One of Andrea’s interest areas is gut health, and how it can be closely linked to both mental and physical wellbeing. As fitness professionals, we of course often talk about the importance of good nutrition to help support our fitness goals. However there are many more factors in play than we might have thought.
Here follows an article on our how our gut is intricately linked to our immune, nervous and endocrine systems and how this entwined relationship affects what ends up in our blood, how our hormones and neurotransmitters are produced and how our immune system constantly battles valiantly to achieve homeostasis within our body.
The microbiome – thousands of species living in our gut
The bacteria, fungi, viruses and archaea which live in your gut and on your skin are called your microbiome. The microbes are a natural ecosystem totally cultivated by you. There are around 90 trillion of them … that is 1,500 times more than the number of humans on our planet, all squashed into your belly. (Or more on one of your fingertips than there are people in Britain!) Obviously, they are microscopic, (it would be a bit scary if they weren’t) and of those 90 trillion, there are 5,000 different species. What is interesting is that we only have 10 trillion human cells in our bodies, which means that by cell count, we are only 10% human.
It is even more astonishing statistically when we discuss our DNA. Humans have just shy of 21,000 genes, which sounds quite a lot, but when you discover that a fruit fly has 31,000 genes and a rice plant 42,000 genes, it begs the question, how do we run this complex human body with such a small number of genes? Well, our microbes collectively between them house 4.4 million genes, and it is these genes that run our bodies. Our microbiome houses huge intelligence and is very powerful. If it is healthy then so will we be, but if we damage it, then the results can be catastrophic.
Our gut – home to not one, but three important organ systems
Our gut is a 9-metre tube stretching from mouth to anus and if we were to take it out and spread it flat, its surface area would be the size of a badminton court! Our gut passes from our mouth on into our oesophagus and then our stomach. Our stomach empties into our small intestine, followed by the large intestine.
Mainly water is absorbed in our large intestine. The majority of absorption of vitamins, minerals, fats, proteins and carbohydrates takes place in the small intestine helped by finger-like villi which capture and absorb the nutrients from our food. These villi also serve the purpose of increasing the surface area of our gut. However, the lining of the gut here is very thin, just a single layer of cells line the villi, and this single layer of cells is essentially what protects our insides from the world outside. Being one-cell thin, it is very delicate and easily damaged.
Embedded in the lining of our gastrointestinal tract lie three important organ systems: our immune system, our nervous system and our endocrine system, with a few facts to follow on each of these:
- 80% of our immune cells line our gut, which makes sense as this in the interface between potential toxins from the outside world passing through into our bodies.
- The nervous system in our gut is called the enteric nervous system and a vast number of neurons are contained here, similar to the number of neurons in the spinal cord and far more than in any other peripheral organ. The nervous system is our body’s communication system and many of our neurotransmitters, chemicals that transmits messages around our body via our neurons, are made in our gut. For example, 90% of the neurotransmitter serotonin is made in the gut.
- The gastrointestinal tract is the largest endocrine organ in the body producing a large number of our hormones, collectively called the enteric endocrine system.
Our microbes
It isn’t just the cells lining our gut that are responsible for the absorption of nutrients and the production of our neurotransmitters and hormones, our cells also work closely with our microbiome. The lining of our gut is covered by a layer of mucus which is also full of microbes which is our first line of defence when it comes to stopping anything bad from getting into our bloodstream. Immune surveillance is essential at this gut/blood interface, every molecule has to be assessed and quarantined. Our microbes cleanse and maintain the integrity of the gut wall as well as working collectively to digest and absorb our foods and to protect us from lurking pathogens.
Our microbes are highly organized; working together to ensure that homeostasis exists between microbe populations. The majority of our gut microbiome resides in our large intestine. Our stomach and small intestine should be relatively sterile. If one group of microbes grows out of control, or they migrate up into the small intestine where they should not reside, we suffer from something called gut dysbiosis causing the delicate, one-cell-thin gut lining to break down resulting in ‘leaky gut’ or ‘intestinal permeability’.
Immune, hormonal and nervous health
Because the large surface area of our gut is closely linked to our immune, nervous and hormonal systems, an unhealthy dysbiotic gut can affect the health of each of these systems:
- Gut dysbiosis can trigger the immune system to fire off inflammatory molecules which can leak into the blood stream where they are then at liberty to travel throughout the body causing havoc with other bodily systems.
- Gut dysbiosis can affect the production of neurotransmitters; chemical messengers that help our body to function optimally.
- Gut dysbiosis can dysregulate our production of hormones.
So, it is the cells lining our gut together with our microbes that affects what ends up in our blood, how our hormones are produced, how our nervous system (including our brain) functions and how our immune system responds. If we develop a leaky gut, then the effects are wide reaching and not just restricted to the gut but to the rest of the body. Indeed, dysbiosis can show up:
- In your digestive system as IBS (Irritable Bowel Syndrome) or more seriously and an IBD (Inflammatory Bowel Disease) such as Crohn’s or Ulcerative Colitis.
- On your skin as eczema, psoriasis, rosacea or acne.
- In your joints as stiffness and aching.
- In your nervous system as mood swings and fatigue.
- In your brain as anxiety and depression.
How to heal your gut
A healthy gut is essential to the health of the whole body. But if we have damaged it, how do we heal it and keep it healthy? Well, that mainly depends on what and when we eat and that discussion is for another time.
In the meantime, if the topic interests you further, you can find out more by visiting Andrea’s website,
