Uncovering the ‘gut:everything’ connection

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By The Gut Health Doctor Team

Dr Megan Rossi in a lab looking through a microscope

When we think of gut health, we naturally think of digestive health. But did you know that your gut also influences all your other organs, including your skin and pretty much every facet and function of your body?

Your gut microbiota (or GM for ease) is the scientific name given to the trillions of microbes, including the bacteria in your gut. And it is incredibly powerful! Thanks to this community (including 40 trillion bacteria), it is capable of thousands of functions. In fact, this newly appreciated organ is pretty much essential to whatever your health goal is, be it successful weight management, improved fitness levels, healthier skin, more resilient immunity, or even your happiness. It also has the power to influence how long you live and to protect you from over 70 chronic conditions and certain cancers.

The empowering thing is that, unlike your genetic make-up, you have the ability to shape your GM simply by how you treat it, which means that a big part of your personal health is in your hands. 

Still need convincing about the importance of the gut? Let’s explore some of those gut connections that live within you.

The gut-immune axis

Around 70% of immune cells reside in your gut (alongside your microbiome), meaning that the gut is a key player in dictating your immunity. Your microbes essentially teach your immune cells what is worth reacting to and what is safe. 

There is some pretty convincing evidence that altering your GM increases your resistance to viruses, particularly when it comes to the common cold and flu (scientifically referred to as upper respiratory tract infections, or URTIs). In 2015, a review was conducted by a global independent network of researchers known as Cochrane, looking at all clinical trials on probiotics for acute URTIs. They found that specific probiotics (remember: not all probiotics do the same thing) could reduce both the chances of you catching colds and flu as well as the duration of symptoms if you did manage to get them. This indicates that, by giving your GM a boost, you boost your cold and flu resistance too. 

And what about ‘that’ virus? Research from Dr Megan Rossi’s colleagues at King’s College London, which involved nearly 600,000 participants, found that people who ate a more varied diet full of plants (aka a gut boosting diet) had a 40% lower risk of becoming unwell with Covid-19.

An illustration of the brain

The gut-brain axis

The gut and the brain are literally connected through hundreds of millions of nerves, known as the enteric nervous system (ENS). This often means that what’s going on in your brain can influence what’s going on in your gut and vice versa.

Disruption along the gut–brain axis has, for example, been associated with disorders including stress, depression, and anxiety, irritable bowel syndrome, autism, schizophrenia, Parkinson’s and Alzheimer’s diseases. There’s even evidence that the state of your GM could be used to predict your risk of depression, the persistence of symptoms, and how well you recover.

The SMILES trial was conducted in 2017 and was a landmark study investigating how supporting our gut through a Mediterranean diet rich in plant-based foods could help to manage depression. Those who followed a diet full of plant-based foods, including all of the Super Six plant food groups (alongside lean meats, fish, eggs, and fermented dairy) — which provided three times more fibre than most of us eat regularly — saw a significant improvement in their mental health. In fact, after 12 weeks, a third of those on the Med diet were in remission from their depression.

An illustration of a women

The gut-skin axis

The skin is considered the largest organ in the body, and, when you think about it, the gut and skin have a lot in common. They’re both key players in defending the rest of our body from pathogenic invaders; they house a community of microbes where diversity and stability seem to be important; and they are also in a constant state of renewal, with parts of their linings shedding roughly every week and month, respectively, making them very hungry for nutrition. 

What we eat and how you treat your gut often play out on your skin — as you may have witnessed after a few days of skipping plant-based foods or having one too many glasses of Prosecco. 

For skin conditions such as acne, there’s a growing body of evidence suggesting that a diet with too few ‘healthy’ plant-based foods and too many ‘unhealthy’ plant-based foods like fruit juice, white bread, and large amounts of non-fermented dairy (particularly, it seems, skimmed milk) may exacerbate acne through alterations in hormones, among other pathways. 

Most of our skin–gut communication happens via the immune system. Simply put, an unbalanced GM is thought to set off a response from the immune system, triggering inflammation, which is normally there to protect us from injury or illness. But, like the stress response, inflammation becomes a problem when it’s triggered too often and left switched on at a low level over time. Many skin conditions — eczema, rosacea, acne, psoriasis, dermatitis, even premature ageing — are inflammatory in origin, so it figures that a limited GM, lacking in diversity, could be involved. 

The gut-metabolism axis

Weight maintenance is not quite as simple as calories in vs. calories out. We know that hormones, activity, genetics, and medical conditions all impact our weight. However, there is a definite link between our GM and our metabolism, and we can use this in our favour… 

Your gut microbes produce chemicals such as short chain fatty acids (or SCFA for short), which essentially tell our body we’ve had enough. This, in turn, halts the production of hunger hormones such as ghrelin and increases our fullness hormones, like leptin. Because SCFA are produced when microbes break down the fibre we eat, this likely explains why it’s often fibre intake — independent of calorie intake or type of diet — that results in healthier weight, as shown in the aptly named 2019 POUNDS study. 

If you add this to the fact that our microbes may influence our taste receptors and mood, it becomes pretty clear that having a higher body weight is way more complex than simply eating too much and not exercising enough. Your microbiome plays a starring role! 


By exploring just some of these gut connections, you may be starting to understand the vital importance of our gut microbiota and wondering how you can look after yours? Spoiler: It doesn’t involve dieting or restrictive diets! At The Gut Health Doctor, we embrace inclusion, flavour and plant diversity to support your gut microbiome. Check out this useful guide on how to get your gut-loving 30 plant points a week

Bloating Masterclass rosette communicating

Are you burdened by bloating?

Dr Megan Rossi’s (PhD, RD) Bloating Masterclass will guide you on a journey to better master your bloating. Combines virtual training with guidance, tools and expert resources to support you to feel more confident, comfortable and in control of your bloating.

For all enquires please email [email protected].


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