While you may know about whey protein, what you may not know about is hydrolyzed protein, which is created by hydrolyzing, or pre-digesting, intact proteins into a mixture of amino acids and smaller proteins.
Some supplement manufacturers’ claim that the “pre-digestion” enhances bioavailability, thereby increasing muscle protein synthesis. Because of their supposed power, hydrolyzed protein can cost as much as 30% to 200% more than their conventional counterparts.
But is hydrolyzed protein worth the extra money? The research gives a definitive answer of “No”.
Whey is a “fast” protein, meaning it is digested quickly and absorbed, and its amino acids are rapidly delivered to the bloodstream and thus muscles. This has been demonstrated time and time again, most recently, by Burd and colleagues:1
Basically, what this study found is that the essential amino acids are higher when a person ingests whey (“fast” protein) as opposed to casein (“slow” protein). This higher concentration of essential acids is associated with higher muscle protein synthesis both at rest (“FED”) and after exercise (“EX-FED”).
This is one reason why ingesting protein before exercise may be superior to after; the spike in amino acids will occur exactly when blood flow to the exercising muscles is maximal, thereby directing the building blocks to where they are most needed.
Protein response is not due to bioavailability alone, which is important in terms of whether you should take hydrolyzed protein. While Koopman and colleagues2 show that the amino acid level is much higher with “fast” protein, the difference between “pre-digested” (hydrolyzed) protein and intact protein was negligible.
Thus, simply being a “fast” protein is not good enough. When comparing hydrolyzed whey and casein, Tang and colleagues3 show something very important about the difference between hydrolyzed whey and casein:
Compare that to the difference observed by Pennings and colleagues:4
What these studies show is that non-hydrolyzed whey is approximately twice as good as casein. This is the same difference between hydrolyzed whey and casein. So, the “pre-digested” whey is no better than intact whey.
The answer we’ve found in these studies is “No”. Koopman and Pennings show that hydrolyzing casein makes it a “fast” protein, but this doesn’t increase its ability to stimulate protein synthesis. The studies from Tang and Pennings show that whey is twice as good as casein regardless of whether or not it is hydrolyzed.
Is there just something magical about whey? Collectively, these data say “yes.” In other words, whey is better than both intact casein, a “slow” protein, and hydrolyzed casein, a “fast” protein.
Intact whey is already a “fast” protein, so how much faster could hydrolyzing make it? Not much. Should you spend more money on “pre-digested” protein? Our conclusion is that in terms of hydrolyzed protein: don’t believe the hype – whey has not been dethroned.