10% off €25 OR 15% off €35
Discover why fermented foods are the hottest new wellness trend – and how to include them in your diet.
Fermentation may be trending right now, but there’s nothing new about it. Back in the day, fermenting was a simple and practical way to preserve food.
These days, fermenting food is recognised as not just being a clever way of keeping perishable foods edible - it’s a clever (and tasty!) way to enrich your body’s natural bacteria and support your digestive system.
Thousands of years ago, our ancestors discovered that sealing food resulted in any carbohydrates that were present being broken down by yeast and bacteria into alcohol and organic acids.
In turn, this preserved the food. It also gave it a unique, tangy flavour.1
Fermented products are easier for us to digest because the natural sugars and starches have been broken down.
They’re also recognised as being a source of good bacteria – or a probiotic – which increase the diversity of the gut bacteria in your gut microbiome.
Fermentation is defined as ‘controlled microbial growth and the conversion of food components through enzymic action.’
Fermentation involves adding beneficial or good bacteria to food and drink, and breaking down more complex components into smaller, more absorbable ones that our gut can use.
Having a healthy gut can reportedly have a positive impact on the symptoms of anxiety, depression and other mental health disorders and reduce the risk of heart disease.
It may also lower cholesterol and blood pressure.
Milk fermentation became popular in the late 19th century when the technology required to produce it on a commercial scale became available.
People have been practicing cheese fermentation and milk fermentation for centuries to preserve dairy products, but the live bacteria is usually stripped from them via pasteurisation before sale.
However, there are some dairy products that have been specifically fermented and processed to preserve the cultures of live bacteria, some of which we’ve listed below.
Food fermentation can have some pretty tasty (and healthy!) results.
Here are 9 of the best fermented foods and drinks, as selected by our in-house nutritionists:
Kefir is a fermented dairy drink that shepherds used to drink in the Casucaus Mountains. In Turkish, the word kefir means ‘good feeling’.
People make kefir by using starter grains called kefir grains, which contain live bacteria, such as lactic acid and yeast.
It also contains essential minerals, vitamins, amino acids, and enzymes.
Kefir tastes a little like yoghurt, but is said to have even more benefits and makes a good snack or breakfast.2
Vegan alternative: Water kefir
Yoghurt is one of the best and most well-known fermented foods.
It’s made from milk that’s been fermented with live, friendly bacteria, namely bifidobacteria and lactic acid bacteria.
It’s an easy way to get your daily dose of probiotics. Try including it in your breakfast with berries and honey or as a satisfying snack with nuts or granola.
Make sure you’re buying the real deal though, and go for yoghurts with ‘live’ or ‘active’ cultures, as some yoghurts will have been processed to kill the bacteria.3
Handpicked content: Granola breakfast cups recipe
Buttermilk was more popular back in the day, but if you can get your hands on some now, it makes a fantastic, fermented treat.
You need to make sure it’s made in the traditional way, though.
Buttermilk is simply the leftover liquid you get when making butter and it’s full of vitamins, minerals, and live bacteria.
Most cheese has been fermented but doesn’t always contain probiotics.
This is because most of the cheese found in supermarkets will have been processed in a way that kills the live bacteria.
Friendly bacteria can sometimes survive the ageing process in some cheese types, including mozzarella, gouda, cottage cheese and cheddar.4,5
Make sure you always check the label for live and active cultures though, if you want some bacterial goodness along with the protein, vitamins and minerals cheese provides.
Soybean fermentation is another extremely popular way to enjoy fermented foods.
Fermenting soybeans has been a firm favourite in Asia for centuries, and recently we’ve been enjoying products like tempeh in the West, too.
Below is a little more information about fermented soy foods:
Tempeh is originally from Indonesia but has become popular all over the world because of its high protein content and ‘meaty’ nutty and earthy taste.
It’s made by fermenting soybeans with a specific type of fungus, which creates its vitamin B12 content (that soybeans don’t naturally contain) and gives it its much-loved texture.
Vegans and vegetarians tend to be tempeh’s biggest fan, as it is an excellent form of animal-free protein and contains vitamin B12, which usually comes from animal foods like meat, dish, eggs, and dairy.6
Miso is another fermented soybean product from Japan and is most popular for its use in miso soup.
It’s traditionally produced by fermenting soybeans with a type of fungus called koji and salt, but it can also be made by mixing soybeans with rice, barley, and rye.
Miso is full of friendly live bacteria, as well as protein, fibre, vitamins, and minerals, including vitamin K and copper.
Vegetable fermentation has been around for centuries, as it is a great way of preserving fresh produce through the winter without needing to use a fridge or freezer.
Only in the last hundred years or so, we have discovered the full benefits of using bacteria in this process for our health.
Miso is also vegan-friendly.
Combine miso and tempeh in this super simple lunch bowl for a gut-friendly recipe.
You may have already experienced sauerkraut on your frankfurter sausage or Reuban sandwich where it provides a deliciously sour and salty flavour.
Sauerkraut has been enjoyed by many European countries for centuries and is made by fermenting finely shredded cabbage with lactic acid bacteria.
Alongside its probiotic benefits, sauerkraut also provides fibre and vitamins B, C, and K, as well as sodium, manganese and iron.7
Make sure you choose an unpasteurised sauerkraut though, as pasteurisation kills any live bacteria.
Sauerkraut is also vegan-friendly.
Similar to sauerkraut, kimchi is another fermented vegetable dish (usually cabbage), but with a lot more seasoning.
It’s made by fermenting cabbage or other vegetables with Lactobacillus kimchi and other lactic acid bacteria, and then adding seasonings like red chilli pepper flakes, ginger, garlic, spring onion and salt.
As well as being a great source of probiotics, it also contains vitamin B2, vitamin K and iron.
Fermented drinks are rising in popularity as they are an easy way to enjoy probiotics, don’t require much prep, and are usually quite tasty, too!
Kombucha is popping up here, there, and everywhere in recent years as a tasty, drinkable way to get your fill of friendly bacteria.
It’s made by fermenting black or green tea with bacteria and yeast.
This yeast fermentation process makes it naturally fizzy, and flavours are usually added, as it is quite the acquired taste…
It’s now thought that regularly including these foods in your diet could help keep your gut happy.
One of the benefits of fermented foods is that they are naturally teeming with the healthy bacteria your body needs – and scientists think this may play an important role in keeping your own community of friendly gut bugs thriving.8
Each of us has over 100 trillion live bacteria in our gastrointestinal tract, aka our gut, which help our body to perform a number of different tasks.
However, our gut bacteria need to be balanced to work at their best.
For example, there needs to be enough good ‘live’ bacteria to balance out the ‘bad’ bacteria that make us ill.
Balanced gut bacteria support the following systems in the body:
In a 2015 review, published in the journal Current Opinion in Gastroenterology, researchers found that having a varied community of gut bugs may play a role in easing a range of bowel conditions, including irritable bowel syndrome.9
As well as helping your digestive health, feeding your gut bacteria may in turn support other aspects of your wellbeing – for example, your mental health.
In 2016, researchers at University College Cork reported that giving healthy people cocktails of friendly bacteria for four weeks altered their brain activity in MRI scans.
Participants were less likely to experience negative thoughts when they felt low.10,11
And we know that in China, Japan and Korea, where people traditionally eat lots of fermented foods, such as kimchi and miso soup, bowel complications are far less common.12
Read more about the health benefits of a healthy and balanced gut in our article on How to have a happy gut.
It’s safe for most people to add fermented food and drink to their daily diet.
However, if you are sensitive or intolerant to histamine, you may experience headaches or migraines.
Generally speaking, minimal side effects have been linked to consuming fermented foods and drinks.
The most common are gas and bloating, which are caused by products containing high numbers of friendly bacteria.
The diversity of our gut bacteria is established at the very start of our development but can be altered by multiple factors.
Our gut microbiome begins to develop when we are still growing in the womb.
It is very sensitive, and something as small as a baby being delivered vaginally vs being delivered by caesarean can affect which strain of bacteria are dominant in our system.
It then continues to evolve over time to become relatively stable at around 3-years-old.13
Right from the start, when we drink either breast milk or baby formula, our diet affects our gut bacteria.
For instance, breastfed babies tend to have better immunity and more diverse gut bacteria than those who have formula milk.
Vegetarian and vegan diets have also been found to be associated with better bacteria diversity than a non-vegetarian diet.
Eating probiotics and prebiotics, such as fermented foods, inappropriate doses have also been seen to cause specific changes in the structure of our gut microbiota and benefit our health.14
Researchers agree a healthy community of gut bugs depends on eating a wide variety of different foods – so including some fermented foods in your diet is a good move.
Here are some everyday ideas for gut health:
Swap your usual bread for sourdough toast for lunch
Try sauerkraut as a veggie side dish with fish or lean meat and mustard mash
We hope this article has you clued up on all things fermented. Here’s a quick re-cap just in case:
Last updated: 10 January 2023
Joined Holland & Barrett: Apr 2019
Masters Degree in Toxicology and BSc Hons in Medical Biochemistry
Bhupesh started his career as a Clinical Toxicologist for Public Health England, advising healthcare professionals all around the country on how to manage clinical cases of adverse exposure to supplements, pharmaceuticals, cosmetics, industrial chemicals and agricultural products.
After 7 years in this role and a further year working as a drug safety officer in the pharmaceutical industry, Bhupesh joined Holland & Barrett as a Senior Regulatory Affairs Associate in 2019.