- 1. What is Casein Protein?
- 2. Whey vs. Casein Protein
- 3. Benefits of Casein Protein
- 4. How is Casein Protein Made?
- 5. Types of Casein Protein Powder
- 6. Using Casein Protein Supplements
- 6a. How to Take Casein Protein
- 6b. When to Take Casein Protein
- 6c. Should You Take Casein Protein Before Bed?
- 7. Best Casein Protein Supplements
- 8. Casein FAQ
- What casein protein powder is, and how it is different than other protein sources like whey protein.
- The different types of casein protein that are available.
- The major benefits of casein supplementation for those looking to build muscle and/or burn fat.
- The recommended amount of casein protein to take, and the optimal times to take it.
If you read our guide on whey protein, you will know that whey protein is the term used to describe a group of milk proteins that are isolated from whey, which is the leftover product of milk after it is coagulated during the cheese-making process.
Casein is the other predominant form of protein found in milk and makes up roughly 80% of the protein found in cow’s milk. Much like whey, casein also contains a host of bioactive peptides that have additional properties beyond their muscle building capacity. Casein is the Yin to whey’s Yang.
Casein protein is often misconstrued in the popular media, and the nuances of it are not well discussed. This expert guide will wade through a lot of the marketing hype and give you the information you need to know about it. We break down what casein is, how it is made, the different forms of it, and some of the most frequently asked questions regarding its use.
Based on what we currently know, which is quite a lot, casein appears to be perfectly safe for human consumption.
There is this age-old myth that protein supplements hurt your kidneys. Well, this just isn’t true. Not at all. Every single study to date has shown that high protein intake does nothing bad to your kidneys if you are a normal healthy individual. Now, if you have established kidney disease, it is likely wise to keep it to moderate amounts, but in otherwise healthy people, even intakes up to 4g/kg per day appears to be just fine.
Sadly, the myths and hyperbole surrounding protein supplementation, including casein, don’t stop there. For a while, it was thought that casein was linked to cancer, but this turns out to be really, really, far from the truth. Let’s dive into that topic.
As a scientist, one of my biggest pet peeves is when someone misinterprets (read over interprets) data and makes a big hot mess of a subject. The China Study did precisely that.
The summary of the China Study as told by the author goes like this, “animal protein caused cancer in mice and consuming more protein was associated with cancer in humans in China”. . . Well, unfortunately, that just isn’t the truth.
So here is the real story of the China Study. . . .
Initially, studies were done on rats that were poisoned and fed a 20% casein diet. They developed cancer-like lesions while those rats that consumed 5% casein did not. Let’s just ignore the fact that mice didn’t evolve to eat high amounts of casein or fish protein or anything else like that and give them the benefit of the doubt and discuss the actual research.
When you look at the actual data from the animal studies (we actually went in and read all of them, there are a lot of them) the cumulative research shows that either fish protein, casein protein, or plant protein can change tumor progression in mice exposed to tumor compounds.1, 2, 3, 4, 5, 6
That is kind of like saying, “If you go into a nuclear reactor you probably are going to get tumors, and eating a ton of protein might make it worse”. To me, the studies from the mice just don’t mean anything to us as humans not walking into toxic chemical plants or nuclear reactors daily.
If I tried to publish a paper like that right now the reviewers would laugh at me. . . and then reject my paper.
Now it gets even worse, when you look at the actual data in the human studies the results are all over the map. Casein/animal protein intake was associated with a small increased risk of some types of cancer in SOME provinces in China.
However, it was also linked to much lower risks of some types of cancer in other provinces in China. Essentially, they found no good correlational data and they certainly found ZERO casual data.
I think it is safe to say that casein is safe for human consumption.
People often make big claims about whey vs. casein. There are probably over 1,000 articles on the internet about this issue, but we really shouldn’t think of them as mutually exclusive. A smart supplementation regimen can include both. Let me cover some data about why this might be.
A study done on 23 individuals showed that both whey and casein had a similar effect on muscle anabolism after resistance exercise.7 Another study showed that whey hydrolysate was more effective at eliciting muscle protein synthesis after exercise than casein.8
The findings of the above study were replicated in an older population where whey again outperformed casein in measures of muscle protein accretion.
Finally, in an isotope-labeled infusion study, researchers were able to show that both whey and casein lead to similar increases in muscle protein synthesis.9
However, as we have discussed above potential benefit of casein over whey is the “fullness” effect of casein. As it is slower digesting, it often results in a longer period of post-prandial satiety. This may help reduce overall caloric intake and benefit weight loss to a greater degree than whey (this is speculative on my part).
Additionally, it has been shown that nighttime casein is effective for recovery.10
So clearly each one has a role. If you need a quick-acting protein, go with whey. If you need one for bedtime, or when you have large breaks between meals go with casein.
This is a genius idea... and something I had not given much thought to before. Mixing whey and casein might be a great way to get some fast delivery of amino acids and also some slow delivery of amino acids.
One thing to note about mixing protein powders is their flavors are often different so be careful of the flavor combo you choose! (Pro tip: mix chocolate with a peanut butter one, and you will get a killer combo).
- Casein is a great way to help hit your daily protein requirements.
- Casein offers a complete profile of amino acids.
- Casein can help with maintaining muscle mass during dieting cycles.
- Casein is an excellent protein source to promote satiety.
- Using casein in baked goods can increase the protein content and add texture.
Consuming dietary protein in the form of supplemental protein is a very well-established tool for weight loss. One of the benefits of increasing protein intake comes from its ability to keep you satiated for longer periods than consuming carbohydrates or fat. For many people, a high protein meal can sustain the feeling of fullness greater than a high carbohydrate or high fat meal.
Both whey and casein supplements have been researched as weight loss tools. When we look at the research from a weight loss perspective casein is likely to have a slight edge on whey protein, albeit it indirectly. One potential benefit of casein over whey is the “fullness” effect of casein.
As it is slower digesting, it often results in a longer period of postprandial (after eating) satiety. This may help reduce overall caloric intake and benefit weight loss to a greater degree than whey.
Like we discussed in the Whey Protein Guide, whey is separated from the milk using straining methods. This results in a liquid whey product. The leftover solid part (also known as the insoluble part) is the casein protein.
When manufacturing casein, whole milk is usually treated with a chemical, typically chymosin, which causes the milk to coagulate and makes the casein form a solid mass.
It is then sent through a series of microfilters that purifies it and concentrates the micellar segments of casein. Micelles are simply arrangements of molecules in which the water-loving part of the molecule (hydrophilic) is directed toward the outside and the water-hating part of the molecule (hydrophobic) is directed toward the inside. This gives it its unique digestive properties.
While you can get casein from casein supplements you can also get a substantial amount from food sources. Casein is highest in dairy products like milk, cheese, cream, and yogurt. Casein is also found in some fish like tuna, although in much smaller quantities than dairy products
Milk is one of the highest sources of casein available as roughly 80% of milk proteins are casein. So if you drink an 8oz glass of milk that has roughly 12 grams of protein, you get about 9.6 grams of casein-based proteins. That is quite a lot!
Micellar casein is the least adulterated form of supplemental casein. It is left in its “intact” molecular structure. This is important as it then is digested in a series of enzymatic and nonenzymatic processes in the body to encourage slow breakdown and absorption by the body.
Hydrolyzed casein is simply micellar casein that has been broken down into smaller peptides by “hydrolyzing” the bonds. This process occurs just like it does in whey where it can be broken down using enzymes or acids. If you decide to go with hydrolyzed casein for some of the reasons we mention below, definitely go with the hydrolyzed as the acid makes it incredibly bitter.
Typically, hydrolyzed casein will be substantially more expensive than micellar casein due to the processing and extra steps in manufacturing. There doesn’t appear to be any magical properties of hydrolyzed casein over hydrolyzed whey. The magic of casein lies in the micellar form, so speaking honestly, if you want something hydrolyzed, go with a hydrolyzed whey.
Here is the deal. It is really difficult for the average person to conduct the necessary tests to find out exactly what the quality of their casein protein is. Honestly, most casein proteins from reputable companies have high-quality protein content. However, just like any other food product, if it is handled and manufactured poorly there can be some dangers. That being said, the potential dangers are so minuscule that they are massively outweighed by the potential benefits for most people.
Chew it by the spoonful. Just kidding! There is no special way to take casein protein. It can be consumed on its own, in a smoothie, in a bowl of oatmeal, or mixed in with ice cream or pudding.
Casein should be considered a supplemental source of protein and not the primary source of protein in your diet as it is not typically as nutrient-dense in vitamins and minerals as animal proteins.
Casein protein can be taken at any time of day and with any meal. It is often slower digesting and conveys longer-lasting satiety than whey protein so it can be used for snacks or other times when you know you will have long stretches without a full meal (i.e. traveling) more effectively than whey protein.
There is also some rationale for taking it a few hours before training to ensure adequate amino acid delivery during training; however, no studies show it to be significantly better than whey protein, although casein may be a bit more effective if you take it a few hours before training than whey might be.
One of the biggest marketing claims for casein protein is that it is the ultimate nighttime protein due to its slow-digesting properties. The theory goes like this: consuming casein before bed ensures a slow, steady infusion of amino acids throughout the entire night.
When you look at the research, one common theme emerges. If you are trying to get jacked and put on muscle, consuming protein before bed is probably going to help you get a little more recovery and muscle protein synthesis than not taking it. When you compare casein to whey, it looks like there might be a slight advantage; however, that advantage doesn’t appear to be gigantic in short-term studies.
Our philosophy is, “you train your face off in the gym, might as well err on the side of gains in your nutrition”. So if you are trying to dial in supplementation as much as you can, taking casein at night might provide some extra benefit for you over whey protein.
|MuscleTech Nitro-Tech Casein Gold||110||0.5g||2g||24g|
|Dymatize Elite Casein||130||2g||4g||25g|
|Rule 1 R1 Casein||120||1g||3g||25g|
|Optimum Nutrition Gold Standard 100% Casein||120||1g||3g||24g|
|AllMax Nutrition Casein-FX||120||0g||4g||25g|
Does whey contain casein?
Whey should not contain casein as it is separated from the casein protein during the process. It is possible that some casein can be found in whey if the processing of your whey protein was not done correctly; however, even in this scenario, the amount of casein present would be incredibly small and not have any meaningful difference in terms of muscle growth or long term outcomes.
Does casein work?
This is a loaded question, but yes casein works and it works quite well for a lot of different goals. It can be used to effectively meet your daily protein requirements. It can be used as a slow-release protein at night and is effective for increasing overnight muscle protein synthesis. It has shown comparable results to whey for lean muscle gains in several studies.
Another really “successful” aspect of casein is its ability to act as a thickener in food. You can make the ever-popular “protein fluff” with it, and you can use it as a type of thickener in baked goods.
Is casein safe for teenagers?
Based on the current scientific evidence (and there is an obscene amount of studies using casein protein in humans), there is no evidence to suggest it is harmful to teens. It may be beneficial for teenagers as a lot of the components of casein will help their growing bodies!
Does casein help you fall asleep?
To our knowledge, there isn’t any good research to support the idea that casein per se can help you fall asleep. There is some rationale that protein intake might help some people fall asleep if it contains a high proportion of tryptophan but that is also pretty much pure speculation.
One thing that can be said is that eating often increases parasympathetic activity and decreases sympathetic nervous system activity. This might aid in helping someone fall asleep but it is more the result of eating than it is the actual casein itself.
Do I have a casein allergy?
I honestly have no idea. You could, or you might not. Casein allergies are not uncommon as it is essentially an allergy to milk proteins. If you find that you have any symptoms of allergic reactions after consuming either milk or casein, you should consult a doctor before taking casein protein or if they experience allergy symptoms after consuming it.
Some people can consume hydrolyzed casein with no side effects as it has been broken down into smaller peptides that don’t cause the same immunologic reaction as the full peptides do.
Is a casein protein supplement OK if I have a milk allergy?
Allergies are primarily an immune response to proteins. As such, most people with milk allergies are allergic to specific proteins in the milk. Casein proteins can contain specific proteins that cause allergic reactions to milk so it is wise to consult a doctor before taking casein.
In general, people who have an allergic response to milk often have an allergic response to casein supplements. If this is the case you might do better with a plant-based protein that contains a full spectrum of essential amino acids.
Is a casein protein supplement okay if I am lactose intolerant?
People have varying degrees of stomach and intestinal reactions to casein protein. Casein proteins are often lactose-free or have a very small amount of lactose. This means it is unlikely that a lactose-free casein product will result in someone having gastric distress as a result of taking it.
However, if you try a casein-based product and find you are indeed sensitive to it, a plant-based product with a full range of essential amino acids is a viable alternative.
Can women take casein protein? Is there a special casein protein for women?
There is no good evidence or theoretical rationale for why women can not or should not consider taking a casein protein. In general, women may weigh less than men which will result in a lower total daily protein intake but that does not indicate that casein supplementation is contraindicated for them.
Do rice, soy, or almond milks contain casein protein?
Casein is an animal milk-based protein. Plant-based protein milks do not contain any animal milk-based products so they do not contain any casein protein.
How much protein should I aim for every day?
Protein requirements or goals occur across a broad spectrum and are often dictated by your goal. There is no single recommendation that pertains to everyone but there are general guidelines that we can follow. Based on the most current data from research, it appears that in order to optimize lean muscle protein intake should be set at a minimum of .6-.7 grams per pound per day. This number can go up to 2 grams per day. A good range for the vast majority of people is to fall somewhere between 0.7 grams to 1.2 grams per pound per day.
Individuals who engage in more endurance-type training (i.e. running, cycling, etc) can stick to the lower end of the range. Individuals who focus primarily on building muscle can stick to the higher end of the range (1-1.2 grams per pound per day).
I’m a vegetarian, can I use casein supplements?
Casein is derived from animal by-products and does not contain any animal flesh so if you are a lacto-ovo vegetarian you can indeed consume casein protein. If you are a vegan and you choose to not consume any animal products, then casein may not be right for you.
Can’t I just drink milk instead of buying a casein supplement?
As we mentioned above, milk is a rich source of casein and you can indeed get a lot of casein protein by simply drinking milk. However, casein supplements may be more versatile and are more easily transported than milk.
Is casein useful for runners (or endurance athletes)?
Casein is 100% useful for runners as it can help them meet their daily protein needs and can be a great source of on-the-go protein. Combining it with whey may make for a great meal replacement option if you are a busy person who needs an on the go meal with high protein content.
- Cheng Z, Hu J, King J, Jay G, Campbell TC. Inhibition of hepatocellular carcinoma development in hepatitis B virus transfected mice by low dietary casein. Hepatology. 1997 Nov;26(5):1351-4. doi: 10.1002/hep.510260538. PMID: 9362383.
- Youngman LD, Campbell TC. The sustained development of preneoplastic lesions depends on high protein intake. Nutr Cancer. 1992;18(2):131-42. doi: 10.1080/01635589209514213. PMID: 1359506.
- Youngman LD, Campbell TC. High protein intake promotes the growth of hepatic preneoplastic foci in Fischer #344 rats: evidence that early remodeled foci retain the potential for future growth. J Nutr. 1991 Sep;121(9):1454-61. doi: 10.1093/jn/121.9.1454. PMID: 1679128.
- Dunaif GE, Campbell TC. Dietary protein level and aflatoxin B1-induced preneoplastic hepatic lesions in the rat. J Nutr. 1987 Jul;117(7):1298-302. doi: 10.1093/jn/117.7.1298. PMID: 2886567.
- O'Connor TP, Roebuck BD, Peterson F, Campbell TC. Effect of dietary intake of fish oil and fish protein on the development of L-azaserine-induced preneoplastic lesions in the rat pancreas. J Natl Cancer Inst. 1985 Nov;75(5):959-62. doi: 10.1093/jnci/75.5.959. PMID: 3863992.
- Appleton BS, Campbell TC. Effect of high and low dietary protein on the dosing and postdosing periods of aflatoxin B1-induced hepatic preneoplastic lesion development in the rat. Cancer Res. 1983 May;43(5):2150-4. PMID: 6131741.
- Tang, J. E., Moore, D. R., Kujbida, G. W., Tarnopolsky, M. A., & Phillips, S. M. (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: Effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology, 107(3), 987–992. https://doi.org/10.1152/japplphysiol.00076.2009
- Bart Pennings, Yves Boirie, Joan MG Senden, Annemie P Gijsen, Harm Kuipers, Luc JC van Loon, Whey protein stimulates postprandial muscle protein accretion more effectively than do casein and casein hydrolysate in older men, The American Journal of Clinical Nutrition, Volume 93, Issue 5, May 2011, Pages 997–1005, https://doi.org/10.3945/ajcn.110.008102
- Reitelseder, S., Agergaard, J., Doessing, S., Helmark, I. C., Lund, P., Kristensen, N. B., Frystyk, J., Flyvbjerg, A., Schjerling, P., van Hall, G., Kjaer, M., & Holm, L. (2010). Whey and casein labeled with l-[1-13C]leucine and muscle protein synthesis: Effect of resistance exercise and protein ingestion. American Journal of Physiology-Endocrinology and Metabolism, 300(1), E231–E242. https://doi.org/10.1152/ajpendo.00513.2010
- Holwerda AM, Kouw IW, Trommelen J, Halson SL, Wodzig WK, Verdijk LB, van Loon LJ. Physical Activity Performed in the Evening Increases the Overnight Muscle Protein Synthetic Response to Presleep Protein Ingestion in Older Men. J Nutr. 2016 Jul;146(7):1307-14. doi: 10.3945/jn.116.230086. Epub 2016 Jun 8. PMID: 27281811.