What Is Casein Protein? – The Ultimate Guide

Everyone knows that the secret to achieving your fitness goals is in the kitchen rather than in the gym. To build and grow your muscle, you need to eat and digest a lot of protein. Although you need to eat a lot of protein, most people take protein supplements to help them reach their goals. The 2 most common protein supplements are whey and casein protein.

Whey protein is the most popular of the 2  because of its fast absorption rate. What we find surprising is the lack of attention towards casein protein, which can be as valuable.

Casein protein can be as useful as whey towards reaching your goals. But first, what is casein protein?

What is Casein Protein?

Casein and whey protein are both derived from whole dairy milk. They are the two types of protein that make up whole milk, with casein making up 80% and whey the other 20%. They are both a complete protein source that contains all the essential amino acids.

Casein protein can be in 2 forms: Micellar casein and Casein hydrolysate.

Micellar casein is the more popular form and you will see it in most casein protein supplements. It is the form of casein protein that digests at a slower rate. On the other hand, casein hydrolysate predigests in your body and absorbs rapidly.

What is the Difference Between Whey?

Although they are both from the same source, whey and casein are near total opposites.

Casein protein is the insoluble part of whole milk or the part that makes the milk thicker. The reason why people take it as a supplement is its slow absorption rate.

When consumed it forms into a type of gel in your stomach. The “gel” over the course of hours, releases amino acids into your bloodstream. This lengthened release of amino acids helps when your body is inactive, like in sleep.

When your body is inactive it breaks down your cells for nutrients to survive. With casein protein, your body will take nutrients from the casein protein. This prevents your body from breaking down your muscle and instead boosts protein synthesis. This means your body will promote muscle growth and sustainability.

In comparison to whey protein, casein offers a much lower peak for blood amino acids. Whey protein no doubt has a stronger effect, but what casein does much better is stalling protein breakdown within your body.

Benefits of Casein

Casein protein also offers a lot of health and unexpected benefits:

Muscle Growth

One of the main benefits of casein protein is that it can promote muscle growth. This may be a result of the high amount of the amino acid, leucine, which promotes muscle protein synthesis.

A study with 3 groups tried to prove just that. Each group uses either whey protein, casein protein, or none. After a certain amount of time, the group consuming the casein improved the most:

  • The casein group lost more fat than the whey protein group.
  • Lost 3x more fat and grew 2x as much muscle as the placebo group.

Casein protein has also been shown to increase your strength more than whey protein. Studies have shown it may increase more strength in your chest, legs, and shoulders. This is possible due to the anti-catabolic property that casein holds.


Another prominent benefit casein protein can have is improving your digestion. When consumed casein protein forms a “gel” in your stomach that your body will supply off of. This can then lower your hunger levels and prevent you from feeling too hungry when not eating as much. The constant flow of amino acids and decreased hunger can last up to 7 hours with one scoop.

Metabolic Rate

Casein protein keeps your body active while you sleep, which in turn can lead to an increased metabolic rate while you sleep. This increase might help grow your muscle and help burn off fat while you are sleeping.


Yes, teeth. Although strange, increasing your casein protein intake can positively affect your teeth. It works by helping reduce and prevent enamel erosion with its calcium nutrients.

what is casein protein man running

What Are Casein Peptides?

In short casein peptides are the smaller pieces your body breaks casein into when you consume it.


AlphaS-1 is a protein found within casein protein that can lead to many health benefits too!

AlphaS-1 can help you achieve better sleep because of its anxiolytic effect. The anxiolytic effect, which reduces anxiety, helps people with higher stress levels. It can also decrease the stress in some people when taken at a controlled amount daily.

c12 Peptide

The c12 peptide is another peptide and component found within the casein protein. The c12 peptide can reduce your blood pressure in pre-hypertensive subjects in controlled usage. Pre-hypertensive subjects are people who are at a higher risk of high blood pressure in the future. The c12 peptide is able to do this because it contains the properties of an ACE inhibitor, which is a medicine used to treat high blood pressure.

A1 vs. A2

Casein protein comes from cow milk and most cows have both components A1 and A2 in their milk. Some cows only hold A2 beta-casein, which has sparked a debate on the topic of which is healthier. A1 beta-casein has been associated with issues like heart disease and type 2 diabetes. As a result, many people see A2 beta-casein as a healthier option.

Since then, these observational studies have been disproven due to a lack of concrete evidence. There are currently no harmful effects of A1 or A2  beta-casein.

How do I Supplement Casein Protein?

The most effective way to use casein protein is before you go to sleep. Taking a scoop of casein protein with water right before bed will maximize its effect. It will prevent protein breakdown and promote protein synthesis.

Most people, including myself, recommend taking both whey protein and casein protein. You should use whey protein post-workout due to it being fast-absorbing.  You should use casein protein before you sleep because of its longer-lasting effect. If you take both of these in this way, it can benefit you a lot more in reaching your goals. Although we recommend you take them both, you should not take them at the same time. The casein and whey protein have opposite functions and will act against each other.

We recommend you take one scoop of casein protein (we like vanilla the best!) with water.

You can or increase your casein protein intake in other ways than a supplement like:

  • Whole Dairy Milk
  • Natural Yogurt (Try high protein!)
  • Cheese (Cottage cheese for a healthier option)
  • Butter
  • Ice Cream


Protein supplements are a very viable way to increase your protein intake in your diet. We recommend you try taking a casein protein powder in addition to whey protein powder. Casein protein, although very helpful, will not provide you the results you want alone.

It is able to prevent your body from breaking down your gains while you sleep, which is what makes it so unique.

Balanced use of both whey protein, post-workout, and casein protein, before you sleep, will provide you with the best results.

Check out our Best Casein Protein Supplements article to find the best option for you!

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