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Gut Health

Bacteria Buzzwords

Bacteria Buzzwords
Abbie Alston
Writer and expert2 years ago
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If you’ve just started learning more about your gut function, some terms may make it confusing to get to grips with! That’s why we’ve put together a list key words used when talking about the gut, along with their definitions, to help you make sense of it all.

The Gut MicrobiotaThe Gut MicrobiomeBacteriaConstipationDiarrhoeaDigestive SystemDysbiosisGut-Brain AxisLeaky GutImmune SystemIrritable Bowel SyndromeProbioticPrebiotic

The Gut Microbiota

The terms ‘Microbiome’ and ‘Microbiota’ are often used interchangeably, but actually mean different things. The gut microbiota consists of a wide variety of bacteria, viruses, fungi, and other microorganisms that live I the human gut – don’t worry, although some of these microorganisms might sound strange, they are all completely normal and are found in each and every one of us!

The Gut Microbiome

The gut microbiome refers to the entire habitat of the human gut, including the microorganisms in the microbiota, their genes, and the surrounding environmental conditions.

Think of it as a house – the gut microbiota are like the residents of the house, and the gut microbiome is the home, made up of the residents, their house, their belongings, the central heating, the food, the carpet and even the wallpaper! It is everything in that environment.

Although it is established during infancy, we can influence the balance of our gut microbiome at all stages of life through diet, exercise, sleep and the environment we live in.

Learn more: Why not read more about Gut Health Foods


Bacteria are teeny tiny single-celled organisms that are found just about anywhere – on the ground, in the sea, on our skin and in our gut. They are classified into five different groups, depending on their shape, and although we often think of bacteria as ‘bad’, some are actually friendly bacteria that are found naturally in our bodies, and may be passed from mother to baby at birth.


Bowel movements vary considerably between individuals, and what is normal for one person may not be normal for another. Did you know a normal range may be anywhere between three bowel movements a day to three bowel movements a week? Constipation is defined as having less than three bowel movements (or poo!) a week, poos that are large, dry, hard or lumpy, or straining when you have a poo. Constipation can result from a number of things, but some common causes are dehydration, lack of fibre in the diet, inactivity, medication and conditions such as IBS. If you do notice any changes in your bowel movements, you should contact your healthcare professional.


Moving to the other end of the spectrum, diarrhoea is defined as three or more loose stools a day. In normal bowel movements, stools are solid because the gut and intestines absorb the nutrients and fluids from our food, and pass on the waste to be secreted. However, if there is a problem during this process, stools can become less formed, and more loose. Diarrhoea can be a result of many things, for example IBS, gastroenteritis, medications, stress and anxiety or food intolerances. Though most episodes of acute diarrhoea get better with time, it is important to speak to your healthcare professional with any changes in your bowel movements.

Digestive System

The digestive system is uniquely designed to break down food, absorb nutrients and excrete waste. It is a series of complex processes that turn the food we eat, be it an apple, a pizza or a sandwich, into nutrients our bodies need for energy, growth and cell repair. As the name suggests, it is a system, with food passing from the mouth through the oesophagus, stomach, small intestine, large intestine, rectum and finally being excreted at the anus.


Our guts are home to millions of different bacterial cells, in fact, there are more bacteria in your gut than there are cells in the body – that’s a lot! For the most part, these bacteria live in harmony in out guts, however, as they are sensitive little things, their balance and diversity can easily be disrupted – this is called dysbiosis.

Gut-Brain Axis

The gut-brain axis is exactly that, a constant communication pathway between the gut and the brain. The two are connected both physically, via the vagus nerve, and biochemically. Think of it as a never-ending loop, from the brain to the gut, and the gut to the brain, sending a constant stream of messages to the other. It explains why we feel butterflies in our tummy when stressed or anxious, and why gut function is so important for our mental health.

Learn more: Why not read more about the Gut-Brain Axis

Immune System

The immune system is an intricate network of communications and pathways working in synchrony to protect us from harm. It does this by detecting threats such as bad bacteria, viruses or other pathogens, allergens and toxins, and signals the body to launch its defence. Some parts of the immune system get to work immediately, whereas others are slower but better at remembering threats and how to defend against them in the future.

Learn more: Why not read more about Gut Bacteria and the Immune System

Irritable Bowel Syndrome

As mentioned above, irritable bowel syndrome (IBS) is a relapsing long-term condition that affects the digestive system. It is quite common, affecting 1 in 10 people globally, causing symptoms like abdominal pain, bloating, constipation and diarrhoea. Whilst we still don’t know exactly what causes IBS, it is thought there are a number of contributing factors such as stress, food intolerances, gastroenteritis, changes in the gut microbiome, and gut-brain interactions.


The walls of our intestines are made up of lots of cells, lined up together with tight junctions between each one. These cells act as a barrier, controlling what substances pass through during digestion – so allowing water and important nutrients, which will then be used in our bodies, to pass through. When the junctions between each cell become loose, additional substances such as toxins, pass from the gut into the bloodstream, and this is what we mean by ‘leaky gut’.


A term we are hearing more and more often, but what does it actually mean? According to the EC Regulations covering nutrition and health claims in the UK, the term ‘Probiotic’ cannot be used in communications to the general public, as currently, there are no authorised health claims, making them very difficult to talk about! But to make it a little easier for you, the term ‘Probiotics’ is often used to describe ‘friendly bacteria’, or ‘live cultures’.


Prebiotics are the ‘food’ for the good bacteria in our guts. They are non-digestible carbohydrates that pass through to the gut and help the good bacteria to grow. Prebiotics can be found naturally in the diet, in foods such as onions, garlic, chicory root, asparagus and bananas.


Overall, the gut function is fascinating but it doesn’t have to be confusing. You can learn more about the gut, the immune system and the microbiome through our blog where we make things a little less complicated.

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Abbie Alston, PrecisionBiotics Nutritionist

Abbie Alston
Writer and expert
View Abbie Alston's profile
Abbie Alston is a Registered Nutritionist with the Association for Nutrition (AfN), a professional and regulatory board for qualified nutritionists. She completed her nutrition degree at Bournemouth University and has a BS in Nutrition Sciences. Abbie has worked in the medical nutrition industry for over seven years, working with products that will promote a healthy gut microbiome in children and in adults, and can be used in a range of medical conditions. She now works as a Nutrition Science Liaison at PrecisionBiotics Group, helping to connect consumers and nutrition professionals with the science of the gut microbiome and its impact on health.