Casein is a slow-digesting milk protein, often used in the evening to provide a gradual supply of essential amino acids throughout the night.
However, it is possible to reproduce this effect by consuming whey, of better nutritional quality, as a dessert to a complete meal, which will slow down its assimilation.
There are various forms of casein used in sports nutrition, such as native micellar casein and calcium caseinate.
Although both types provide slow-assimilating proteins that are useful for limiting catabolism, particularly during dry periods, micellar casein appears superior thanks to its production process, which does not require the addition of a chemical base to neutralize its acidic nature.
This article details the specific features of each form of casein powder and their benefits for muscle development and weight loss, to help athletes choose the protein supplement best suited to their objectives.
What is micellar casein?
Micellar casein is considered the top-of-the-range form of powdered casein, as it supplies native casein micelles and does not involve chemical compounds in its production.
A casein micelle is a colloidal particle present in milk that enables the casein protein and its associated calcium phosphate to remain suspended in the liquid.
Micellar casein is obtained by separating casein from whey, milk fat and lactose using a microfiltration process. This preserves casein's natural micellar structure.
After a micellar casein shaker, the absorbed liquid is emulsified with gastric juices to form a viscous, gelatinous substance that moves relatively slowly through the digestive system.
Micellar casein therefore tends to be absorbed more slowly than other protein sources. Raw micellar casein contains 80-90% protein and has a good BCAA profile, although it is not as rich as whey protein.
What is calcium caseinate?
Calcium caseinate is a calcium-bound casein protein salt, commonly added to solid and semi-solid foods to improve texture.
Caseinates are isolated casein proteins which are normally insoluble in liquids and negatively charged in neutral pH solutions. Caseinates are made soluble by mixing with dilute saline solutions and alkalis, usually calcium hydroxide.
Calcium caseinate is produced on an industrial scale by a multi-stage chemical process from large quantities of skimmed milk.
The milk is acidified to precipitate the casein, then the curd is washed and reacted with an alkaline product such as calcium hydroxide to restore a pH close to neutral. Calcium caseinate contains the same amount of protein, amino acids and glutamine as micellar casein. The difference lies mainly in its chemical form, which must be neutralized by a base.
Casein is also commonly taken before bedtime for its slow digestion and gradual release of amino acids during the night.
Find out more: when should you take your casein?
Micellar casein vs. calcium caseinate
Although both are slow-release protein sources with similar amino acid profiles, micellar casein and calcium caseinate differ in several respects:
- Production process: gentle microfiltration for micellar casein vs. chemical process for caseinate
- Structure: micellar casein retains its natural micellar structure, unlike caseinate.
- Taste: micellar casein tastes more like natural milk than caseinate, which is often described as unpleasant.
So, even though the two offer similar nutritional benefits, micellar casein seems superior in that it better preserves the protein's native structure.
That's why it's often considered the preferred form of casein alongside food sources such as cheese, despite costing more than calcium caseinate.
In short, the main difference is that micellar casein is obtained by a non-denaturing process that preserves its natural structure, whereas calcium caseinate undergoes chemical treatments that modify its properties.
This gives micellar casein a better ability to form a clot in the stomach and release amino acids very gradually, as well as a more pleasant taste.
Is whey a better option?
If we compare whey and casein, whey remains a more nutritionally relevant supplementation option for the majority of athletes.
As we have seen, the main difference between whey and casein is the speed of assimilation: whey is a fast-digesting protein, while casein is slow-digesting, gradually releasing the amino acids. This is often what is required for post-exercise intake.
However, this effect can be reproduced by taking whey with a meal or carbohydrate, which will slow down its digestion, if you're looking instead for a gradual intake of amino acids overnight.
Whey remains nutritionally superior, with more essential amino acids (EAA) and BCAAs (leucine, isoleucine and valine) per 100g. It is therefore the protein of choice in most cases, particularly for mass gain or conversely for weight loss, depending on its use.
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