Between kefir and fermented milk there are three real differences: kefir grains are strained out, reused and multiply; kefir contains yeasts, hence 0.2 to 1 per cent alcohol and a slight fizz; and it works at 20 to 25 °C rather than the 40 to 45 °C a yoghurt needs. On nutrients they are nearly identical.
The figures on this page
This page has been rewritten. The previous version compared them in terms of health benefits, which is not permitted. The differences below are the ones that actually exist.
The question kefir and fermented milk is usually asked expecting a difference in health terms. There is no answer of that kind to give, and no food seller in the European Union may give one. No health claim about kefir is authorised.
There are real differences, though, and they are worth knowing because they change what you get in the glass and what you can do with the culture. Three of them are substantial.
This is the most concrete difference and the one with the clearest consequence.
A yoghurt culture is consumed with the yoghurt. You add it, it works, and it leaves with the product. To make the next batch you either buy another culture or keep a spoonful of the previous yoghurt, which weakens over generations.
Kefir grains are strained out and reused. They are visible in the jar, you recover them with a plastic sieve, and they go straight into fresh milk. And they multiply: from 10 to 20 g you have roughly double in three to six weeks.
The practical result is that you buy the culture once. That is the real commercial argument for kefir and fermented milk, and it needs no mention of health to stand up.
A yoghurt culture is bacteria. A kefir culture is bacteria and yeasts, and the yeasts change three things you can taste.
Traces of alcohol, 0.2 to 1 per cent, higher after a long or warm ferment. Yoghurt and soured milk contain none. This is the difference nobody mentions, and it is the one that matters to anyone avoiding alcohol entirely.
A slight fizz, because the yeasts produce carbon dioxide. Not much in milk kefir, but enough to lift the lid of a tightly closed jar.
A yeasty note, faintly like bread dough, which is also why kefir tastes different from yoghurt even at the same acidity.
Milk kefir on the right. A yoghurt would need 40 to 45 °C held for four to eight hours, which is the practical difference in one line.
| What goes in | Water kefir, 1 litre | Milk kefir, 1 litre |
|---|---|---|
| Culture | 30 g of grains | 10 to 20 g of grains |
| Liquid | 1 litre of unchlorinated water | 1 litre of milk |
| Sugar | 4 tablespoons, about 60 g | none, the lactose is enough |
| Dried fruit | 1 fig or 2 dried apricots | none |
| Citrus | 1 lemon or 1 orange | none |
| Duration | 24 h, up to 48 h | 24 h |
| Temperature | 20 to 25 °C | 20 to 25 °C |
Less visible, and it explains why one is made at home more easily than the other.
Yoghurt needs 40 to 45 °C held steady for four to eight hours. That means a yoghurt maker, an oven at its lowest setting, or a well insulated container. Get it wrong and the result does not set.
Kefir needs 20 to 25 °C, which is an ordinary kitchen, for 24 hours. No equipment, no thermometer, no monitoring. That is the single biggest reason kefir is simpler to keep going than yoghurt.
Soured milk sits with kefir on temperature, at room conditions for 12 to 24 hours, but its culture is not recovered and contains no yeasts.
The phrase kefir and fermented milk covers a longer list than most people realise, and the names vary by country, which is where much of the confusion comes from.
Soured milk, cultured with lactic acid bacteria at room temperature for 12 to 24 hours. Pourable, mildly acidic, culture not recovered.
Buttermilk, traditionally the liquid left after churning butter, today usually a cultured milk sold under that name. Thinner, quite acidic, mostly used in baking.
Labneh, skyr, quark and similar products are fermented milks that have been strained, so they are thicker and more concentrated in protein. Straining is a step, not a different culture.
And kefir itself has strained forms: hang milk kefir in a cloth for twelve hours in the fridge and you get a spreadable fresh cheese on top and whey below. That is the same product, concentrated.
The useful thing to take from this list is that most of the distinctions are about the culture used, the temperature and whether the product was strained. None of them is about an effect.
This is the part that disappoints people, and it is worth stating plainly.
On energy, protein, fat and calcium, milk kefir, yoghurt and soured milk made from the same whole milk land in the same place. Roughly 110 to 130 kcal per 200 ml, about 6 to 7 g of protein, about 240 mg of calcium. They start from the same milk, and fermentation barely touches those figures.
What fermentation does change in all three is the lactose, which is partly consumed, the pH, which falls to around 4.2 to 4.6, and the texture. Those are the same changes in all three cases, to different degrees.
So anyone looking in kefir and fermented milk for a clear nutritional gap will not find it in the numbers. The differences are the yeasts, the reusable grains, the temperature and the taste.
One important point. If you have a diagnosed intolerance, an allergy or a treatment, no change is decided from a web page. We cannot state a residual lactose figure and we cannot claim tolerability.
First, cutting the sugar. By far the most common. The 4 tablespoons per litre feed the grains, not the drinker. After 24 hours a good part is gone. Halving it starves the culture, and within three cycles it stops multiplying. For a less sweet drink, extend the time.
Second, chlorinated water. Chlorine is made to kill microorganisms, and it does the same to your culture. Bottled water, filtered water, or tap water left uncovered for 12 hours all solve it.
Third, a jar that is too small. A litre of drink needs a 1.5 litre jar. The carbon dioxide has to go somewhere. A jar filled to the brim overflows and smells unpleasant within two days.
Fourth, rinsing every cycle. The grains are rinsed only when visibly coated, in cool unchlorinated water. Rinsing at every turn takes away the film that protects them.
Fifth, metal. A plain metal sieve or spoon reacts with the acidity. Plastic or stainless steel solves it, and it is the only point where equipment genuinely matters.
The best way to understand how this works is to follow one jar from arrival to its steady rhythm.
Day 1, activation. The grains arrive hydrated. They go into 30 cl of water with 40 g of sugar for 24 hours, with no fig and no citrus. This is a wake-up cycle, not a drink. The liquid is poured away.
Days 2 to 7, the first cycles. The first two drinks may be flat or too sweet. That is not a fault in the grains, it is the time they need. Strain at 24 hours anyway, always with the same quantities.
Week 2, the rhythm. The drink becomes consistent. Bubbles at the rim, a slightly tart taste, the fig rising around the twelfth hour. From here you can tell by eye whether a jar is ready.
Weeks 3 to 6, multiplication. The grains visibly take up more room. When you strain, you have more than you put in. At that point you divide. Part stays in the jar, the rest starts a second litre or is dried as a reserve.
It belongs here, because the question is almost always asked in the hope of a health distinction.
No authorised claim for kefir. The register held by the European Food Safety Authority contains nothing, on any subject. Nor is there anything for yoghurt as a food in general. The authorised claims in that area apply to specific nutrients in proven amounts, such as calcium, and they require a known quantity in the finished product.
Not lactose free, none of the three. The culture consumes part of the lactose and the longer it ferments the more it consumes, but how much remains in your jar is unknown without an analysis. Lactose free is a claim tied to a threshold.
No microorganism count. For a homemade preparation a count per millilitre does not exist, in any of the three cases.
And the word probiotic is not an argument. It is treated as a health claim in several member states, because its definition contains a benefit.
Milk kefir if you want the least equipment and a culture that lasts. An ordinary kitchen temperature, 24 hours, five minutes of work a day, and grains you never buy again.
Yoghurt if you want a set texture and a milder taste, and you are willing to hold 40 to 45 °C. The result is closer to what most people expect from a dairy product, and the culture has to be renewed.
Soured milk if you want the simplest possible thing. A culture added at room temperature, no recovery, no reuse.
On kefir and fermented milk that is the whole of a comparison we can stand behind. Three products, three cultures, three temperatures, and the same milk underneath all three.
| Previous wording | Why it is a problem |
|---|---|
| «health benefits and uses» | a comparison in health terms, in the title and the URL |
| «kefir is richer in probiotics» | restricted term, and a claim with no authorisation |
| «better for your gut than yoghurt» | physiological effect asserted, and a comparative claim |
| «more digestible» | claim about digestion, not authorised |
| «more beneficial bacteria» | a count that does not exist for a home ferment |
None of those sentences was written in bad faith. They came from copied articles. The difficulty with kefir and fermented milk is that the real differences are genuinely interesting, so there was never any need to invent health ones.
The health claims authorised in the European Union are listed in the register of the European Food Safety Authority. Guidance on home food hygiene is published by the Food Standards Agency.
Live cultures, water and milk
Shipped hydrated and active, ready for the first cycle on the day they arrive.
See the culturesThe real differences here are good enough that nobody needed to invent health ones. A culture you buy once, yeasts you can taste, and a kitchen temperature instead of 45 °C.
And if this page is useful for one thing, let it be the alcohol line. On kefir and fermented milk that is the one difference that can actually matter to someone, and it is the one almost every comparison leaves out.
Three substantial ones: kefir grains are strained out and reused while a yoghurt or soured milk culture leaves with the product; kefir contains yeasts, hence 0.2 to 1 per cent alcohol and a slight fizz; and kefir works at 20 to 25 °C whereas yoghurt needs 40 to 45 °C.
We cannot answer in those terms, and no food seller in the European Union may. No health claim about kefir is authorised. On energy, protein, fat and calcium the two are nearly identical, because they start from the same milk.
Correct. Kefir contains 0.2 to 1 per cent, higher after a long or warm ferment, because its culture includes yeasts. Yoghurt and soured milk contain none. This is the difference most pages leave out.
The temperature. Kefir works at 20 to 25 °C, which is an ordinary kitchen, for 24 hours. Yoghurt needs 40 to 45 °C held steady for four to eight hours, which means a yoghurt maker or an insulated container.
Not in the same way. A yoghurt culture is consumed with the yoghurt; you can keep a spoonful to start the next batch, but it weakens over generations. Kefir grains are recovered with a sieve, reused indefinitely, and they multiply.
Yes. From 10 to 20 g you have roughly double in three to six weeks if the recipe is kept to. That is why the culture is bought once. The surplus starts a second jar or is dried as a reserve.
Made from the same whole milk, all three land around 110 to 130 kcal per 200 ml, with about 6 to 7 g of protein and about 240 mg of calcium. Water kefir, which is made on water, is 30 to 50 kcal.
No, and that claim would not be permitted for any of them. The culture consumes part of the lactose and the longer it ferments the more it consumes, but how much remains in your jar is unknown without an analysis.
We cannot use that word as a selling point. It is treated as a health claim in several member states. And no count exists for a homemade preparation in any of the three cases.
Milk kefir if you want the least equipment and a culture you never rebuy. Yoghurt if you want a set texture and are willing to hold 40 to 45 °C. Soured milk if you want the simplest possible thing.
