Skyr & Quark: Nutrients, What Research Shows and Safety
Skyr and quark, thick fermented milks: what small trials found on protein, fullness and muscle, composition we could verify, and lactose, pregnancy and allergy cautions.
Content last updated . This page has not been medically reviewed.
Skyr is a thick, spoonable fermented milk that comes from Iceland, and quark is a fresh cheese made from fermented milk. Both are known as thick, protein-rich dairy foods. Research papers often call imitations "skyr-type yogurt," so what is sold under the name varies. This page covers skyr and quark as foods, not as supplements, and it separates what small studies found from marketing talk.
Read this first
- Composition varies by product. Our USDA data file has no entry for skyr or quark, so we do not give USDA numbers. Read the Nutrition Facts label of the product you buy. The lab-made examples we could read are in the table below.
- It is milk. Skyr and quark are not safe for a cow's milk allergy. For trouble breathing or swelling of the face, lips or throat, call 911 (or your local emergency number). [12]
- Pregnancy. The NHS says pasteurized soft cheeses such as cottage cheese are fine and unpasteurized dairy should be avoided. [10] The CDC says any cheese made with raw milk should be avoided unless heated. [11] Quark is not named in either source, so check the label for "pasteurized."
- Evidence in one line: a few small, short studies show effects on blood amino acids and muscle building after exercise, but we found no good trial showing skyr or quark improves weight, blood sugar or heart disease. [1] [2] [3]
What is in it (composition we could read)
There is no USDA household-portion entry in our data file for these foods, so we cannot give a per-serving table or % Daily Value. The only composition values we read come from laboratory studies of products made in the research setting, shown per 100 g.
| Product (study) | Fat per 100 g | Protein per 100 g | Water |
|---|---|---|---|
| Quark-type cheese, full fat, cow milk, made in a Greek lab [6] | 13.95 g | 10.31 g | 71.96% |
| Quark-type cheese, reduced fat, same lab [6] | 10.39 g | 12.84 g | 73.08% |
| Skyr-type yogurts, lab-fermented, three probiotic versions [5] | 2.31 to 2.53 g | 5.73 to 5.88 g | not reported |
These are averages from small experiments. They are not a guide to commercial products, which differ in fat, protein, salt and added sugar. Sodium, calcium and vitamins were not reported in the abstracts we read. Straining a yogurt produces a by-product called acid whey, and heating the milk and straining time change fat, lactose and total solids in the thick yogurt. [7] We did not read a source that gives lactose values for skyr or quark.
Plant compounds are not the story here. Skyr is a fermented food, and a 2024 review notes that nearly all Nordic fermented milks use mesophilic lactic acid bacteria, with skyr as the one notable exception. [8]
What research says
| Health goal | What the sources found | Strength of evidence | What was studied |
|---|---|---|---|
| Muscle building after exercise (quark) | 14 young and 15 older men ate quark providing 30 g of protein after a leg workout. Muscle protein building rose at rest and rose further in the exercised leg, with no difference between age groups. [2] | Promising but limited (a 4-hour measure, 29 men, not a muscle-gain trial; FrieslandCampina funding is in the record) | Quark, men aged 18-35 and 65-85 |
| Weight and body fat with a high-protein breakfast | In 56 women with overweight, a 34 g protein breakfast for 12 weeks raised fullness but did not change energy intake, body composition, lipids or glucose tolerance versus a 6 g protein breakfast. The abstract does not name skyr. [3] | No good evidence of benefit for body composition | Women aged 18-30 |
| A diet with more dairy including skyr | In a 6-week crossover trial of 30 adults with overweight or obesity, a high-dairy diet (milk, skyr and full-fat cheddar) did not change the main inflammation marker (IL-6) or body weight. One marker (TNF-alpha) fell and another (IL-4) rose. Funding included Dairy Farmers of Canada. [1] | Insufficient evidence (skyr was one of three foods) | Adults with overweight or obesity |
| Gut bacteria | In women with overweight or obesity whose dairy intake was changed, daily skyr raised fecal bacterial diversity and one bacterial group. Some links to a gut fatty acid (valerate) were seen only in people who carried a specific bacterium. [4] | Insufficient evidence (microbiome markers, not health outcomes) | Women, 12 weeks, plus lab work |
| Anti-inflammatory effects of probiotic skyr-type yogurts | Cell tests showed lower TNF-alpha with two probiotic versions. [5] | Lab or animal only | Lab-made skyr-type yogurts, cell models |
| Blood sugar, blood pressure, heart disease | Proper evidence not found in the sources we read | None | Not applicable |
Eaten as food vs other forms. All of this is about skyr and quark eaten as foods. Protein powders, flavored dessert-style skyr or quark with added sugar and sweeteners are different products; sweetener and sugar choices change flavor and may change how healthy a product is. [15]
How much is a normal serving
We did not find an official household portion for skyr or quark in our data. The Nutrition Facts label serving on the package is the best guide. The WHO advises keeping free sugars under 10% of daily energy, which matters for sweetened versions. [16] That is information, not a prescription. We could not open the MyPlate dairy page, so we do not quote its serving rule.
Safety, allergy and medicines
- Milk allergy. Cow's milk is one of the most common food allergens; a milk allergy is an immune reaction. Anaphylaxis is a medical emergency, so call 911 for trouble breathing, throat swelling or fainting. [12] One review found limited, weak evidence that some fermented foods lower allergenicity, so do not treat these as safe for milk allergy. [17]
- Lactose. NIDDK says yogurt and hard cheeses are easier to tolerate than other dairy foods and that many people tolerate about 12 g of lactose. [13] It does not name skyr or quark. Lactose amounts vary with how the product is made. [7] Start with a small amount if you are intolerant.
- Pregnancy. The NHS says pasteurized soft cheeses are fine, mold-ripened soft cheeses should be avoided unless cooked, and unpasteurized dairy should be avoided. [10] The CDC says Listeria is rare but serious in pregnancy and lists any cheese made with raw milk among those to avoid unless heated. [11] Choose products labeled "pasteurized."
- Live cultures. Whether a product still has live microbes depends on the label. ISAPP says fermented foods are not automatically probiotics. [9] NCCIH says harm from probiotics is more likely in people with severe illness or weakened immunity, but it does not discuss skyr or quark. [14]
- Sweeteners and sugar. Flavored skyr-type products can contain sucrose or other sweeteners. [15] Read the label.
- Medicines, kidneys, children. We did not find a skyr- or quark-specific medicine interaction in the sources we read, and we did not read a source on protein-rich dairy for people with kidney disease or for young children. Ask a clinician; see kidney disease: potassium and oxalates.
Choosing, storing and food safety
- Look for "pasteurized" on the label, especially in pregnancy. [10] [11]
- Compare protein, fat, sugar and sodium on labels; products vary widely. [5] [6]
- We did not read a source on storage times or home straining, so follow the label.
Related pages
Health connections for Skyr & Quark
What research links to eating or drinking this food, and how strong the evidence is. Many studies are observational or use juice, powder, oil or extracts rather than the food as eaten; each card says which.
Quark and muscle protein building after exercise
Preliminary or mixedIn 14 young and 15 older men, a quark portion providing 30 g of protein after a leg workout raised muscle protein synthesis at rest and more in the exercised leg, with no difference between age groups. The record lists FrieslandCampina funding.
Supplements: A 4-hour measure in 29 men; it does not show muscle gain over time.
High-protein breakfast, fullness and weight
Preliminary or mixedA 12-week trial in 56 women with overweight found a 34 g protein breakfast raised fullness but did not change energy intake, body composition, lipids or glucose tolerance compared with a 6 g protein breakfast. The abstract does not name skyr.
Supplements: The trial supports fullness only, not weight change; skyr was not named.
Dairy-rich diet with skyr and inflammation
Preliminary or mixedIn a 6-week crossover trial of 30 adults with overweight or obesity, a high-dairy diet (milk, skyr and full-fat cheddar) did not change the main inflammation marker (IL-6) or weight; TNF-alpha fell and IL-4 rose. Funding included Dairy Farmers of Canada.
Supplements: Small trial; markers only.
Skyr and gut bacteria
Preliminary or mixedIn a study of women whose dairy intake was changed, daily skyr raised fecal bacterial diversity and Streptococcaceae; people carrying a bacterium called Megasphaera had higher fecal valerate. These are microbiome markers, not health outcomes.
Supplements: Early; mixes lab and human data.
Probiotic skyr-type yogurts in cell tests
Lab or animal research onlyLab-made skyr-type yogurts fermented with probiotic strains lowered TNF-alpha by 32% in cell tests and showed enzyme inhibition after simulated digestion.
Supplements: Laboratory only.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (1)
- Muscle RecoveryPreliminary or mixed
Quark after exercise raised muscle protein building in a 4-hour study in 29 men; not shown to improve recovery or muscle size.
Body parts (1)
- MusclesPreliminary or mixed
The same study: more muscle protein synthesis after quark, more so in the exercised leg.
Habits (1)
- Resistance TrainingPreliminary or mixed
The quark study measured the response after a leg resistance workout.
Conditions & symptoms (3)
- Cow Milk AllergyDocumented risk
Skyr and quark are milk foods and are not safe for cow's milk allergy.
- Lactose IntoleranceDocumented risk
Lactose amounts vary with how the product is made; tolerance differs by person.
- ListeriosisDocumented risk
Fresh cheeses and dairy made from unpasteurized milk carry Listeria risk for pregnant people and other at-risk groups; quark is not named in the sources read.
Documented risks and interactions (5)
- Added sugar and sweeteners in flavored versions. Flavored skyr-type yogurts can be sweetened with sucrose or other sweeteners. WHO advises keeping free sugars under 10% of daily energy.
- Lactose in this dairy food. NIDDK says many people with lactose intolerance tolerate about 12 g of lactose at a time and that yogurt and hard cheeses are easier than other dairy foods. The sources read give no lactose values for skyr or quark.
- Unpasteurized dairy and pregnancy. The NHS says to avoid unpasteurized milk, yogurt and other dairy in pregnancy. The CDC lists raw milk and any cheese made with raw milk among foods to avoid for people at higher risk of Listeria (pregnant people, adults 65 and older, people with weakened immune systems). A university extension sheet says unpasteurized milk foods should be avoided in pregnancy.
- Weakened immunity and live-culture products. NCCIH says harm from probiotics is more likely in people with severe illness or weakened immune systems, and that some products contain organisms not listed on the label. ISAPP says fermented foods are not automatically probiotics.
- Milk allergy is a different problem from lactose intolerance. Milk is one of the most common food allergens, and an allergy is an immune reaction that can cause anaphylaxis. Lactose intolerance is a digestive problem and not an allergy. For trouble breathing or swelling of the face or throat, call 911 (or your local emergency number).
Frequently asked questions
Is skyr healthier than Greek yogurt?
We did not find a trial comparing them. Composition differs by product, so compare Nutrition Facts labels. See Greek yogurt vs regular yogurt.
Does high-protein skyr or quark help with weight loss?
A 12-week trial of a high-protein breakfast in women with overweight raised fullness but did not change body composition or energy intake. The abstract does not name skyr. [3]
Does quark build muscle?
A small study found quark raised muscle protein building after exercise in young and older men. [2] That is a short measure, not proof of muscle gain over time.
Is quark a cheese or a yogurt?
Researchers call the product "quark-type cheese," a fresh cheese made from cow milk. [6] Skyr is a thick, yogurt-like fermented milk, and research papers often use the term "skyr-type yogurt" for imitations. [5]
Is quark safe in pregnancy?
Quark is not named in the NHS or CDC pages we read. They advise choosing pasteurized dairy and avoiding cheese made from raw milk. [10] [11]
References
- Prowting JL et al. Inflammatory cytokine responses to 6 weeks of increased dairy intake in individuals with overweight and obesity: a randomized crossover trial. J Nutr 2026 (abstract read via Europe PMC; funding from the record). Read 2026-10-24.
- Hermans WJ et al. Acute quark ingestion increases muscle protein synthesis rates at rest with a further increase after exercise in young and older adult males in a parallel-group intervention trial. J Nutr 2023 (abstract read via Europe PMC; funding from the record). Read 2026-10-24.
- Dalgaard LB et al. No effects of high- vs. low-protein breakfast on body composition and cardiometabolic health in young women with overweight: the NewStart randomised trial. Br J Nutr 2025 (abstract read via Europe PMC). Read 2026-10-24.
- Huertas-Diaz L et al. Megasphaera contributes to lactate-driven valerate production in the human gut. Microbiome 2025 (abstract read via Europe PMC). Read 2026-10-24.
- Zepeda-Hernandez A et al. Probiotic fermentation enhances the technological properties and health-promoting potential of skyr-type yogurts. Int Dairy J 2025;167 (abstract read via Europe PMC; no PMID listed). Read 2026-10-24.
- Lepesioti S et al. Quark-type cheese: effect of fat content, homogenization, and heat treatment of cheese milk. Foods 2021 (abstract read via Europe PMC). Read 2026-10-24.
- Karastamatis S et al. Effect of modified manufacturing conditions on the composition of Greek strained yogurt and the quantity and composition of generated acid whey. Foods 2022 (abstract read via Europe PMC). Read 2026-10-24.
- Narvhus JA, Abrahamsen RK. Traditional and modern Nordic fermented milk products: a review. Int Dairy J 2024 (abstract read via Europe PMC; no PMID listed). Read 2026-10-24.
- Marco ML et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol 2021 (abstract read via Europe PMC). Read 2026-10-24.
- NHS. Foods to avoid in pregnancy. Read 2026-10-24.
- CDC. Preventing Listeria infection. Page dated 2025-01-31. Read 2026-10-24.
- MedlinePlus. Food allergy. Read 2026-10-24.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Eating, diet, and nutrition for lactose intolerance. Last reviewed February 2018. Read 2026-10-24.
- National Center for Complementary and Integrative Health (NCCIH). Probiotics: usefulness and safety. Read 2026-10-24.
- Pereira CTM et al. Influence of a prebiotic and natural sweeteners on the sensory profile of skyr yogurt with mango pulp. J Food Sci 2021 (abstract read via Europe PMC). Read 2026-10-24.
- World Health Organization. Healthy diet fact sheet. Dated 26 January 2026. Read 2026-10-24.
- Hyseni B et al. The role of fermented foods in managing food allergies in children and adults: a systematic review. Front Nutr 2025 (abstract read via Europe PMC). Read 2026-10-24.