Fermentation is basically the breakdown of sugars by bacteria and yeast. Not only does this help preserve foods; these foods can increase the number of probiotics (beneficial bacteria) in your digestive tract.
As a reminder, beneficial bacteria help to “ crowd out” pathogenic bacteria and yeast, ensuring we have a plentiful and diverse range of beneficial strains which support better digestion, immunity, emotional well being and even body composition**.
Fermentation also helps break down nutrients in food, making them easier to digest. For example, lactose (the natural sugar in milk) is broken down during fermentation into simpler sugars. These are then much easier to digest. As the fermented dairy is virtually lactose free at that point, those that are lactose intolerant generally tolerate kefir and live natural yoghurt well.
Fermenting foods also helps dismantle compounds known as anti nutrients (e.g. phytates and lectins). These can interfere with the absorption of certain minerals from foods such as seeds, nuts, grains, and legumes.
Cabbage based fermented food like sauerkraut are high in Lactobacillus plantarum which is a real star in terms of probiotics (helps immune system, combats toxins, helps prevent anxiety, IBS and other digestive complaints).
Common fermented foods.
- Kefir : fermented yoghurt drink
- Kombucha: fermented, slightly fizzy, black or green tea drink
- Miso: fermented beans, most often as a soup or paste
- Tempeh: fermented soybeans – a high protein meat substitute
- Natto: fermented soybeans, often paired with rice
- Sauerkraut: cabbage fermented by lactic acid bacteria
- Pickled veg (gherkins, cornichons, beetroot etc)
- Kimchi: korean spicy fermented cabbage/radish- great for reducing insulin resistance
- Live natural yoghurt (natural and live as not all yoghurt contains probiotics- many killed off during processing!)
- Sourdough bread
- Olives
- Vinegar
- Beer and wine
Introducing fermented foods
If you are not used to eating fermented foods, a good rule of thumb is to introduce them “slow and low”. The high probiotic content can result in a temporary increase in gas and bloating as your guts adapts to the introduction of the beneficial bacteria (and as some of the pathogenic bacteria “die off”, they can release toxins that create some bloating). These symptoms might be stronger with the higher fibre options like kimchi and sauerkraut.
Not all fermented foods are created equal. Some may contain high levels of added sugar or additives so do your food detective work and check the labels! Try fermented products made with organic vegetables if possible and steer clear of any with artificial additives and a higher sugar content.
Who should avoid eating too many fermented foods?
- Fermented foods can be high in histamine which is a chemical produced by our immune system. If eating fermented foods leave you feeling a bit nauseous, inflamed, very bloated or even feeling anxious, you may be sensitive to histamine-producing bacteria or foods. For some of us, a genetic predisposition or a damaged gut can lead to low levels of the enzymes needed to break down the amount of histamine coming in via the diet and when the body can’t metabolise that histamine, it starts to accumulate in your bloodstream and cause symptoms.
- If you suffer with potential candida overgrowth (symptoms such as thrush, UTIs/cystitis, skin/nail fungal infections, long term sinus infections), then it may be wise to limit some fermented foods (in particular kombucha) as some will contain yeast and prebiotics which may potentially feed not only the “good” bacteria but also promote the “bad” bacteria and yeast; not helpful if you already have an overpopulation of yeast. Pickled veg like sauerkraut or gherkin however don’t contain yeast and have such good levels of helpful lactobacilli bacteria, which help control overgrowth of the unhelpful stuff.
In summary, fermented foods can be superfoods for the gut, increasing microbial diversity and delivering a host of benefits, but only if those bacterial cultures agree with you. Some products or types may suit you more than others, so it is worth experimenting. And remember, if fermented foods don’t sit well with you, it’s ok to not eat them!
** researchers believe that particular strains can influence how the body harvests energy. More research is needed however. Some studies have found links between certain probiotic strains — including Lactobacillus rhamnosus and Lactobacillus gasseri — and weight loss and decreased belly fat.
