The Gut-Brain Connection

  • Introduction
  • The Influence of Brain Injury on our Health
  • Outcomes
  • Shutting off the Biochemical Cascade
  • References


Great science can take a while to get to the public domain, and when it does all kinds of fads can swamp our social and general media feeds. In the main, it is best to ignore the ‘fads’ and get back to the real science that started it all. Marketing articles of this nature can send us off in all kinds of directions, but rarely help us to understand the full story or relate specifically to brain injury.

When it comes to getting a poorly body and injured brain healthy again, it is always going to take more than eating the latest superfood. Marketers can spin as well as any political group, and not all of it is based on research – so be aware! Not everyone wants to give you complete information so that you can make up your own mind.

Without a doubt, scientific breakthroughs can influence what we do and what we buy faster and in a more significant way than the latest good thing to eat brought to us by TV personality chefs. Many articles are designed to sell products, which is all well and good, as long as you understand what is relevant to you and are careful about what you read and take on board – because sometimes the information is based on profit before good or sound advice.

Non-commercial permission Springer Nature

Scientific discoveries about the connection between the gut microbiome and brain environment have taken huge leaps forward and teach us a great deal about the connections between what we put into our bodies and how we feel. Articles abound and show us that everything matters.

If we think of the potential toxins in the environment around us, we can apply the same kind of consideration to what is happening to our cells in our microenvironment. Our cells are not immune to toxins. When we overload them with say sugar, they feel like a petrol engine filled with diesel.

We tend to think that our inner physiology is robust because we don’t immediately react to all or many toxins – this doesn’t mean that they aren’t doing us harm though. Just because you ate fries and survived doesn’t mean that your inner organism isn’t holding its’ fist up at you while trying to fight fires and keep you alive. Damage is damage – no matter how slowly it seems to creep upon us.

The thing is that we do get warning signs. Bloating, bellyache, wind, headache, spots/acne, hives and rashes, dry skin, ‘irritable’ legs, sleep problems, diarrhoea, constipation, sinus problems, swollen breasts, asthma, hay fever, dark circles and bags under our eyes and a whole load more everyday ‘symptoms’ that tell us our microenvironment is unhappy and struggling. We reach for over the counter solutions, and when they don’t work, we visit the doctor. Prescriptions for stronger medications, designed to alleviate symptoms, often produce side-effects.

When we stop and think these ‘side-effects’ are yet more symptoms that are designed to tell us that our bodies are not happy with what we are subjecting them to – more toxins! It is no wonder that our cells are waving red flags – they were never designed to manage the kind of overload that they are subjected to by modern living.

If your microenvironment is shouting – listen to it.

Understanding the gut/brain axis helps us get back to the basics and tackle brain injury symptoms from the outside in and the inside out. Take a look at this video – The Gut-Brain Axis.

The influence of brain injury on our health

We tend to think of brain injury as something that explicitly affects brain function. The thing is that the secondary outcomes of brain injury are the predominant cause of many of the symptoms historically associated with the primary trauma, and this can and does affect our general health. The biochemical cascade disturbs so much more than just the brain and is known to be the cause of the prolongment of symptoms – including those diagnosed with a concussion, post-concussion syndrome, and mild traumatic brain injury.

It can get confusing for people who have been diagnosed with a ‘mild’ traumatic brain injury (mTBI) and have been told they should get over it in a couple of months, and yet, years or even decades later, people are often still struggling to get their lives back together. There is a very good reason for this, and explaining requires a few myth busters.

The term ‘mild’ doesn’t mean that your brain has sustained less damage – it means that you either didn’t lose consciousness or, if you did, it was for a short period, i.e. minutes rather than hours. Your personal outcomes are just that – totally unique to you. A severe whiplash or blow may not cause prolonged loss of consciousness, but it can cause severe alterations in your brain environment and structure.

A brain injury of any severity can affect your overall health. Much of this will depend on criteria such as age, fitness, diet, environmental factors, and general health at the time of injury. In fact, what you are told at the time of the injury can also affect outcomes. For example, if you are diagnosed with a concussion or mTBI and are told this will clear up on its own and it doesn’t, because of other factors, then the psychological impact of this can, on its’ own, affect how well people recover. Post Concussion Syndrome (PCS) can be debilitating. No one should ever be made to feel that they are complaining or malingering.

We need to know what we are dealing with so that we can manage expectations and beliefs. Our beliefs have a placebo or nocebo effect on us and are, therefore, incredibly important factors in recovery.

Facts and truth can help us in many ways. Importantly, if we know what we are dealing with, then we can tackle it. Understanding the associated implications is often harder for people who have non-physical severe brain injuries with a loss of insight or awareness as this can affect the ability to understand what has happened.

It is the area of the brain that has been physically damaged that determines the consequences – not the period of unconsciousness. As brain injury is better understood, so diagnostic tools, diagnosis and understanding, and prognosis will improve. Many people who have been in a prolonged coma or who have severe physical outcomes maintain executive function and a sense of self. People who are physically affected by stroke can likewise maintain their executive and cognitive function. There are no hard and fast rules – every brain injury is unique. You can have memory problems but remain able to think and work out your own strategies. The brain is complex, and so are the diverse range of outcomes.

What does always happen in everyone, and is being researched in greater degrees to find out how to stop the secondary outcomes causing more damage, is the biochemical cascade that occurs as a result of all brain injuries.

This cascade affects our whole body – not just the brain. Importantly the inflammation affects our gut health, and in turn, this affects the balance of the immune system and also how we and our brains ‘feel.’

When we consider that poor gut health in a ‘normal’ person can affect mental health and then add in that in these populations stress alone can exacerbate depression, anxiety and mood swings, then we get a glimpse of how the cascade of negative hormones and inflammation can aggravate, and be causal to and change, all kinds of thinking parameters for people post brain injury.

If we can address the inflammatory biochemical cascade quickly, we may be able to minimise some of the impacts a brain injury brings. We may be able to reduce the effect this has on overall health – especially regarding the prolongment of brain injury symptoms.

What happens

Good bacteria is essential for proper gut health, immune system functioning, and is important for neurological/central nervous system and psychological health. When brain injury strikes, the negative inflammatory response can change the environment of our gut and thus affect our microbiome and brain environment. It becomes a vicious circle. An on switch gets flicked and doesn’t switch off until we do something to interject and address this response.

When our gut microbiome is compromised, we can start to use our vitamin and mineral reserves. When things get bad we can struggle with our weight – up and down – healing skin wounds, muscle elasticity and even start to look aged because of dark eye circles and bags, premature wrinkles, sagging skin and greying of hair or hair loss. These are all symptoms telling us that our inner microenvironment is unhappy.

On top of this the lymphatic system becomes congested with toxins emulating from the biochemical cascade and this, in turn, slows the cleaning systems – the liver, spleen and kidneys. Any damage to the brain stem can exacerbate this as messages for functionality to the bodily organs can also be blocked. We need to be serious about our health care because any small added extra can have the equivalent effect of a tonne of bricks falling. Also, see ‘fatigue‘ and our article about ‘Emotional Flattening.’

The two-way axis between the gut and the brain has been found to have several unexpected effects by a team from the University of Maryland School of Medicine. Other studies have demonstrated how magnetic brain stimulation can alter a person’s gut microbiome also how gut bacteria could potentially play a role in the onset of PTSD. However, these new studies revealed a gut-brain connection between traumatic brain injury (TBI) and intestinal damage. Researchers previously identified a relationship between TBI and alterations in a person’s gastrointestinal tract, but this is the first study to understand this interaction in detail, revealing the two-way process involved.

The researchers looked at mice subjected to TBI and discovered that following the brain trauma, the animal’s colon became more permeable, meaning that bacteria can more easily move from the intestine to other areas in the body.

The team also looked at how irregularities in the gut could affect inflammation in the brain after TBI. After infecting TBI-inflicted mice with ‘bad’ gut bacteria, the animal’s brain inflammation was seen to worsen. This interesting result suggests that the harmful effects of TBI can be influenced directly by gut dysfunction.

Lead researcher, Alan Faden said, “These results indicate strong two-way interactions between the brain and the gut that may help explain the increased incidence of systemic infections after brain trauma and allow new treatment approaches,”

How well people improve after a brain injury is down to how well the bodily systems can recover. The human body has in-built healing mechanisms, but a brain injury can thwart these. We can change this. We can do things that support the body and improving the prevalence of symptoms allowing us to focus on neurological damage within the structures of the brain.

When we clear the fog, we can ‘see’ what needs ‘fixing.’

Shutting off the biochemical cascade

Shutting off the biochemical cascade after a brain injury is, without a doubt, the most important thing you need to address. Many of the outcomes you struggle with may appear to take precedence – but the chances are that if you tackle the effects, your brain injury has had on your gut that many of the issues you felt were so important will fade into the background.

These improvements may all seem impossible, but until you decide to try and take your life and control back – you will never know.

The very real consequence of a brain injury, coupled with poor diet, environmental toxins and stress, can lead to higher risk of developing neurological diseases such as Alzheimer’s and the range of associated dementias, right through to Parkinson’s, motor neurone disease and many other inflammatory diseases such as fibromyalgia, MS, CFS, rheumatic disease and so many more. Tissue damage associated with a severe injury can result in profound inflammatory responses that may trigger autoimmune development in lupus-prone individuals. Science is addressing the many connections between brain injury, trauma, stress, and other diseases.

In brain injury, it is imperative to address the negative biochemical cascade as early as possible. Other adverse health factors include the possible eventuality of lowered levels of the output of cortisol and the balance of adrenalin which are typical in later stages of brain injury. Cortisol is a hormone that plays a critical factor in the health of our mitochondria and energy levels, and low levels result from adrenal fatigue because of the prolongment of the biochemical cascade. The secondary outcomes of a brain injury cause excessive outputs of this hormone, which act in a corrosive manner on the adrenals. In addressing the biochemical cascade early on, we can decrease incidences of adrenal fatigue and resultant brain fog and neuro and physical fatigue.

By directly addressing the causes of fatigue, brain fog, and all the other symptoms of brain injury, we can affect our inner environmental health and thus influence brain injury recovery and healing.

Taking the direct route

In considering current known scientific research, there are a limited number of ways to tackle the ‘on’ switch of the biochemical cascade. You will recognise if this biochemical cascade is still a part of your daily life, by observing your reactions to ‘everyday’ stressors.

If your reactions to everyday stressors are over-the-top and out-of-character for you, then the chances are strong that you are struggling with adrenal fatigue, poor gut microbiome and the adrenal or fight/flight switch being stabilised at ‘on.’ The same for those of you who have prolonged problems with PTSD.

When Xenon gas ( an anaesthetic drug) is used immediately post-injury, research shows that it can halt or slow the biochemical cascade, but what do you do years later to get the ‘on switch’ to turn off? How do you get the gut-brain axis to work again?

Always speak to your doctor about any changes you are considering and ask for support with helping yourself.

There are many things you can do:

  • Detox your inner environment
  • Deal with the external environment – stop using chemicals in and around your home
  • Next, deal with what comes into your body – ‘weeding’ is about getting rid of harmful foods such as processed and sugary foods and substances such as alcohol, drugs, and tobacco. Stop taking in foods and substances you think you are intolerant to such as gluten and dairy
  • Start ‘seeding’ your microbiome by eating for nutrition – eat seeds, nuts, beans, vegetables, and fruit to support your good gut bacteria and absorption of supplements
  • The next thing to do is to start ‘feeding’ your microbiome so it can feed your brain – add prebiotics such as onions, garlic and sweet potato to your diet and also add probiotics in the form of supplementary capsules and natural unsweetened goat yoghurts and kefir which are full of beneficial bacteria
  • Add a probiotic. This is something you can speak to your doctor about. There is quite a lot of information to be aware of when buying and using probiotics


NCBI – A Review of Traumatic Brain Injury and the Gut Microbiome: Insights into Novel Mechanisms of Secondary Brain Injury and Promising Targets for Neuroprotection

University of Maryland Scool of Medicine – University of Maryland School of Medicine Scientists Find that Traumatic Brain Injury Causes Intestinal Damage

Dr Mark Hyman – Do probiotics really work?

NCBI – A Review of Traumatic Brain Injury and the Gut Microbiome: Insights into Novel Mechanisms of Secondary Brain Injury and Promising Targets for Neuroprotection

Endocrine Society – Magnetic brain stimulation causes weight loss by making gut bacteria healthier

Science Direct – Bidirectional brain-gut interactions and chronic pathological changes after traumatic brain injury in mice – From gut dysbiosis to altered brain function and mental illness: mechanisms and pathways

Psychosomatic Medicine – The Microbiome in Posttraumatic Stress Disorder and Trauma-Exposed Controls: An Exploratory Study