The two most popular supplemental powder forms of protein, whey and casein, are both milk proteins, but is one better or worse than the other? Well, frankly, they both have some merit and application in many instances, especially when we are concerned about performance and physique enhancement.
Given this, we will take a look at what the pros and cons are to both whey and casein protein powders, what the research shows about each, which instances are best suited to each, and who should consider using them.
Whey and casein: Difference in digestive rates
Most people generally refer to whey and casein proteins as the “fast” and “slow” digesting proteins, respectively.
When we talk about the slow digestion rate of casein, we are essentially saying that it will raise blood amino acid levels slowly and for an extended period of time versus whey protein, which does the inverse. Therefore, many people find that ingesting a whey protein promptly after exercise is best since it provides an acute, intense elevation of blood amino acids and thus muscle protein synthesis.
Casein, on the other hand, is generally reserved for periods of time when people know they won’t be able to eat for a lengthy period of time and need a protein that is slowly releasing amino acids into the blood stream.
That being said, studies seem to suggest that mixing protein sources may provide advantage over relying on one, single source repeatedly. The delayed gastric emptying rate of casein and high leucine content of whey can provide a sustained elevation of protein synthesis for several hours after ingestion, an effect not observed with solely whey protein ingestion since it is digested rather rapidly.  This is why dairy milk is a popular beverage of choice for many individuals who are looking for whey and casein proteins.
While the digestion rates do differ between whey and casein, there are several other factors to consider when it comes to these proteins.
Whey and casein: Assessing the amino acid content
One such factor to take into consideration is the amino acid profile of whey and casein proteins. While both of these proteins are considered “complete”, whey protein does contain a larger proportion of leucine, which appears to be a key regulator of muscle protein synthesis. 
This isn’t to say that casein lacks a nominal amount of leucine (or other essential amino acids) for muscle protein synthesis, but just that you will need a larger amount of casein on a per gram basis to ingest the same leucine content as a pure whey protein.
This chart below shows both the biological value (BV) and the protein digestibility corrected amino acid score (PDCAAS) of various protein sources. The former refers to a measurement that assesses the degree to which an animal is able to utilize that protein while the latter is a number between 0 and 1 that evaluates protein quality based on amino acid content in relation to human’s requirements for them:
|Whey Concentrate and Isolates||104-159||1.00|
As you can see, the PDCAAS for both whey and casein are equivalent, but the BV of whey proteins can be more than two times the value of casein.
However, in the bigger picture, the BV doesn’t necessarily mean that all the protein sources that have lower values aren’t useful. Consider that many bodybuilders and physique athletes alike rely heavily on seafood, beef and chicken for the majority of their protein intake and still maintain a large amount of muscle tissue. This is just a point in case that as long as you’re getting a variety of animal and animal-derived protein sources the BV is not too much of a concern. The exception would be for vegans who rely heavily on plant proteins, which is another topic in and of its self.
Whey and casein: Calcium content
Calcium is oft touted for it’s beneficial effects on bone health and may also assist the fat loss process. Calcium is a generous component of casein micelles and thus is more abundant in casein protein supplements than whey protein supplements.
Micellar casein protein contains roughly 3x the amount of calcium when compared to an equivocal amount of whey protein (concentrate and isolate). For individuals who struggle to meet their daily calcium quota through food sources, casein protein supplementation can be an easy alternative to calcium supplementation.
Whey proteins do contain some calcium as well, but it is considered a minimal component. This is yet another reason that a blended protein containing both whey and casein proteins may be the best bang for your buck (more on this below).
Whey and casein: Texture and use in food applications
Some people may not have much concern for using their protein supplements as part of food recipes and just prefer the good ol’ shaker cup and water method, but it is becoming increasingly popular for individuals with culinary imaginations to create some pretty fantastic foods that incorporate protein powders.
When considering the texture of casein protein powder, it tends to be a bit “fluffier” and coarser than whey protein powder. Also, whey protein powder’s texture will vary based on its protein content and the method of filtration used. Generally, pure whey isolates are very fine powders, almost like sand, while some whey concentrates with higher fat and carbohydrate content are less fine and more “chalky”.
As far as their applicability in food recipes and baking, it is often advised to stick to whey protein when you plan on actually cooking something since casein protein will not solidify thoroughly when heated and could leave baked products mushy and falling apart.
Many people find that they like to make cold recipes, like puddings and yogurts, with casein protein since it mixes much thicker than whey protein does and absorbs more water content.
For more information on recipes using whey protein and casein protein powders, check out the M&S recipes section here.
Should I use whey, casein or both?
Ultimately the most pertinent question to answer is which of these proteins is most appropriate for health enthusiasts and physique competitors alike. As we have broken down some of the advantages of each in the previous sections of this article, it would be asinine to claim that one is unanimously superior to the other given that certain instances may be better suited for one or the other (or both) and will vary depending on the individual in question.
That being said, I think it’s safe to say that a blended protein that contains both casein and whey proteins would be an effective supplement for most any time of the day or situation. Reason being is that these proteins tend to compliment each other so that you ultimately are getting the best of both worlds.
Moreover, it’s become lucid that the idea of needing fast-absorbing whey protein immediately prior to and/or after training isn’t really founded on much more than dogma. The bigger issue is just simply taking in a sufficient, quality protein source in a decent timeframe after training has occurred.
Another factor to take into consideration is that concomitant ingestion of other nutrients can significantly alter the digestive rate of whey and casein proteins. Whey protein may absorb rather rapidly on its own, but if you eat a bunch of fibrous veggies and unsaturated fats along with it (which delay gastric emptying) than it could take hours to completely digest and utilize that protein. This is why it’s improper, if not impractical, to say that whey should always be used around training time and casein at other times because many people eat other foods when they take their protein supplements.
If you can’t pick one or the other, it might be best to choose a protein supplement that contains a variety of protein sources to sort of “cover all your bases”. You don’t have to buy separate whey protein and casein protein supplements if that doesn’t fit your budget, but if you can afford it than it’s safe to say there is plenty of use for both in your supplement stash.
1) Drummond MJ, Dreyer HC, Pennings B, Fry CS, Dhanani S, Dillon EL, Sheffield-Moore M, Volpi E, Rasmussen BB. Skeletal muscle protein anabolic response to resistance exercise and essential amino acids is delayed with aging. J Appl Physiol. 2008 May;104(5):1452-61.
2) Reidy, P. T., Walker, D. K., Dickinson, J. M., Gundermann, D. M., Drummond, M. J., Timmerman, K. L., & Rasmussen, B. B. (2013). Protein blend ingestion following resistance exercise promotes human muscle protein synthesis. The Journal of nutrition, 143(4), 410-416.
Considering how old this article is I am sure I won't get a response but its worth a shot. Fairly new to all of this, so I don't exactly understand everything in this article. I currently take why three times a day, Between breakfast and lunch, between lunch and dinner and then late in the evening after my workout. Due to my daily schedule I can only get to the gym in the evening and I know I should be eating smaller meals rather than three large but I'm working on that. So question is would it be appropriate to change the post workout to casein? Also, what is the real physiological advantages to a slower digesting protein? I understand that your body will process it over a longer period of time, but what is the real advantage to digesting it over a long period rather than a shorter period with the whey?
Great post. I am a nutrition adviser and have this argument with people all the time. I always consume my post-workout with milk
A. For better taste and B. For extra protein
My friends will argue that you need to take it with water to maximise whey absorption but I've always got the impression from researching that the two are digested differently and so the body will still digest the whey quickly whilst the casein acts slower. Is this true or have I read some bogus stuff?
It's surprisingly a difficult topic to find much information on really! You tend to just stumble upon
"Whey is fast acting so take after workout"
"Casein is slow acting so take at night"
Nutrition is rarely that simple haha. Any advice or links to research/good reads on the topic are greatly appreciated :)
i am having problem to gain weight. i have 66kg weight and i'm doing workout so help which way i can get about 75 to 80kg.
I have MS and don't no which 1 to take so I need help, I've lost weight & body fat.
Meh, meal timing and frequency is largely a personal preference. As long as your hitting your targeted cals/macros for the day you're fine; it doesn't matter when and how often you're eating. The bottom line is figure out what works for you and stick with it. There are people who thrive on intermittent fasting, train in a fasted state, eat before/after training, eat several times/day, skip breakfast, skip dinner, etc.
And if you want a cheap, effective blend of casein/whey then a tall glass of milk will get you there.
Hello, I find that when I take a casein shake before bed it makes me need to go to the bathroom in the early hours of the morning, which is quite annoying. Do you have and ideas to remedy this?
You can take the casein 90 minutes before bed and attempt to use the bathroom right before bed... (Seems to work for me) or you can take your casein shake with less water. (Much thicker almost pudding like texture)
Thanks for article Elliot..
But a question... Does casein affects on digestion speed rate of whey?? I mean combining water and whey protein after workout is better than combining it with milk??
I heard something that the casein sediments faster than whey thus the digestion rate of whey decreases. Is it that scientifically correct or just being broscience?? On other hand you mentioned that the casein contains more Ca on its own and the Ca has a high molecular mass, does it lead to sooner digesting casein than whey?
Thanks a lot..