What is Casein Protein and Should I Use It?

Among the many protein sources on the market, the two best-known are the milk proteins whey and casein.


Although, whey tends to get most of the attention, casein protein powder is as equally useful and important when it comes to reaching your health and fitness goals.


But what exactly is casein? Should you be using it?  


Starting With Milk


As mentioned, both whey and casein are milk proteins, existing in about a 20/80 ratio in milk, respectively. To fully understand how these two components exist together in a glass of milk, we need to think what some might consider to be an unrelated industry: cheese making.


Many basic cheeses begin by curdling the milk through the use of heat, acid or a combination of the two. This separates the solid and liquid portions of the milk, with the solids being used to actually the create the cheese.


The liquid by-product is actually whey – the same substance that later becomes your favorite protein powder.  

Cheese curds in a wooden bowl


Those solids, however, don’t have to become cheese. Sometimes called curds, that portion of milk is actually casein protein – removed from the liquid.  


Casein Protein Benefits


But why make yet another protein supplement out of casein? Isn’t whey good enough? After all, that casein could be make into some pretty fantastic cheese.


The fact is that – although they are both derived from milk and rich in protein – whey and casein have some significant differences. For one thing, casein and whey have slightly different amino acid profiles – providing different biological benefits beyond their nutritional value.


Primarily, casein is particularly rich in the conditionally essential amino acid glutamine which becomes especially important during exercise. While your body is generally able to produce glutamine itself, this vital substance must be taken in through your diet during intense workouts. Since casein is generally taken in conjunction with a workout routine, this works perfectly.


To understand the other major advantage that casein has over whey, we must return to our discussion of cheese.


Do you remember the form that casein took when separated from the liquid portion of milk? It becomes the solid chunks. This clumping behavior of casein changes the way that it’s digested by your body, and nutrients are released into your system much more slowly than whey.


This is especially true with micellar casein, in which this behavior has been enhanced. For this reason, casein is generally taken before bed so that it provides a steady supply of amino acids throughout your night-time fast.   


Man sitting in a gym drinking a protein shake

Whey or Casein? 


At this point, people typically want to know the answer to just one question: Should I be taking whey or casein? The answer is both.


Naked Casein product on astroturf
As mentioned, whey and casein differ in the types and levels of amino acids that they provide. When taken together, their profiles complement and complete each other. Remember, these two proteins are components of milk, a substance intended to care for all of an animal’s nutritional needs.   


Comparison table of whey protein and casein protein


Unlike casein, though, whey is a sort of “fast-acting” protein that is absorbed and put to use quickly. In some situations – such as immediately after your workout when you just need something fast for recovery – whey is perfect. At other times though the steady slow drip of protein and nutritional value of casein would be best.