Dairy Protein Shoot-Out: Intact Casein, Casein Hydrolysate, or Whey, What's the Most Satiating Protein and Boosts Fatty Acid Oxidation Most Effectively? And What Does it Imply?

I doubt any of the shakes the subjects consumed looked that delicious!
If you click on "protein supplements" on the website of any Internet supplement vendor, it will be quite obvious that dairy proteins dominate the supplement market. For a good reason! They are easily digested, taste good and have a ton of research to back their superior efficacy as potent muscle builders (Hulmi. 2010).

If you look closer, you will realize that whey proteins are mostly marketed as fast-digesting post-workout muscle builders, while casein proteins, which have a much lower market-share, are said to be slow digesting or even "time-released" proteins that promote long-lasting anabolism and satiety.
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If you've been around for quite some time, you will know that this is generally true, but the cheap caseinates (calcium or sodium), or casein hydrolysates are not exactly "slow" digesting.

Against that background the results of a recent study by scientists from the University of Copenhagen, the National Institute of Nutrition and Seafood Research in Bergen, Norway, and the Bispebjerg Hospital in Copenhagen could be particularly enlightening, because they could help us determine the "best protein" for particular purposes.

In said study, Line Q. Bendtsen and her co-workers compared the effects of hydrolysed casein, intact casein (calcium caseinate) and intact whey on energy expenditure (EE) and appetite regulation in order to find out, whether and how the amino acid composition and the rate of absorption affect these parameters.
"On the basis of the expected differences in absorption rates, we hypothesised that whey and hydrolysed casein would be more satiating and have a greater effect on EE shortly after protein consumption, whereas intact casein would be more satiating and have a greater thermogenic effect several hours after protein consumption." (Bendtsen. 2014)
In addition, the scientists hypothesized that whey would have a more satiating effect than hydrolysed casein due to its higher protein quality. Now, this is obviously something that would go against the previously formulated general rule of thumb that casein (no matter which type) was the most satiating dairy protein... but hey, we'll see.
We're not talking about lean athletes, here: As a SuppVersity Reader you know that science can be a bitch and getting financial support for your research usually requires using overweight or older subjects (who cares about young men and women who want to look good naked ;-). It will thus not come as a surprise that the subjects of the study at hand were thirty-six healthy, but overweight to moderately obese (BMI: 27 – 35 kg/m²) men and women aged 22 –40 years and thus not exactly representative of the average physical culturist. We will get back to the potential implications in the bottom line, but I wanted to point this out right away, for you to be able to put the study outcomes into the right perspective.
After the "bad news" in the red box, there is yet also "good news" which is the fact that the researchers used a "metabolic chamber" and thus a pretty accurate method to determine the exact effects on energy expenditure and fatty acid oxidation in response to the ingestion of ~30g (3g/1MJ energy intake) of supplemental protein (HC, IW or IC) in liquid / shake form. Each of the shakes the participants ingested on three seperate conditions contained 26 E% [energy percent] from protein, where hydrolized casein (HC), intact whey (IW) and intact casein (IC) contributed to 22.3% of the total energy in the respective shakes.

Table 1: Amino acid composition of hydrolysed casein (HC), intact casein (IC) and intact whey (IW) - Single free amino acids (Leu, Phe, Pro, Trp and Tyr) were added to HC to match the amino acid composition of IC (Bendtsen. 2014).
Table 1 summarizes the exact amino acid composition of the three shakes on a milligram per gram base. As you would have expected the whey protein shake contained a significantly higher amount of BCAAs (leucine, isoleucine, valine), but lower amounts of glutamic acid / glutamine, arginine and phenylalanine compared to the two casein proteins.

To assess the appetite of the subjects who received identical diets on day 1 of all three occasions (breakfast 26E% from protein, 50E% from CHO and 24E% from fat | lunch 18E% protein, 57E% CHO and 25E% fat | dinner 17E% protein, 58E% CHO and 25E% fat) and had ad libitum access to water, the scientist used a classic visual analogue scale.
So, what's the best protein then? There is no single best protein, but as I have outlined in previous articles, the combination of whey and micellar casein at ratios of 30:10 and 10:30 mark the extremes you can use to induce a pro-anabolic state of hyperaminoacidemia post-workout (immediate sustained elevations of amino acids) and pre-bed (long-lasting elevation of amino acids), respectively | learn more and even more about the "ideal" protein mix.
In addition, the ad libitum intake on the lunch the subjects were served on day two (spaghetti Bolognese | 15 E% from protein, 55 E% from CHO and 30 E% from fat) after a protein shake only breakfast was recorded as a measure of the real-world relevance of potentially differential effects of the three types of protein on appetite ratings.
Figure 1: Experimental design. All twenty-four subjects made three visits during the study period (Bendtsen. 2014)
I know that's quite complicated, but I guess the graphical overview in Figure 1 is going to help you to understand the exact procedure and timing. Right? Ok, then let's take a look at the results:
Figure 2: .Substrate oxidation during daytime (A) and after the breakfast meal (B) on day 1 (Bendtsen. 2014).
  • There was no differences in 24 h and postprandial energy expenditure or appetite regulation.
  • The estimated lipid oxidation (based on the respiratory quotient (RQ) that was measured in the metabolic chamber) was found to be increased after consumption of intact whey (IW) and hydrolyzed casein (HC) during daytime (P < 0.014), but not after the ingestion of intact casein (IC).
  • The concentration of non-esterified fatty acids (NEFA) in the blood of the subjects was found to be higher after consumption of intact whey than after consumption of either form of casein (P < 0.01). 
  • The concentrations of insulin or glucagon-like peptide 1 (GLP1 | learn more) were identical in all three conditions.
In other words, the effects on energy expenditure and appetite regulation do not differ significantly between the three types of protein. If anything, the "fatty acid oxidation advantage" of whey may be something to keep in mind - specifically, if you don't depend on the long-lasting hyperaminoacidemia (elevated and thus pro-anabolic amino acid levels) in response to the ingestion of intact casein.
There is another "hidden" problem: The "intact" casein used in the study is not intact. It's Miprodan (R) a calcium caseinate and thus a fast digesting, some would say "inferior" form of casein (compared to micellar casein). It's thus not surprising that there were no differences in the insulin response to whey and no wonder that the "regular" casein placed last in the comparison - another good reason not to overrate the results of the study at hand.
Bottom line: Overall the differences are probably too small to use them as a basis for your decision for or against a specific form of protein. If you look at the graphs in Figure 2, the most important message for the average gymrat probably is that the recently hyped casein hydrolysates are probably not worth it. With an inferior amino acid composition (compared to whey) and similar fast absorption kinetics as intact whey isolates, there is no real reason to chose them over the alpha male among dairy proteins: Whey!

It is furthermore unlikely that having normal-weight or athletic subjects would have changed the results much. As you've learned in a recent SuppVersity Article, the thermogenic effect in response to food is blunted in overweight / obese individuals, but that's a disadvantage, all three forms of protein had to deal with. It's thus unlikely that using lean subjects would have had a major effect on the overall (allegedly rather disappointing) outcome of the study | Comment on Facebook!
  • Bendsen et al. "Effects of hydrolysed casein, intact casein and intact whey protein on energy expenditure and appetite regulation: a randomised, controlled, cross-over study." British Journal of Nutrition (2014). Ahead of Print.
  • Hulmi, Juha J., Christopher M. Lockwood, and Jeffrey R. Stout. "Review Effect of protein/essential amino acids and resistance training on skeletal muscle hypertrophy: A case for whey protein." (2010).
Disclaimer:The information provided on this website is for informational purposes only. It is by no means intended as professional medical advice. Do not use any of the agents or freely available dietary supplements mentioned on this website without further consultation with your medical practitioner.