Take it from a Chemist: WTF is Casein?!?

Last week, we discussed the difference between whey, iso, and hydrolysate. If you haven’t given it a read you can check it out here: Take it from a Chemist: What’s the Difference Between Whey, Iso, & Hydrolysate?

THIS week, I want to take a look at another type of protein: Casein

and I know what you’re thinking.. Another one?!?! WTF is Casein?? Yeah, I know.. I thought the same thing too.. As if supplements weren’t confusing enough! So today let’s learn a little bit more.

Whey and casein are two of the most popular protein supplements available on the market. What do they have in common? First of all, they’re both milk-based proteins that are made as a by-product of the cheese making process. IN FACT! Milk is actually roughly 80% casein and 20% whey. AND they both contain high-quality, highly bioavailable, complete proteins that are rich in branched chain amino acids (or BCAAs for short). They are also great for both muscle growth and repair.

BUT, where these two protein differ is in how your body digests them. Whey is considered a fast digested protein while casein is considered a slow digested protein. Casein actually coagulates when it hits stomach acid and this is why it can take up to 5-7 hours to digest, whereas whey can be digested within a couple hours.


Protein mixed into an acidic solution.

Left: Casein (Coagulated)     Right: Whey (Liquid)

Kinda gross right???

AND, as I mentioned above, both proteins contain a high amount of BCAA’s per serving, whey is considered to be more anabolic (or muscle building) because of its ability to rapidly promote a spike in blood amino-acid levels, which are necessary to kick-start muscle protein synthesis, while casein, on the other hand, is often considered to be anti-catabolic (or good for preventing muscle breakdown) because it produces a steady stream of amino acids over time that help inhibit breakdown.


But wait! Let’s back up for a second. What exactly do these speeds and big biology words all mean?!?

Well, the speeds refer to the amount of time it takes for the protein to be FULLY metabolized or in other words: to be digested, absorbed into the blood, taken up by bodily tissues, and complete one of many metabolic fates.

Whey protein is “fast” as in it takes about 20 minutes before what you have consumed is broken down and it’s amino acids are making their way through your veins to all parts of your body. Somewhere between 20-40 minutes, the level of amino acids in your blood has reached its max and within the hour it will have gone through all of the various metabolic processes (protein synthesis, oxidation, etc..). If you look at the graph below you’ll see that whey’s amino acid peak is super high – this is because when consuming whey, the synthesis of new muscle protein is greater than the breakdown of muscle protein – #Gains.



In comparison, casein is considered “slow.” When you consume casein, you will reach a peak in blood amino acids and protein synthesis between 3 to 4 hours (Remember – it was about 40 minutes for whey). Also, if you take a look at the chart below, casein’s peak amino acid amount is nowhere near the amount from whey found in the blood. This is because casein dramatically slows the rate of protein breakdown. And because building muscle is dependent on both the synthesis of new protein as well as a decreased rate of muscle breakdown, what this means for you is also more #Gains.


So.. I know what you’re thinking… No Brainer! Why not get the best of both worlds!! WHEY + CASEIN COCKTAIL!!!!!

But not so fast!! I’m going to highly advise against doing that. Remember when I showed you those gross beakers and told you that casein coagulates when it touches stomach acid? Well, that reaction causes other proteins present to be digested and absorbed at a much slower rate as well – basically it brings all other proteins down to casein’s level. Which would take away whey’s most important selling point:  its ability to flood your system quickly with amino acids and stimulate protein synthesis!


So as I said before – Cheers Eat . Whey . Love Nation! To Casein (and Whey)!

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