What's The Difference Between Casein And Whey Protein? - Healthline

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Evidence BasedWhat’s the Difference Between Casein and Whey Protein?

Medically reviewed by Kim Rose-Francis RDN, CDCES, LD — Written by Gavin Van De Walle, MS, RD — Updated on November 25, 2025

Both come from milk
Absorption
Muscle growth
Bioactive compounds
Protein benefits
Which one is better?
Summary

Casein and whey protein, both milk products containing all essential amino acids, are popular protein powders. But certain qualities set them apart. Here’s how to tell the difference and decide which is a better fit for you.

There are more types of protein powder on the market today than ever before — from rice and hemp to insect and beef.

But two types of protein have remained well regarded and popular over the years: casein and whey.

Though both are derived from milk, they differ greatly.

Let’s explore the differences between casein and whey protein, their health benefits and how to choose the right one for your needs.

Both casein and whey are derived from milk

Casein and whey are the two types of protein found in cow’s milk, making up 80% and 20% of milk protein, respectively.

They’re high-quality proteins, as they contain all essential amino acids, which you must get from food since your body cannot make them. In addition, they’re easily digested and absorbed (though whey is digested faster).

Both casein and whey are byproducts of cheese production.

During cheesemaking, special enzymes or acids are added to heated milk. These enzymes or acids cause the casein in the milk to coagulate, or change to a solid state, separating from a liquid substance.

This liquid substance is the whey protein, which is then washed and dried into a powdered form for use in food products or dietary supplements.

The remaining curds of casein can be washed and dried to create a protein powder or added to dairy products like cottage cheese.

Your body absorbs casein protein slower than whey

One of the significant differences between casein and whey protein is how quickly your body absorbs them.

Your body breaks down protein into many small molecules called amino acids, which circulate in your bloodstream until they’re absorbed.

Levels of these amino acids stay elevated in your blood for up to 6 hours after you consume casein. According to other research, levels of amino acids stay elevated only 60 to 90 minutes after you consume whey.

This is because the two proteins digest at different rates.

As it does in cheesemaking, casein forms curds once exposed to the acids in your stomach. These curds lengthen your body’s digestion and absorption processes.

Therefore, casein protein provides your body with a slow, steady release of amino acids, making it ideal before fasting situations, such as sleep.

On the other hand, because your body digests and absorbs whey protein much quicker, it makes the perfect bookend to your workouts, as it will kickstart the muscle repair and rebuilding process.

Whey protein is better than casein for building muscle

Whey protein is not only better suited for workouts because it’s quickly absorbed but also due to its amino acids profile.

It contains more of the branched-chain amino acids (BCAAs) leucine, isoleucine and valine, while casein contains a higher portion of the amino acids histidine, methionine and phenylalanine.

While all essential amino acids are important for building muscle, leucine is the one that jumpstarts the process by activating a signaling pathway within muscle cells.

Owing in part to its higher leucine content, whey protein stimulates muscle protein synthesis — the process by which muscles grow — more than casein, especially when consumed in tandem with your workouts.

However, it’s unknown whether this greater stimulation in muscle protein synthesis results in more muscle growth long term.

What is known is that your total protein intake over the course of each day is directly correlated to muscle size and strength.

Whey and casein both contain different beneficial compounds

Casein and whey protein contain different bioactive peptides, which are compounds that benefit your body.

Casein protein

Casein contains several bioactive peptides that have been shown to benefit your immune and digestive systems.

Some bioactive peptides found in casein also benefit your heart by lowering blood pressure and reducing the formation of blood clots. However, most of the research was done on animals and evidence in human trials remains limited.

These peptides work similarly to angiotensin-converting enzyme (ACE) inhibitors, a class of drugs commonly prescribed to control blood pressure.

They also bind to and carry minerals like calcium and phosphorus, improving their digestibility in your stomach.

Whey Protein

Whey protein contains a number of active proteins called immunoglobulins that boost your immune system.

The immunoglobulins in whey are known to have antimicrobial properties, either killing or slowing the growth of harmful microbes, such as bacteria and viruses.

Numerous animal and test-tube studies have also shown that these proteins exert antioxidant effects and inhibit the growth of tumors and some cancers.

In addition, some proteins found in whey transport important nutrients like vitamin A through your body and enhance the absorption of other nutrients like iron.

The benefit of protein in your diet

Protein serves many important roles in your body, making it incredibly important for your health.

These roles include:

Enzymes: These are proteins that carry out chemical reactions in your body.
Antibodies: These remove foreign particles, such as viruses, to help fight infection.
Messengers: Many proteins are hormones, which coordinate cell signaling.
Structure: These provide form and support to your skin, bones and tendons.
Transport and storage: These proteins move substances including hormones, medicines and enzymes through your body.

Beyond its basic nutritional functions in your body, protein has several other benefits, including:

Fat loss: Protein aids fat loss by decreasing your appetite and boosting your metabolism.
Blood sugar management: When consumed in place of carbs, protein can improve blood sugar management in people with type 2 diabetes.
Blood pressure: Studies show that people who consume more protein — regardless of the source — have lower blood pressure.

These benefits are associated with a higher protein intake in general, not necessarily with casein or whey.

Whey or casein: Which one is best for you?

Despite their different bioactive components, whey and casein protein vary little when it comes to their nutrition data.

Depending on the product, per standard scoop (30 grams, or 4 tablespoons), whey protein contains about:

Calories: 110
Fat: less than 1 gram
Carbohydrates: 0 grams
Protein: 26 grams
Iron: less than 0.3 mg (less than 2% of the recommended daily intake (RDI)
Calcium: 119 mg (9% of the RDI)

Depending on the product, per standard scoop (30 grams, or 4 tablespoons), casein protein contains about:

Calories: 110
Fat: 0 gram
Carbohydrates: 0 grams
Protein: 25 grams
Iron: 0% of the RDI
Calcium: 580 mg (45% of the RDI)

Keep in mind that these nutrition facts may vary, depending on the specific product you buy, so be sure to read labels carefully.

What’s more, there are some other factors to consider:

Casein protein powder can be more expensive than whey.
Whey protein powder tends to mix better than casein.
Whey protein powder often has a better consistency and taste than casein.

You can also buy protein blends, which typically contain a combination of casein and whey, giving you the benefits of each.

Alternatively, you can buy both powders individually and take whey protein powder with workouts, then casein before bed.

How to take whey or catein

You may mix each with either water or milk. Milk will make your protein shakes — especially those with casein — thicker.
If possible, mix your protein powder and liquid with a blender bottle or other type of blender instead of a spoon. Doing so will ensure a smoother consistency and more equal dispersion of protein.
Always add the liquid first, followed by the scoop of protein. This order keeps the protein from sticking to the bottom of your container.

Takeaway

Casein and whey protein are both derived from cow’s milk.

They differ in digestion times — casein digests slowly, making it effective before bedtime, while whey digests quickly and is ideal for workouts and muscle growth.

Both contain different bioactive compounds that may boost your immune system and offer other benefits.

Choosing one over the other won’t necessarily bestow better results in the gym or markedly improve your health, so select the one that you prefer, or buy a blend that contains both.

Above all, remember that your total daily intake of protein matters most.

While casein and whey have their differences, they each play important roles in your body and provide numerous health benefits.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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Medically reviewed by Kim Rose-Francis RDN, CDCES, LD — Written by Gavin Van De Walle, MS, RD — Updated on November 25, 2025

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Nutrition

Nutrition

Both casein and whey are derived from milk

Your body absorbs casein protein slower than whey

Whey protein is better than casein for building muscle

Whey and casein both contain different beneficial compounds

Casein protein

Whey Protein

The benefit of protein in your diet

Whey or casein: Which one is best for you?

How to take whey or catein

Takeaway

How we reviewed this article:

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