Gut health 101 - your gut microbiome
By Dr Marissa Kelaher
Gut health is a MASSIVE topic, and one that lots of people are interested in right now - for good reason!!
Research increasingly shows that our gut health, in particular our gut microbiome, plays a big role in our overall health.... affecting everything from mental health to allergies, and even our risk of heart attacks and cancer .
Yet its also an area where a lot of misinformation abounds… so if you want to know the REAL facts, read on!!
This is the first blog post in a series on gut health - as it's a massive area with a lot to talk about - our second one covers simple ways to improve your gut health.
The gut microbiome is also a fairly complex topic, so we'll try to break it down and give you the key points you need to know (without needing a medical degree 😉)
In this first post we'll talk about the basics of how our gut microbiome works and why it's the key for gut health.
Our next one dives more into how to create a healthy gut, based on solid scientific evidence, rather than social media trends ;-)
And for a full exploration of how gut health works, and how to optimise it, check out our Nutrition and Reboot courses. We also have loads of resources on gut health topics in our members area!
So WHAT IS OUR GUT MICROBIOME?
The gut microbiome refers to all of the microbes in your intestines - did you know we have so many microorganisms in our intestine, they weigh about the same as a human brain (1-2kg)??!
This is why the gut microbiome is often referred to as an organ system - not surprising when you understand all the functions it has in our body.
For many years, scientists were only able to detect around 200 different microbes using traditional techniques (culturing them in the lab). As most gut microbes are anaerobic (don't need oxygen), they are very difficult to culture outside the human body.
Yet when DNA sequencing was discovered, we started to realise there were FAR more microbes in our guts than we ever imagined - between 16-30,000 different ones have been found in humans so far, and this number is growing!!!!
HOW THE GUT MICROBIOME AFFECTS HEALTH
Our gut microbiome is made up of bacteria, fungi, viruses, parasites, and archae (ancient microorganisms).
Bacteria seem to play the main role in health as far as we know at present.
Our microbiota are involved in many key functions in our bodies, including:
food breakdown
blood sugar control
hormone regulation
maintaining a healthy weight
reducing inflammation
training our immune system to work well.
The 'good' bacteria in our gut also increase the acidity levels in our gut, making vitamins, improving digestion and inhibiting the growth of bad bacteria, protecting us from tummy bugs such as salmonella, campylobacter, and E coli.
Having a 'healthy' microbiome (ie the right balance of bacterial species) is shown to be linked with a lower risk of
food allergies
autoimmune disease
asthma
digestive disorders such as crohns and colitis
even severe covid and long covid!!!
Our microbiota also play an important role in our brain health, mood, and ability to deal with stress, as they sends messages to and from the brain via the gut brain axis.
PLUS there is emerging research they are involved in other areas of our health, such as heart disease, diabetes, and even cancer risk!!
If this isn't enough to make you want to pay attention, did you know our gut bacteria play a key role in keeping our intestinal wall healthy, and preventing what is commonly known as 'leaky gut' (intestinal permeability)?
And the more ‘good ‘bacteria we have, the more they encourage the growth of other ‘good’ bacteria, via producing fuel them.
They truly are at the root of a healthy gut and healthy life!!
SO WHAT IS DYSBIOSIS?
We use the term ‘dysbiosis’ to refer to a loss of microbial balance within the gut.
In a healthy gut we ideally want a diverse population of different microbes, with lots of 'good' bacteria - the ones shown to promote health, and not many ‘bad’ ones (ie enough good to balance or suppress the bad).
Research consistently shows that having a greater diversity of gut microbes (ie lots of different types) is linked with better health and a lower risk of many diseases, including type 2 diabetes, obesity, high cholesterol and inflammation.
This research also shows that eating a large variety of different whole plant foods each week is THE BEST way to have a diverse gut microbiome.
You may have heard of the '30+ a week' concept - this is based on gut microbiome research, and refers trying to eat 30 different types of plant foods each week to feed your gut bugs!! It isn’t just fruit and veges that count for the 30+ either - this also includes whole grains, legumes, herbs and spices - which also taste so good too ❤️
Think of your gut as a garden, with different microbes all needing different types of nutrition to have a lovely range of diverse species.
In contrast, when we have dysbiosis, this means our 'good' bacteria levels are lower, and we have more 'bad' bacteria in our gut aka a less healthy microbiome.
Within just 2 weeks of reducing fibre in our diet, the changes in our gut microbiome can start to damage our gut cell lining, causing inflammation and all the issues related to this
But ‘feeding ‘our gut with fibre and fermented foods, can dramatically improve our gut microbiome diversity, in just a matter of weeks!! We take a deep dive into plant foods, fibre, fermented foods and how to eat for a healthy gut microbiome in our Nutrition and Reboot courses if you’d like to know more.
WHAT MAKES SOME BACTERIA BAD?
So why are some bacteria ‘good ‘and others bad?
There are two main reasons:
One is that ‘bad’ bacteria are also those known to cause infections such as salmonella, campylobacter, E coli (ie gastroenteritis or tummy bugs)
But the main (real) reason, is due to the compounds that these bacteria produce, called postbiotics.
Postbiotics are chemical compounds bacteria in our large intestine produce when they break down food.
Some, such as those produced by ‘good ‘ bacteria, are highly beneficial for our health (see the next section).
In contrast, the postbiotics produced by ‘bad ‘bacteria can actually be harmful to our health, and increase levels of inflammation.
One of the most well known harmful postbiotic compounds is a chemical called TMAO (trimethylamine oxidide).
TMOA producing bacteria are fed by animal products, in particular red meat, and to a lesser extent eggs seafood poultry and dairy. Interestingly vegans don't produce TMAO at all, even if they are fed meat - as they do not have the trimetholomine producing bacteria in their gut.
Having higher levels of TMAO in our blood is strongly associated with a higher risk of having heart attacks, strokes and early death, as well as higher risk of cancers such prostate cancer and colon cancer.
One study showed that people with elevated serum TMAO are 3.4x more likely to develop bowel cancer!!
So in the most basic terms, to avoid high levels of TMAO, limit red meat and eat more plants - which just happens to be the same advice heart and cancer specialists give their patients!
HOW OUR GOOD GUT BACTERIA HELP US
Next, we'll cover a bit more about the postbiotics we just mentioned.
Our gut bacteria live mostly in our large intestine, in particular in an area called the caecum (near our appendix) .They feed off our food, meaning what we eat directly affects them.
Different bacteria feed on different foods, so if we eat more of certain foods, it feeds the bacteria that eat these foods, and makes them grow and reproduce.
In contrast if we don't eat certain foods it starves the bacteria that feed on these, causing them to reduce in number and even become extinct. This happens very rapidly - in less than 24 hours of changing our diet, our gut biome changes dramatically!
Our good bacteria are all fed by complex carbohydrates - mostly fibre, and also resistant starch. These foods are called prebiotics and are the main food for our microbiome.
Prebiotics are ONLY found in plants, as they are part of plant cell walls, so as we mentioned previously, eating a diverse range of high fibre plant foods is the best way to 'feed' your good bacteria.
When bacteria digest prebiotics, they release chemical compounds called postbiotics - these are like chemical messengers that travel around our body and affect it in various ways.
Postbiotics are thought to be one of the main ways our gut microbiome impacts on our health
✓ 'good' bacteria produce beneficial postbiotics, that help us to stay healthy
✓ 'bad' bacteria produce harmful postbiotics, that can contribute to disease (such as the TMAO we mentioned)
The most commonly known postbiotics produced by 'good' bacteria are compounds called short chain fatty acids (SCFA),including butyrate, acetate and propionate.
WHAT ARE SHORT CHAIN FATTY ACIDS?
Short chain fatty acids (SCFA) have several crucial ROLES in our body :
they bind to specialized cells on the gut lining which send signals to our organs, helping them to stay healthy and reduce inflammation.
they are the main fuel for our gut wall cells, and keep them and our intestinal lining healthy (butyrate provides around 70% of the energy needs of our gut wall cells)
they work as anti inflammatory molecules and cancer suppressors
they help make our gut immune cells more tolerant of foods (ie reduce the risk of food allergy, via ‘training’ our gut not to react to foods)
they affect blood sugar regulation, weight, and hunger signals
they help to keep our immune system in balance
they improve motility (gut muscle contractions ie digestion) and reduce visceral hypersensitivity (pain signals sent from our gut to brain such as in irritable bowel syndrome)
they affect our mental health and brain health, via the gut brain axis (and may even play a role in conditions such as Parkinsons disease and autism)
So as you can see, having lots of good bacteria, producing lots of good postbiotics, is so beneficial for both our gut health and overall wellbeing!!! It sounds complex but it's also so simple - feed your gut bugs lots of whole plant foods to help them grow.
So thanks for sticking with us - that was a lot to cover - but hopefully it's helped to give you an understanding of just why our gut microbiome is vital to true health
The saying from Hippocrates over 2000 years ago that 'all disease begins in the gut' may well be true after all!!!
To find out what affects our gut microbiome, and how to improve it, check out our next post here ❤️
Plus If you'd like to learn more about evidence based gut health and how to improve it, we cover this in depth in our Reboot Your health course and Transform Your Nutrition course - teaching you all you need to know to start having a healthier happier gut!!