What's the Difference Between Casein and Whey Protein?

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 stood the test of time, remaining well regarded and popular over the years: casein and whey.

Though both are derived from milk, they differ greatly.

This article explores the differences between casein and whey protein, their health benefits and how to choose the right one for your needs.

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Casein and whey are the two types of protein found in cow’s milk, making up 80% and 20% of milk protein respectively (1).

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 (2).

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, such as cottage cheese.

Summary

Both casein and whey are dairy-based proteins and byproducts of cheese production.

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 four to five hours after you consume casein but only 90 minutes after you consume whey (3).

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 (4, 5, 6).

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 (7, 8, 9).

Summary

Casein protein digests slowly while whey digests quickly. These differences in absorption rates make casein protein good before bed and whey protein ideal for around your workouts.

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 (3).

While all essential amino acids are important for building muscle, leucine is the one that jumpstarts the process (10).

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 (11, 12, 13).

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

What is certain is that your total protein intake over the course of each day is the strongest predictor of muscle size and strength (14).

Summary

Whey protein’s amino acid profile may stimulate the muscle building process more than casein’s.

Casein and whey protein contain different bioactive peptides, which are compounds that benefit your body (15).

Casein Protein

Casein contains several bioactive peptides that have been shown to benefit your immune and digestive systems (16, 17).

Some bioactive peptides found in casein also benefit your heart by lowering blood pressure and reducing the formation of blood clots (18, 19).

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 (20, 21).

Whey Protein

Whey protein contains a number of active proteins called immunoglobulins that boost your immune system (22).

The immunoglobulins in whey are known to have antimicrobial properties, either killing or slowing the growth of harmful microbes, such as bacteria and viruses (23, 24).

Animal and test-tube studies have also shown that these proteins exert antioxidant effects and inhibit the growth of tumors and cancer (25, 26).

In addition, some immunoglobulins transport important nutrients — such as vitamin A — through your body and enhance the absorption of other nutrients like iron (27).

Summary

Casein and whey protein contain different bioactive compounds that benefit your health in a multitude of ways.

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

These roles include (28):

• Enzymes: 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 (29, 30, 31).
• Blood sugar control: Protein, when consumed in place of carbs, can improve blood sugar control in people with type 2 diabetes (32, 33).
• Blood pressure: Studies show that people who consume more protein — regardless of the source — have lower blood pressure (34, 35, 36).

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

Summary

Protein plays a vital role in your body by acting as enzymes and antibodies, as well as regulating blood sugar and blood pressure.

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

Per standard scoop (31 grams, or 1.1 ounces), whey protein contains (37):

• Calories: 110
• Fat: 1 gram
• Carbohydrates: 2 grams
• Protein: 24 grams
• Iron: 0% of the Reference Daily Intake (RDI)
• Calcium: 8% of the RDI

Per standard scoop (34 grams, or 1.2 ounces), casein protein contains (38):

• Calories: 120
• Fat: 1 gram
• Carbohydrate: 4 grams
• Protein: 24 grams
• Iron: 4% of the RDI
• Calcium: 50% 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 is generally 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 Use

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.

Summary

Casein and whey protein each have unique advantages. When deciding on one over the other, you may also want to consider the cost, mixability and taste. What’s more, it’s possible to mix both types.

Casein and whey protein are both derived from milk.

They differ in digestion times — casein digests slowly, making it good 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.