Skip to main content

24 Aug, 2023

Eve Kalinik on Gut Health as the Root of Health

When Hippocrates famously said “all disease begins in the gut” he probably didn’t imagine that we had a whole entire universe living inside of us all. Thousands of years later we now have the benefits of scientific research which tells us that this ecosystem, otherwise known as the gut microbiome, has a much more greater role in our overall health than we previously imagined. Let’s explore…


Picture an entire universe with planets and stars, rich, rolling landscapes, scenic diversity, colourful flora and fauna, and trillions of life forms loving together in harmony. This might sounds like an imaginary galaxy but this extraordinary and unique universe exists in every one of us. It is our gut microbiome - the trillions of microbes and their genetic material that live in our gut. Individually these microbes might be tiny but collectively their effect is seismic.

The gut microbiome is mostly made up of bacteria but living alongside them are fungi, parasites and viruses. Each of us has our own unique set of gut microbes that make up our own personal gut microbiome. Think of it like a finger print. In fact, we are almost 99% microbial from a genetic perspective and they slightly outnumber us in terms of human cells so technically we are more microbe than human. Our gut microbiome also houses around 22 million genes which make up more than observable stars in the universe. Microbes don’t just outnumber us in this regard but also their time on this plant. They were the earliest forms of life appearing on earth around 4 billion years ago and over this time have evolved with and alongside all living species.

We have a truly symbiotic relationship with our gut microbiome. We provide them with a home and (hopefully) feed them well and they reciprocate in many positive ways. Here’s how..

Digestion & absorption

It seems obvious that our gut helps us digest and absorb nutrients from our food but it is a far more complex and arduous process that happens from the moment we eat to the resulting poop the other end. Our gut microbiome has a pivotal role in this process producing compounds such as bile acids and enzymes that aid the processing and conversion of nutrients from our food. Furthermore they eat what we can’t digest in the form of dietary fibre.

Making nutrients

Vitamin K, biotin, thiamine, folic acid and B12 can all be made by our gut microbes. The latter of which is essential for cognitive health and nervous system functioning. Moreover, our gut bugs are also able to synthesise amino acids, which are the building blocks of protein, so that we have a readily available supply should these run low.

Keeps our immune system strong

Our gut microbiome has a pivotal role in teaching and training our immune system to react appropriately which starts from the moment we are born. Alongside this our microbiome protects us against potential pathogenic microbes that might otherwise make us unwell. Moreover gut immunity is one of the most important parts of our overall immune system in the form of gut-associated lymphatic tissue (GALT) accounting for 70-80% of total immune cells in the body.

Gut feelings

Neurotransmitters such as serotonin dubbed the ‘happy hormone’, dopamine which creates feelings of reward and GABA which has an inhibitory ‘calming’ effect are not just created and stimulated in our brain but also in our gut. In fact, almost 95% of all serotonin production and 50% of dopamine happens in the gut. We therefore need to have a happy gut to help us produce sufficient amounts of these neurotransmitters.

Synthesising SCFA’s

Short-chain fatty acids (SCFA’s) are beneficial substances that our gut microbiome generates upon fermenting dietary fibre. These SCFA’s are incredibly important for many processes in the body including the health of our gut barrier, cognitive health, supporting the immune system, metabolic health and managing inflammation more systematically.

Managing appetite and metabolism

Our gut microbiome has a significant influence on a multitude of biochemical processes that include managing hunger and satiety hormones such as ghrelin, leptin and GLP-1 as well as blood sugar levels and inflammation that can all contribute to metabolic health and weight management.

You can now understand just how much our gut microbiome does for us but how do we know if our microbes need a little more love?

Some more obvious gut troubles can range from excessive bloating and gas after meals (a bit of this is normal by the way), discomfort, inconsistency with bowel movements, pale or floating stools and lack of satiety. However there might be more subtle and not necessarily digestive symptoms such as poor immunity and/or recovery from viruses and colds, fatigue, low mood and skin issues.

Just to note it is very important if you do notice changes in bowel habits, blood or mucus in the stools or persistent bloating you should visit your GP first. However, even if you don’t have any of these symptoms we all need to show love and support to our gut microbiome so it can perform all of its amazing roles.

How can I help to support my microbiome?

Nourishing your gut microbes begins with feeding them plentiful amounts and diverse sources of plant foods which includes all types of fruit, vegetables, whole grains and nuts & seeds. ‘Eating the rainbow’ sounds a bit cliched but it is an excellent representation of this. Plus this analogy means we naturally consume more in the way of ‘phytochemicals’ which are special plant compounds that often give plants their colour and may also have a positive impact on the gut microbiome. Including prebiotic foods (read our other post) can help to amplify this further and don’t forget about herbs and spices, even the dried ones count, as these can often contain super high levels of phytochemicals. Alongside this fermented foods provide excellent sources of beneficial bacteria and yeast which may exert a positive influence on our gut microbiome.

We have therefore designed the 10-day Gut Reset to incorporate all of the above to help you set the foundations for a healthy and happy gut. If you are not used to eating a lot of fibre you may notice that your bowel movements become more regular and perhaps a slight increase of gas but this should soon settle back down. It is really your gut microbes happily fermenting all of the delicious plants and nourishing food you are generously providing.

Experience a full gut reset with our 10-Day Gut Reset, offering 10 days of a delicious, gut-focussed menu and bundle of amazing gifts to nurture and support a happy, thriving gut. For transformative, long-lasting health benefits. Find out more here.

Eve Kalinik, nutritional therapist and author of bestselling 'Happy Gut, Happy Mind'. Explore more of Eve's work here.


  • Barko PC, McMichael MA, Swanson KS, Williams DA (2018) ‘The Gastrointestinal Microbiome: A Review’ J Vet Intern Med. 2018 Jan;32(1):9-25. doi: 10.1111/jvim.14875. Epub 2017 Nov 24. Brody H. (2020) ‘The gut microbiome’ Nature. 2020 Jan;577(7792):S5. doi: 10.1038/d41586-020-00194-2.
  • Fraga CG, Croft KD, O’Kennedy D, Tomás-Barberán FA (2019) ‘The effects of polyphenols and other bioactives on human health’ Food Funct. 2019 Feb 20;10(2):514-528. doi: 10.1039/c8fo01997e.
  • Haahtela T (2019) ‘A biodiversity hypothesis’ Allergy. 2019 Aug;74(8):1445-1456. doi: 10.1111/all.13763. Epub 2019 Apr 4.
  • Holscher H. (2017) ‘Dietary fiber and prebiotics and the gastrointestinal microbiota’ Gut Microbes. 2017 Mar 4;8(2):172-184. doi: 10.1080/19490976.2017.1290756. Epub 2017 Feb 6. Leeuwendaal NK, Stanton C, O’Toole PW, Beresford TP (2022) ‘Fermented Foods, Health and the Gut Microbiome’ Nutrients. 2022 Apr 6;14(7):1527. doi: 10.3390/nu14071527.
  • Makki K, Deehan EC, Walter J, Bäckhe F (2018) ‘The Impact of Dietary Fiber on Gut Microbiota in Host Health and Disease’ Cell Host Microbe. 2018 Jun 13;23(6):705-715. doi: 10.1016/j.chom.2018.05.012.
  • McDonald, D et al (2018) ‘American Gut: an Open Platform for Citizen Science Microbiome Research’ mSystems, 3(3), e00031-18. Available at Şanlier N, Gökcen BB, Sezgin AC (2019) ‘Health benefits of fermented foods’ Crit Rev Food Sci Nutr. 2019;59(3):506-527. doi: 10.1080/10408398.2017.1383355. Epub 2017 Oct 20.
  • Tierney BT, Yang Z, Luber JM, Beaudin M, Wibowo MC, Baek C, Mehlenbacher E, Patel CJ, Kostic AD. (2019) The Landscape of Genetic Content in the Gut and Oral Human Microbiome. Cell Host Microbe. 2019 Aug 14;26(2):283-295.e8. doi: 10.1016/j.chom.2019.07.008.