Fermentation and Your Gut: Kombucha, Kefir & Beyond

variety of prebiotic foods, raw green banana, asparagus, onions, garlic, leeks, berries and green beans for gut health

How’s your digestive synergy these days? Are your prebiotics and probiotics in symbiosis? Or does something seem a little off? Of course, you might have no idea what we’re on about…

The point is gut health, or your digestion. Maintaining a healthy balance and not ending up with stomach woes seems to take lot of effort and a fair bit of information gleaning. For instance, it seems we only ever hear about probiotics, about consuming enough live cultures in foods like yogurt to ensure everything is in working order, but what of prebiotics?

Well, if you’ve ever wondered, prebiotics are the fuel for probiotics (bacteria that assist in maintaining a natural balance of microorganisms or microflora in the intestines). Simply put, prebiotics are natural, non-digestible carbohydrates or oligosaccharides which when fermented by probiotics create the fatty acid, butyric acid. This maintains the healthy lining of the intestines, promoting proper digestion and supporting regular bowel movements. Indeed, prebiotics can be useful in easing Crohn’s disease, ulcerative colitis, and leaky gut. Some believe they might even play a part in the levels of cortisol, or the stress hormone, in our bodies, too.

Nonetheless, IBS is a very subjective – and widely publicised – autoimmune disease and many find that any extra fermentation process worsens their symptoms.  Indeed, those suffering from IBS are advised to reduce FODMAPs (or Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) in their diet.  To give a brief overview, both garlic and rye contain oligosaccharides; dairy products, disaccharides; honey and watermelon contain monosaccharides; and apricots and mushrooms, polyols.  There is also a tributary galacto-oligosaccharide category, under which legumes and beans fall.  All this goes some way to understanding why the foods we eat affect our digestion so.

Fibre Facts

Without fibre, not much would be happening in the bowel department. Nonetheless, without water, fibre would be nothing, needing to absorb liquid in order to be digested. Sources include grains like barley, spelt, and quinoa (softer acting on the colon), as well as fruits and vegetables and the lauded flaxseed. Have you had your fibre fill today?

According to a report by YouGov, 43% of the UK population suffers some form of digestive complaint.  Given that 70% to 80% of a person’s immunity is in the gut, it comes as no surprise that the answer to digestive issues is most certainly in each individual’s microbiome.

A microbiome describes the trillions of microbes in a person’s gut, consisting of 10,000 or so species.  These can be bacteria and yeasts, fungi and parasites.  What is fascinating is that these microbiota are more unique than DNA.  Some say a person should consume 50 plus foodstuffs in one week to provide a diverse enough diet for this microbiomic environment to thrive – quite a daunting task on the face of it when many fall into an easy-is-best eating approach, more often than not readymade and on-the-go, to suit the manic modern lifestyle.

However, fermentation as a preserving process has been around for centuries; some zymological historians believe as far back in time as 7000BC.  The word ‘fermentation’ comes from the Latin, ‘fervere’, which means ‘to boil’ (very likely what happens in most wine and bread).  However, ‘fermentation’ more correctly describes the anaerobic process whereby lactic acid bacteria (in the main from the Lactobacillus species) convert sugar into lactic acid.  It is the lactic acid that then acts as a preservative – a crucial food storage method when times were a lot agriculturally harder than they are today.  And a brilliant way to ensure we consume both prebiotics and probiotics in our diet.  Here are some optimum choices:


A form of fermented tea, made with a scoby (or ‘symbiotic colony of bacteria and yeast’), Kombucha – the wonder drink of the moment – is full of living enzymes, amino acids, and antioxidants. 

An energizer by grace of the B vitamins and iron replete within its sips (iron being an oxygenator for the blood and good old oxygen being a boon for the brain and by extension body), many adherents pass on the coffee for a morning glass of this brew.  And a brew it is indeed, containing sometimes up to 0.5% of alcohol.  A brew, also, due to its caffeinated tea part (black or green).

Kombucha aids digestion, is detoxifying (especially for the liver; move over Milk Thistle), skin clearing, and acts as an overall boost to immune system health.  Some also believe in its anti-arthritic potential, too, given the generous presence of glucosamine in a glassful.

All that said, those with compromised immune systems and pregnant and breastfeeding women have been advised to avoid kombucha and/or consult a doctor first.


Pass on the tofu and make your soybean choice a fermented one.  Tempeh undergoes a natural culturing wherein the beans bind together, creating a higher fibre and protein foodstuff.  This in turn makes it easier to digest and – but of course – offers a bounty of vitamins and minerals for the savvy consumer.


Miso (which, translated, literally means ‘fermented beans’) is traditionally made from soybeans, rice, and/or barley, salt and – la pièce de résistance – kōjin (a type of fungus).  Full of antioxidants, miso can be made into a broth for a hot drink or as a base for noodles, added to stir-fries or a basic ingredient for simpler couscous recipes, or even spread on toast for a sharp treat for the senses.


Sauerkraut also undergoes a fermentation process whereby essential and healthy bacteria are encouraged to form (bacteria such as lactobacilli and bifidobacteria).  This good bacteria veritably flourishing, consumers with a palate pleased by this cabbage dish can hope to benefit from digestive aid, by cause of the breaking down of food, thereby removing the bad bacteria (such as E. Coli) and letting only the good to survive within their gut.  Nicely done.


Kimchi is sauerkraut’s Asian cousin.  An acquired taste, this spicy little fermented number can please the palate either in the usual cabbage or radish format, or in a plethora of other vegetable styles, including celery and aubergine.  Some have dubbed it the ‘supercharged’ sauerkraut.  All we know is: yum!


Kefir was originally made with either cow’s milk or goat’s milk and was a key food for many centuries in Eastern Europe and Russia, as well as the Middle East and even certain parts of Asia.  That said, vegan yogurt can be made from a variety of non-dairy sources (almonds, soya, cashews, etc.), too, so logic follows: why not kefir?  Coconut seems to lend itself best. 

Kefir that doesn’t depend on a cow for one of its main ingredients can also be made with water.  All you need is the grains to make this ‘yogurt of drinkable consistency’ that reduces intestinal irritation and prevents toxins and pathogens from getting into your blood.  Not bad… Pass us some, please.

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