If whey protein powder is so great, why do so many bodybuilders and fitness enthusiasts insist on having a casein protein shake before bed?
I’ll admit that I am as guilty of this as anyone else because for years I choked down blenders full of crappy tasting casein protein powder before bed because that’s what I was told to do by all of the books, magazines, and online fitness gurus.
So what is it about casein that keeps us coming back for more?
Why do we bother with something that tastes horrible, doesn’t seem to mix well with any liquid on earth, and has the consistency of thick mud?
Is casein really worth all of the trouble?
What is casein?
First of all, casein (kā-sēn) is a dairy protein that comes from milk.
In fact, 80% of the protein in cow’s milk is casein, while the remaining 20% is whey. Casein is also the primary protein found in most dairy products such as cheese and greek yogurt.
Micellar casein is the type of casein protein that is found in milk and is what we traditionally think about when we talk about casein. Micellar casein forms a thick blob in your stomach, which is a good thing because it slows digestion and can elevate protein levels for 6-7 hours compared to 3-4 hours with the faster-digesting whey protein.
The other two types of casein protein that you’ll often find in supplements are casein hydrolysates and caseinates which are both derived from micellar casein but have gone through an additional processing step that further breaks down the casein protein to allow for faster digestion.
Why do we use casein at all?
Again, when we talk about casein, we’re mostly talking about micellar casein, and we use it primarily because of its slower digestion.
However, even the most die-hard bodybuilders don’t use casein as their primary protein source. Pretty much everyone (unless they are a vegan or possibly lactose intolerant*) uses whey protein for the majority of their supplemental protein needs.
*Many people don’t realize that even if they are lactose intolerant, they can still use a whey protein isolate supplement because virtually all of the lactose has been filtered out.
Most of the people who use casein only use it as a pre-bedtime supplement because of its slower digesting properties. Knowing that it can provide valuable amino acids for a longer period of time while they are sleeping.
It’s kind of like a time-release medication in the fact that it helps keep your body in a positive nitrogen balance without having to wake up in the middle of the night to down another protein shake.
The case against casein
Although protein is responsible for many different processes in the body, let’s face it, most people who use a protein supplement are primarily interested in its muscle building and repair effects.
Compared to whey, casein protein has less of the essential amino acids (EAAs) including leucine, which is believed to be the key for initiating muscle protein synthesis (i.e., muscle building and repair)
And this, unfortunately, is where casein protein may fall short.
While it’s true that casein hydrolysate and caseinate protein are faster digesting than micellar casein, this is the one advantage (slow digesting) casein has over whey. However, because these faster-digesting proteins are derived from micellar casein, they still have significantly lower amounts of leucine for initiating muscle protein synthesis.
Is slow digestion even an advantage?
While casein digests slower and protein levels stay elevated longer (6-7 hours with micellar casein vs. 4 hours with whey), it has been discovered that both whey and casein are only able to increase muscle protein synthesis for the first 3-4 hours.
So even though your overall protein levels may stay elevated longer with micellar casein versus whey, at least from a muscle repair and building perspective, the muscle building and repair effects, are essentially the same either way.
In other words, if you’re like me you’ve probably been choking down weird tasting casein shakes for no reason.
The type and amount of protein matters, not timing
It turns out that it doesn’t matter if you consume protein right before bed or not. Research has shown that it’s far more important that you consume enough protein and a fast digesting protein (preferably whey, but also casein hydrolysate or caseinate) than worrying about when you consume it.
Having said that, I still think there is something to be said for spreading out your daily protein intake more evenly throughout the day (every 4-6 hours) rather than simply getting all of your protein in one or two large servings, not necessarily from a muscle building perspective, but as a way to better manage your hunger and blood sugar levels.
The bottom line…
If you haven’t eaten enough protein throughout the day, then having a casein shake (or any other type of protein snack or shake) before bed is probably worth it.
The overall amount of protein you consume each day matters more than when you eat it with the possible exception of a post-workout meal or protein shake.
It now appears that that the disadvantages of micellar casein protein (mediocre taste, inability to mix, and unusually thick consistency) may no longer be worth its ability to digest slowly and keep overall protein levels higher for longer.
Studies have shown that a faster-digesting protein source such as whey increases muscle protein synthesis (aka muscle building and repair) for just as long (3-4 hours) as micellar casein.
Finally, whey protein has been found to be more effective when it comes to muscle building and repair than other fast digesting proteins like casein hydrolysate and caseinate because whey protein contains a higher amount of the essential amino acids (EAAs) including leucine.
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Boirie Y, et al. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci U S A. 1997 Dec 23;94(26):14930-5.
Wang X, et al. Gastric digestion of milk protein ingredients: Study using an in vitro dynamic model. J Dairy Sci. 2018 Aug;101(8):6842-6852.
Res PT, et al. Protein ingestion before sleep improves postexercise overnight recovery. Med Sci Sports Exerc. 2012 Aug;44(8):1560-9.
Trommelen J, et al. Presleep dietary protein-derived amino acids are incorporated in myofibrillar protein during postexercise overnight recovery. Am J Physiol Endocrinol Metab. 2018 May 1;314(5)