Most Icelandic yogurt sold in the U.S. does contain live probiotic cultures, but the answer depends on the brand and how the product is processed after fermentation. Like all yogurt, skyr starts with live bacterial cultures that ferment milk. Whether those cultures survive into the final product comes down to one step: whether the skyr is pasteurized after fermentation.
How Skyr Gets Its Cultures
Skyr is made by heating skimmed milk, cooling it to around 110°F, then adding live bacterial cultures to make it coagulate. Traditionally, the culture came from a pinch of skyr saved from the previous batch, a practice stretching back centuries in Iceland. This means skyr is a fermented product at its core, and fermentation requires living bacteria.
The cultures used in skyr are similar to those in regular and Greek yogurt. Icelandic Provisions, for example, lists its cultures as Streptococcus thermophilus (their proprietary heirloom Icelandic strain), Lactobacillus bulgaricus, and Bifidobacterium. These are the same families of bacteria found in most probiotic yogurts, though the specific Icelandic strains have been passed down through generations of traditional skyr-making.
The Pasteurization Problem
Here’s the catch. Some manufacturers pasteurize skyr after fermentation to extend shelf life. This kills the live cultures. Iceland’s largest dairy producer, MS Iceland Dairies, began doing this and doubled the product’s shelf life from two weeks to four. The tradeoff: no more living bacteria in the finished product.
One Icelandic skyr maker discovered this the hard way when he tried using store-bought skyr as a starter for homemade batches and couldn’t get the milk to coagulate. The pasteurized product simply had no living cultures left to do the work. He eventually found an unpasteurized variety (labeled “unstirred skyr”) that still contained active cultures.
For U.S. consumers, this means you need to check the label. Products that say “live and active cultures” contain bacteria that were alive at the time of packaging. The Live & Active Cultures (LAC) seal, administered by the International Dairy Foods Association, certifies that a product contains at least 100 million cultures per gram at the time of manufacture. That’s ten times higher than the FDA’s minimum requirement for yogurt.
What U.S. Brands Actually Contain
The major Icelandic yogurt brands sold in America do include live cultures, and some go further by adding probiotic strains beyond the basic starter bacteria.
Icelandic Provisions lists 3 billion probiotics per serving in its plain low-fat skyr, with active cultures including its heirloom Icelandic strain plus Lactobacillus bulgaricus and Bifidobacterium. Siggi’s, another popular brand, sells a probiotic drinkable yogurt containing 7 billion probiotics per serving, specifically Bifidobacterium species. Siggi’s also makes a drinkable product called filmjölk that includes Lactobacillus acidophilus, a well-studied probiotic strain.
Not every product from these brands carries the same probiotic count, though. A standard cup of skyr will have live cultures from fermentation, but the specific number of organisms and the strains present vary by product line. Drinkable and explicitly “probiotic” labeled products tend to have higher counts and additional strains added beyond the starter cultures.
Do the Probiotics Actually Reach Your Gut?
A study published in the Journal of Functional Foods tracked what happened when overweight and obese women consumed skyr daily over an extended period. The starter cultures from skyr successfully transmitted to participants’ gastrointestinal tracts, meaning the bacteria survived digestion and reached the gut alive. The study also found that regular skyr consumption changed the composition of gut bacteria and altered the production of short-chain fatty acids, which are compounds your gut bacteria produce that play a role in inflammation, metabolism, and the health of your intestinal lining.
The researchers noted that skyr consumption had a major impact on what’s called microbial cross-feeding, where one type of gut bacteria produces something that another type feeds on. This cascading effect means the probiotics in skyr don’t just add new bacteria to your gut. They change how the existing bacterial community functions.
How Skyr Compares to Greek Yogurt
The probiotic strains in skyr are similar to those in Greek yogurt, and both products go through a straining process that makes them thicker and higher in protein than regular yogurt. Some preliminary evidence suggests Greek yogurt may actually contain more probiotics than skyr, though no definitive studies have settled the question. Many U.S. brands of both Greek and Icelandic yogurt now add extra probiotic strains beyond the basic starter cultures, which blurs the line further.
Where skyr stands out is protein. A serving of Icelandic Provisions plain skyr delivers 17 grams of protein with no added sugar, which is competitive with or higher than most Greek yogurt options. The straining process also removes a significant amount of lactose, which is why some people with mild lactose intolerance find both Greek and Icelandic yogurt easier to digest than regular yogurt. The fermentation process itself converts some lactose into lactic acid, reducing the total amount your body needs to process.
How to Check Your Label
If probiotics are your priority, look for three things on the packaging. First, the phrase “live and active cultures” somewhere on the container. Second, the specific strains listed in the ingredients, ideally including names like Lactobacillus, Bifidobacterium, or Streptococcus thermophilus. Third, a number: some brands now print the probiotic count per serving directly on the label, which gives you a concrete sense of what you’re getting.
Avoid assuming that all skyr contains probiotics just because it’s a fermented product. If the skyr was heat-treated after fermentation, the cultures are dead. Products with shorter shelf lives (closer to two weeks) are more likely to contain robust live cultures than those engineered to last a month or more. When in doubt, the LAC seal is a reliable shortcut, certifying that the product met a high threshold for live cultures at the time it was made.