Whey Protein v.s. Casein: Which is Best? THE VERDICT
- Where do whey and casein come from?
- How to know the QUALITY of a protein?
- The Differences between Whey Protein and Casein
- Conclusion: Whey Protein v.s. Casein: The-Verdict
Whey protein and casein are the two most well-known and supplemented protein powders amongst fitness enthusiasts and bodybuilders. They are both derived from milk, and their relative effectiveness is often debated when it comes to how much they promote muscle building. Which is better? Are they better when taken together? And which one should you be taking?
This blog post will walk you through what whey and casein are, as well as the differences between them, on both a functional level and a health level.
By the end of this post, you’ll have all the necessary knowledge to make an educated decision on which of the two you should be supplementing.
Where do whey and casein come from?
The protein in milk is divided into two main categories: whey protein (which is the water-soluble part) and casein (which is the curd – coagulated milk part). Milk protein is a blend of 80% casein and 20% whey protein (in cheese, the more solid the more casein).
In the fitness community, whey is considered ‘the god of all proteins’ and is supplemented en masse. The majority of all protein research has been undertaken with whey and multiple studies find whey to be the most effective protein powder when it comes to muscle protein synthesis – or the building of muscle. Its forgotten counterpart – casein – is often left behind in the race, deemed less effective and of less high quality.
Is this a fitness myth or based on true facts? To understand this, let’s take a look at the definition of protein quality.
How to know the QUALITY of a protein?
The quality of a protein is important to acknowledge because it appears to play a key role in the extent of muscle growth following resistance exercise.
Protein quality can be assessed by looking at protein availability and amino acid profile.
Protein availability and amino acid profile
A protein is considered highly bioavailable (available to the body) if it’s easy to digest, absorb and – after conversion into its constituent amino acids – build into other proteins.
Proteins are made out of amino acids, of which some your body can synthesize and others it cannot. The ones which you cannot synthesize, but do need for survival, are called essential amino acids (EAAs). Among these are branched-chain amino acids (BCAAs), which are of crucial importance to your muscles. Leucine is the most anabolic (muscle-building) BCAA.
A protein is considered complete when it has enough of each EAA (in proportion to its overall amino acid content).
If a protein has both a high bioavailability and a complete amino acid profile, it’s referred to as a ‘high-quality protein’.
Different forms of whey have a different quality
As a supplement, whey is sold as dry powder with various levels of processing that affect how concentrated the protein is and how quickly it is absorbed. The different forms of whey protein, in order of increasing quality (and price), are:
- Whey concentrate (60-80% protein)
- Whey isolate (90-95% protein)
- Whey hydrolysate (>95% protein)
The latter – whey hydrolysate – is absorbed more rapidly by the body, thereby increasing insulin levels more than other forms of whey, leading to an increase in muscle protein synthesis. Whey hydrolysate may also be less allergenic than other forms of whey, and easier to digest (lower risk of bloating due to lower lactose content).
Studies have suggested that whey hydrolysate may be more effective because of its quicker digestion and higher BCAA content compared to other rapidly-digested proteins. A rapid digestion rate and a high BCAA content are two primary factors for increasing muscle protein synthesis following resistance exercise.
Different forms of casein have a different quality
The different forms of casein, in order of increasing quality (and price), include:
- Micellar casein (~90% protein)
- Caseinates (~90% protein)
- Casein hydrolysates (~90-95% protein)
Micellar casein forms a gel-type substance when it interacts with stomach acid, slowing down the emptying of your stomach and delaying the absorption of amino acids from your bloodstream. It is a slow-digesting protein.
Caseinates and casein hydrolysates are fast-digesting proteins (similar to whey), and therefore lead to a greater increase in muscle protein synthesis than micellar casein.
What are the Differences between Whey Protein and Casein?
The Speed of Digestion MATTERS
The most noticeable difference between both is that whey is a fast-digesting protein and casein a slow-digesting protein.
Fast-digesting proteins have been shown to be more effective in leading to muscle protein synthesis. As whey is a fast-digesting protein and casein is not, whey is more effective at promoting muscle protein synthesis (122% more than casein after exercise and 93% more at rest, in a study with young men). Even when comparing caseinates or casein hydrolysates to whey protein – which are all three fast-digesting proteins – whey still promotes muscle protein synthesis the most.
In line with this, if you would drink a whey protein shake all at once after a workout on one day, and drink an identical shake the next but then sipping it slowly over a period of time, the protein would be less effective in promoting muscle protein synthesis the second time. This is because of the difference in effectiveness between a fast-digested and a slow-digested protein. So keep in mind that speed of digestion matters.
Nevertheless, casein’s slower rate of digestion has one lucky advantage: it allows for a reduced rate of muscle protein breakdown compared to whey. This is due to the gradual, steadier exposure of its amino acids to your muscles.
Now you may be thinking, should I then mix these two proteins for optimal benefits?
In the athletic community, some claim a mix of slow- and fast-digesting proteins to be a better option concerning muscle building, but research has shown that this is probably not true. Given proteins of similar quality (like micellar casein and whey protein, which make up milk protein), a 1:1 blend of the slow- and fast-digesting protein won’t benefit your muscles more than just a fast-digesting protein.
In contrast, if a blend of whey, casein and soy protein is taken, there does seem to be a significantly better effect than if these were taken individually. This would be due to the disparities in their digestion rates: whey is very fast to digest, soy intermediate and casein very slow. The researchers hypothesize that taking a blend of whey, casein and soy protein is an optimal formulation as the soy protein would bridge the gap in amino acid release between whey and casein. This means that the soy protein would extend the time period of high levels of amino acids in the blood, which would allow your muscles more time to take up these amino acids.
So combining fast, intermediate and slow-digested proteins would prolong total digestion time, consequently increasing muscle protein synthesis.
The Amino Acid profile MATTERS
Even though whey and casein are both complete proteins – meaning they contain each essential amino acid (EAA) in sufficient quantity – their amino acid profile still differs.
Casein has less EAAs than whey, notably leucine – the most important BCAA for muscle building.
This, together with a slower digestion rate, makes casein a slightly less high-quality protein than whey protein.
The Peptide profile MATTERS
The last important element to consider is casein’s peptide profile. In casein, you find two versions of a certain bioactive peptide called beta-casein: A1 and A2.
- A2 is the natural and original form, found in the milk of humans, sheep, goats, and purebred Asian and African cattle.
- A1 is a different form that originated following a genetic mutation, which appeared about 5000 years ago in European cattle. Due to crossbreeding, most dairy products today contain both A1 and A2.
The distinction between these is that out of A1, your digestive enzymes can form an opioid named BCM-7. This opioid has been associated with a multitude of diseases such as type 1 diabetes, heart disease, delayed development in children and autism.
Although research about BCM-7 is still limited, there is consistent evidence that consuming A1 contributes to inflammation. Some scientists even suggest that people who think to be lactose intolerant are in fact sensitive to A1 instead and would not report symptoms of lactose intolerance when drinking only A2 milk.
According to this body of research, whey protein seems to be a safer option than casein. This research, however, has greater implications than only pointing at whey as a preferential protein supplement: it more broadly discourages the consumption of today’s mainstream cow milk. Since the last few years, the healthful community has increasingly been criticizing cow milk consumption, as studies have found it to be linked to a list of health issues (allergies, inflammation, endocrine disruption, etc.) and diseases (cancer, heart disease, acne, etc.). If you would like to know more about a much safer and healthier dairy alternative than cow milk, have a look at goat milk.
Conclusion: Whey Protein v.s. Casein: The Verdict
When comparing casein and whey protein quality in terms of digestion rate and amino acid profile, as well as the health risks associated with casein’s peptide profile, all arrows seem to point at whey protein being the better alternative.
Indeed, whey protein is a higher quality protein than casein and leads to a greater increase in muscle protein synthesis (the best form of whey being whey hydrolysate). It also seems to win on the level of health adversities, although both milk-derived proteins share a range of common health risks (further outlined here).
Considering opting for a plant-based protein instead of animal-based one like whey or casein? This blog post will give you everything you need to make the best possible protein decision.
Stay tuned for my next blog post: Why you should NEVER drink COW milk again and opt for GOAT milk instead: implications for cancer, athletes and much more
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