Casein Protein

optimum 100 casein protein

What Is Casein Protein?

Casein protein is the primary protein found in milk. It makes up about 80% of the protein in cow’s milk, with the remaining 20% being whey. Casein protein is extracted from the milk through ultrafiltration. Chemicals are not used in the process. The result of this process is an increase in the amount of bio-active milk peptides that support immune function. They also stimulate muscle growth. Casein protein is a slow digesting protein with an excellent amino acid profile.

Types Of Casein Protein

There are three forms of casein protein: calcium caseinate, micellar casein and milk protein isolate. Calcium caseinate is the lowest quality casein protein. It is commonly used as a food ingredient. Micellar casein is a more purified form of casein and will typically not contain whey. Milk protein isolate will contain some whey along with the casein. As in cow’s milk, the typical protein profile of most milk protein isolate products is about 80 percent casein to 20 percent whey. This makes it a more economical choice.

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Benefits of Casein Protein

  • Slow absorption rate, critical at night time or any time you’ll be without protein for long periods
  • Anti- catabolic meaning it will help prevent muscle protein breakdown

Since casein protein enters the bloodstream slowly, it does not have much impact on protein synthesis. It does have a strong effect in suppressing protein breakdown. In other words, it’s a muscle-sparing protein. Some would use the term “ anti-catabolic, a term popularized when the original Met-RX was being marketed back in the 90’s. This is one of the big selling points of that product. I can remember quite a few articles detailing the concept and its importance.

Casein & Nitrogen Balance

Going back to casein, muscle growth is dependent on the balance of protein synthesis and protein breakdown. Put another way, remaining in a state of positive nitrogen balance as opposed to a state of negative nitrogen balance. What is nitrogen? As defined in my medical dictionary: “nitrogen constitutes approximately 78% of the atmosphere and is a component of all proteins and a major component of most organic substances in living cells”. Nitrogen is essential to the synthesis of necessary proteins. During a 24-hour period in a healthy individual, nitrogen excreted in the urine, feces, and perspiration. Together with the nitrogen retained in dermal structures, such as the skin and hair, this equals the nitrogen consumed in food and drink.

The process of protein metabolism accounts for this nitrogen balance. When protein catabolism exceeds protein anabolism, the amount of nitrogen in the urine exceeds the amount of nitrogen consumed in foods. This produces a negative nitrogen balance or a state of tissue wasting. A positive nitrogen balance exists in the body when the nitrogen intake in foods is greater than that excreted in urine. Conditions usually associated with positive nitrogen balance include those related to growth, pregnancy, and convalescence from a tissue-wasting illness”. This is a great definition that clearly defines one of the reasons protein is so important in the muscle building process.

So, you want to increase protein synthesis and decrease protein breakdown. You can achieve this by supplementing with whey protein. Whey is a fast absorbing protein that promotes protein synthesis. In contrast, casein protein is a slow absorbing protein that suppresses protein breakdown.


To take full advantage of both whey and casein protein, you need to use them at the right times of the day. Timing is everything when it comes to protein! Casein protein should be the only protein you take before going to sleep. This goes back to the positive/negative nitrogen balance. You are basically fasting for the time you sleep until you get up in the morning and eat. This is anywhere from 6 to 10 hours. You don’t want your hard-earned muscle being broken down during the night. Using a protein powder that is slowly released over time will prevent this. Whey protein is critical in the morning or after a workout when you need a fast digesting protein. Yet it would do very little before bed as it’s absorbed and used within a few hours.

Do you have to go more than three hours without food during the day? If you are using a protein shake as a meal replacement, use a blend of whey and casein – about 50/50. This will give you a quick shot of protein and a sustained release of protein to carry you through to your next meal. Finally, if you are eating every two to three hours, you can use whey protein by itself in between meals. Now it should be said that you want to use whole food sources as much as you can. In fact many people advocate only whole food and shun the idea of a powder. However, they are missing the point of using a powder.

Specialized Needs

We are talking about specialized uses of different powders here. While you could potentially achieve these benefits with food, you would be taking in a lot more calories and possibly fat by doing so. This approach may not fit into your goals. Additionally, many people do not like to eat a meal before bed. Also, not everybody has time during the day to eat whole food meals. I’d like nothing better than to be able to eat whole food meals every 3 hours. But, I live in the real world, and that does not happen often, if at all. However, with the ease and convenience of a protein powder, I can make and drink a shake in no time. A shake fulfills my protein needs and I can be back on the job in no time at all.

Finally, bear in mind that whole food will take much longer to break down and digest than a liquid will. Eat whole food when you can. However, pay attention to the critical timing of protein at those key times of the day we’ve talked about. At those times, take full advantage of the opportunities presented by using a powder.

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Here is an excellent study on the benefits of casein:

Proc Natl Acad Sci U S A. 1997 Dec 23; 94(26):14930-5.

The speed of absorption of dietary amino acids by the gut varies according to the type of ingested dietary protein and the particular individual. This could affect postprandial protein synthesis, breakdown, and deposition. To test this hypothesis, two intrinsically 13C-leucine-labeled milk proteins, casein and whey protein, of different physicochemical properties were ingested as one single meal by healthy adults. Postprandial whole body leucine kinetics were assessed by using a dual tracer methodology.

Whey protein induced a dramatic but short increase of plasma amino acids. Casein induced a prolonged plateau of moderate hyperaminoacidemia, probably because of a slow gastric emptying. Whole body protein breakdown was inhibited by 34% after Casein ingestion but not after whey protein ingestion. Postprandial protein synthesis was stimulated by 68% with the whey protein meal and to a lesser extent (+31%) with the Casein meal. Postprandial whole body leucine oxidation over 7 h was lower with Casein (272 +/- 91 than with whey protein (373 +/- 56 Leucine intake was identical in both meals (380

Therefore, net leucine balance over the 7 h after the meal was more positive with Casein than with whey protein (P < 0.05, Whey protein vs. Casein). In conclusion, the speed of protein digestion and amino acid absorption from the gut has a major effect on whole body protein anabolism after one single meal. By analogy with carbohydrate metabolism, slow and fast proteins modulate the postprandial metabolic response, a concept to be applied to wasting situations.


This study is considered the premier casein study and compared micellar casein head to head with whey protein for absorptive and digestive characteristics. The casein used was micellar (whole) casein. The major difference noted in this study was the short lived increase in the amino acid pool produced by whey protein as compared to the much longer increase shown by micellar casein.

Also important to note is the implication that whey protein sources may provide a benefit as part of a post exercise drink due to the very rapid increase in amino acids seen in this study. Increasing the amino acid pool just after exercise may provide a benefit to muscle recovery and decreasing catabolism.

Increasing the amount of protein consumed in a diet will result in a significantly lower amount of weight gained following weight loss. This is due in part to proteins’ ability to increase satiety and thermogenesis.

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Casein Protein Supplements, Timing and Dosage

Timing has been discussed already, dosage is typically one scoop to 8oz liquid but you have to take into account your daily protein requirements: most people take their daily total ( 1 to 1.5 grams per pound of body weight) and divide by the number of planned servings a day to get a average intake per meal or shake. Casein products are almost all basic, pure protein powders, while there are blends available, you have to be careful as they may contain poor quality proteins alongside the whey and casein.

You can also find casein as part of a blend in weight gain powders. Shop carefully, if you want a blend, choose one that is whey and casein only, if you prefer to buy your casein and whey separately, choose high quality sources. If you are shopping for a weight gain, choose one low in sugar. As always, read the label fully before using.

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