Introduction to gut health
Gut health is a vital aspect of our overall wellbeing - and it involves so much more than just digestion. Each day we are learning more and more about how the gut affects our body in regions well beyond the gut itself.
Our gut plays a crucial role in not only breaking down food but also in nutrient absorption, immune function and even mental health and skin health.
As we will learn below, gut health is strongly affected by various factors including diet, lifestyle, sleep and stress levels.
Anatomy of the gut
The gastrointestinal tract (ie the gut) begins with the mouth, where the digestion process starts as we chew our food. Here the food is mixed with saliva that contains enzymes to break down carbohydrates.
From there, food travels down the oesophagus to the stomach which uses its acids and enzymes to further break down the food into a semi-liquid form. The next stop is the small intestine, where the majority of nutrient absorption occurs. Here, with the help of enzymes from the pancreas and bile from the liver, nutrients are extracted and absorbed into the bloodstream.
The large intestine (or colon) follows, where water and electrolytes are absorbed from the remaining indigestible food matter. This process turns the waste into stools, which are then excreted from the body.
The gut microbiome
The gut microbiome refers to the vast community of microorganisms (primarily bacteria, but also fungi and viruses) that reside in our digestive system, especially the large intestine. This complex ecosystem is crucial to many aspects of our health. It helps break down food, absorb nutrients, and even synthesises some vitamins and amino acids that our body can't produce on its own.
These microbes also play a significant role in our immune system and help to protect against harmful pathogens. They also produce neurotransmitters and other chemicals that can influence our brain function and mood.
Each person's gut microbiome is unique and is influenced by their diet, lifestyle and environment.
Benefits of having a healthy gut
They are many and varying - and affect many parts of the body outside the gut.
Some key benefits of a health gut are:
Improved digestion: A gut in healthy balance will break down food and absorb nutrients more efficiently. This reduces the severity of common digestive issues like bloating, gas, IBS, diarrhoea and constipation
Reduced inflammation: Having a healthy gut can help reduce inflammation.
Immune function: Studies have shown beneficial bacteria in our gut promote a more resilient immune system.
Mental health: Beneficial microbes in our gut may influence mood, brain function and emotional wellbeing. More on the gut-brain axis below.
Reduce severity of allergies: Certain beneficial microorganisms in our gut have the potential to reduce the severity of allergic conditions, particularly in children and infants.
Heart health: Some microorganisms may protect against cardiovascular diseases by lowering bad cholesterol and improving blood pressure.
Skin health: Gut health affects skin health by influencing inflammation, immune response and nutrient absorption. Imbalances in the gut microbiome are often linked to conditions like acne and eczema.
Tolerance to lactose: Some microorganisms can improve the digestion of lactose and make dairy products more tolerable to some people.
Weight management: Some microorganisms can aid in weight management by influencing appetite and energy usage in the body.
The gut–brain axis
The gut-brain axis is a strong nerve connection between our gut and the brain and studies have shown there is a profound connection between our gastrointestinal system and mental health.
The main aspect of this connection is the vagus nerve which allows signals to be sent between the gut and the brain, and vice versa. We are learning more about this connection all the time, but it is thought that this connection strongly influences both physical and mental health.
The gut is often referred to as our 'second brain' because of its ability to operate independently of the brain and spinal cord. It contains a vast network of neurons and produces a range of neurotransmitters, including a significant amount of serotonin, which plays a key role in regulating mood.
The gut microbiome, with its trillions of bacteria, is integral to this axis. These microbes produce substances which can influence our emotions, pain perception and stress responses. As well as this, our brain can affect gut health as stress and anxiety can lead to digestive issues like irritable bowel syndrome (IBS). These gut issues can then further exacerbate mental stress in a vicious cycle.
In contrast, a healthy gut can contribute to a more positive mood and better mental health.
Prebiotics
Prebiotics are typically indigestible fibres or sugars which the beneficial bacteria in your large intestine use as food. Prebiotics provide sustenance for these microbes and allows them to multiply. The process also produces by-products called postbiotics which are beneficial to our health.
Common examples of prebiotics include: inulin, fructooligosaccharides (FOS), galactooligosaccharides (GOS), xylooligosaccharides (XOS), polydextrose, isomaltooligosaccharides (IMO) and acacia gum.
While supplements can make it easy to get prebiotics in your system, it’s perfectly possible to get all your prebiotic needs from eating the right whole foods and especially prebiotic vegetables such as onions, leeks, artichokes and whole grains.
Probiotics
Probiotics are live microorganisms, such as bacteria or yeast, that provide health benefits to us - especially to our gut.
To be considered a probiotic, these microorganisms need to have been proven to be sufficiently beneficial to our health - so not all live bacteria or yeasts are considered probiotic.
Common probiotic strains include:
Lactobacillus: Found in yogurt, kefir and fermented foods
Bifidobacterium: Found in some dairy products and supplements
Streptococcus thermophilus: Used in making yogurt and cheese
Bacillus coagulans: Found in certain probiotic supplements and foods. Especially common in commercial kombuchas
Saccharomyces boulardii: A beneficial yeast used in some supplements
Probiotics are available in various forms - usually in fermented food and drinks or as a supplement.
Probiotic foods
Various traditional, fermented foods provide good levels of probiotics.
Some common examples are:
kimchi
sauerkraut
yoghurt
cheese
olives
Probiotic drinks
Similar to fermented foods, there are many traditional fermented drinks which are rich in probiotics.
Some examples are:
kefir: one of the richest and most diverse sources of probiotics
traditional ginger beer (not commercial soft drink versions)
tepache: a fermented pineapple drink
Probiotic supplements
Supplements can be a great way to complement a healthy diet rich in probiotic foods.
They can be especially beneficial:
in times of general poor gut health
after antibiotics
during bouts of diarrhoea or constipation
after food poisoning
during skin outbreaks
during periods of poor immunity
Postbiotics
In very simple terms, postbiotics are things which probiotics (ie beneficial bacteria) produce which are healthy for us. Unlike probiotics, which are live organisms, postbiotics are not living things.
Postbiotics can be produced in our own guts by healthy bacteria or by the healthy bacteria in fermented foods.
There are many types of postbiotics and some of the most common and important for our health include:
short-chain fatty acids such as butyrate
bacteriocins which are antimicrobial peptides
exopolysaccharides which are complex sugar molecules
vitamins such as vitamin K and various B vitamins (eg B12 and folate)
These postbiotics collectively support gut health by:
nourishing gut cells
reducing inflammation
improving gut barrier integrity
enhancing immune function
promoting beneficial bacteria
regulating bowel movements
aiding nutrient absorption
deterring harmful microbes
supplying essential nutrients that support blood clotting, energy production, nerve function and DNA synthesis
Getting postbiotics
Postbiotics can be found in fermented foods which are rich in probiotics. As these probiotics ferment fibre in the food they produce postbiotics.
Examples of such foods include yogurt, kefir, sauerkraut, kimchi and miso. These foods not only provide a source of probiotics but also contain the beneficial postbiotics produced during the fermentation process.
To increase the production of postbiotics in our gut, we should focus on a diet rich in prebiotics and probiotics. By consuming prebiotic-rich foods we can stimulate the growth and activity of beneficial gut bacteria, which in turn produce more postbiotics.
Gut health nutrition
A nutritious diet is fundamental for maintaining a healthy gut. Eating a variety of fruits, vegetables, legumes, nuts, seeds and grains ensures an influx of different fibres, vitamins, minerals, polyphenols and antioxidants.
Diversity in diet causes a healthy diversity in gut flora. Try to ‘eat the rainbow’ - that is a wide variety of natural, whole foods of different colours. Following this simple rule can help create a varied diet without much thought and fuss.
Read more about the best foods for gut health.
The role of fibre in gut health
Fibre plays a key role in maintaining gut health. It's not just essential for regular bowel movements, it also feeds the beneficial bacteria in our gut microbiome. There are two types of dietary fibre: soluble and insoluble. Soluble fibre, found in foods like oats, apples and beans, dissolves in water and helps to regulate blood sugar levels and reduce cholesterol. Insoluble fibre, present in whole grains, nuts and vegetables, adds bulk to stool and helps prevent constipation.
A diet high in fibre has been linked to a reduced risk of chronic diseases like type 2 diabetes and heart disease.
Prebiotic vegetables
Certain vegetables stand out for their superior prebiotic content such as garlic, onions, leeks, asparagus, Jerusalem artichokes, radishes, beets and parsnips. These vegetables contain fibres and compounds that our bodies cannot digest. Instead, these fibres act as food for our gut bacteria which promotes their growth and activity.
These prebiotic vegetables give you the best bang for your buck if you’re trying to increase your vegetable intake for gut health, but ultimately all vegetables are good!
Fermented foods
Fermented foods such as yoghurt, kefir, sauerkraut and kimchi undergo a process of lactofermentation where bacteria feed on the sugar and starch in the food, creating lactic acid. This process not only preserves these foods but also creates beneficial enzymes, B vitamins, short-chain fatty acids and a thriving colony of probiotics.
Regular consumption of these fermented foods can help create a diverse and balanced gut microbiome. Additionally, fermented foods can aid in restoring the gut flora after it has been disrupted, for example, by antibiotics or a poor diet.
Hydration
Hydration plays an important role in maintaining gut health. Adequate water intake is crucial for digestion as it helps to break down food and increase nutrient absorption. Water also aids in softening the stool which helps prevent constipation. By assisting in the smooth movement of waste through the digestive tract, proper hydration ensures that toxins and waste are removed from the body.
Foods to avoid for gut health
Maintaining gut health involves not only adding beneficial foods to your diet but also being mindful of those that can be harmful. Certain foods can disrupt the balance of your microbiome and should be consumed in moderation or avoided.
Processed and high-sugar foods: Foods high in refined sugars and processed ingredients can feed harmful bacteria and yeasts which can cause an imbalance in your gut. This includes sugary snacks, soft drinks and most processed foods.
Artificial sweeteners: Some studies suggest that artificial sweeteners like aspartame and sucralose may negatively affect the gut microbiome. They can potentially inhibit the growth of beneficial gut bacteria.
High-fat foods: Excessive intake of saturated fats found in fatty meats, butter and some dairy products can contribute to a less diverse and more inflammatory gut environment. Trans fats, often found in fried and baked goods, are particularly harmful.
Red meat: Regular consumption of large quantities of red meat has been linked with the presence of certain bacteria known to trigger inflammatory responses in the gut.
Alcohol: Excessive consumption of alcohol can erode the gut lining which disrupts microbial balance and increases inflammation. On top of this, drinking alcohol can promote the eating of unhealthy foods both when drinking and the following day as a hangover cure. Potentially leading to quite an unhealthy period for the gut!
Caffeine: For some individuals, too much caffeine can irritate the gut which may lead to symptoms like acid reflux, indigestion and diarrhoea.
Gluten and dairy: For those with sensitivities or intolerances, gluten and dairy can cause inflammation and gut discomfort. It's important to listen to your body and avoid foods that consistently cause issues. If you are suffering from gut issues, you may like to try periods without these foods to see if it improves your symptoms.
Common gut health issues
Gut health issues are increasingly common and can range from mild discomfort to more serious conditions. Below are some common examples.
Irritable bowel syndrome (IBS)
IBS is a common disorder affecting the large intestine. It is characterised by symptoms like cramping, abdominal pain, bloating, gas, and diarrhoea or constipation. While the exact cause is unknown, it's thought to be linked to a combination of gut-brain axis issues, poor gut motility and sensitivity to certain foods.
Gastroesophageal reflux disease (GERD)
GERD occurs when stomach acid frequently flows back into the oesophagus. This can irritate the lining of your oesophagus and cause heartburn, regurgitation and sometimes difficulty swallowing.
Inflammatory bowel disease (IBD)
This term primarily covers two conditions – Crohn's disease and ulcerative colitis. Both involve chronic inflammation of the gastrointestinal tract and can cause severe diarrhoea, fatigue, weight loss and malnutrition.
Celiac disease
A serious autoimmune disorder where the ingestion of gluten leads to damage in the small intestine. Symptoms include diarrhoea, bloating, gas, fatigue and anaemia.
Food intolerances and allergies
These occur when the digestive system reacts adversely to certain foods, leading to symptoms like nausea, bloating and abdominal pain. Common culprits include lactose and gluten.
Small intestinal bacterial overgrowth (SIBO)
SIBO happens when there is an abnormal increase in the overall bacterial population in the small intestine, particularly types of bacteria not commonly found in that part of the digestive tract. (Remember, most bacteria usually reside in the large intestine.)
Leaky gut syndrome
Although not a medically recognised condition, this term is used to describe increased intestinal permeability where bacteria and toxins can pass into the bloodstream, potentially causing widespread inflammation.
Managing issues
These issues can significantly impact quality of life but are often manageable through a combination of diet, lifestyle changes and medical treatment. If you suspect you have a gut health issue, it's important to consult with a healthcare professional for an accurate diagnosis and appropriate treatment plan.
Gut health through life stages
Gut health influences our overall wellbeing from birth to old age.
Infancy and early childhood
A child's gut microbiome begins to develop at birth. It is influenced by factors like how the baby is delivered and whether it is breastfed. Breast milk not only provides essential nutrients but also prebiotics that promote the growth of healthy gut bacteria. As children transition to solid foods, a diverse diet rich in fruits, vegetables and other whole foods helps establish a robust gut microbiome.
Adolescence
This period brings significant hormonal changes that can impact gut health. This is also a key time to establish healthy eating and lifestyle habits that will benefit gut health in the long term.
Adulthood
Maintaining a balanced diet, managing stress, sleeping well and staying active are essential for keeping the gut healthy and functioning properly in adults.
Older age
As we age, changes in the gut microbiome can lead to issues with digestion and nutrient absorption. A focus on fibre-rich foods, adequate hydration and probiotic supplements can help maintain gut health during this period of life.
Lifestyle and gut health
Daily habits and everyday choices significantly influence the health of our gut.
Exercise and gut health
Engaging in regular physical activity has been shown to significantly improve the diversity of the gut microbiota.
Exercise also stimulates the muscles in the gastrointestinal tract which promotes regular bowel movements. This is particularly beneficial for those suffering from constipation or irregular bowel habits. By improving the movement of stools through our gut, exercise ensures that waste and toxins are effectively removed from the body.
Additionally, the benefits of exercise extend beyond the gut. By enhancing cardiovascular health, regulating blood sugar levels and reducing stress, physical activity creates a positive feedback loop that further supports gut health. Lower stress levels, for instance, can reduce the likelihood of gastrointestinal issues like irritable bowel syndrome (IBS) and acid reflux.
Stress and gut health
Chronic stress can have a profound effect on the digestive system, often leading to disrupted digestion and exacerbating conditions such as irritable bowel syndrome (IBS) and gastroesophageal reflux disease (GERD). Because the gut and brain are closely linked through the gut-brain axis, emotional and mental stress can directly impact gut function.
Activities like meditation and yoga not only calm the mind but also benefit the gut by reducing the physiological stress responses that can disrupt digestive processes. These practices also lower cortisol levels, a stress hormone, that when elevated can lead to inflammation and imbalances in gut bacteria.
Simple breathing exercises are another practical tool for stress management. Deep breathing can help activate the body's relaxation response which can reduce stress and improve oxygenation.
Sleep and gut health
The body’s circadian rhythms, which regulate sleep, are closely linked to the gut. This means that disrupted sleep patterns can affect the gut microbiome. Lack of sleep or irregular sleeping patterns can lead to imbalances in gut bacteria, which in turn can cause or exacerbate digestive issues such as bloating, gas and irregular bowel movements.
During sleep, the body undergoes repair and rejuvenation processes that are essential for a healthy digestive system. Adequate sleep also helps to regulate hormones that control appetite and digestion.
Try to maintain a regular sleep schedule and avoid stimulants such as caffeine and electronics before bedtime.
Healthy gut habits
Nurturing gut health is an ongoing exercise which requires day-to-day attention.
The key to maintaining a healthy gut lies in healthy eating habits and moderating the frequency and severity of our naughty binges. Try to be mindful of everything you eat and drink - think about how this food will make you feel afterwards and consider whether that food choice will help or hinder your goal of having a healthy gut.
But most of all, if you have a bad day of eating, don’t give up - come back the next day and try to eat better. Eventually the cravings for bad food will subside as you build a healthy gut. You will start to want the foods which leave you feeling good and want to avoid the foods which make you feel bad. You will soon create a virtuous cycle of healthy eating and cravings.
Read my story for a first-hand account of breaking a bad eating cycle.
Top 10 tips for gut health
Eat a wide variety of whole foods such vegetables, legumes, grains, nuts, seeds and fruits
Limit processed foods
Incorporate fermented foods
Drink ample water daily
Use antibiotics judiciously and only when prescribed
Consider probiotic and prebiotic supplements to support gut health
Exercise regularly to promote healthy gut movements
Adopt relaxation techniques such as mindfulness or time spent in nature
Ensure you get enough sleep
Limit caffeine and alcohol
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