Casein: Fast Gains from Slow Protein?

Casein is a high-quality protein that provides all the amino acids you need for building muscle. It’s a natural milk protein found in dairy products and in protein supplements.

Casein is popular with athletes looking to gain muscle and to prevent the loss of muscle during a diet. In this article, you will find everything you need to know about casein protein: what it is, when to use it, how much to take, and much more.

What is Casein?

Casein is one of the two proteins you find in milk and other dairy products. The other is whey.

Untreated casein is a slow-digesting protein. It forms a blob of gel in your stomach after you ingest it. This slows absorption down, decreasing the rate of amino acid uptake from the intestine compared to, for example, whey protein.

Due to the slow release of amino acids into the bloodstream, casein does not stimulate muscle protein synthesis in the same rapid and powerful way as whey. Instead, your muscles have access to amino acids much longer. This means that casein is able to keep your muscle protein synthesis elevated for several hours longer than whey protein.

Where Does Casein Come From?

Casein is a milk protein, meaning you will only find it in milk, other dairy products, and in foods containing some form of dairy. Unlike whey protein, which only constitutes a minor part of foods containing milk and dairy, the majority of the protein content of most dairy products is casein.

All mammals produce milk containing more or less casein protein, but the most common source in the average human diet, by far, is cow’s milk. The majority of the protein in cow’s milk, 75–80%, comes from casein, while the rest comes from whey.

This article is about casein protein from regular cows.

The protein in cheese, cottage cheese, and quark is almost all casein. The liquid whey part of milk is separated from the casein during cheesemaking. When you drink milk or yoghurt, you get the whey protein as an added bonus.

Casein is also one of the most common proteins found in protein supplements.

The Composition of Casein

Casein protein is actually made up of a family of proteins, made up of alpha-s1-casein, alpha-s2-casein, beta-casein, and kappa-casein. Casein from cow’s milk contains 36±40% alpha-s1-casein, 34±41% beta-casein, 10±24% kappa-casein, and 5±19% alpha-s2-casein.¹

Just like almost every other protein from the animal kingdom, casein is a complete protein. A complete protein is a protein that provides you with enough of all the essential amino acids you need to build, repair, and maintain your body’s tissue, including your muscles.

This is what the amino acid composition of casein (the middle column) looks like, compared to whey and soy protein.

Just like the other milk protein, whey, casein contains plenty of the amino acid leucine. Not as much as whey does, but more than many other complete proteins. Leucine is the amino acid that kick-starts muscle protein synthesis when you eat a protein-rich meal. In addition, casein contains abundant amounts of glutamine.

Different Types of Casein

If you get your casein from a protein supplement, you have three different types to choose from. They all have different properties, and only one of them provides you with a significant long-term release of amino acids.

Micellar Casein

The protein in milk can be found in structures called micelles. These are microscopically small spheres, as tiny as 0,01–0,03 micrometers in diameter, containing around 25,000 casein molecules each.

Micellar casein is the least processed of the casein protein supplements. It is produced by taking milk and separating the casein from the whey using filtration methods. This process leaves the casein micelles intact in the finished product. The casein protein remains undenatured until it arrives in your stomach. Denaturation of a protein means that the structure of the protein is disrupted. It is a  common misconception that this is something bad, but in reality, denaturation of a protein is actually necessary for you to be able to use it to build muscle and other tissue. When a protein is intact and undenatured when you ingest it, like micellar casein, it is denatured in the acidic environment in your stomach. After that, enzymes break it down into the amino acids your muscles can utilize for repair and synthesis.

This entire digestive process takes time, which means that micellar casein is a slow-release protein. If you are looking for a protein with slow absorption over a number of hours, micellar casein is your protein of choice.

Calcium Caseinate

Calcium caseinate is derived from milk, treated and separated by adding calcium hydroxide. This causes the protein to denature during the manufacturing process. Unlike micellar casein, caseinate is already denatured when it reaches your stomach. This does not lower the quality of the protein itself, but it does eliminate some of the slow-release properties of casein. Caseinate skips a large part of that step after you have ingested it.

Unlike micellar casein, caseinate does not clot in the stomach to any particular extent. It is fairly soluble. While caseinate digests at a slower rate than whey, the uptake is not nearly as slow as that of micellar casein. Over time, it actually has effects on plasma amino acids comparable to those of whey.² That is not bad in and of itself, but if you use casein for the slow-release properties, caseinate is not the type of casein you are looking for.

This also means that calcium caseinate, unlike micellar casein, effectively stimulates muscle protein synthesis. The hour or so after intake, whey is more effective, but looking at a longer period of time, the same amount of calcium caseinate improves muscle protein synthesis just as well.³

Casein Hydrolysate

Hydrolyzed protein is pre-digested and already broken down into amino acids and peptides. Because of this, the absorption rate of hydrolysates, including casein hydrolysate even though it originates from a slowly digested protein, is very rapid. In fact, it might actually be too rapid, if you want to stimulate muscle protein synthesis. Plasma insulin and amino acid levels rise so rapidly that muscle protein synthesis can’t keep up. Instead, protein synthesis in the gut and the visceral organs increase, while the anabolic response of other tissue, like your muscles, is less than optimal.⁴

For older individuals, maybe 60 and over, it might be the other way around. In the elderly, casein hydrolysate stimulates muscle protein synthesis more than an intact protein.⁵ In young individuals, a slow-release protein improves protein balance more during the hours after ingestion, but in elderly, it’s the opposite. If you are a senior, casein hydrolysate is an effective option to stimulate protein synthesis. If you are young, it probably builds more gut and liver than muscle. And even if you are elderly, you might as well use a fast protein like whey, which is at least as effective, costs less, and tastes better.⁶

When and How to Use Casein Protein?

You don’t have to treat casein with any kind of special respect. You don’t need to dose and time your intake any differently than with any other protein source in your diet. Regardless if you get your caesin from regular dairy products or from a slow-release casein protein powder.

Just add any casein you eat or drink to your total daily protein intake, and treat it as any other protein source. Simple as that. Almost all protein in your regular diet is absorbed over a long period of time, just like casein, if not slower. Casein does not have any properties that differentiates it dramatically from any other protein in your diet. You will utilize it to build muscle and other tissue, regardless of how and when you take it.

You can use casein, both from dairy products in general and from protein supplements, at any time during the day. As a main source of protein in any meal, as a snack, or after a workout.

How Much Casein Should You Take?

If you are looking to stimulate muscle protein synthesis to any significant extent, you should aim for at least 20 grams of protein per feeding. This goes for all proteins, not just casein.

If you ingest a very large amount of whey protein and nothing else at once, a lot of it is probably going to waste, at least if you were hoping to utilize it to build muscle. This is not the case for casein or other slow-release proteins from regular food. Slow proteins are released and absorbed over many hours, and your body can use it to build muscle and other tissue over a much longer time. If you eat a lot of it in one meal, it just affects your protein synthesis and protein breakdown longer.

In order to stimulate muscle protein synthesis as much as possible the hours after a protein intake, you need at least 3 grams of leucine per meal. That’s why recent research recommends ingesting around 0.4 grams of protein per kilogram of body weight and meal, for good measure.⁷ This goes for any protein source, not just casein. Casein is no special case in this regard, but this is a good amount to shoot for, if you use a casein protein supplement or use casein in any form as a protein source in a meal.

If your meal planning calls for more protein per meal than that, it’s no problem. The effects of, for example, whey protein do not last for more than a couple of hours, but after 30 grams of casein, the leucine levels in your blood will still be 60% higher than normal 300 minutes later.⁸ And that’s after ingestion of casein and nothing else. Protein you eat as part of a complete meal is digested over an even longer period of time.

Read more: How Much Protein from a Single Meal Can Your Body Use to Build Muscle Mass?

Casein and Your Muscles

What happens after you eat or drink casein protein? Do you build more muscle or do you reduce muscle breakdown?

Protein Synthesis

After ingesting casein protein, the amino acid levels in your blood increase. Since casein forms a gel in your stomach, causing the protein to be released into your intestines over a prolonged period of time, the uptake of amino acids into your bloodstream is also slow, extending over many hours.

When you eat or drink whey, on the other hand, a protein which is the polar opposite of casein and is rapidly absorbed, your plasma amino acid levels increase a lot in a short period of time. This activates muscle protein synthesis in a powerful way. Responding to these signals, plenty of amino acids mobilize and form new muscle tissue. However, only an hour or two later, this effect is over. Plasma amino acids return to normal levels, as does muscle protein synthesis.

Muscle protein synthesis following a casein meal produce looks quite different. The levels of amino acids in your blood never peak in the same fashion, like when you eat or drink whey. Instead, they rise quite substantially from baseline, but do not reach close to the same levels. However, they stay elevated at that level for many hours, keeping your muscle protein synthesis stimulated over time.

The triangles show plasma leucine levels following ingestion of 30 grams of whey protein, while the black circles show leucine levels induced by the same amount of casein protein, over 420 minutes.

The leucine levels never reach the heights required for maximum stimulation of muscle protein synthesis, but on the other hand, they moderately stimulate it for much longer. Thirty grams of whey stimulate muscle protein synthesis by around 70% above normal levels for a little while. The same amount of  casein keeps muscle protein synthesis at 30% above baseline, but for much longer. 

Looking at protein breakdown, we see it reduced by, on average, 34% after a 30-gram casein shake.

Due to this difference between protein synthesis and protein breakdown, whey is often called an anabolic protein, while casein is called an anti-catabolic protein, a protein that prevents or reduces breakdown.

This is a common misconception. Not the fact that protein is anabolic, that it builds muscle, but that it reduces muscle breakdown.

Muscle Protein Breakdown

Many of you reading this have probably heard that casein reduces muscle protein breakdown. There is not a whole lot of evidence for this. When you eat protein, muscle protein breakdown does decrease, but this is mainly due to the fact that protein causes insulin release, not due to the protein itself. Insulin has anti-catabolic properties and reduces muscle protein breakdown. Reduced muscle protein breakdown is a hormonal effect, not an amino acid effect.⁹

The study these results, and the diagram above, come from has given rise to claims and marketing saying that you reduce muscle protein breakdown by drinking a casein shake. That study didn’t even measure muscle protein breakdown, but whole body protein breakdown, which means the protein breakdown in your body in general: your gut, skin, and other organs. The decrease in muscle protein breakdown observed during the hours after a meal is the result of the insulin response to that meal.¹⁰ Anything caloric you eat, with the exception of pure fat, causes insulin release, meaning there is nothing special with casein in this regard.

Amino acids from the protein you eat stimulate muscle protein synthesis. Insulin release following a meal reduces muscle protein breakdown.

In addition, muscle protein breakdown only plays a minor role in controlling the balance between synthesis and breakdown. That balance is mostly regulated by stimulating muscle protein synthesis through feeding and strength training.

Muscle protein breakdown does decrease, like we said, after you eat casein, simply because your insulin levels increase as a response to the protein. You don’t have to eat a lot of protein to cause insulin release high enough to maximally decrease muscle protein breakdown. As little as 20 to 25 grams of protein increase insulin levels to 15–20 µU/ml. Even if you add enough protein or carbs to that meal to produce much higher insulin levels, like 65 µU/ml, your muscle protein breakdown does not decrease further.^{11 12} Eating in general reduces muscle protein breakdown, by causing insulin release, but the macronutrient composition of said meal is of minor importance.

In summary: casein improves the balance between muscle protein synthesis and muscle protein breakdown, mainly by keeping muscle protein synthesis elevated over baseline levels over a long period of time. Not by reducing muscle protein breakdown. Muscle protein breakdown does decrease following casein ingestion, but that is not due to some inherent properties of the protein itself, but a result of insulin being released. The same thing happens after you eat anything with calories causing your insulin levels to increase.

Which is Best: Casein or Whey?

This depends on several factors. Whether or not you eat the protein in question on it’s own or as a part of a mixed meal, your age, and the amount of time we are looking at.

Young Individuals

Like we said earlier, whey exerts a powerful but short-lived effect on muscle protein synthesis. The effect of casein is less powerful, but lasts longer.

If you were to measure your muscle protein synthesis for 2 hours following whey or casein ingestion, whey would leave that battle victorious. However, if you extend that time period to  5–7 hours, casein would give you the overall best balance between synthesis and breakdown. Only a few hours after the whey meal, muscle protein synthesis is back to normal fasting levels. The amino acids from a casein meal, on the other hand, are absorbed for much longer and keep your muscle protein synthesis elevated for hours on end.

When you eat whey or casein as part of a mixed meal, these differences even out, because the presence of fiber and other nutrients slow down the absorption of the whey. Muscle protein synthesis following a mixed meal high in whey protein no longer reaches the same heights, since your blood isn’t flooded by amino acids in the same way. Instead, the stimulation of muscle protein synthesis lasts longer. Looking at a period of 5–7 hours after ingestion, the difference between casein and whey is diminished when the protein is part of a mixed meal. Casein still improves protein balance more than whey, though.¹³

Elderly Individuals

In the elderly, it’s the other way around. Here, a fast protein like whey improves protein balance more over a longer period of time. This is likely caused by aging bringing a resistance to amino acids. We need larger amounts of amino acids, leucine in particular, in the bloodstream to initiate the same kind of muscle protein synthesis response after a protein-rich meal, compared to when we were young.

A slow protein like casein does not increase the amino acid levels in the blood to the same degree. This could be the reason elderly individuals do not respond to smaller feedings of slow-release protein with a substantial increase in muscle protein synthesis. You can counteract this effect simply by eating more protein, or by adding more leucine to the meal.¹⁴ When these anabolic signaling deficits appear and become noticeable is unclear, and most likely highly individual, but sometime after the age of 60.

Post-Exercise Casein: A Good Option for Building Muscle?

Three studies have demonstrated that post-exercise casein stimulates muscle protein synthesis to an extent comparable to whey.^{15 16 17}

Two other studies show that whey offers the superior anabolic response after a workout.^{18 19}

Why the difference?

As you may remember from earlier in the article, micellar casein is THE slow-release protein, while calcium caseinate is absorbed more rapidly. The three studies that found casein and whey to have a comparable effect on muscle protein synthesis all used caseinate, the rapidly absorbed type of casein. The studies in which whey proved superior compared it to micellar casein, which is released more slowly.

This means that yes, you can use casein as a source of protein after a workout in order to stimulate muscle protein synthesis, maybe as effectively as with whey. However, you would need caseinate to do so, not micellar casein. Micellar casein most likely does not provide a rapid enough rise in plasma amino acids for a substantial effect on muscle protein synthesis. It’s not useless after a workout by any means, though. Your muscles will still be able to utilize the amino acids for repair and protein synthesis when they do appear. However, it’s most likely the lesser choice. At least on paper.

In a real-world setting, it likely won’t make or break your workout. If rapidly absorbed protein after a workout was essential, protein powder after a workout would be essential as well, since all the protein you get from your regular meal is absorbed slowly. And you demonstrably do not need protein supplements to get big and strong.

Casein or Whey: Does It Really Matter Which One You Use?

Which protein has the most impressive muscle protein synthesis graphs might be interesting in it’s own way, but does it really matter when it comes down to gains? Do you actually build more muscle using one or the other?

Let’s assume that you eat a fairly balanced, normal diet. You want to add a protein supplement to increase your protein intake. Does it matter which one you pick? Casein or whey?

If you haven’t eaten for hours, and you know it’ll be a long time before you have a chance to eat your next meal, micellar casein is the best choice, if you have to choose. Whey only stimulates muscle protein synthesis for an hour or two, so you’ll be back to baseline before your next regular meal. Casein, on the other hand, keeps your muscle protein synthesis elevated for a number of hours, long enough to last you all the way to your next meal. If it IS only an hour or two until you get to eat, whey is the better choice.

After a workout, both whey and caseinate are good choices. They are both absorbed rapidly enough to provide a robust anabolic effect. Micellar casein less so.

However, keep in mind that it is still not certain by any means that you will notice any difference in actual gains by using one protein or another, as long as your total protein intake is the same. Your total protein intake is, by far, the most important factor here.

• If you are going to eat a protein-rich meal within a few hours: use whey.
• If the next meal is many hours away: use micellar casein.
• Whey is probably the most versatile protein supplement. You get slow-release protein from pretty much every other protein source in your diet anyway.
• If you are looking to make puddings, mousse, and other protein-rich dishes using your supplement, casein is the powder of choice. Whey lacks the ability of casein to gel into a pudding-like consistency.

Will a Casein Supplement Make You Gain More Muscle?

Yes, you can gain more muscle by adding a protein supplement,

No, the protein supplement per se will not make you build more muscle.

Let me explain.

Data from 49 studies with more than 1,800 subjects and decades or research shows that using a protein powder can help you get stronger and gain up to 300 grams more muscle mass than training the same way without a protein supplement.

However! This is only apparent if you eat less than 1.62 grams of protein per kilogram of bodyweight and day. If you already eat this amount of protein, or more, adding even more protein in the form of a supplement will gain you nothing.

Any protein supplement, regardless of whether it’s casein, whey, or any other protein, can help you gain muscle, but only if it increases your total protein intake and if you don’t already consume enough protein. “Enough protein” in this case equals 1.6 to 1.7 grams per kilogram of bodyweight and day.²⁰ And adding the same amount of protein to your total daily intake simply by eating more of any other regular protein source would provide the same effects.

If you already cover your protein needs, but still want to use a protein supplement, feel free to do so. You don’t have to add protein that won’t give you any extra benefits, but you can use a protein supplement, like casein, as part of your regular protein intake, for ease of use and for the potential cost-effectiveness.

Reading this, you might think protein supplements are a waste of your money, but that is not necessarily the case. They are just nothing special, nothing you have to treat with any kind of respect just because the protein comes in the form of a powder instead of in the form of regular food. Protein supplements, like casein protein, are just a low-cost, easy-to-use alternative to the same amount of protein from food. They are food, in concentrated form. If you want or need such a concentrated source of protein to supplement your regular protein intake, it’s not a waste of money. Even if protein supplements do not have any kind of unique effects you can’t get anywhere else.

Is Casein a Pre-Sleep Protein?

Casein is often called a night protein or a pre-sleep protein. You might have seen claims that casein is extra beneficial before you go to bed.

Previously, it has been suggested that you should avoid eating right before bedtime. This could affect your body composition in a negative way, trigger fat gains, and even have negative health effects, like increasing the risk of diabetes and heart disease.

This might, possibly, be the case, if we are talking about living a sedentary lifestyle and still eating a massive meal right before going to bed. However, recent research actually demonstrates positive effects from eating a small meal of isolated nutrients, like protein, before bedtime. Doing so also provides your muscle with building materials for repair and growth during the overnight fast, even leading to improved gains. A number of studies from the last decade show that a pre-sleep, post-workout casein intake can improve overnight muscle protein synthesis and even lead to greater long-term gains in muscle mass and strength.^{21 22 23 24 25 26 27 28 29}

If you eat a slow-release protein, like casein, before hitting the hay, you give your body what it needs to increase muscle protein synthesis all night long, compared to going to sleep in a fasted state. When you eat or drink casein the last thing you do before bedtime, the amino acids from that protein are easily absorbed during the night and used by your muscles to maintain muscle protein synthesis while you sleep. This process is amplified even more if you have worked out in the afternoon or evening.

A casein intake at bedtime, combined with an earlier workout improves overnight muscle protein synthesis and can lead to greater gains over time.

This all sounds awesome! What’s the catch?

The catch is that the control groups of these studies received a non-protein placebo supplement. This means that the subjects who drank a casein shake before bed also ended up with a higher total protein intake over the day as a whole.

For example: in one of the studies, the subjects drank 40 grams of either casein protein or a non-protein placebo half an hour before bedtime. Overnight muscle protein synthesis in the casein group improved 22% more than in the control group. The problem with this result is that the casein group ended up at 1.7 grams of protein per kilogram of bodyweight and day, while the placebo group only got 1.2 grams per kilogram. That amount is not enough for someone looking to maximize the effects of strength training and gain as much muscle mass as possible. That number is, as we mentioned earlier, somewhere between 1.6 and 1.7 grams of protein per kilogram of bodyweight and day. The very amount the casein group hit, while the placebo group did not.

This is a recurring problem with these studies. You can’t really say that pre-sleep casein per se will make you gain more muscle. Eating more protein will. It’s just as likely, or even more likely, that adding casein simply leads to a higher daily protein intake, and that is the relevant factor behind the observed gains.

This does not mean that drinking a casein shake before bedtime is a bad thing. On the contrary, it’s an excellent choice of protein at this time, providing building materials for your muscles all through the night. However, casein is probably not something special, something that gives you advantages over eating any other regular protein-rich food at that time.³⁰ If anything, research suggests that the same amount of casein earlier in the day gives you the same benefit over the day as a whole, and gives you the same anabolic advantage over time.³¹

Pre-sleep casein does not seem to shut down overnight fat oxidation. Your fat metabolism does not slow down during the night after eating or drinking casein before you go to sleep.^{32 33} If you had eaten 10 pre-sleep maple syrup pancakes instead, this might not have been the case.

Satiety and Weight Loss

Protein is more satiating than fat or carbohydrate. This makes your protein intake an important weapon in your arsenal, when looking to lose weight and body fat. Protein provides benefits both by boosting muscle protein synthesis, helping you keep your fat-free mass while losing weight, and by making you feel full longer. If you are not walking around hungry, chances are you will be less likely to spontaneously put things you shouldn’t in your mouth.

Protein affects food intake, body weight, and body composition through stimulation of muscle protein synthesis, by regulating hormones controlling satiety, appetite and calorie intake, and by mediating communications between your gut, your digestive system, and your brain.

Rapidly absorbed protein, like whey, is more satiating that slow-release protein, like casein, in small doses. If you eat what is considered a normal amount at any one time, the differences between the proteins are minimal.

The satiating effect of whey is more immediate than that of casein. The two hours after ingestion, whey protein decreases food intake more than other proteins. Looking at 5 hours or more, however, casein provides a better satiating effect than whey or soy.³⁴

Safety

Nothing indicates safety issues with casein protein. As long as you aren’t allergic to milk, of course.

Milk Allergy and Lactose Intolerance

The exception to that safety statement is if you are allergic to milk protein in general, and to casein protein in particular. Milk allergy is one of the most common forms of food allergies, and there is no effective treatment or cure.³⁵ If you are allergic to milk protein, casein is not for you. Not from regular food and not in the form of protein supplements.

Lactose intolerance is a possible exception. Lactose intolerance is not a form of allergy, and is not potentially dangerous in the same way as milk allergy. However, it can be both unpleasant and painful. If you are lactose intolerant, you are sensitive to the sugars in milk, because you lack an enzyme called lactase, which breaks down lactose.

Since casein is produced from milk, you will always find at least some lactose in a casein protein supplement. If you are lactose sensitive, you can look for a casein supplement with added lactase. Unless you are very lactose intolerant, you will likely be able to use those. As for regular dairy products, you can easily find lactose-free alternatives regardless of what you are looking for. Hard cheeses are naturally free from lactose. Almost all the lactose is eliminated when the whey is separated from the cheese, and the rest is eaten up by lactic acid bacteria during the manufacturing process.

A1 and A1: Two Controversial Proteins in Milk

Different types of cows produce casein with different protein composition. As we mentioned in the beginning of the article, there are a number of casein proteins. One of these is beta-casein. Beta-casein has two sub-groups of proteins: A1 and A2. Most cows produce milk containing both A1 and A2 to varying degrees. Some common types of cows, like Holstein, mostly produce A1.

Epidemiological research suggests a link between A1 and a higher risk of several chronic diseases, including diabetes and heart disease.^{36 37}

Epidemiology does, however, not show cause and effect. Most often, controlled studies can’t find any negative health effects by consuming A1. A recent and extensive systematic review did not find any evidence that beta-casein A1 will affect your health negatively.³⁸ Moderate quality evidence did show that sensitive individuals might notice digestive issues after consuming A1-type milk, though. The evidence for other negative health effects were all found to be of low or very low quality. 

It should be noted that this research is ongoing, so things might change over time, and future studies could come to different conclusions.

Inflammation

Milk, other dairy products, and casein, are often implicated as being inflammatory. However, up-to-date meta analyses and reviews conclude that dairy products could have significant anti-inflammatory properties. At worst, they seem to be neutral for inflammatory markers.^{39 40}

Kidney Function

An old and classic warning is that you should refrain from eating too much protein, since it could put a strain on your kidneys and even lead to decreased renal function. There is no evidence for such claims. While it is true that some types of kidney diseases and kidney disorders require a lower than usual protein intake, you don’t develop those issues through a high protein intake, if you don’t already have them.⁴¹

Positive Health Effects from Casein

Apart from the fact that your muscles appreciate the casein protein you give them, casein might also improve some markers or health.

Casein is one of the reasons milk is good for your teeth, and not just because of the calcium. It can also help prevent the leading cause of tooth decay, the bacteria Streptococcus Mutans, from latching onto your dental enamel.^{42 43}

Casein has a beneficial effect on blood lipids after a high fat meal, and also seems to to be able to lower blood pressure if you suffer from high blood pressure.^{44 45 46}

Summary and Conclusions

Casein is a slow-release protein. It is absorbed over a long period of time and improves your muscle protein synthesis for hours.

Casein does not reduce muscle breakdown, not beyond the insulin release it stimulates. This is a common misconception. Insulin, not protein per se, reduces muscle protein breakdown.

The slow uptake of casein makes it a good choice when you know it’s going to be a long time to the next meal.

There is no evidence that casein is something extraordinary as a pre-sleep protein. It is a good choice before you go to bed, since it provides amino acids for your muscles all through the night, but so does every other protein from the regular food you eat. Nothing wrong with casein before hitting the hay, but it’s probably not superior to the same amount of protein from something else.

You can use casein post-workout. If you do, caseinate is the better option, stimulating protein synthesis similarly to whey protein. Micellar protein is likely too slow for a robust anabolic response.

Casein is safe, as long as you are not allergic to milk. If you are, stay away, but you won’t develop milk allergy by using casein, if you aren’t already allergic.

That’s it! You’ve reached the end of our guide on casein protein.

Want to learn more about dietary supplements? Which ones are worth your money, and which are questionable or useless? Check our StrengthLog’s Supplement Guide, our free guide where I review 26 of the most popular supplements.

If you’d like to read more articles of this kind on anything related to strength training, be sure to sign up for our free newsletter below, to be notified of new posts!

Sign up here:

Leave this field empty if you’re human:

References

1. Walstra, P., Jenness, R., Badings, H.T., 1984. Dairy Chemistry and Physics. Wiley, New York
2. Am J Physiol Endocrinol Metab. 2011 Mar;300(3):E610. A comparison of whey to caseinate.
3. Am J Physiol Endocrinol Metab. 2011 Jan;300(1):E231-42. Whey and casein labeled with L-[1-13C]leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion.
4. The American Journal of Clinical Nutrition, Volume 90, Issue 4, October 2009, Pages 1011–1022. Hydrolyzed dietary casein as compared with the intact protein reduces postprandial peripheral, but not whole-body, uptake of nitrogen in humans.
5. The American Journal of Clinical Nutrition, Volume 90, Issue 4, October 2009, Pages 1011–1022. Hydrolyzed dietary casein as compared with the intact protein reduces postprandial peripheral, but not whole-body, uptake of nitrogen in humans.
6. J Physiol. 2003 Jun 1;549(Pt 2):635-44. The rate of protein digestion affects protein gain differently during aging in humans.
7. Front Physiol. 2015; 6: 245. Nutritional interventions to augment resistance training-induced skeletal muscle hypertrophy.
8. PNAS December 23, 1997 94 (26) 14930-14935. Slow and fast dietary proteins differently modulate postprandial protein?accretion.
9. Diabetologia volume 59, pages 44–55 (2016). Role of insulin in the regulation of human skeletal muscle protein synthesis and breakdown: a systematic review and meta-analysis.
10. J Physiol. 2012 Mar 1; 590(Pt 5): 1049–1057. Muscle protein synthesis in response to nutrition and exercise.
11. Sports Medicine volume 49, pages185–197(2019). The Muscle Protein Synthetic Response to Meal Ingestion Following Resistance-Type Exercise.
12. Medicine & Science in Sports & Exercise: July 2011 – Volume 43 – Issue 7 – p 1154-1161. Carbohydrate Does Not Augment Exercise-Induced Protein Accretion versus Protein Alone.
13. J Physiol. 2003 Jun 1; 549(Pt 2): 635–644. The rate of protein digestion affects protein gain differently during aging in humans.
14. Am J Physiol Endocrinol Metab. 2006 Aug;291(2):E381-7. A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly.
15. Scand J Med Sci Sports. 2011 Dec;21(6):e372-83. Stimulation of muscle protein synthesis by whey and caseinate ingestion after resistance exercise in elderly individuals.
16. Medicine & Science in Sports & Exercise: December 2004 – Volume 36 – Issue 12 – p 2073-2081. Ingestion of Casein and Whey Proteins Result in Muscle Anabolism after Resistance Exercise.
17. AJP Endocrinology and Metabolism 300(1):E231-42 · November 2010. Whey and casein labeled with L-[1-13C]leucine and muscle protein synthesis: Effect of resistance exercise and protein ingestion.
18. J Appl Physiol (1985). 2009 Sep;107(3):987-92. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men.
19. British Journal of Nutrition. Volume 108, Issue 628 September 2012 , pp. 958-962. Greater stimulation of myofibrillar protein synthesis with ingestion of whey protein isolate v. micellar casein at rest and after resistance exercise in elderly men.
20. Br J Sports Med. 2018 Mar;52(6):376-384. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults.
21. Am J Physiol Endocrinol Metab. (2012) 302:E52–60. Intragastric protein administration stimulates overnight muscle protein synthesis in elderly men.
22. Med Sci Sports Exerc. (2012) 44:1560–9. Protein ingestion before sleep improves postexercise overnight recovery.
23. J Nutr. (2015) 145:1178–84. Protein ingestion before sleep increases muscle mass and strength gains during prolonged resistance-type exercise training in healthy young men.
24. J Nutr. (2016) 146:1307–14. Physical activity performed in the evening increases the overnight muscle protein synthetic response to presleep protein ingestion in older men.
25. Sports Exerc. (2016) 48:2517–25. Resistance exercise augments postprandial overnight muscle protein synthesis rates.
26. Am J Physiol Endocrinol Metab. (2016) 311:E964–73. Presleep protein ingestion does not compromise the muscle protein synthetic response to protein ingested the following morning.
27. J Appl Physiol. (2017) 122:20–7. Neuromuscular electrical stimulation prior to presleep protein feeding stimulates the use of protein-derived amino acids for overnight muscle protein synthesis.
28. J Nutr. (2017) 147:2252–61. Protein ingestion before sleep increases overnight muscle protein synthesis rates in healthy older men: a randomized controlled trial.
29. Am J Physiol Endocrinol Metab. (2017) 273:2016. Pre-sleep dietary protein-derived amino acids are incorporated in myofibrillar protein during post-exercise overnight recovery.
30. Front. Nutr., 06 March 2019. The Impact of Pre-sleep Protein Ingestion on the Skeletal Muscle Adaptive Response to Exercise in Humans: An Update.
31. Journal of the International Society of Sports Nutrition volume 15, Article number: 24 (2018). Daytime and nighttime casein supplements similarly increase muscle size and strength in response to resistance training earlier in the day: a preliminary investigation.
32. Nutrients. 2016 Aug; 8(8): 452. The Effect of Casein Protein Prior to Sleep on Fat Metabolism in Obese Men.
33. The Journal of Nutrition, Volume 150, Issue 1, January 2020, Pages 47–54. Lipolysis and Fat Oxidation Are Not Altered with Presleep Compared with Daytime Casein Protein Intake in Resistance-Trained Women.
34. J Nutr Health Food Eng. 2017;6(6):186-193. The role of source of protein in regulation of food intake, satiety, body weight and body composition.
35. Comprehensive Reviews in Food Science and Food Safety · November 2017. Bovine Milk Allergens: A Comprehensive Review.
36. Ann Nutr Metab 2006;50:177–183. Lower Consumption of Cow Milk Protein A1 ?-Casein at 2 Years of Age, Rather than Consumption among 11- to 14-Year-Old Adolescents, May Explain the Lower Incidence of Type 1 Diabetes in Iceland than in Scandinavia.
37. Medical Hypotheses, Volume 56, Issue 2, February 2001, Pages 262-272. ?-casein A1, ischaemic heart disease mortality, and other illnesses.
38. Nutrition Reviews, Volume 77, Issue 5, May 2019, Pages 278–306- Milk A1 ?-casein and health-related outcomes in humans: a systematic review.
39. Advances in Nutrition, Volume 10, Issue suppl_2, May 2019, Pages S239–S250. Milk and Dairy Product Consumption and Inflammatory Biomarkers: An Updated Systematic Review of Randomized Clinical Trials.
40. Nutrition, Metabolism and Cardiovascular Diseases, 13 February 2020. Effects of dairy products consumption on inflammatory biomarkers among adults: a systematic review and meta-analysis of randomized controlled trials.
41. Nutr Metab (Lond). 2005; 2: 25. Dietary protein intake and renal function.
42. Nestle Nutr Workshop Ser Pediatr Program. 2011;67:55-66. Milk and oral health.
43. Caries Res 1995;29:498–506. The Effect of Milk and kappa Casein on Streptococcal Glucosyltransferase.
44. The Journal of Nutrition, Volume 145, Issue 12, December 2015, Pages 2657–2664. Casein Compared with Whey Proteins Affects the Organization of Dietary Fat during Digestion and Attenuates the Postprandial Triglyceride Response to a Mixed High-Fat Meal in Healthy, Overweight Men.
45. J Nutr Sci. 2013; 2: e43. Casein improves brachial and central aortic diastolic blood pressure in overweight adolescents: a randomised, controlled trial.
46. Biosci Biotechnol Biochem. 2011;75(3):427-33. Effect of an excess intake of casein hydrolysate containing Val-Pro-Pro and Ile-Pro-Pro in subjects with normal blood pressure, high-normal blood pressure, or mild hypertension.