Post by Greentea on Jan 6, 2005 9:04:43 GMT -5
Nutri-ForeFronT said:
PART IIWhey¡¦s Frequently Touted ¡¥Virtue¡¦ Is Actually Its Downfall
Again, whey is often said to be superior to casein because of its ability to deliver amino acids into your bloodstream rapidly. Yet this is not a virtue; rather, it¡¦s a weakness.
When it comes to amino acid absorption, haste makes waste. The rate at which amino acids are broken down, or catabolized, is directly related to the level they achieve in the bloodstream (Reeds et al., 1992). The faster the amino acids provided by the protein you eat exit your gut and enter your bloodstream, and the higher the blood levels they attain, the more they get wasted.
The higher your blood levels of the amino acid leucine, for instance, the greater its rate of catabolism. Eating whey protein drives blood leucine levels very high (Boirie et al., 1997). Not surprisingly, this results in a corresponding loss of leucine through catabolism (Boirie et al., 1997). And as indicated above, whey generates more urea ¡Vthe waste product of amino acid breakdown¡X than casein.
Barnyards, Hair and Feathers
There¡¦s another longstanding issue we need to clear up. To do so, let¡¦s go visit the animals in the barnyard. A barnyard filled with cows, sheep, dogs, rats, cats, chickens.
What do all these creatures have in common? And what the heck has this got to do with bodybuilding and whey protein supplements?
Plenty, in fact. To answer the first question, unlike you and me, all of above barnyard creatures are covered in either hair or feathers. Hair and feathers are made of the protein known as keratin, which is rich in the sulfur-containing amino acid, cysteine (found in keratin in its oxidized form, cystine).
Cysteine can be produced in animals from another sulfur-containing amino acid, methionine. Since whey has more sulfur-containing amino acids than casein, hair- or feather-covered animals require less whey than casein to achieve protein balance. But this advantage will clearly does not apply to humans, a relatively hairless and featherless species, as the Boirie et al. study would seem to agree.
Nevertheless, studies performed over a half-century ago on hair- or feather-covered animals which demonstrated the ¡¥superiority¡¦ of whey over casein, have been used as marketing ¡¥support¡¦ by companies selling whey protein supplements.
Back in 1947, Tomarelli and Bernhart demonstrated that feeding whey protein (hydrolyzed ƒÑ-lactalbumin, more specifically) to rats produced greater protein retention than did casein (e.g., Tomarelli and Bernhart, 1947). The rats required about 70% more casein nitrogen than whey nitrogen per day to maintain nitrogen balance. These results are consistent with a number of similar studies performed around this time. The trouble is that these studies, too, were performed on animals covered either in hair or feathers ¡Vrats, dogs, and chickens, for instance. Thus, these data are applicable to barnyard animals, but not to humans.
Methionine is an essential sulfur-containing amino acid. As I noted earlier, it can be used by your body to synthesize cysteine (as in the production of keratin). Rats, which were commonly used in early studies to determine the frequently-quoted ¡§Biological Value¡¨ (BV) of various dietary proteins, have a methionine requirement that is around 50% greater than you or I (Sarwar et al., 1989). This contributes to the lower BV numbers reported for dietary proteins containing relatively less methionine when such proteins are fed to rats, as compared to humans (Bricker and Mitchell, 1947).
Johnson et al. (1946) relate: ¡§In the case of the human experiments, then, it would be concluded that the methionine requirement is lower, and is not a limiting factor in the attainment of nitrogen excretion in these experiments, or that the requirement is met by the body protein breakdown plus any dietary protein¡K.Since the addition of further methionine did not reduce the nitrogen excretion on the low protein diet, it can be concluded that no more methionine is required under these circumstances than that represented by the entire sulfur excretion, or 1.4 gm methionine per day for our average subject¡K.the present experiments suggest that the human body is not limited in its ability to conserve nitrogen by the need to meet a methionine requirement.¡¨
Cox et al. (1946) clarify even further: ¡§comparison of the nitrogen retention of a casein hydrolysate with and without added methionine in rats, dogs and man has clearly shown a striking species difference. The addition of methionine increased the rate of growth in rats and the magnitude of nitrogen retention in dogs. In man, however, it was without effect on nitrogen retention¡KAn explanation for this difference does not seem difficult, based on the fact that the rat and dog are covered with hair, and that man is not. Since hair contains large amounts of cystine, it is reasonable to suppose that the requirement for this amino acid (or methionine) is considerably greater than that of man¡KThe generally recognized nutritive difference between casein [lower in cystine] and lactalbumin [higher in cystine] is valid for the rat and for the dog, but not for man.¡¨
CONCLUSION
As the above evidence hopefully makes clear, the claim that whey is superior to casein for building muscle is simply not valid.
The study performed by Boirie et al. (1997) found evidence to suggest that casein is superior to whey for promoting a positive protein balance. But that doesn¡¦t necessarily mean it will build muscle any better than whey, or a chicken breast meat, for that matter.
Protein supplement ads and articles frequently cite Biological Value (BV) numbers (e.g., 104 and sometimes even higher) for whey as evidence for its superiority; however, these BV values were derived from studies on hair- and feather-covered animals that require more of the sulfur-containing amino acids that whey is rich in. These results do NOT apply to humans.
REFERENCES:
Boirie Y, Dangin M, Gachon P, Vasson M-P, Maoubois J-L, Beaufrere B (1997). Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci USA, 94: 14930-14935.
Bricker ML, Mitchell HH (1947). The protein requirements of the adult rat in terms of the protein contained in egg, milk and soy flour. J Nutr, 33: 491-504.
Cox WM JR, Mueller AJ, Elman R, Albanese AA, Kemmerer KS, Barton RW, Holt LE Jr (1946). Nitrogen retention studies on rats, dogs and man: The effect of adding methionine to an enzymic hydrolysate. J Nutr, 32: 437-457.
Demling RH, DeSanti L (2000). Effect of a hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers. Ann Nutr Metab, 44: 21-29.
Fereday A, Gibson NR, Cox M, Pacy PJ, Millward DJ (1998). Variation in the apparent sensitivity of the insulin mediated inhibition of proteolysis to amino acid supply determines the efficiency of protein utilization. Clin Sci, 95: 725.
Garlick PJ, McNurlan MA, Patlak CS (1999). Adaptation of protein metabolism in relation to limits to high dietary protein intake. Eur J Clin Nutr, 53: S34.
Johnson RM, Deuel HJ, Morehouse MG, Mehl JW (1946). The effect of methionine upon the urinary nitrogen in men at normal and low levels of protein intake. J Nutr, 32: 371-387.
Melville S, McNurlan MA, McHardy KC, Broom J, Milne E, Calder AG, Garlick PJ (1989). The role of degradation in the acute control of protein balance in adult man: Failure of feeding to stimulate protein synthesis as assessed by L-[1-13C]leucine infusion. Metabolism, 38: 248-255.
Price GM, Halliday D, Pacy PJ, Quevedo RM, Millward DJ (1994). Nitrogen homeostasis in man: 1. Influence of protein intake on the amplitude of diurnal cycling of body nitrogen. Clin Sci, 86: 91-102.
Reeds PJ, Fiorotto ML, Davis TA (1992). Nutrition partitioning. An overview. In: Bray GA, Ryan DH, eds. The Science of Food Regulation. Volume 2. Baton Rouge: Louisiana State University. p. 103-120.
Sarwar G, Peace RW, Botting HG, Brule D (1989). Relationship between amino acid scores and protein quality indices based on rat growth. Plant Foods Hum Nutr, 39: 33-44.
Shigemitsu K, Tsjuinutsa Y, Miyake H, Hidayat S, Tanaka N, Hara K, Yonezawa K (1999). Structural requirement of leucine for activation of p70 S6 kinase. FEBS Lett, 447: 303.
Tomarelli RM, Bernhart FW (1947). A bioassay for protein and protein digests. J Nutr, 33: 263-272.
Incidently, NFFT already knew the benefits of Casein (or Micellar form) when we first came onto the sports nutrition scene in 1999. We also acknowledged that whey is a great protein in its on right. We were the first to introduce our BEST seller Isomatrix (original), which had a combination of whey isolate, micellar casein, egg yolk isolate, soy isolate, back in 2000 that had people talking! No one single protein source is superior as each has their good points as well as bad. But combining the top end processing system of deriving these different proteins will result in the BEST protein blend available.
Great one