of species. Recently, scientists discovered that the composition of your gut flora also depends on where you live.
Between us and our gut flora it is not merely a matter of peaceful co-existence. We have a very important relationship with mutual benefits. We offer our bacteria a place to live, eat, and procreate. But what does our gut flora do for us? That makes up quite an impressive list! They ferment dietary fiber; they train our immune system; they prevent the growth of harmful species; they are involved in regulating the development of the gut; and they play a role in the production of vitamins, namely B and K, and of hormones.
The concept of a gut-brain axis is all the rage lately. When they use this concept, scientists refer to the biochemical signalling between the gastrointestinal tract and the central nervous system. The gastrointestinal system contains the enteric nervous system: a vast number of neurons with complex connectivity, also called our ’second brain’. These neurons relay information from the gut to the brain. They can communicate with bacteria to gather information. Bacteria in the gut are able to produce a range of molecules that activate neurons, such as serotonin, melatonin, acetylcholine, and histamine.
That dark place which you only think about when you get the urge to go to the toilet, turns out to be highly developed. It does an indispensable job and is involved in sophisticated tasks.
So if your gut flora isn’t healthy a lot can go wrong. Gastrointestinal microbiota that have gone out of balance, seem to be linked to a host of inflammatory and auto-immune conditions. Issues with the gut flora have been implicated in for instance inflammatory bowel diseases such as Crohn’s disease, allergies, asthma, diabetes type 1, irritable bowel syndrome, metabolic syndrome, and obesity.
Since microbiota can influence the brain, theories are being tested whether there may be a link between gut flora and anxiety and mood disorders, schizophrenia, autism, Parkinson disease. Canadian researchers of McMaster University transplanted faecal microbiota from patients suffering from irritable bowel syndrome (IBS) into mice. IBS is often accompanied by anxiety and depression. The mice that received the transplant from IBS patients developed changes not only in intestinal function, but also in behaviour. Compared to mice that had healthy microbiota transplanted, they showed anxiety-like behaviour.
The University of California also came up with an association between gut bacteria and emotion. Faecal samples of healthy women were profiled and scans of the brains of the participants were made. This showed a larger presence of certain bacteria results in more connections in specific brain areas. Different gut bacteria interact with different regions in the brain, mainly associated with mood and behaviour, according to the researchers.
A lot of things may disrupt the functioning of a healthy gut flora. The most important factors are antibiotics, stress, and parasites. They can change the numbers of bacteria in the gut and also the amount of species. An active area of research is the gut flora and its role in modulating the immune system. The western diet, which lacks whole grains and fibers and contains an overabundance of simple sugars, may cause changes in the gut flora that negatively influence the immune system.
To correct unbalanced gastrointestinal microbiota, changing our diet of course is the first line of attack. Make sure your gut flora gets the right kind of nourishment and it will flourish.
In more serious cases, transplantation of faecal bacteria from healthy people is a possibility. Administration of the faecal transplants can be done nasogastric (via the nose into the stomach), via an enema, or with capsules. It seems the transplant of microorganisms from the stool of a healthy donor is a safe and effective way to increase the diversity of good bacteria in the guts of patients. Just like in a forest where a storm has swept away trees and bushes and has left a clearing, pioneer species colonise the open area. They alter the ecosystem to pave the way for other species to settle. Eventually the area is wooded again or, in the case of the intestine, a complex gut flora is restored.
The University of Helsinki has developed a faecal bank where frozen transplants of healthy, tested donors are kept. In Finland, faecal transplants are an established treatment for people with recurrent antibiotic associated diarrhoea (Clostridium difficile-infection) with a success rate of over ninety percent.
Another possibility to supply the gut with new bacteria are probiotics. These are live microorganisms consumed by way of capsules or powders. Scientific evidence of the effectiveness of this method is still scarce. A 2017 study of McMaster University in Canada was the first to show that probiotics may relieve symptoms of depression in patients with irritable bowel syndrome, as was confirmed by brain scans.
A new frontier will be to find out whether autism can be treated by targeting the gut. For decades, reports have signalled a link between the composition of bacteria in the gut and autistic behaviour. Maybe making the gut flora healthy by diet changes, faecal transplants, and probiotics will result in a reduction of symptoms of autism spectrum disorder.
Things we don’ talk about © beeboys – Fotolia.com
Examples of gut bacteria © timonina – Fotolia.com
Gut-brain axis © Anatomy Insider– Fotolia.com