Our gut, also known as our ‘gastrointestinal tract,’ processes food from the time it enters our mouth until our body absorbs it and the unwanted matter is passed out. So gut health (or digestive health as the title suggests) refers to the health and wellbeing of our gut, and how well it processes food.
There are approximately 100 trillion micro-organisms in the human gastrointestinal tract, collectively referred to as ‘the microbiome.’
Each of us has a unique microbiome. It is determined by our genes and influenced by our diet, lifestyle, antibiotic use, our level of physical activity and the environment we live in.
Why is this important?
Firstly, because many of us experience digestive health issues:
- Around 1 million people in the U.K. have a serious bowel disease and at any one time IBS (irritable bowel syndrome) affects 10-20% of individuals.
- The most frequently experienced digestive symptoms in the U.K. include abdominal pain/discomfort, followed by diarrhoea, bloating, flatulence and constipation.
- And approximately 40% of people have at least one digestive symptom at any given point.
Secondly, because gut health problems may be implicated in a number of other illnesses:
- Recent research has found an association between the gut microbiome and risk of developing a number of chronic conditions such as cardiovascular disease, inflammatory bowel disease (IBD), obesity, type 2 diabetes, inflammatory skin diseases such as psoriasis and atopic dermatitis and autoimmune arthritis.
- The gut microbiome can also impact the ‘gut–brain–axis’ and conditions such as depression, schizophrenia, anxiety and autism have been associated with an altered gut microbiome.
An association between two factors doesn’t automatically mean that one causes the other, so more research is needed into whether there is a cause and effect relationship here – but, given the association, it does seem a possibility.
FACTORS AFFECTING THE GUT MICROBIOME:
A number of factors, particularly early in life, may affect how our gut microbiome develops:
- Babies delivered vaginally appeared to develop a microbiome with greater amounts of bacteria compared to those delivered by Caesarean section.
- Infants that were formula fed had a decrease in total number of bacterial species as compared to those that were breast-fed. The breast-fed group also had a reduced risk of age-related gastroenteritis.
- Insufficient fibre in our diet may result in the loss of certain bacteria leading to a decreased production of their helpful metabolites/end products.
Whilst bacteria were traditionally thought to be harmful to health, researchers have now found that many ‘good bacteria’ are beneficial to health and that it helps to have a diverse range of these ‘good bacteria’ in our gut microbiome.
To put it simply, a healthy gut is a happy gut!
- Maintaining a healthy gut is likely to enhance our immune function, reduce GI symptoms (like bloating, abdominal pain etc.), improve absorption of nutrients and reduce the risk of metabolic disturbances.
- The health of our gut is dependent on the balance of beneficial bacteria and pathogenic (harmful) bacteria that are present. When the levels of beneficial bacteria reduce and pathogenic bacteria levels increase this can allow bacteria to leak through the intestinal wall into the bloodstream. The phenomenon is known as ‘leaky gut’.
- This may be detrimental to the immune system in diseases like inflammatory bowel disease (IBD), diabetes, asthma, and in psychiatric disorders including depression, anxiety, and autism – although the NHS is sceptical as to how harmful this is, in practice, for most people.
SO HOW DOES OUR MICROBIOME and GUT AFFECT US?
As far as the food we eat is concerned, gut health affects our food choices and what we eat affects our gut:
- Diets high in fat, refined carbohydrates (sugars) and processed foods can cause an imbalance in the gut microbiome and result in symptoms such as bloating, acidity, constipation, etc.
- There has been a significant increase in both the incidence and severity of food intolerances and food allergies , particularly in developed countries, and scientists have identified one of the underlying causes as intestinal overgrowth.
- The gut microbiome also plays a critical role in managing inflammation & immunity (protecting the body from harmful bacteria that cause infections).
- Another important function of the microbiome is to synthesize vitamin K, B group vitamins and a number of essential molecules that are fundamental for daily functioning.
It is important tonote the difference between food intolerances (a digestive system response- i.e. difficulty digesting certain foods and having an unpleasant physical reaction to them) and food allergies (an immune system response, caused when the body mistakes an ingredient in food as harmful and creates a defence system to fight it).
DISEASE RISK ASSOCIATED WITH AN UNHEALTHY MICROBIOME:
In a healthy gut, the microbiota interact with the host and have a mutually benefiting relationship. The intestine provides the microbes with nourishment and an environment to grow, while the microbes contribute to maintaining homeostasis (a healthy steady state within the body) and modulate several physiological processes. The disruption of this balance may lead to a spectrum of chronic diseases.
- The microbes in the gut play a vital role in digestion, and may also influence whether we become obese or not
- There is a specific imbalance in the composition of the gut microbiome in individuals with type 2 diabetes compared with non-diabetic individuals. The specific imbalance was found to be associated with increased risk of insulin resistance.
- In the case of both IBS (irritable bowel syndrome) & IBD (inflammatory bowel disease) large–scale alterations have been seen in the abundance and diversity of certain bacteria in the gut.
- Healthy gut function has been linked to normal CNS (central nervous system) functioning, whereas a disturbed gut microbiome has been linked to behavioural and cognitive alterations (which include anxiety, depression, autism).
- Some studies have suggested that probiotic supplementation reduced anxiety and depression symptoms with a similar effect to regular prescription medication.
WHAT CAN YOU DO?
- Observe how your gut is functioning and pay attention if you experience any symptoms of discomfort particularly before and after a meal and throughout the day.
- If you do experience any unpleasant digestive symptoms, start maintaining a food diary to make a connection between what you are feeling and what you are eating.
- If you experience foods that don’t suit you; eliminate them for some time and then begin to reintroduce small quantities while observing how much you can eat without symptoms reappearing.
- Include generous portions of whole grains, fruits, vegetables and lentils to make sure that you get enough fiber in your diet, as this plays a crucial role in maintaining microbiome homeostasis. However increase fibre consumption gradually, as your body takes time to adapt.
- Reduce intake of inflammatory foods (foods that are highly processed, high in fats, sugar and refined carbohydrates).
- Replenish and maintain good bacteria through consumption of probiotic rich foods and fermented foods (yogurt, tempeh, miso, kefir, kombucha, sauerkraut, kimchi etc).
- Discuss with a nutritionist or a medical professional whether a probiotic supplement is likely to be helpful.
- Ensure you get 30 minutes of physical activity at least three times a week, as current research shows that exercise has a beneficial impact on gut microbiota diversity.
Hannah Kurian September 2018. Review date August 2022.