If there is one supplement that you simply cannot go without, it is protein powder.
While it won't get you jacked up like a pre-workout, or increase your strength and power like creatine, it does provide your body with everything it needs to build new muscle tissue -- which makes it integral for athletes and weekend warriors alike.
However, you can't just buy a simple “protein powder” and be done with it.
See, there are several different types of protein powder that are all suggested to have their own unique pros and cons -- of which two of the most common are “casein” and “whey”.
But what's the difference between these two options, and more importantly, is one better than the other?
Casein and Whey Protein
While they do have some key differences, the first thing I want to point out is that casein and whey protein also share some major similarities.
Firstly, they are both derived from dairy milk. Secondly, they are both considered to be “complete protein” sources, which means that they provide your body with a full array of essential amino acids (i.e. the building blocks of your cells), rather than just a couple.
So, how are they made?
Dairy milk is made up of a number of different components. These include water, sugar (or lactose), several vitamins and minerals, and finally two very unique proteins -- which are obviously casein and whey protein.
To keep it simple, casein is found within the solid part of milk, while whey is found in the liquid part.
And how do we actually get the protein powder out of the milk?
Well, it all comes down to cheese...
When cheese is made, it starts off as dairy milk, before undergoing a number of unique production processes. During processing, the liquid component of the milk is separated from the solid to make it thicker, and then the thickest curds are fully extracted to stop it going lumpy.
These curds are then washed and dried to create casein protein powder, while the watery component is filtered to extract the whey (which is also dried into a protein powder).
Now, as I mentioned above, while they are indeed very similar, they also have some notable differences that influence when you might choose to take them.
Casein vs. Whey: Nutritional Information
The first major difference between casein and whey relates to their nutrient breakdown.
Because casein is naturally thicker, it undergoes a less stringent filtration process than whey. This means that it typically contains a little less protein per gram than whey, in addition to a little more carbohydrate and fat.
For example, the Amino Z micellar casein contains 81.5 grams of protein, 5 grams of carbohydrates, and 1.3 grams of fat, per 100 grams of protein powder.
This also means that casein contains more total calories than whey, which could influence your choice if you were in a cutting phase.
Now, it is important to note that this doesn't have a huge impact when we are looking at the typical 30-40 gram serving size of most protein powders, but it does still need to be considered.
Casein VS. Whey: Absorption
Arguably the biggest difference between casein and whey protein powder is that they are absorbed at different rates after consumption.
Like any protein source, both casein and whey are broken down into thousands of tiny little compounds called amino acids after consumption. These amino acids are then absorbed into your bloodstream, shuttled around your body, before eventually being used to create new tissue.
But the rate at which this occurs is very different between casein and whey .
Interestingly, when casein enters your digestive tract it interacts with your stomach acid to form curds. These curds are quite thick and clumpy, and subsequently take quite some time to break down and absorb.
As a result, after consuming casein, you will slowly absorb amino acids for up to the next five hours.
On the other hand we have whey.
Because whey is much more refined than casein, it is broken down rapidly in your intestine, before being absorbed extremely quickly. In fact, it will only take about 90 minutes for all of the amino acids from whey to be absorbed and shuttled around your body.
Which probably gives you a bit of insight into what type might be better when it comes to post-workout nutrition...
Casein vs. Whey: Post workout nutrition
Because whey protein is absorbed so quickly, it stands to reason that it is going to a better choice immediately post-workout -- but this is not the only reason.
Whey protein also contains a higher number of branched chain amino acids than casein . Branched chain amino acids are a group of three specific amino acids that play a primary role in the production of new muscle tissue.
In fact, despite only being three of them (there are a total of 10 amino acids), they comprise about 35% of all the muscle tissue in your body -- which makes them pretty important for muscle growth.
Therefore, because of these two distinct factors, whey has been shown to increase muscle protein synthesis (the production of new muscle tissue in your body) to a greater extent than casein .
This means that it is more likely to contribute to muscle growth after exercise is completed.
Casein vs. Whey: Night time nutrition
Post workout nutrition is obviously important, but when it comes to optimizing muscle growth, your total daily protein intake is arguably the most important factor. Within this, you also want to make sure that you are evenly distributing your protein throughout the day .
This keeps a constant stream of amino acids trickling into your body, ensuring that muscle protein stimulus is maximised throughout the day.
With this in mind, consuming casein before bed is a great way to optimise muscle protein synthesis throughout the night's duration. While this is not the most important factor to eliciting muscle growth, it is an important step that can make a notable difference over time.
This would suggest that despite not being optimal post workout, casein offers a unique benefit that whey cannot provide.
Casein vs. Whey: Additional Benefits
Lastly, both Casein and Whey contain several unique compounds that can have additional benefits to your general health and function.
For starters, casein is full of unique bioactive peptides that have been shown to improve immune system function and digestive system health . Within this, they also appear to help lower blood pressure, suggesting benefits to your cardiovascular health 
These immunoglobulins have been shown to have potent antimicrobial properties, in which they can kill off harmful bacteria and viruses. Consequently, they can boost your immune system function and make you less prone to illness .
When considering each of these factors, it is not really a case of one being better than the other. Instead, it is simply acknowledging that both of these protein sources offer some unique benefits that sit outside the realm of muscle growth -- and therefore may both have a place in your supplement regime.
And the winner is… BOTH.
When it comes to casein and whey, they both have pros and cons that makes their use very context dependent.
Whey is absorbed much faster than casein, where it also promotes a greater spike in muscle protein synthesis. This makes it a much better source of protein for your post-workout shakes. On the other hand, because of its slow digestion, casein is a great option to take before bed so you can keep protein synthesis high throughout the night.
So, if you want to maximize your results, it might be worth opting for both.
- Dangin, Martial, et al. "Influence of the protein digestion rate on protein turnover in young and elderly subjects." The Journal of nutrition 132.10 (2002): 3228S-3233S.
- West, Daniel WD, et al. "Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise–." The American journal of clinical nutrition 94.3 (2011): 795-803.
- Stokes, Tanner, et al. "Recent perspectives regarding the role of dietary protein for the promotion of muscle hypertrophy with resistance exercise training." Nutrients 10.2 (2018): 180.
- Mohanty, D. P., et al. "Milk derived bioactive peptides and their impact on human health–A review." Saudi journal of biological sciences 23.5 (2016): 577-583.
- Fekete, Ágnes A., D. Ian Givens, and Julie A. Lovegrove. "Casein-derived lactotripeptides reduce systolic and diastolic blood pressure in a meta-analysis of randomised clinical trials." Nutrients 7.1 (2015): 659-681.
- Ng, Tzi Bun, et al. "Antiviral activities of whey proteins." Applied microbiology and biotechnology 99.17 (2015): 6997-7008.