How to choose a kefir from the label, not the marketing

Choose a plain kefir whose ingredients are milk and kefir cultures, then check sugars per 100ml and ignore most of the front. In Great Britain no live culture has an authorised health claim, and UK dietitians do not class kefir as a probiotic, so the back of the bottle tells you far more than the marketing does.

That is the whole method. The rest of this page is why each step matters, and what to make of the words you will see in the chiller, whichever supermarket you are standing in.

What is kefir, and what should the ingredients say?

Kefir is milk fermented with a mix of bacteria and yeasts. The international food standard for fermented milks, the Codex standard, describes its starter culture as one prepared from kefir grains, with lactic acid bacteria and both lactose fermenting and non lactose fermenting yeasts living together. The yeasts are what set it apart from yoghurt.

So a plain kefir’s ingredients list should be short: milk, then the cultures. Ingredients are listed in descending order of weight, so milk comes first and everything after it is a smaller part of the bottle. Some brands name every strain of bacteria and yeast. Some print kefir cultures and leave it there. A longer culture list is more information, not proof of a better drink.

One more phrase worth looking for. Under the same standard, a fermented milk that has been heat treated after fermentation is no longer expected to contain live organisms, and it should say heat treated in its name. If you see those words, the cultures are not the point of that product.

Is kefir a probiotic?

Not in the eyes of UK dietitians. The British Dietetic Association’s view is that kefir and kombucha may contain beneficial microorganisms, but neither is considered a probiotic, because the scientific evidence on their health benefits is lacking. The NHS is cautious about probiotics in general too: there is little evidence behind many of the health claims made for them, and you cannot always be sure a product contains enough bacteria to have an effect.

That does not make kefir pointless. It is a fermented milk you might enjoy, with the protein and calcium that come with milk. It means the health halo is ahead of the evidence, and it is worth paying for a kefir because you like it rather than because the bottle hints at what it will do.

What can a kefir label legally claim?

Less than the design suggests. A statement of fact, such as contains live cultures, is allowed because it describes what is in the bottle and promises nothing. A health claim, meaning anything that says or implies a link between the food and your health, has to be on the GB register of authorised claims.

Probiotic itself is treated as a health claim in Department of Health and Social Care guidance, and the advertising rules allow it only when a relevant authorised claim sits beside it. Gut friendly is not an authorised claim in Great Britain at all. And while the register does authorise wording about the immune system, every one of those claims belongs to a named vitamin or mineral, such as vitamin C, vitamin D or zinc. None belongs to a live culture.

So when a kefir says something about immunity, look for the added nutrient. The claim is about that, not the fermentation.

What do the big culture numbers on the front mean?

Less than they look. The international standard expects at least 10 million starter organisms per gram in a kefir, up to its best before date. Multiply that by 100 and a kefir that meets the standard has at least a billion in every 100g before anyone prints a number on it. A front of pack figure in the billions describes a normal kefir. It does not mark one out.

If a flavoured kefir prints a culture count, remember that the fruit takes up room in the bottle. The standard’s criteria for a flavoured fermented milk apply to the fermented milk part, not the whole drink.

How much sugar should a kefir have?

As little added sugar as possible, and the ingredients list tells you more than the number does. A plain kefir will still show sugars on its panel, because the of which sugars figure counts everything, including the sugar that comes from milk. Milk sugars are not free sugars. Plain yoghurt can show as much as 8g of sugars a serving with nothing added at all, and plain kefir is the same story.

Flavoured kefirs are where it changes. Fruit purée, fruit juice concentrate and sugar are all free sugars, the kind adults are advised to keep below 30g a day. A useful habit: put the plain and the flavoured version from the same range side by side. The gap between their sugars per 100ml gives you a rough idea of what the flavouring added.

Then compare against the drink thresholds. A low sugar claim on a drink needs 2.5g of sugars or less per 100ml. On a front of pack traffic light label, a drink goes red for sugars above 11.25g per 100ml. Both are per 100ml, so they work on any bottle size.

Should I try kefir if I have IBS?

Ask a dietitian first if you have a gut condition. That is the BDA’s advice for anyone with a gut condition who wants to try a probiotic, and a fermented milk drink is close enough to apply it. If you are already drinking kefir and feel fine, there is nothing in this page that says stop.

If you are reading kefir labels because your gut has been bothering you for a while, the label is not where the answer is. Ask for an urgent GP appointment or get help from NHS 111 if you have lost a lot of weight for no reason, you are bleeding from your bottom or have bloody diarrhoea, or you find a hard lump or swelling in your tummy.

Where does kefir fit with yoghurt and the rest of the chiller?

The same checks work on a pot of yoghurt as on a bottle of kefir: plain base, short ingredients, sugars against the 2.5g and 11.25g lines for a drink or the 5g and 22.5g lines for a spoonable pot. Gut friendly yoghurt labels takes the yoghurt shelf apart the same way, and probiotic and live cultures on labels goes further into the claim wording.

If you want to check how fast you can read a label like this one, try the label test. And if gut friendly on a pack still sounds like it should mean something, what gut friendly means on a UK label explains why it does not.