Casein is a high-quality form of protein commonly used in protein and meal-replacement powders. Though not as well known as whey protein, casein excels at providing the most critical amino acids our bodies need to spare muscle mass and help support the formation of new muscle. With a potent 20.5% glutamine content, casein outperforms other popular protein sources, including whey, soy, and egg proteins.

Other names for Casein

caseinate, caseinate protein

Where to find Casein

The main protein of cow’s milk that’s formed when milk curdles — technically, it is the separation of casein from whey in milk.


Why athletes use Casein

It has been clearly established that athletes (of all types) under the stress of intense training have an elevated need for protein — among many other functions, protein is essential for muscle growth and recovery. Casein is an excellent source of the quality protein athletes require.

Casein’s high quality and value make it a popular addition to many protein powders and meal-replacement drinks. Thus, you rarely have to go looking for it — pick up a supplemental protein, and it will find you.

Ways that Casein can enhance Muscle Gain & Recovery:

  • Spare muscle mass during intense training phases
  • Provide an excellent source of high-quality protein to support muscle growth and recovery
  • Supply essential amino acids, including high concentrations of the potent anti-catabolic, glutamine


Signs of Casein deficiency

No deficiency conditions are known to exist.

Potential uses for Casein

Research indicates that Casein may be useful in the treatment of:

  • Catabolism (muscle wasting)
  • Wounds/injuries


More about Casein

Although available for some time, casein is what you might call a late “rising star” in the protein supplement arena. Casein is often found in various protein powder drink mixes and MRP’s as caseinate (an acid form that’s usually combined with sodium, calcium, or potassium). Recent studies have revealed this amazing protein not only supplies the most critical amino acids our bodies need to spare muscle mass during intense training sessions, but there’s strong evidence it may even help us increase muscle mass as well.

Found naturally in rather small amounts in cottage cheese or one of many protein powder or MRP’s, casein’s an especially rich source of the immune-boosting and muscle-protein-sparing amino acid glutamine. In fact, it has a potent 20.5% glutamine content — higher than whey, soy, or egg albumen protein sources. It’s also a great source of arginine, the well-known “growth-hormone-releasing” amino acid.

And because casein has one of the highest tyrosine-to-tryptophan amino acid ratios of any protein (almost 5 to 1), it’s also considered one of the most stimulating and may even help suppress appetite after consumption. This is because tyrosine is considered the “pick-me-up” amino acid that increases levels of excitatory chemical signals in the brain and, therefore, creates a sense of overall satisfaction and “fullness.”

A worthy protein choice

During intense training phases, our bodies require more protein to help reduce muscle protein breakdown and supply the needed amino acids to help our muscles rebuild bigger and stronger. In fact, studies show protein may be especially important to consume about an hour after a workout for optimal uptake of these muscle-building aminos. Because casein is found in many of the protein supplement drinks and MRP’s and is less expensive than many whole-food proteins, many active people find it helps them meet their increased needs for protein in a convenient drink mix.

Casein is an ideal protein to consume immediately before bed. You see, casein digests more slowly than many other protein choices (such as whey, which absorbs very quickly) and could almost be considered a “time-released” protein because it forms a “gel-like” substance in the gut, which slows its absorption rate. So late into the night — for hours longer — our muscle cells continue to be supplied with muscle-building protein and amino acids, lessening the time our bodies are “fasting” and increasing the likelihood of prolonged muscle-building activity and improved nitrogen retention.

Nevertheless, experts have agreed it’s a good idea to consume both casein and whey proteins throughout the day for maximum results. This popular combination of proteins typically can be found in MRP’s (usually found in their so-called “proprietary protein formulas,” as seen on the label) as well as many protein powders.

A better choice of casein?

Technology may have supplied us with an even higher quality casein protein product called Micellar™ casein. It is isolated from milk by cold filtration instead of the usual heat processing, using a series of enzymes and a process called nano-filtration to create an undenatured (undamaged protein matrix) casein. Thus, the structural integrity of the protein may be preserved more so than with other processes and therefore offer some additional immune-boosting and muscle-building benefits.

Ultimately, this “special” form of casein would be considered “the supreme” if we could use such a word to describe its place on the protein hierarchy. Hint: You can tell if the protein supplement you’re considering has this high-tech casein by looking for the “iMicellar” insignia on the label. However, the price is usually higher for these products, and the research, though intriguing, is still preliminary and not yet conclusive.


While casein is a wonderful protein source, it does contain a small amount of the milk sugar lactose and, therefore, may not be the best choice for anyone who is lactose intolerant. Anyone who is allergic to milk proteins should also avoid any products which contain casein.

In conclusion

It can be difficult to meet our bodies’ protein needs — especially for active individuals who, according to many experts, need from 1 gram to 1.5 grams of protein per pound of bodyweight. Fortunately, science has yielded a protein source, such as casein, that is convenient, inexpensive, and very nutritious.



Studies supporting optimal protein intakes indicate intensely training people need between 1 and 1.5 grams of protein per pound of bodyweight.


Casein can be consumed anytime throughout the day to increase protein intake. But it may be most beneficial when consumed at night, before going to bed, because it is released more slowly and therefore may help support the body’s ability to absorb the amino acids more efficiently.


Many individuals claim they feel “fuller” when supplementing with casein, as opposed to whey, because of its “gelling” effect. This causes it to more slowly leave the gut (called “transit time”), thus helping the body feel fuller, longer. This effect could be ideal for those who are restricting calories.

Synergists of Casein

No synergists have been noted.

Safety of Casein

Do not use if you are allergic to milk or caseinates.

Toxicity of Casein

No known toxicity.

Bans and restrictions

None reported.


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  • Demling, R.H., and DeSanti, L., “Increased Protein Intake During the Recovery Phase After Severe Burns Increases Body Weight Gain and Muscle Function,” J Burn Care Rehabil 19.2 (1998) : 161-8.
  • Gaudichon, C., et al., “Net Postprandial Utilization of (15N)-Labeled Milk Protein Nitrogen Is Influenced by Diet Composition in Humans,” J Nutr 129.4 (1999) : 890-5.