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Whey or Casein?
How to Use Various Proteins for Maximal Results
By
Jeff Stout, PhD
Protein ?Ethe building blocks
The word protein is derived from the Greek word meaning "of prime importance." And suffice it to say that protein is pretty darn important to the human body. Enzymes, antibodies, muscle tissue, red blood cells, organs, and many other structural and functional components of your body are comprised of proteins.
Although the primary function of protein is to provide the needed amino acids for maintaining an anabolic state, there are times when it may actually be used as a fuel source. This usually occurs when you’re in a carbohydrate-depleted state (ex. on a low carb diet, exercising continuously for >2 hours). The RDA of 0.8 grams per kilogram body weight per day is much too low for athletes. Current research suggests that 1.5-2.0 grams per kilogram per day is better suited for athletes. If you happen to be metric-illiterate, that translates into 0.68 to 0.90 grams per pound of bodyweight. To be on the safe side, perhaps 1.0 grams of protein per pound of bodyweight is best.
Which proteins are best?
You want to eat a complete protein; one that has all of the essential amino acids. Incomplete proteins, such as from peanuts, do not contain all essential amino acids. But if you mix incomplete proteins (e.g., rice and beans), you can get all the essential amino acids. But they are not as well assimilated as protein from animal sources. In addition, we have fast and slow proteins. How can we take advantage of the properties of these special proteins? Like the glycemic index for carbs, the speed in which you absorb various amino acids dictates how well your body uses them. For instance, when you eat a large protein meal, you’ll get an initial high peak in blood levels of amino acids followed by a rapid decline. But if you take the same protein in a slow but continuous fashion (e.g., eat small meals throughout the day) you get a smaller, but more sustained increase in serum amino acids. And even though you may be eating the same quantity of the various amino acids, the time in which they’re delivered can have a profound effect on protein synthesis and breakdown. So which is better, a large quick rise followed by a quick drop? Or a slow rise that’s sustained for a longer period of time? The answer’s easy. Both.
In a study performed by French scientists, they examined the effects of casein and whey protein as a single meal ingested (dose = 0.45-0.61 grams protein per kg body weight) by normal healthy adults. They examined blood levels of amino acids for up to seven hours after consuming the protein meal. As expected, the whey protein group experienced a quick rise in blood levels of amino acids with a steady decline while the casein group showed a slow increase that was sustained for the seven hour period. Whole body protein breakdown decreased by 34% after casein ingestion but not with whey protein. On the other hand, protein synthesis increased by 68% in the whey protein group while the casein group increased by 31% (1).
So why the tremendous differences in protein metabolism? Whey protein is rapidly emptied from the stomach yet casein clots in the stomach. Casein’s absorption tends to be much slower. Although casein stimulated protein synthesis less than whey, it had a better effect on inhibiting protein breakdown. This was not due to differing insulin levels (i.e. insulin is a potent inhibitor of protein degradation) since blood levels were similar between the two meals. Interestingly, it may be that you need to maintain a minimal sustained level of blood amino acids in order to inhibit (support?) protein synthesis.
So which is better, casein or whey? Depends on your circumstances. If you are pressed for time and can only get in 2 or 3 meals a day, perhaps a combination of whey and casein will work. On the other hand, if you can eat multiple meals (5-6) throughout the day, it may be best to stick with whey protein. Also, whey protein contains subfractions of various peptides (i.e. small proteins) (e.g., alpha-lactalbumin, beta-lactoglobulin, immunoglobulins, and lactoferrin). Each of these subfractions may have health benefits.
1. 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.
How to Use Various Proteins for Maximal Results
By
Jeff Stout, PhD
Protein ?Ethe building blocks
The word protein is derived from the Greek word meaning "of prime importance." And suffice it to say that protein is pretty darn important to the human body. Enzymes, antibodies, muscle tissue, red blood cells, organs, and many other structural and functional components of your body are comprised of proteins.
Although the primary function of protein is to provide the needed amino acids for maintaining an anabolic state, there are times when it may actually be used as a fuel source. This usually occurs when you’re in a carbohydrate-depleted state (ex. on a low carb diet, exercising continuously for >2 hours). The RDA of 0.8 grams per kilogram body weight per day is much too low for athletes. Current research suggests that 1.5-2.0 grams per kilogram per day is better suited for athletes. If you happen to be metric-illiterate, that translates into 0.68 to 0.90 grams per pound of bodyweight. To be on the safe side, perhaps 1.0 grams of protein per pound of bodyweight is best.
Which proteins are best?
You want to eat a complete protein; one that has all of the essential amino acids. Incomplete proteins, such as from peanuts, do not contain all essential amino acids. But if you mix incomplete proteins (e.g., rice and beans), you can get all the essential amino acids. But they are not as well assimilated as protein from animal sources. In addition, we have fast and slow proteins. How can we take advantage of the properties of these special proteins? Like the glycemic index for carbs, the speed in which you absorb various amino acids dictates how well your body uses them. For instance, when you eat a large protein meal, you’ll get an initial high peak in blood levels of amino acids followed by a rapid decline. But if you take the same protein in a slow but continuous fashion (e.g., eat small meals throughout the day) you get a smaller, but more sustained increase in serum amino acids. And even though you may be eating the same quantity of the various amino acids, the time in which they’re delivered can have a profound effect on protein synthesis and breakdown. So which is better, a large quick rise followed by a quick drop? Or a slow rise that’s sustained for a longer period of time? The answer’s easy. Both.
In a study performed by French scientists, they examined the effects of casein and whey protein as a single meal ingested (dose = 0.45-0.61 grams protein per kg body weight) by normal healthy adults. They examined blood levels of amino acids for up to seven hours after consuming the protein meal. As expected, the whey protein group experienced a quick rise in blood levels of amino acids with a steady decline while the casein group showed a slow increase that was sustained for the seven hour period. Whole body protein breakdown decreased by 34% after casein ingestion but not with whey protein. On the other hand, protein synthesis increased by 68% in the whey protein group while the casein group increased by 31% (1).
So why the tremendous differences in protein metabolism? Whey protein is rapidly emptied from the stomach yet casein clots in the stomach. Casein’s absorption tends to be much slower. Although casein stimulated protein synthesis less than whey, it had a better effect on inhibiting protein breakdown. This was not due to differing insulin levels (i.e. insulin is a potent inhibitor of protein degradation) since blood levels were similar between the two meals. Interestingly, it may be that you need to maintain a minimal sustained level of blood amino acids in order to inhibit (support?) protein synthesis.
So which is better, casein or whey? Depends on your circumstances. If you are pressed for time and can only get in 2 or 3 meals a day, perhaps a combination of whey and casein will work. On the other hand, if you can eat multiple meals (5-6) throughout the day, it may be best to stick with whey protein. Also, whey protein contains subfractions of various peptides (i.e. small proteins) (e.g., alpha-lactalbumin, beta-lactoglobulin, immunoglobulins, and lactoferrin). Each of these subfractions may have health benefits.
1. 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.