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From Clare Backhouse, Nutritional Therapist at Transformation Nutrition
I’m a registered nutritionist who remembers what it was like before gut health became ‘a thing’. People would mention it like a crazy woo-woo hobby: “Oh Clare, you like ‘guts’ don’t you… what were you saying about those bugs that live in our tummy?” Now – thankfully – everybody knows something about gut health. You can even buy gut pills for your dog! And if you wouldn’t mind seeing improvements in your immune system, your skin, your mental health – well, pretty much any area of health – then gut health is definitely worth your attention.
What actually is “gut health”?
As a trained nutritionist, a good part of my job is supporting the gut health of my clients. This means making sure that the structure of the gastro-intestinal tract, our internal digestion tube that runs from mouth to backside, plus its microbiome (the amazing 2 kg or so of bacteria it contains) are operating in beneficial ways. This is because those healthy (or probiotic) gut microbiota affect so many aspects of human health. They do marvellous things for us, like produce vitamins and help absorb nutrients from our food. They support our energy levels, our emotions (producing the happy and calming neurotransmitters serotonin and GABA), our cognition, and our immune system. Gut microbiota can even impact our bone density and affect how our body reacts to heavy metal exposure. And support anti-viral immune function. Honestly, their benefits do seem endless.
So why all the fuss about gut health now?
Gut health is headline news, because our gut microbiomes have been under threat for the last 100 years or so and the impact is finally being felt, in a big way. Since the 20th century, products like antibiotics in medicine and pesticides in farming have alleviated many problems, but they also introduced new ones – namely, harming the health and diversity of our gut microbiomes. Given that we inherit our gut microbiomes from our mothers and then alter them with our diet and lifestyle, as a population we’re seeing a generational, compound impact on our guts. It’s getting more and more common to see dysbiosis, or imbalance in gut bacteria, skewing to less beneficial strains, and in turn compromising our overall health. However, thanks to the work of Tim Spector and others, you may have heard about the importance of a ‘diverse’ microbiome, which is encouraged by 1. eating a wide variety of different plant foods whose fibres ‘feed’ beneficial bacteria and 2. consuming fermented foods and drinks which help to foster the gut microbiome. Since different beneficial bacteria provide different benefits, it makes sense to have the broadest benefits possible. And that’s where fermented foods come in.
What are fermented foods?
Fermented foods are foods that have been changed by the presence of edible microorganisms, which then produce new flavours and new microorganisms, which in turn both preserves the food, and benefits the consumer. Fermented foods include kefir and yoghurt (made of milk), sauerkraut and kimchi (made of cabbage), and kombucha (made of tea), but really, you can ferment almost anything, if you have the right methods. So for example if you take a cabbage and leave it to rot, it will just start to smell nasty. But if you take a cabbage, chop it up, and add a little salt and whey, it will break down into a fermented food. The fermenting process will cause the cabbage to last for ages, smell nice, and – most importantly – harbour the probiotic bacteria Lactiplantibacillus plantarum, whose numerous health benefits have been shown to include bringing down the pre-diabetes marker HbA1c.
What do fermented foods do for our health?
I think of probiotic bacteria from fermented foods as being a bit like influencers on Instagram, or extraverts at a party. They may not stay around for ever, but they definitely promote a certain atmosphere, and create changes while they are there – which may have a long-lasting impact. That’s why it’s possible to buy well-researched, clinically-proven probiotic pills designed to support everything from skin health to mental health to dental health. But you don’t necessarily have to buy pills to get these benefits. You can kill two birds with one stone and enjoy delicious fermented foods and drinks as part of everyday life, which provide both nutrients and probiotic bacteria at the same time. Consuming fermented foods over a period of time means that you’re keeping up a friendly atmosphere in your gut, a bit like having a cheery visitor come to your house every week. You may notice a number of benefits to your digestive health such as reduced bloating, more regular, comfortable trips to the bathroom, and less gas. And you may also notice better mood, energy and mental focus.
Are fermented foods for everyone?
Having said all of this… I’m a holistic nutritionist, who uses personalised medicine to provide each of my clients with bespoke support. So I’m always going to be a little cautious about blanket health statements! Fermented foods may be the most wonderful game-changer for you. But it is possible for fermented foods to disagree with people. This may be due to consuming too much of a good thing at once, which might cause bloating. Or, in some cases, people with histamine-related issues may need to begin consuming fermented foods (which contain naturally-occurring histamine) in very small quantities to begin with, so as to gain the benefit without overloading histamine. If in doubt, always consult your primary healthcare practitioner. But I usually find that, if you haven’t got an allergy or intolerance to the food or drink itself, it’s possible to try fermented foods at least in small quantities.
Where does kombucha come in?
Kombucha is an amazing fermented drink made from tea, sugar and starter culture. The sugars get processed by the culture and turned into the most wonderful probiotics which benefit the drinker. It used to be a rather niche product, loved mainly by nutritionitst like me ten years ago. But now, it’s becoming fashionable everywhere. I love that it’s now possible to buy a reliably tasty, reliably elegant-looking kombucha to serve my friends. As a practitioner, I have found Holos kombucha to be revolutionary for my clients who want to reduce alcohol intake. Sparkling, delicious kombucha in smart bottles is a million miles away from a miserable glass of orange juice – and of course (unlike the juice) it’s not super-sugary, and benefits the gut. I love that my friends, who used to raise their eyebrows at fermented foods and ‘bugs in our tummies’, are now quaffing fabulous kombucha with enthusiasm. And while they quaff, it’s busy supporting their gastro-intestinal health and, by extension, many other areas of health. There’s a special joy to find myself now, ten years on, celebrating gut health with a company like Holos, whose products encourage it.
Clare Backhouse is a qualified nutritional therapist, whose clients routinely report improvements in energy, digestion, and mood. Clare specialises in supporting thyroid and immune health with a functional approach. She creates a bespoke health roadmap for each client, providing personalised support every step of the way. Find Clare at https://www.transformationnutrition.org/
References
Coryell, M., McAlpine, M., Pinkham, N.V., McDermott, T.R., Walk, S.T., 2018. The gut microbiome is required for full protection against acute arsenic toxicity in mouse models. Nat Commun 9, 5424. Costa, M.A. de C., et al., 2023. Effect of kombucha intake on the gut microbiota and obesity-related comorbidities: A systematic review. Critical Reviews in Food Science and Nutrition 63, 3851–3866. Maier, L., et al., 2018. Extensive impact of non-antibiotic drugs on human gut bacteria. Nature. Mukherjee, et al., 2025. Impact of fermented foods consumption on gastrointestinal wellbeing in healthy adults: a systematic review and meta-analysis. Front Nutr 12, 1668889. Tobias, J., et al., 2025. The benefits of Lactiplantibacillus plantarum: From immunomodulator to vaccine vector. Immunology Letters 272, 106971. Traditional Foods From Tropical Root and Tuber Crops: Innovations and Challenges, 2019. , in: Innovations in Traditional Foods. Woodhead Publishing, pp. 159–191. Valencia, S., et al., 2025. Human Gut Microbiome: A Connecting Organ Between Nutrition, Metabolism, and Health. Int J Mol Sci 26, 4112. Zhang, S., et al., 2022. Characterization of microbiota of naturally fermented sauerkraut by high- throughput sequencing. Food Sci Biotechnol 32, 855–862. Zhang, R., et al., 2024. Harnessing the Power of Fermented Tea to Improve Gut Microbiota and Combat Obesity Epidemic. Biology (Basel) 13, 779.