The Impact of Gut Health

Why our gut health is critical to our overall health

The role of our gut in health and disease is a topic of interest for a number of researchers and health professionals and for good reason with poor gut health recognised as contributing to a number of chronic conditions not only affecting the digestive system but other organs such as the brain.

It is interesting to note that the idea of gut health impacting our overall health and wellbeing isn’t new. The father of modern medicine and Ancient Greek physician, Hippocrates is quoted as saying ‘All disease begins in the gut’ almost 2500 years ago.

Our gut is home to over 100 trillion microorganisms that have an important role in keeping us healthy. These microorganisms, that are mostly bacteria, are responsible for producing vitamins, acting as a barrier for the immune system, fighting harmful invaders, helping to digest food and supporting healthy digestive and immune function.

Our gut bacteria also produce short-chain fatty acids (SCFAs) that have a role in gut health, blood sugar control, weight management and immunity. Bacteria produce SCFAs in the colon through a process called fermentation when the bacteria feed on non-digestible dietary fibre, also known as prebiotics. These SCFAs that are produced include butyrate, acetate and proponate.

Gut health affects digestive function

Our gut bacteria have an important role in ensuring healthy digestive function. A number of digestive complaints have been linked to imbalances in gut bacteria.

Beneficial bacteria and the SCFAs they produce help improve the transportation of food through our large intestine and provide the cells in our colon with energy.

Gut bacteria also help nourish and strengthen the protective mucous layer of our gut lining that’s necessary for healthy digestion. If our gut lining becomes damaged it is possible for harmful bacteria, food particles and toxins to flow through the intestinal wall and enter the blood stream.

Gut health affects immunity

Approximately 70% of our immune system is located in gut associated lymphoid tissue, highlighting the importance of a healthy gut and balanced gut bacteria for proper immune function. Beneficial bacteria help to teach our immune system what foreign invaders it should fight against.

Beneficial bacteria also support immune function as they help prevent harmful bacteria from becoming dominant in the digestive tract. They do this by competing with the harmful bacteria for nutrients, space in the digestive tract and by producing short chain fatty acids to make it harder for harmful bacteria to survive.

Gut health affects our weight and blood sugar control

Our gut bacteria are understood to have a role in maintaining blood sugar levels and weight management. Particularly, the SCFAs produced by beneficial bacteria impact how energy is metabolised.

Gut health affects mood and brain function

A healthy gut and balanced gut bacteria are recommended for maintaining healthy brain function and mood. Imbalances in gut bacteria have been linked with low mood and impaired ability to cope with stress.

The number and type of bacteria in our gut is understood to impact our brain function, attention, and emotional responses.

We also understand that the gut is responsible for the production of hormones and chemical messengers called neurotransmitters that affect mood. The gut produces an estimated 95% of the neurotransmitter serotonin that helps us feel happy.

With research increasingly showing the influence of gut bacteria on our digestive health, immune function, weight management and mood there is plenty of reason to want to look after your gut bacteria. Nurture your gut bacteria and help them with SCFA production by eating a varied and balanced diet with plenty of fibre, prebiotic and probiotic rich foods.

The Brain and the gut

How the gut influences the brain

Our gut is often referred to as our second brain and while it isn’t responsible for making complex decisions, it does have a powerful role in how our brain functions.

You have probably experienced the connection between your gut and brain before when you have felt butterflies in your stomach before a big presentation, or when you have felt sick in the stomach after receiving some bad news.

The brain and gut communicate with each other through the central nervous system and enteric nervous system. This is called the gut-brain axis. The trillions of bacteria in our gut are able to stimulate neurons of the enteric nervous system that allows the gut to send signals to the brain, as well as receive messages from the brain. This occurs via the vagus nerve, a nerve that is responsible for unconscious body functions such as digesting foods and regulating our heart rate.

Our gut is also responsible for making hormones and chemical messengers called neurotransmitters that communicate with our brain. One neurotransmitter of particular interest is serotonin, a chemical that makes us feel good. It is estimated that 95% of serotonin is made in the gut suggesting the potential role for gut health to impact our mood.

Understanding the link between our gut and brain helps us to understand that changes to our gut bacteria have the potential to alter digestion and brain function. Gut bacteria can become imbalanced where the bad bacteria in our gut dominate our good bacteria. This imbalance is referred to as dysbiosis and can occur as a result of infection, antibiotic use, poor diet, smoking, alcohol consumption, stress or poor sleep. Early research associates dysbiosis with a number of conditions that alter brain and digestive function.

The gut’s role in mental health and cognitive function

Impaired gut health and gut bacteria are associated with a number of mood disorders such as low mood and impaired cognition. Research in humans is exploring exactly how our gut bacteria have a role in brain function and mental health.

The bacterial strains Oscillibacter and Alistipes appear to be linked to an altered stress response, while consumption of the probiotic Bifidobacterium longum NCC3001 alters gut bacteria and can improve the quality of life in some patients.

Preliminary research on the impact of gut bacteria on brain function has shown that variations in gut bacteria are associated with a heightened emotional response. A study of healthy women has shown that women with a greater number of Bacteroides bacteria present in their gut experience a heightened response when shown negative imagery compared to women with a greater number of Prevotella bacteria.

How the brain affects the gut and digestion

Just as our gut has the potential to influence our brain, our brain can also impact our gut and digestive health. Our brain can affect our digestive system functions by initiating intestinal contractions and digestive enzyme secretions, as well as increase our susceptibility to infection.

We can also see the impact our brain has on the gut in times of heightened stress. Elevated stress can disrupt our gut bacteria balance and exacerbate symptoms in various digestive conditions.

How to support gut and brain health

If you want to achieve optimal brain function and a healthy mood, eating a healthy diet and practicing healthy lifestyle habits may be worthwhile. A diet rich in fibre, prebiotics and probiotics and low in sugar, processed carbohydrates and bad fats is recommended to support brain and gut function. Combine this diet with regular exercise, adequate sleep and stress management for optimal gut and brain health.

How gut bacteria affect our immune system

Our intestines contain more immune cells than the rest of our body. With over 70% of our immune system located in our gut, it is easy to see why looking after our gut and the bacteria that live there is important for immune health.

Our immune system protects us from foreign invaders such as germs, parasites and abnormal cells. It is also responsible for recognising what materials belong to us and what are harmful foreign materials. A healthy immune system recognises harmful materials and attacks the material to prevent it from causing harm.

However immune system malfunction can sometimes cause the body to mistake its own tissue for harmful material and attack the healthy tissue. Allergies can also occur from immune dysfunction. This is where the body mistakes a harmless foreign material as harmful, causing the immune system to overreact and damage normal tissues.

Our gut bacteria have an important role in supporting the immune system and maintaining immune health. Our gut bacteria tell our immune system what to fight against and help modulate the immune system response. Our gut bacteria produce short-chain fatty acids that are anti-inflammatory and needed for a healthy immune response. The bacteria in our gut also strengthen the gut lining and compete with harmful bacteria for nutrients and space in the digestive tract. When harmful bacteria are unable to find space and have insufficient food they are unable to dominate the gut.

Alterations in our gut bacteria can impact immune health and cause inflammation. Imbalance in our gut bacteria is called ‘dysbiosis’ and can be caused by antibiotic usage, infection, pregnancy and lifestyle changes. Dysbiosis has been linked to the development of a number of inflammatory conditions affecting health.

The role of gut bacteria in healthy immune function can be seen in allergy and asthma sufferers. Infants who develop allergies and asthma later in life have altered immune responses to gut bacteria from an early age. At one year of age they have a lower number of immunoglobin A (IgA) antibodies bound to their gut bacteria at one year of age compared to infants who stayed healthy. IgA is a protein made by the immune system that helps to fight foreign invaders. Reduced gut bacterial diversity is also associated with allergy and asthma sufferers.

Understanding that our gut bacteria have a role in immune development and function highlights the importance of looking after our gut bacteria for healthy immunity. Achieve gut bacteria diversity and balance by avoiding high consumption of foods that contain bad fats and sugars and reduce the overuse of antibiotics that may damage gut bacteria. Mothers should also opt to deliver their children naturally and breastfeed where possible to promote optimal gut bacteria development. If you want to encourage the growth of beneficial bacteria including foods that are high in fibre, prebiotics and probiotics in your diet can also be beneficial.

How gut health can affect your skin

When we think about trying to achieve radiant skin many of us would not consider our gut, although it may be a worthy consideration given the potential link between the health of our gut and our skin.

A number of individuals suffering from skin conditions also suffer from digestive complaints highlighting a potential relationship between gut and skin function. This is recognised as the gut-skin axis.

In our gut we have over trillions of bacteria that help to maintain our health by supporting digestive, immune and metabolic function. Any damage to these bacteria can cause skin or internal inflammation and increase our risk of infection. It can also cause our immune system to overact to foreign materials and attack our own body tissues by mistaking them for harmful invaders.

Another way that gut health affects skin integrity and promotes inflammation is when there is intestinal permeability. Intestinal permeability is when there is damage to the gut lining that allows foreign particles to pass through the gut lining and into the blood stream possibly causing inflammation.

The potential for our gut bacteria to impact our skin health is evident as supplementing with the probiotic Lactobacillus paracasei NCC 2461 has been shown to enhance skin health and reduce skin sensitivity.

How gut health affects acne

Acne is a common skin condition experienced by 85% of the population at some stage during their life. Acne is when there is inflammation of the pores in the skin caused by hormones, skin oils and bacteria. This can result in red bumps, pimples, blackheads, whiteheads and/or cysts that occur on the face or body.

Impaired gut health may have a role in the development of acne with 54% of acne sufferers shown to have altered gut bacteria compared to healthy individuals. Individuals with acne are also more likely to suffer from gut symptoms such as constipation, bad breath, gastric reflux and abdominal bloating.

Intestinal permeability may be one reason for this with acne sufferers having a larger number of lipopolysaccharide (LPS) endotoxins that can cause inflammation. This inflammation may contribute to the development of acne development by increasing oil production in the skin.

To support gut integrity and prevent intestinal permeability it is best to avoid overeating and consuming high amounts of bad fats and sugar. Including prebiotics and probiotics in your diet is also an effective method to support your gut health.


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