Interesting article about Casein Protein
Milk proteins are made up of Whey (about 20%) and casein (about 80%). And as you probably already know, whey is a fast digesting protein compared to casein which is a slower digesting protein. The result is that aminoacidemia (levels of amino acids in blood) is faster in whey than in casein, which is of benefit post-workout for example.
However, not all casein proteins are the same. If you take the time to read casein protein labels or happen to compare several casein products you will see that some products contain Calcium Caseinate while others contain Micellar Casein. The products that contain Micellar Casein will most often display it prominently on the label, for one good reason: Micellar casein is a better form of casein than Calcium Caseinates.
First of all, Casein, as it exists in milk is Micellar Casein. Micellar is derived from the term “Micelle” which is a chemical term for a special type of aggregate or “bubble”. Micellar casein, when consumed, clots in the stomach, forming relatively large globules of protein that empty from the stomach much more slowly than whey protein and is thus digested slowly (1). The problem with Micellar Casein is that it is not soluble and therefore less desirable to the food industry. To solve this problem, Caseinates are made by reacting micellar casein with alkalis like Sodium Hydroxide and Calcium Hydroxide to make Sodium Caseinate and Calcium Caseinate respectively. As you would expect, this treatment with alkalis affect the quality and biological value of the caseinates, making them of lesser quality to Micellar Casein.
In a recent study done in Denmark, researchers found no difference between whey and calcium caseinate in terms of release of amino acids into the blood stream (2) (aminoacidemia). Calcium caseinate, as distinguished from micellar casein, is soluble (and is thus used in numerous food processes), and so digestion rates of this form of casein are not likely to be overtly different from those of whey.
The above, however, does not mean that you should ditch your caseinate into the bin. Caseinate is still a good source of protein of relatively lower cost. But be careful of supplement companies trying to pass caseinate as micellar casein because we are talking about two different qualities of protein here. Some companies selling caseinates are honest, clearly telling users that they are selling caseinates. Micellar casein is much more expensive than caseinates and if your goal is to get a true slow-release protein, then micellar is worth your buck. If you are not able to afford, milk is nature’s blend of whey and MICELLAR casein.
References:
1. Phillips SM. A comparison of whey to caseinate. Am J Physiol Endocrinol Metab. 300: E610, 2011
2. Reitelseder S, Agergaard J, Doessing S, Helmark IC, Lund P, Kristensen NB, Frystyk JF, Flyvbjerg A, Schjerling P, van Hall G, Kjaer M, Holm L. Whey and casein labeled with l-[1-13C]leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion. Am J Physiol Endocrinol Metab 300: E231–E242, 2011
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