Gut instinct

Kefir is becoming increasingly mainstream, as its refreshing taste and purported health benefits win over more acolytes. Louise Crane digs into the science and history of this ancient fermented drink.


Touted as a miracle food alongside kombucha and pro-biotic yogurt, kefir is the ancient, fermented drink that has come down the mountain to set up life on the supermarket shelves. Teeming with ‘good’ bacteria, it is said to provide a range of health benefits, from gut health to a better immune system. With the big, recent focus on health and wellness, consumer demand for kefir drinks has soared. UK supermarket Tesco experienced a 400% rise between August 2018 and February 2020 according to, making it one of the major food trends last year. This success is set to continue as brands like The Collective, Bio-tiful and Yeo Valley provide major supermarkets with an ever-widening range of kefir products - yogurts, ice cream and drinks.

Kefir has been popular in Eastern Europe and the Caucus Mountains for 2,000 years. The usual explanation is that it was discovered by shepherds who kept cow’s and goat’s milk in their handy leather knapsacks, open to the natural air with all its yeast and bacteria. As we know here at Ferment, carbohydrate plus yeast and/or bacteria equals fermentation, the sugars used for fuel becoming acidic, which gives kefir its subtle tang. In kefir’s case, the alcohol produced is minimal, around 2% abv for a natural kefir made by early 20th century Russian methods, though commercial kefirs today are around 0.3%. The name means “feeling good after food” in Turkish, and we can’t help but wonder if this is, in part, down to its gentle booze factor.

More likely is that “feeling good” from kefir results from its rich bacterial diversity, which is evidenced to improve gut health. All of us have bacteria in our digestive system, the “human microbiome”, which helps break down food by using up its energy-rich molecules to keep themselves alive. One result of this is the production of gas. So-called bad bacteria produce unhelpful, unwanted and generally foul-smelling gas like methane, which comes out in rather unfortunate burps and farts. Drinking kefir provides us with more good, pro-biotic bacteria than bad, resulting in a better balance of bacteria in our gut, and less-stinky pants.


Did you know?  Kefir has become known in parts of Latin America as búlgaros, or “Bulgarians”.


Kefir comes in two main varieties: milk kefir, the most common variety, and water kefir. Each type has its own kefir grains, a mesophilic symbiotic culture or “scoby” made up of lactic acid bacteria (LAB) and yeasts that, together, look like a humble cauliflower. The sharp-witted among you will remember from our kombucha and bacteria articles of previous years that a scoby is also responsible for making kimchi and sourdough bread, 2020’s favourite lockdown bake. Fermenting milk kefir grains with milk produces a drink that is protein-rich, abundant in vitamins and minerals, creamy but tangy (since the milk sugars are converted from lactose to lactic acid), thinner than yogurt but with much more bacterial diversity. Ferment water kefir grains with sugary water, and you make a tart, fizzy potion similar to kombucha, and better-tasting according to kefir fans.

The rise of kefir in the UK started about 20 years ago, when Tesco began stocking it as part of its Polish food range. Previously available only in health food and specialist shops, kefir could be bought as part of your weekly shop. Demand took off in the last decade due to trends in wellness, wellbeing and a focus on gut health. This has been scientifically linked to many human and animal conditions, though London-based The Nutrition Society published a report in 2017 noting there is a “need for systematic clinical trials to better understand the effects of regular use of kefir as part of a diet, and for their effect on preventing diseases.”

The consensus is that a healthy gut (i.e. one with a diverse range of good yeasts and bacteria) means we can better break down the food we eat and absorb its nutrients more fully. A healthy gut offers protection from pathogens like bad bacteria, as well as the aforementioned lack of farts. There is ample evidence that probiotics and probiotic foods can alleviate many digestive problems, such as diarrhoea, IBS and ulcers caused by infection with the H. pylori acid. Your immune system will function better as well as all the body’s cells, which helps to manage weight, cholesterol, blood pressure and blood sugar. It’s possible that an immune system stimulated by probiotics might help to reduce tumour growth. 

Mental health is strongly linked to gut health too. 90% of our receptors for serotonin, the chemical in our bodies that helps with mood stabilisation, sleeping, eating and digesting, are found in the gut. Our minds and guts are inextricably linked, with negative emotions causing our digestive system to speed up or slow down. 

So why kefir in particular? The probiotic strain Lactobacillus kefiri, which is unique to kefir, has been demonstrated to inhibit the growth of various harmful bacteria, including Salmonella, Helicobacter pylori and E. coli according to two studies. Kefiran, a type of carbohydrate present in kefir, also has antibacterial properties according to Brazilian scientists, and it supresses asthma responses in animals. Test-tube studies show that kefir may reduce tumour growth, and one such study in the Journal of Medicinal Food found that kefir extract reduced the number of human breast cancer cells by 56%, compared to only 14% for yogurt extract.

A 175ml serving of low-fat kefir contains up to 15% of our recommended daily intake of calcium, phosphorus, and vitamins B2 and B12, as well as 3% of our recommended magnesium, and a decent dose of the sunshine vitamin D, according to The U.S. Department of Agriculture. The natural B12 in kefir contributes to the normal function of the immune system. Full-fat kefir is also a great source of vitamin K2, which helps the body to absorb calcium and likely reduces the risk of fractures. 

In the last decade, milk kefir has been produced in the UK by around ten companies. More recently, start-ups including Chuckling Goat and Nourish Kefir hope to emulate the success of Scotland-based small business Graham’s the Family Dairy. Owner Robert Graham puts the long-term trend as based around the attributes of “provenance, natural and protein”. There are three major producers, all with their own twist on kefir.

Bio-tiful Dairy is the top-selling brand in the UK. Their range includes milk kefir drinks, kefir yogurts, ice cream and shots, and many products with added protein in the form of Quark and seeds. Biotiful Kefir contains over 40 strains of gut-friendly cultures and is made with British milk. Their website is a mine of information about the researched health benefits of probiotics. Founder Natasha Bowes estimated the liquid kefir category in the UK in October 2020 to be worth around £40m, compared to about £2m at the start of 2017. “It’s been a stratospheric rise”, she told Just Food magazine

PHOTO: Yeo Valley

Yeo Valley, a Bristol-based dairy that puts nature first, offers a kefir yogurt range made with their organic milk and packed with live cultures from 14 different bacterial strains including the well-known Lactobacillus acidophilus as well as the more exotic-sounding Leuconostoc mesenteroides. Top notch flavours are on offer, from mango and passion fruit to blueberry, and you can buy the yogurt as a fridge-temperature or frozen treat. 

The Collective, a UK dairy that originated in New Zealand, makes kefir products alongside their fantastically thick, best-selling yogurts. Their kefir drink comes in original, coconut, mango, berries and passion fruit and all flavours can be found in their kefir yogurt range. They have developed a more controlled process for making their kefir so they can reliably guarantee each kefir drink has a whopping 60 billion live cultures per 250ml serving.

The effect of Covid-19 on kefir sales is remarkable. Yeo Valley has had unprecedented demand for its fermented yogurts during the pandemic. Commercial Marketing Manager Tor Crockatt said: “As a result of COVID‐19… consumers look to maintain and enhance their long-term health. There’s no doubt that shoppers are seeking brands with strong ethical, environmental and natural credentials.”

The main limit to kefir’s world domination is the price. A 250ml bottle from more established brands costs around £1.45, but cheaper Polish brands sell for £1.50 per litre. A 500ml Bio-tiful drink can cost £2.25 in Sainsbury’s, the UK’s second-largest grocer by sales. Even with the uncertainties created by coronavirus and less-deep consumer pockets, Natasha Bowes sees kefir as recession-proof and still expects Bio-tiful sales in 2020 will have doubled, as the business has done for the “last few years”.

With demand rising, overseas businesses are nudging their way into the UK: Lifeway Foods in the US with kefir smoothies and ice cream; Finland’s Valio with fermented yogurt, and Lowicz, Krasnystaw, Milko and Jana, all originating from Poland, are also available in some UK supermarkets. 

Kefir is a trend that doesn’t look to be going anywhere. Yeo Valley Market-analyst Molly Benbox told Just Food magazine “Kefir innovation is now popping up in multiple categories outside of yogurt and yogurt drinks.” Expect kefir cheese – but what about kefir beer? As we say here at Ferment, “Nice kefir you, kefir you nice!”.


Make your own milk kefir at home

Kefir is easy to make at home, with kefir grains widely available online, and in health food stores for those who are prepared to face the outside world. Unlike with yogurt or beer, extra heat is not required in the preparation.

Full-fat animal milk is best, either raw or pasteurised, but skimmed just about works too. UHT milk is a no go. For a non-dairy option, coconut milk can be used, but the kefir grains will lose their vitality after a while. If the grains stop working for any reason, pop them back into some full-fat dairy milk to refresh them. Other dairy-free milks tend to be unsuccessful.

1) Put around 1 tablespoon (14g) of activated kefir grains into a clean, pint-sized glass jar. To activate dried grains, soak them in fresh milk at room temperature for between 3 and 7 days, changing the milk every 24 hours.

2) Add about two cups (500ml) of milk, leaving a one inch/2.5 cm gap at the top of the jar. If you desire a thicker kefir, add some full-fat cream.

3) Cover the jar with cheesecloth or a clean paper towel and leave for 12–48 hours at room temperature.

4) Shake or whisk if the mixture separates.

5) When it begins to look clumpy and/or taste tangy, strain out the kefir grains with a small strainer into the container for storing your milk kefir.

6) Put the grains in a new jar and start again – just like a sourdough.

You can then drink or refrigerate the milk kefir, it will keep for a week.

Using this method, you can make a fresh batch of kefir roughly every 24 hours. To take a break from making kefir, place the grains in fresh milk, cover tightly, and refrigerate. Note that kefir grains can become weakened by exposure to metal although brief exposure, like using a metal strainer or stirring with a metal spoon, is fine.

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