Skyr: The Icelandic Viking Superfood
Skyr is a thick, high-protein Icelandic dairy food that has been made since the Norse settlement of Iceland. Despite the way it is sold today, it is technically a fresh soured cheese rather than a yogurt: it is made with rennet as well as bacterial cultures, and roughly four cups of milk go into one cup of skyr. That is why it is so dense, so high in protein and so low in fat.
Norse settlers brought dairying with them when they colonised Iceland in the late 9th century, and skyr is the one food from that world that never went away. It is still eaten daily in Iceland, and in the last decade it has appeared in supermarkets across Europe and North America. For the wider picture of what the Norse actually ate, see our guide to Viking food and drink.
What is skyr?
Skyr is a cultured dairy product that has been a staple of Icelandic cuisine for centuries. It is made from skimmed milk, so almost all the fat is removed before culturing, and it is then strained heavily, which is where its density comes from.
Although it is sold in yogurt pots and eaten like yogurt, skyr is closer to a fresh cheese. The distinction is not pedantry: skyr is made with rennet in addition to bacterial cultures, and rennet is what separates cheesemaking from yogurt-making. Icelandic food authorities and dairy producers classify it as a soft cheese for exactly that reason.
The cultures traditionally used are Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, which convert the lactose in the milk into lactic acid. That acidity is what gave skyr its practical value to a Norse household: fermentation preserved the milk, so it kept far longer than fresh milk in a world with no refrigeration.
Is skyr a Viking food?
Yes, in the sense that matters. Skyr is recorded in the Icelandic sagas, and dairying was central to the Norse farm economy. Whey, a by-product of making skyr and cheese, was itself used both as a drink (syra) and as a preservative for meat, because its lactic acid slowed spoilage.
What is worth being careful about is the modern packaging. The skyr in a supermarket chiller is a modern industrial product made to a traditional principle. It is not a Viking-Age recipe reproduced exactly, and nobody knows precisely how a 10th-century Icelandic farm made theirs.
How skyr is made
Milk is heated to around 85°C and held there to pasteurise it. Cultures are added once it has cooled, then rennet, and the mixture is left to set. The set curd is then strained to remove the whey, and it is the straining that concentrates everything: roughly four parts milk become one part skyr, whereas ordinary yogurt is closer to one to one.
That concentration is the whole story of skyr's nutrition. It is not that skyr is enriched. It is that most of the water and nearly all the fat have been taken out, leaving the protein behind.
Skyr nutrition
A typical 170 g serving of plain skyr contains roughly:
- about 110 calories
- 15 to 17 g of protein
- around 7 g of carbohydrate
- under 1 g of saturated fat
- useful amounts of calcium, phosphorus, potassium and vitamin B12
Exact figures vary by brand and by whether the pot is plain or flavoured, so read the label: flavoured skyr often carries considerably more sugar than plain. Much of the protein is casein, which digests slowly, which is the main reason a pot of skyr tends to be more filling than the same weight of ordinary yogurt.
A note on the health claims that follow skyr around online: high-protein dairy is a sound everyday food, but skyr is not a medicine and it is not the reason Icelanders live a long time. Life expectancy is driven by healthcare, income, diet as a whole and genetics, not by one dairy product. Treat skyr as a good source of protein and calcium, and be sceptical of anything stronger than that. This article is general information, not dietary or medical advice.
How to make skyr at home
You can make a very good approximation at home. You need 1 litre of skimmed milk, one tablespoon of shop-bought plain skyr as a starter culture, and a few drops of liquid rennet if you want it properly thick.
- Heat the milk gently to about 85°C, stirring so it does not catch, and hold it there for around 10 minutes.
- Take it off the heat and let it cool to roughly 40°C, which is warm but comfortable to the touch.
- Stir in the tablespoon of skyr, and the rennet if using.
- Cover the pot with a cloth and leave it somewhere warm and undisturbed for about 12 to 15 hours, until set.
- Strain it through muslin or a clean cloth until it reaches the thickness you want. The longer you strain, the denser it gets.
- Chill it and eat within about a week. Keep some back as the starter for your next batch.
Traditionally it is eaten plain, or with berries and a little honey, which was the only sweetener the Norse had. Bilberries and crowberries are the Icelandic choice.
Keep exploring: the full picture of what Vikings ate and drank, what they drank it from in Viking drinking vessels, and the story of Viking beer and ale, or browse our Norse mugs and drinking vessels.
Skyr FAQ
Is skyr a yogurt or a cheese?
Technically a cheese. Skyr is made with rennet as well as bacterial cultures, which is what distinguishes cheesemaking from yogurt-making, and it is classified as a fresh soft cheese in Iceland. It is sold and eaten like a yogurt because that is how it behaves on a spoon.
Did the Vikings really eat skyr?
Yes. Skyr appears in the Icelandic sagas and dairying was central to the Norse farm. Fermenting milk this way preserved it without refrigeration, which mattered enormously in a northern climate.
Why is skyr so high in protein?
Because it is heavily strained. Roughly four cups of skimmed milk go into one cup of skyr, so the protein is concentrated while the water and fat are removed. A 170 g serving typically carries 15 to 17 g of protein.
Is skyr healthier than Greek yogurt?
They are close. Skyr is usually a little higher in protein and lower in fat because it starts from skimmed milk and is strained harder, but both are strained cultured dairy and both are reasonable choices. Flavoured versions of either can carry a lot of added sugar.
Can you make skyr at home?
Yes. Heat skimmed milk to about 85°C, cool it to roughly 40°C, stir in a spoonful of shop-bought skyr as a starter plus a little rennet, leave it covered somewhere warm for 12 to 15 hours, then strain it to the thickness you want.
What does skyr taste like?
Plain skyr is thick, mild and only lightly sour, less tangy than most Greek yogurt, with a clean dairy finish. Its density is the thing people notice first: a spoon will stand up in it.