Not All Caseins Are Created Equal
Not all casein protein powders are created equal. There are various forms of casein protein that you will find in the marketplace. The most popular forms found in the food and supplement industry are sodium caseinate, calcium caseinate, fresh curd caseinate and micellar casein. For the sake of this article, we’ll focus on the 3 most popular in protein supplements—micellar casein, calcium caseinate and sodium caseinate. Before we start talking about each version, let’s see where all casein is derived from.
Casein protein is the predominant protein in milk. It makes up 80% of the total protein content (whey comprises the other 20%). Keeping that in mind, you’ll only find naturally occurring casein (in the form of micellar, which we’ll cover in more detail below) in dairy foods, with cheese products and milk being the main dietary sources. If your goal is to get more of this important protein in your diet, on an ounce per ounce basis, these are expensive ways to tap into the benefits of casein protein. To get to the pure stuff, it needs to be extracted from milk solids. Depending on how it’s extracted or processed, the end will result will be one of the various forms of casein protein.
So what is micellar casein? Micellar casein is the purest, most natural form of casein. Micellar casein can be found in all mammals’ milk. As milk’s function is to nourish offspring, it’s not surprising that only the best digested and utilizable form of casein is found here. In milk, micellar casein is suspended in a unique spherical structure called a “micelle”. The micelle structure of casein is its natural structure; you can think of it as its undamaged and unprocessed state. Along with the casein proteins in this micelle, important minerals, such as calcium and phosphorous become bound inside.
The micelle structure is very delicate. It can be easily disrupted, damaged, and changed by the addition of acid or alkali to milk or by heat exposure. Casein in the form of fresh curd casein, sodium caseinate or calcium caseinate no longer contains casein in its natural form. When you precipitate casein using chemicals or heat, you destroy the micelle colloidal suspension in milk. Once a casein micelle is destroyed, it will not re-form, resulting in different characteristics between micellar casein and the other forms.
Why is this important? Micellar casein has the ability to thicken into a gel or bolus-like substance in the stomach. This solid bolus then digests much more slowly over time, gradually releasing amino acids over a much longer period of time. Think about that–natural time-released amino acids being released into your muscles. Regular caseinates, on the other hand, don’t do this. Therefore, caseinates don’t provide the time-release effect that micellar casein does. So if you’re looking for a slow protein, there’s only one choice–micellar casein.
In order to extract this delicate, natural form of casein from milk, a different process is used. Instead of heat or chemicals, a more expensive method that uses mechanical filtration (or ultrafiltration) is employed to keep the protein intact and also to increase the amount of natural bioactive milk peptides in the protein. These peptides not only support immune function, but also muscle growth. Furthermore, with micellar casein more of the important chelated minerals remain intact. You can think of micellar casein as undenatured and, therefore, the most superior form of casein protein.
All this is not to suggest that caseinates are worthless sources of protein. When it comes to amino acid profiles and protein content, micellar casein and caseinates are comparable. So when you see caseinates on your label, you are still getting an effective source of protein. However, if you are specifically looking a "slow" protein source, the kind proven by research, then there's only one choice–micellar casein. If you are paying for micellar casein, make sure you are getting it and not a substitute.