Casein protein is the main protein found in milk and cheese.
Of the true proteins found in milk, about 82% is casein. The other, is none other than whey.
Casein is responsible for the white and opaque appearance of milk, as it is a combination of calcium and phosphorus.
It contains all of the amino acids essential to life, so casein is a complete profile, and considered a highly nutritious protein.
One prominent property of casein protein is that it is digested slowly.
As such, you will only reach a peak in blood amino acids and protein synthesis between 3 to 4 hours, after consuming casein protein.
This is in stark contrast to whey protein which peaks in about 40 minutes, and its effects wear off in an hour.
Using a scale of 1-10 (10 is the fastest), whey protein would be a 10, while casein is a 2.
So how is such a property useful for us?
The Functions of Casein Protein:
1. Greater Muscle Retention
Casein is used primarily as an anti-catabolic – that is a protein to help limit muscle breakdown.
This is possible as casein is digested slowly and as such is available for longer periods of time to feed your muscles.
To be more precise, it takes between 5-7 hours to be fully digested.
According to a study (1), subjects either took casein protein hydrolysate in comparison with a whey protein hydrolysate, while also eating a hypocalorie diet and performing resistance training.
While both groups did show fat loss, the group using the casein protein came out of the study with a higher total body percentage of lean mass compared with their previous measure.
This indicates a greater lean muscle retention rate, demonstrating casein to be especially effective at maintaining muscle.
2. Higher Quality of Protein
Researchers reported in the Journal of Nutrition that casein protein is of a much higher quality as compared to soy.
The benefit, is that higher quality sources of protein are better absorbed by the body and less will be excreted. As such you’ll need less proteins overall to maintain lean muscle mass.
This could be an especially useful source of protein for vegetarians if you’re fine with consuming dairy products.
What Studies of Casein Protein Have Shown
A study (2) has found that casein was good at preventing protein breakdown but not so good for increasing protein synthesis.
Whey protein, on the other hand, had basically the opposite effects: it increased protein synthesis but didn’t prevent protein breakdown.
The superior long-lasting effect of casein was attributed to a delayed gastric emptying and slower absorption rate from the gastrointestinal tract to the blood.
Types of Casein Protein
There are 3 types of casein protein.
1. Calcium caseinate
2. Micellar casein
3. Milk protein isolate
The first one is the less qualitative of the 3 and is more frequently used in food industry.
Micellar casein retains 100% casein protein where the five types of casein (alpha, beta, gamma, delta and kappa) remain unchanged and thus with higher glutamine content necessary for muscle recovery and more bioactive properties and muscle growth enhancers.
As for milk protein isolate, it is made by precipitating whey proteins and casein from skim milk. The milk protein isolate is then washed to remove impurities, providing greater than 85% protein and virtually no lactose or fat.
How to Use Casein Protein
1. Can be consumed every night before sleep to maintain lean muscle mass.
2. Can be used for those into low calorie diets satiety lasts longer thus eating more than necessary is avoided.
3. Can also be taken at daytime as meal replacement if there are long gap in between meals.
4. Should be used in conjunction with whey protein for maximum muscle gains – casein before sleep, and whey protein right after workouts and after waking up
Possible Side Effects of Casein Protein
An allergy to casein in adults is uncommon since tolerance is usually developed in the first three to four years of life, explained by Dr C. Solinas in a study.
Some symptoms to watch out for are fever, hives, sneezing and problems breathing as this might indicate an allergy.
People who are unable to digest casein or take too much can experience gastrointestinal disturbances. Some symptoms could be bloating to nausea, vomiting or diarrhoea.
How to Choose The Most Appropriate Casein Protein
You won’t go wrong with micellar casein or milk protein isolate. Micellar casein is a purer form of casein protein, while milk protein isolate is more economical, so it really depends on your situation.
Personally, I use the Optimum Nutrition 100% Gold Standard Casein Protein (click the link to find out more).
It is made up of micellar casein protein and is one of the best selling casein proteins on the bodybuilding.com store.
It has really helped me minimize muscle loss, because as an ectomorph, I tend to lose muscle mass rather quickly, which can be very irritating.
(1) Boirie, Y., Dangin, M., Gachon, P., Vasson, M.-P., Maubois, J.-L., & Beaufrère, B. (1997). Slow and fast dietary proteins differently modulate postprandial protein accretion. The National Academy of Sciences of the USA, 94 (26) 14930–14935. http://goo.gl/iV4otN
(2) Demling, R. H., & DeSanti, L. (2000). Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers. Annals of Nutrition & Metabolism, 44:21–29. http://www.pnas.org/content/94/26/14930.long