Fermenting Food For Health

Fermenting food for health – an array of pickles

What Is It with Fermented Foods?

Over the last few years, dozens of fermented food and drink products have started popping up on shelves everywhere. More and more we are fermenting foods for health and to preserve them. But what exactly are fermented foods? And why is everyone talking about them?

Fermenting For Alcohol

Humans have been fermenting foods for over ten thousand years. Admittedly some of the first forays into fermenting involved the production of alcohol. Before that we were fermenting milk, probably initially by chance, but soon deliberately. Because we discovered that fermented milk turns into cheese and yoghurt and these products have a much longer “shelf life”. They are also a lot more portable than milk.  

Virtually every country in the world has some form of traditional fermented food. Some countries, particularly in hot climates, have many different fermented products. Fermentation was (and still is) one of the best low-tech ways to preserve food.

Fermenting For Food Storage and Safety

It isn’t just exotic sounding foods like kombucha and kimchi that are fermented. Beer is fermented. So is sourdough bread. And vinegar. So are cheese and wine. Fermentation happens when bacteria and yeasts digest starches and sugars in food. And when the right bacteria and yeasts work on the right foods, something amazing happens.  

A lot of fermented foods probably started out as happy accidents. Nobody knew what it was that made certain foods change from one thing to another – rice into wine, milk into yoghurt, cabbage into sauerkraut. People just knew that if you prepared rice (or milk or cabbage) in a certain way, put them into a certain vessel and stored them in a certain place then a magical transformation occurred. The rice (or milk, or cabbage) changed into something completely different: something with a much longer shelf life, which also happened to be good to eat (or drink).

It’s the Bugs

The invention of microscopes meant that people could start looking very closely at the process of fermentation. And this close examination found that fermentation was driven by live microorganisms. Not only that, but many of those microorganisms also lived in and on the human body.  

For quite a long time, some branches of science (and marketing) viewed live microorganisms as a universal evil. And the public bought into the idea that refrigeration and disinfectants would keep those pesky bacteria and yeasts at bay.  

Social Changes

Other stuff changed too. A hundred years ago multiple generations would live in the same house, or at least in the same street. The skills and knowledge in that pool of grandmothers, aunties and mothers were passed down from generation to generation. Now we live separate lives, too busy to cook, too busy to learn those old skills that we see as redundant. Why should we bother to learn when we can go and buy from a hygienically shiny supermarket?


It is only relatively recently that the idea of fermented foods being beneficial to health has come to the fore. In the last few decades, interest in the bacteria and yeasts that create fermented foods has started to grow.

Because those microorganisms are also known as probiotics, the beneficial bacteria found in premium processed milk drinks, “live” yoghurts, and expensive food supplements. And the colonies of beneficial microorganisms that inhabit our bodies have been rebranded as “the microbiome”, which is now being intensively studied in hundreds of studies across the world.

The Microbiome

The microbiome in our gut is a key factor in maintaining our health and wellbeing. It is made up of trillions of bacteria, viruses, yeasts, and fungi. Some of these are “good guys” that support our immune system. They help to reduce inflammation, keep cholesterol and blood sugar in balance, maintain a healthy weight. They even make neurotransmitters which our brain and nervous system need.

At the other end of the microbiome spectrum are “bad guys”. These will make us sick if they get the chance. So it is really important to keep our microbiome healthy and happy. We need to make sure there are more good guys than bad guys.

The Benefits Of Fermented Food

These days we don’t need to ferment food to preserve it. But the health benefits of fermented foods have not gone away. Eating fermented foods puts good guys into our systems, helping to keep our microbiome in balance.

There are hundreds of different fermented foods from all over the world. But the most common ones in the UK right now are fermented milk foods like yoghurt and kefir, fermented cabbage like sauerkraut and kimchi, fermented tea (kombucha) and sourdough bread.

Yoghurt and Kefir

Fermenting milk makes it easier to digest because the protein (casein) and the sugar (lactose) are broken down in the fermentation process. Fermentation also produces an enzyme (lactase) that helps us digest milk properly.

The probiotic bacteria that do the fermenting reach our gut alive and have active benefits, including making antioxidant compounds and extra vitamins. There is even evidence that kefir can support the work of antibiotics in clearing an infection of Helicobacter Pylori, the bacteria that cause stomach ulcers.

Making kefir is relatively quick and easy, you combine whole milk with kefir grains and leave it at room temperature for 24 hours. You can buy kefir grains online. A good recipe can be found here.


Kombucha has appeared on shelves all over the place in recent years. But what exactly is it? It’s tea. Specifically, it’s tea with sugar that is fermented by a combination of bacteria and yeast working together in a Symbiotic Culture Of Bacteria and Yeast, or “SCOBY”.  The scoby digests the sugar, creating a fizzy, slightly sweet, slightly sour drink.

Although drinking kombucha has been linked with good health for thousands of years, there are no studies yet showing health benefits in humans. But lots of studies show that kombucha contains high levels of antioxidants as well as substances which support the health of the microbiome. There are also many animal studies that show kombucha supports liver function, the immune system, the digestive system and the brain; it may also help to protect against heart disease and diabetes.

Clear glass container of kombucha
Kombucha – Photo by Megumi Nachev on Unsplash

Making kombucha is not difficult: you just need tea, sugar, a scoby, a little bit of live kombucha, and patience, giving it long enough to ferment (about two weeks). You can buy a starter kit online. A good recipe can be found here.


Literally translated as “sour cabbage”, some people love sauerkraut, others, not so much. 

Sauerkraut is shredded cabbage, mixed with salt and then left to ferment. It does not need a “starter” like kefir grains or a kombucha scoby. Instead, the bacteria and yeast that are naturally present on the surface of the cabbage, on the hands of the person making it, and in the air, start breaking down and fermenting the sugars and starches in the cabbage leaves.

Sauerkraut is high in vitamins C, B1, B6 and K and the fibre in cabbage is a “prebiotic” meaning it feeds the bacteria in our gut. Not only that, but the bacteria found in sauerkraut reach the gut alive, which makes them probiotics.

Sauerkraut is easy to make, but it is quite a lot of work, because you have to shred an entire cabbage and then massage salt into the shreds. If you would rather buy it, make sure you buy the stuff in the chiller cabinets rather than the bottled stuff on shelves – the bottles are probably pasteurised which kills off the probiotic bacteria.  If you want to make sauerkraut a good recipe can be found here.


Kimchi is so important in Korean culture that when South Korea’s first astronaut went into space, he took kimchi with him!

In the west we tend to think of kimchi only as pickled Chinese cabbage, but kimchi means any kind of vegetables which have been fermented using salt, chili, onions, garlic, ginger, and salted fish. It is strongly flavoured and spicy and is eaten as a side dish with most meals in Korea.

Benefits Of Kimchi

Kimchi is packed with nutrients, including lots of B vitamins, vitamin A, and vitamin C. On top of that, the probiotic bacteria in kimchi pack a significant health punch, helping with weight loss and supporting the immune system. Eating kimchi every day can help to reduce cholesterol, keep blood sugar in balance, and even reduce inflammation.

Making kimchi isn’t difficult but waiting for the fermentation process requires patience.  If you want to make it, make sure you wear disposable gloves, because if you have even the smallest cut on a finger when you massage the chili and salt into the cabbage, boy will you know about it!  A good recipe can be found here.

Sourdough bread

Sourdough is the oldest form of leavened (risen) bread. It does not use commercial yeast but instead uses a “starter” of flour and water fermented by bacteria and yeasts naturally present in the flour and the air. You can make a starter (takes about a week), or you can buy one. 

Once you have one you must feed it with flour and water to continue the fermentation process. When you want to make bread, you simply use some of the starter instead of yeast and replace the amount you take out with fresh flour and water.

Sourdough bread on round wooden platter
Sourdough bread – Photo by Vicky Ng on Unsplash

Sourdough has a distinctive sour taste, a chewy texture, and a crackly crust, all very different from commercially produced yeast bread. Both the starter and the bread have a long fermentation process which makes sourdough bread more digestible than commercially produced yeasted bread.

The baking process kills the bacteria and yeasts which ferment sourdough but, despite that, sourdough still has a beneficial effect on the microbiome, possibly because the fermentation changes the fibre content in the flour used to make the bread.    

Making sourdough is time consuming, certainly to start with if you are making a starter. I think its easier to buy it. But if you fancy having a go, a good recipe can be found here.

The Key To Health?

The key to a healthy gut is a balanced microbiome with a wide range of microorganisms. All of the food and drink discussed here are fermented by different microorganisms. Eating a range of different fermented products every day can help to keep your microbiome healthy, and a healthy microbiome supports a healthy you.

You can buy fermented foods in supermarkets, in health food shops, even in corner shops. But you can also make them. Some of them are really quick to make, others take a little more time to ferment. Some are a lot of work; others are ridiculously easy.

Right now, I have kombucha, kefir, vinegar and kimchi all fermenting in my kitchen and pantry. Yum!