Types of Milk Protein: Casein and Whey

Types of milk protein

You may be familiar with the fact that milk protein is the most famous protein source available on the market. But, did you know that there are two types of milk protein: Casein and Whey?

This article will discuss two types of dairy proteins and their health benefits and will explore the difference between both casein and whey. Interestingly, despite being derived from milk, these proteins vary largely.

But, it’s necessary to know about protein to understand the insights better.

What is a Protein

In simple terms, protein is made up of amino acids, which are joined together in the form of chains, similar to strings of beads. The protein’s shape is made upon twisting and folding these strings.

Upon ingestion, these proteins are separated into individual amino acids, which are then utilized by our body to make proteins of their own need.

There are 20 different types of amino acids, which can join in various unique ways and make a vast variety of proteins, which are used for necessary body functioning (1).

However, excluding 9 amino acids, the human body has the ability to create all the amino acids on its own.

Dairy-based Protein

Evidence from scientific research shows that the total protein content in milk is about 3.5% by weight.

As mentioned earlier, there are two types of protein present in milk or dairy foods. These proteins are commonly known as casein and whey. Most importantly, all essential amino acids that which human body can’t make and must be obtained from food are present in milk protein; this is why they are considered high-quality protein (2).

Commonly, both whey and casein are made as the result of cheese making process.

In the production of cheese, milk is heated, and additives (usually acids or enzymes) are added. This addition results in the separation of milk casein from a liquid substance by coagulation or changing the form into a solid state.

The remaining liquid is known as whey, which could be washed or dried to make powder whey for usage in food and dietary products (3).

Casein protein

Casein is the most abundant type of milk protein, and about 80% of cow’s milk protein is comprised of casein. Actually, this protein has different forms, the most abundant of which is known as alpha-casein.

Generally, casein is known as a “slow protein” due to its ability to slower digestion rate. This decreased digestion is due to the creation of curd once protein is exposed to acid present in the human stomach (As occurred in the cheesemaking procedure).

As a result, the release of amino acids to muscle becomes slow and prolonged, increasing the process of digestion and absorption in the body (4). It takes casein about 6-7 hours in the body to get fully digested.

This makes it a perfect protein for fasting and bed-time (before sleep). Moreover, casein is also used for post-exercise recovery before bed (5).

Casein can be utilized as a protein supplement as it has the ability to supply the essential amino acids to muscles which are helpful in strength building.

The reduced rate of digestibility of casein enables the steady supply of amino acids to damaged tissues, resulting in better recovery after a workout for a longer period.

The slower digestibility also helps control food cravings and assists in satiety as it is beneficial to help you feel full for longer.

Casein contains different useful bioactive compounds (peptides), which improve the immune and digestive systems of humans. Within the human body, casein has the ability to increase mineral absorption, i.e., calcium and phosphorus. Moreover, the bioactive peptides are also helpful in reducing blood pressure (6).

The bioactive components are also capable of binding and carrying minerals, especially calcium and phosphorus, improving their availability in the body (7).

Whey protein

Generally, about 20% of milk protein is composed of protein. Whey is the most important source of dietary protein and has a rich amino acid profile.

Unlike casein, whey is known as a “fast-acting” protein as it is digested quickly in the body and provides a higher amount of amino acid in a shorter time.

Whey is known for its high amount of branched-chain amino acids, especially leucine and cysteine (4).

Scientific studies show that leucine plays an important role in muscle growth and strength (8).

On the other hand, cysteine is the precursor of glutathione which is a natural antioxidant. Therefore, among both types of milk protein, whey is more suitable for workouts, muscle building, and growth.

Whey protein also contains immunoglobulins (active proteins), which improve the immune system of the human body and act as an anti-microbial agent (9).

Casein or Whey: Which is best for you?

Although both types of milk proteins (casein and whey) have different bioactive compounds, they have a minimal difference when it comes to their nutritional profile.

It is essential to note that different protein content may vary in different products. This mainly depends on the processing steps used to make that specific product.

So, remember to read the label on the product at the time of buying to find out the exact protein content. In general, one scoop of whey (30 grams) contains:

• 120 calories
• 24 grams of protein
• 1.5 grams of Fat
• 3 grams of carbohydrates
• Calcium: 10% of recommended dietary intake.

Similarly, one scoop of casein (33 grams) contains:

• 120 calories
• 24 grams of protein
• 3 grams of carbohydrates
• 1 gram of fat
• Calcium: 50% of the recommended dietary intake (10).

Casein and whey protein powders are easily available in the market, but whey is cheaper than casein. The taste and mixing tendency of whey are also better than casein. In addition, mixed proteins where casein and whey are blended are also available in the markets.

The protein requirement of a person depends on lifestyle, workouts, age, gender, etc. Typically, adult males are advised to take at least 56 grams of protein per day, while an adult female should consume at least 46 grams of protein per day.

However, the required amount may be different from person to person, especially in the case of athletes, bodybuilders, and pregnant women.

In the end, it’s your choice to buy according to your needs.

How to use whey and casein protein?

In powder form, whey or casein can be mixed with water or milk. The addition of milk will lead to thicker protein shakes.

It’s better to mix the combination of liquid and protein powder with a blender bottle for better consistency and uniformity. Protein should be added to liquid instead of liquid addition in protein. This activity will prevent the protein from sticking to the bottom.

Interestingly, both types of milk protein powders can also be used as the ingredient for a number of food and beverages as the source of high-quality proteins.

Apart from muscle-building supplements, these proteins have the capacity to be used as an ingredient in your favourite dishes.

Too much protein intake?

Remember not to take too much protein. Consuming more protein than the body needs can lead to more calories and, eventually, unnecessary weight gain.

It should be noted that high protein supplement intake can be dangerous for specific persons, such as those with impaired functioning of kidneys. The additional supplement increases the load on weak kidneys (12).


Both types of milk protein, whey, and casein, differ in their digestibility despite being derived from milk. Casein digests in a slow manner, while whey is known for quick digestion. Thus, casein is a bed-time protein, and whey is better suited for workouts and muscle growth.

These proteins contain bioactive compounds and present almost similar nutritional content, except casein is especially famous for providing calcium.

It’s better to select the protein according to your preference, as choosing one won’t necessarily increase the benefits as compared to the other. You can try buying a blend of both. Only you can take the final decision.

Still, milk proteins provide the necessary amino acids and play a role in improving your health.