Which Milks Contain Casein? An In-Depth Look at Dairy and Alternatives

January 4, 2026 •

4 min read

Casein is the primary protein found in mammalian milk, making up about 80% of the protein content in cow's milk. For those with dairy sensitivities or allergies, understanding which milks contain casein is crucial for making informed dietary decisions. This comprehensive guide breaks down the casein content across different animal and plant-based milks.

Quick Summary

This guide explains which animal milks contain casein, distinguishing between common dairy types and variants like A2 milk. It also identifies naturally casein-free plant-based milk alternatives and notes where hidden casein might appear in other foods.

Key Points

All Mammalian Milk Has Casein: Milk from all mammals, including cows, goats, and sheep, contains casein protein in varying concentrations.
Concentrations Vary by Species: Sheep's milk has a higher casein content than cow's milk, while human milk has a lower percentage relative to whey.
A1 vs. A2 Milk: A2 milk contains a different type of beta-casein protein than regular A1 milk, which some people find easier to digest, though both contain casein.
Plant-Based Milks are Casein-Free: Alternatives like soy, almond, oat, and coconut milk are excellent casein-free options for those with allergies or sensitivities.
Hidden Casein in Processed Foods: Casein can be found in processed foods labeled as 'non-dairy' through ingredients like 'sodium caseinate'.
Casein is a Slow-Digesting Protein: Due to its micelle structure, casein releases amino acids slowly, which is beneficial for sustained protein delivery.

What Exactly is Casein?

Casein is not a single protein but a family of related phosphoproteins (e.g., αs1, β, κ) commonly found in the milk of mammals. In milk, casein proteins form complex clusters called micelles, which are held together by calcium and hydrophobic interactions. It is this structure that plays a critical role in milk's curd-forming properties during cheese production. Casein is known for its slow digestion rate, which allows for a sustained release of amino acids into the body, a trait popular with athletes seeking muscle recovery.

Casein in Animal-Based Milks

All mammalian milk, by its nature, contains casein. The concentration and specific types of casein vary significantly between species. For those with a casein allergy, all animal-based milks and products derived from them must be avoided.

Cow's Milk

Cow's milk is the most common source of dairy and is famously high in casein, with approximately 80% of its protein content being casein. A notable distinction exists between A1 and A2 beta-casein, two genetic variants of the beta-casein protein.

A1 and A2 Milk: Most dairy cows produce a mix of A1 and A2 beta-casein. However, certain breeds, like those used to produce A2 milk, contain only the A2 type. For some individuals, the A1 variant is associated with digestive discomfort, though research on this is ongoing.

Goat's Milk

Goat's milk is often suggested as an alternative for those with sensitivities to cow's milk, but it is important to remember that it is not casein-free. Goat milk does contain casein, though its protein structure is slightly different, leading some to find it more digestible. The casein profile differs, but the protein is still present.

Sheep's Milk

According to some studies, sheep's milk has a higher casein content per liter than most other milks, making it one of the most concentrated natural sources. It also contains several major casein fractions, similar to cow's milk.

Buffalo's Milk

Buffalo milk typically contains a high percentage of both fat and protein, and its casein content is comparable to, and in some cases higher than, cow's milk.

Human Milk

Human breast milk also contains casein, though at a much lower concentration than cow's milk. The ratio of whey to casein is different, and the specific casein proteins vary, making it generally better tolerated by infants.

Naturally Casein-Free Milk Alternatives

For those who need to avoid casein entirely, several plant-based options are naturally free of this animal protein. These are excellent choices for individuals with allergies or dietary restrictions like veganism.

Soy Milk: Made from soybeans, soy milk is a popular alternative that does not contain casein. However, some processed foods with added "non-dairy" ingredients might contain caseinates, so label reading is essential.
Almond Milk: This nut-based milk is naturally casein and lactose-free. It's a light-tasting alternative suitable for many uses.
Oat Milk: Derived from oats, oat milk is another naturally casein-free option that has gained significant popularity.
Coconut Milk: Extracted from coconut flesh, coconut milk is dairy-free and, therefore, casein-free.
Rice Milk: A good hypoallergenic choice, rice milk is also free of casein and other common allergens.
Hemp Milk: Made from hemp seeds, this alternative is naturally free of dairy proteins like casein.

Identifying Casein in Other Products

Casein is not limited to liquid milk but is also a component of many other dairy products and, surprisingly, some processed foods where it is used as a binder or thickener.

Common dairy products containing casein include:

Cheese (all types)
Yogurt
Ice cream
Butter and Ghee
Sour cream and half-and-half

Processed foods that may contain casein:

Non-dairy creamers (check labels for 'sodium caseinate')
Processed meats like hot dogs
Some tuna packed in water
Certain breads, crackers, and snacks
Some infant formulas

Milk Type vs. Casein Content


Milk Type	Casein Content	Notes
Cow's Milk	High (~80% of protein)	A1 and A2 beta-casein variants exist; most milk contains both.
Goat's Milk	Medium (~26g/L)	Contains casein but with a different protein structure; some find it more digestible.
Sheep's Milk	High (~40g/L)	One of the most concentrated natural sources of casein.
Buffalo's Milk	High (~35g/L)	Similar to cow's milk, with high fat and protein content.
Human Milk	Low (~40% of protein)	Casein content varies and profile differs from cow's milk.
Plant-Based Milks	None	Naturally casein-free, good for allergies and vegan diets.

Conclusion

Casein is a key protein in all mammalian milk, and its presence varies by species. Cow, goat, sheep, and buffalo milk all contain significant amounts of casein, while human milk contains less. For individuals with casein allergies or sensitivities, a casein-free diet requires avoiding all animal milk and checking food labels for hidden casein additives like 'sodium caseinate'. Fortunately, a wide variety of plant-based milks—such as soy, almond, oat, and coconut milk—provide delicious and nutritious alternatives that are naturally casein-free. Being aware of what you consume is the first step toward managing your health effectively. For more detailed information on specific milk proteins and their health-related aspects, see the National Institutes of Health article on milk proteins.

Frequently Asked Questions

Casein and whey are the two primary proteins in milk. Casein is the slower-digesting protein, making up about 80% of milk protein, while whey is the faster-digesting protein, accounting for the remaining 20%.

No, plant-based milks such as almond, soy, oat, coconut, and rice milk do not naturally contain casein, as casein is a protein exclusive to mammalian milk.

Lactose intolerance is a different condition from a casein allergy. People with lactose intolerance lack the enzyme lactase to digest milk sugar (lactose), while a casein allergy is an immune reaction to the milk protein. While related, one does not necessarily cause the other.

No, A2 milk contains casein, specifically the A2 beta-casein variant. The 'A2' designation refers to a specific type of the casein protein, not its absence.

No, it's important to check the ingredients list. Some 'dairy-free' items may contain casein derivatives like 'sodium caseinate,' used as an emulsifier or thickener. Look for products certified as kosher pareve to ensure they are casein-free.

According to some studies, sheep's milk has one of the highest concentrations of casein, followed by buffalo and cow's milk.

Casein is often used as a food additive due to its functional properties, such as acting as an emulsifier, binding agent, or thickener, to improve the texture and consistency of processed foods.