Photo by The Matter of Food on Unsplash
In short: Fermented foods are foods that friendly bacteria or yeasts have slowly changed, giving them their tangy taste. Some of them, like plain yoghurt, kefir, raw sauerkraut and kimchi, still contain living bacteria when you eat them, and they can be a lovely addition to a gut-friendly way of eating. Start with a spoonful or two a day, choose ones that are truly “live”, and try making your own sauerkraut: all you need is a cabbage, salt and a jar.
You’ve probably heard that fermented foods are good for your gut. Perhaps you’ve looked at the jars of kimchi and the bottles of kombucha in the shop and wondered whether you should be buying them, which ones are worth it, and whether sauerkraut from a tin counts. Perhaps you’ve read that you can make your own, and pictured bubbling crocks and complicated instructions.
The truth is much simpler and much older. People all over the world have been fermenting food for thousands of years, long before fridges, as a way of keeping the harvest through the winter. Your grandmother may well have made her own. In this little guide I’d like to explain what fermented foods are, how to choose them, and how to make a jar of sauerkraut on your kitchen counter. No special equipment, and no fuss.
What are fermented foods?
Fermentation is what happens when friendly bacteria or yeasts feed on the natural sugars in a food and slowly change it. As they work, they make acids and gases, which give fermented foods their tangy, lively taste and help keep them from spoiling.
You eat more fermented foods than you might think: yoghurt, cheese, crème fraîche, sourdough bread, wine, vinegar, soy sauce, miso, olives, even chocolate and coffee go through a kind of fermentation on their way to you. Fermentation is one of the oldest kitchen skills there is.
But here’s an important difference. In some fermented foods, the bacteria are still alive when you eat them. In others, they’ve been killed by baking, heating or pasteurising. Sourdough bread is fermented, but after the oven nothing is alive in it. Raw sauerkraut, kefir and plain live yoghurt still carry their bacteria. For your gut, it’s the live ones that bring something extra.
Why are fermented foods good for my gut?
Living in your gut is a huge community of bacteria, which I like to call your gut garden. Most of the time, the best thing you can do for it is feed it: with plenty of plants and fibre, in many colours. Live fermented foods add something else: friendly bacteria of their own, passing through, a bit like visitors bringing news to the garden.
Fermentation can also make some foods easier to digest. The bacteria have already done part of the work, which is why some people who find milk difficult are fine with kefir or yoghurt. And fermented foods are full of flavour, so a spoonful can lift a simple meal. If you have questions about your gut in general, you may find answers in my frequently asked questions on gut health.
I’d like to be honest with you, though. You may read that fermented foods will cure anxiety, prevent all kinds of diseases or melt away inflammation. Those promises go much further than we know. I see fermented foods as a delicious, traditional part of a varied way of eating, alongside fibre, colour, good sleep and calm meals. I explain how they work together with fibre in The gut health trio: prebiotics, probiotics and fermented foods, and how your gut talks to the rest of you in how your gut and brain communicate.
How do I know if a fermented food is really “live”?
This is where many people get caught out in the shop.
Look in the chilled section. Live sauerkraut, kimchi and kefir usually need to be kept cold. A jar on a warm shelf has almost always been heated to keep it, and the bacteria are gone.
Read the label. Look for words like “raw”, “unpasteurised”, “live” or “contains live cultures”.
Watch out for vinegar. Most gherkins and pickles in jars are made with vinegar, not fermented. They’re tasty, but they’re not live.
Choose plain yoghurt. Plain live yoghurt or kefir, with fruit added at home, is a lovely everyday choice.
Making your own is the surest way to know your sauerkraut is alive, and it costs almost nothing.
Which fermented foods should a beginner start with?
Start with what you already like, and with foods that fit easily into your meals.
Plain yoghurt and kefir are the gentlest start: at breakfast with oats and fruit, or as a sauce with herbs and garlic. Raw sauerkraut is lovely with sausages, eggs, a lentil salad or on a slice of rye bread with cheese. Miso stirred into a soup once it’s off the heat gives it a deep, savoury taste. Kimchi, the spicy Korean cabbage, wakes up a bowl of rice and vegetables. And aged cheeses and real sourdough are fermented favourites you probably already enjoy.
A spoonful or two a day is plenty to begin with. If you bloat easily, start with a teaspoon and let your gut get used to it.
What fermented foods are eaten around the world?
Almost every food tradition has its own. Here are a few:
Sauerkraut, fermented cabbage, much loved across Central and Eastern Europe and in Alsace, where it becomes choucroute.
Kimchi, fermented cabbage and other vegetables with chilli and garlic, from Korea.
Miso and natto, made from fermented soya beans, from Japan.
Tempeh, a firm cake of fermented soya beans, from Indonesia.
Kefir, a fermented milk drink from the Caucasus mountains.
Yoghurt, made for centuries across the Middle East, Central Asia and the Balkans.
Injera, a soft, spongy fermented flatbread from Ethiopia.
Kvass, a lightly sour drink made from bread, from Eastern Europe.
Kombucha, a fizzy fermented tea that has become popular all over the world.
My easy homemade sauerkraut
This is the recipe I always suggest to beginners. Sauerkraut is just cabbage and salt. The salt draws the water out of the cabbage, the cabbage sits under its own salty juice, and the friendly bacteria that already live on the leaves do the rest.
Ingredients
1 white or green cabbage, about 1 kg (2¼ lb)
20 g (¾ oz) fine sea salt, with no added iodine (about 1 heaped tablespoon)
1 teaspoon caraway seeds or a few juniper berries (optional)
Equipment
a large bowl and a sharp knife or a mandoline
a very clean glass jar of about 1 litre (1 quart)
a weight that fits inside the jar: a small glass jar filled with water works well
a clean cloth or a lid
Method
Take off one or two of the outer leaves and keep them. Cut the cabbage into quarters, remove the hard core and slice it very thinly.
Put the cabbage in the bowl and sprinkle the salt over it. Massage it with your hands for a few minutes, squeezing as you go. Leave it for a little while and massage again. It will soften and give off a surprising amount of juice.
Stir in the caraway or juniper, if using.
Pack the cabbage into the jar a handful at a time, pressing down hard with your fist each time so the juice rises. Pour in any juice left in the bowl.
Fold one of the outer leaves on top and press it down, then put your weight on it. The cabbage must stay completely under the juice. Leave a little space at the top of the jar.
Cover with a cloth, or rest the lid on loosely so the gases can escape. If you close the lid fully, open it once a day to let the gas out. Put the jar on a plate, in a cool spot out of the sun.
Check it every day or two and press it down if the cabbage has risen above the juice. After about a week, start tasting. When you like the sourness, which may take one week or several, take out the weight and the leaf, close the jar and keep it in the fridge.
Your sauerkraut will keep for several months in the fridge, as long as it looks and smells right, and its flavour keeps developing. In autumn, try a red cabbage version, or add a grated carrot, a grated apple or a little fresh ginger.
Is homemade fermentation safe?
Yes, when you follow a few simple rules. Use a very clean jar and clean hands. Use enough salt. Keep the vegetables under the juice at all times, because that’s what protects them. Bubbles, a sour smell and cloudy juice are all normal signs that your ferment is alive.
But if you see fuzzy mould, or the sauerkraut smells rotten, feels slimy or looks wrong, throw the whole jar away. When in doubt, throw it out, and start again. It happens to everyone now and then.
What helps?
Here’s how I suggest bringing fermented foods into your everyday meals.
1. Start small
A teaspoon or a spoonful a day is a lovely beginning. Your gut likes gentle changes, so build up slowly over a few weeks.
2. Feed your gut garden too
Fermented foods work best alongside plenty of fibre and plant variety: lentils, beans, oats, leeks, onions, apples, vegetables in many colours. I wrote about colour in Colour your plate with nutrients.
3. Add them to meals you already eat
A spoonful of sauerkraut with your eggs or your lentil salad, kefir in your overnight oats, miso stirred into your soup at the end. A warming autumn soup with a spoonful of miso makes a lovely winter lunch, and you’ll find a soup to start with in Eating with the seasons.
4. Don’t cook the live ones
Heat kills the friendly bacteria, so add sauerkraut, kefir and miso at the end, once the dish is off the heat. Cooked sauerkraut, like choucroute, is still delicious, it just isn’t live any more.
What doesn’t help?
Eating a whole jar on day one. Your gut needs time to get used to them.
Relying on fermented foods alone. Without plenty of plants and fibre, they can’t do much on their own.
Sweet, flavoured yoghurts and drinks. Plain is better; add your own fruit.
Expecting them to fix everything. They’re one lovely part of the picture, not a cure.
Try this for one week
Choose one fermented food you think you’d enjoy: plain yoghurt, kefir or raw sauerkraut. For seven days, have one spoonful at one meal each day.
At the same time, start your first jar of homemade sauerkraut. Look at it each day, press it down, notice the bubbles.
At the end of the week, write down how your belly felt and which way of eating your spoonful you enjoyed most. And by then, your sauerkraut will be ready for its first taste.
Frequently asked questions
Is shop-bought sauerkraut as good as homemade?
It can be, if it’s raw and unpasteurised, usually found in the chilled section. Sauerkraut in tins or jars kept on a warm shelf has usually been heated, so it no longer contains live bacteria.
How much fermented food should I eat?
There’s no magic amount. A spoonful or two a day is a pleasant, gentle start, and you can build up from there if you enjoy it and your gut feels comfortable.
Is fermented food safe for everyone?
Most people can enjoy it, but please check with your doctor first if your immune system is weakened, if you’re pregnant (especially before drinking unpasteurised kombucha), if you take a type of antidepressant called an MAOI, or if you react to histamine. Sauerkraut and miso are salty, so if you’ve been told to watch your salt, ask your doctor too.
When should I talk to my doctor?
If fermented foods give you strong bloating, pain, headaches or a rash, stop and ask your doctor. And see your doctor about any digestive change that doesn’t settle, before reaching for probiotic supplements or remedies.
Would you like some help?
Looking after your gut is about much more than one jar of sauerkraut: it’s how you eat, sleep, move and slow down. I run group programmes in nutrition and health, such as Six Tuesdays in Montignac, where we look at your gut and your everyday meals together, in a practical way. If you’d like to hear when the next group opens, write to me at hello@catherinepolet.coach.
You can also work with me one to one, online. Book a free 20-minute call, tell me how your digestion feels, and we’ll find a gentle, delicious place to start.
About Catherine
I’m Catherine Polet, a holistic nutrition health coach, yoga and autogenic training teacher for more than 30 years, author and speaker. I help people find a way of eating and living that suits their own body, online in English, French, Spanish and German, and in person in Southwest France.
