Key findings
- 1Kefir grains contain 30-50 species of bacteria and yeast; far more probiotic diversity than yogurt's 2-6 strains, making it the most microbiologically complex common dairy product
- 2The fermentation process breaks down part of the lactose, so a cup of kefir carries less of it than the milk it was made from
- 3Plain kefir is one of the least processed dairy products available, transformed entirely by microbial cultures rather than industrial processes
Why is Kefir Level 2 on average?
Kefir fermentation is fundamentally different from yogurt production. Yogurt uses 2-3 defined bacterial strains added to heated milk. Kefir uses kefir grains; gelatinous clusters containing 30-50 different species of bacteria and yeast living in a symbiotic matrix of proteins and polysaccharides. These grains are added to milk, ferment for 18-24 hours, and are then strained out and reused indefinitely (some kefir grains have been passed down through families for generations). The resulting beverage contains 12-30 probiotic strains compared to yogurt's typical 2-6, plus yeasts not found in any other common dairy product. The fermentation also partially breaks down the lactose and produces B vitamins, vitamin K2, and bioactive peptides. Plain kefir is literally just milk transformed by microbial cultures. Flavored kefir adds cane sugar (8-12g per serving), natural flavors, and fruit puree, which makes it more processed than plain. In our analysis, kefir products average a Processing Score of 3.8, which is Level 2.
How 283 kefir products break down
Share of products at each processing level, in our analysis.
Kefir brand comparison
From least to most processed in our database.
How to read a kefir label
- 1
Plain kefir should list: pasteurized milk and live active kefir cultures; nothing else needed
- 2
Flavored kefir: check sugar content (plain has ~8g natural lactose, flavored adds 8-12g on top)
- 3
Look for "live and active cultures"; pasteurized kefir has been heat-treated and no longer contains live probiotics
- 4
Plain kefir is milk and cultures, while flavored varieties add sugar and flavors; compare the two labels within the same brand
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Frequently asked questions
Is kefir better than yogurt?
From a processing standpoint, plain kefir and plain yogurt are both simple fermented milks. Kefir contains significantly more probiotic diversity (12-30 strains vs 2-6 in yogurt) and includes yeasts not found in yogurt. The thinner, drinkable texture makes it easier to consume on the go. Nutritionally, they are comparable in protein and calcium.
Is Lifeway kefir ultra-processed?
Lifeway plain kefir lists milk and kefir cultures, a very short list. Lifeway flavored kefir adds cane sugar and natural flavors, which makes it more processed than the plain. Check the specific bottle.
Can lactose-intolerant people drink kefir?
Kefir fermentation breaks down 20-30% of the lactose in milk, so a cup carries less lactose than the milk it started as, and the cultures themselves carry lactase. Whether that is enough for a given person is a medical question rather than a processing one.
What are kefir grains?
Kefir grains are not actual grains, and they are gelatinous clusters of 30-50 species of bacteria and yeast held together by a matrix of proteins and polysaccharides. They look like small cauliflower florets and can be reused indefinitely, with some families passing them down for generations. They are the most complex natural fermentation starter known.
Is kefir good for gut health?
That is outside the scope of processing analysis. What the ingredient list shows: plain kefir contains 12-30 live bacterial and yeast strains, and the fermentation produces bioactive peptides and vitamin K2. Flavored kefir adds cane sugar and natural flavors on top of the plain.