WHEY PROTEIN IS MORE ANABOLIC THAN ESSENTIAL AMINO ACIDS!

For the past year, researchers have been going back and forth debating which was more anabolic…whey protein or essential amino acids (EAAs). A few months ago, it seemed that EAA was the winner; in a previous study, researchers administered either 15 grams of whey protein or 15 grams of EAA to elderly participants. They found that ingestion of 15 grams of EAA more than doubles muscle protein balance in elderly persons when compared to that of the ingestion of 15 grams of whey, which would support a greater importance of the EAA (as opposed to whey) in improving muscle protein synthesis in elderly persons. EAA seemed like the more anabolic supplement, but the researchers went back and examined the data and found that 15 grams of whey protein contained only 7 grams of EAA! So, the study did not have the exact same EAA mix for whey protein compared to the EAA mix (7 grams of EAA found in whey compared to 15 grams of EAA).

The same research group went back and administered a dose-to-dose comparison and administered 15 grams of whey, which contains roughly 7 grams of EAA and compared it to an equivalent EAA dose (~6.72 grams of EAA). To the researchers’ surprise, whey protein resulted in greater anabolic effects than EAA when compared dose per dose. The study reported that EAAs are not solely responsible for the anabolic properties of whey protein. The researchers concluded that whey protein (whole consumption) is greater than the sum of its parts (EAA), or effects beyond that of just the amino acid content. So what ingredient in whey protein could be enhancing anabolic actions? It is interesting that the two dosages each had the exact same dosage of leucine, so there was something else in whey protein causing the greater anabolic effect. The researchers hypothesized that the increase in the plasma concentration of the amino acid cysteine from whey protein, which has previously been found to augment muscle protein anabolism, may have enhanced muscle protein synthesis. Whey protein resulted in a greater insulin response than EAA, which also could have augmented the anabolic actions of whey protein. The researchers explained that whey protein is a potent stimulator of Gastric Inhibitory Polypeptide (GIP), also known as the glucose-dependent insulinotropic peptide. It is now believed that the function of GIP is to induce insulin secretion. Relative to that, it is known that whey protein is a strong stimulator of GIP secretagogue, possibly through bioactive peptides present in whey or formed during its digestion, and that the plasma GIP concentration is greater after ingestion of intact protein than a similar amount of protein in the form of free amino acids. The researchers also commented that whey protein is inexpensive and also has additional health benefits that can’t be found in EAA. For example, cysteine-supported glutathione synthesis is implicated in protection against oxidative stress, whereas beta-lactoglobulin and alpha-lactalbumin are major whey proteins modulating immune function. The researchers concluded that the anabolic actions of whey go beyond just EAAs and the whole (whey protein) are greater than the sum of parts (EAA).

Key Points:

• On a dose-per-dose base, whey protein was more anabolic than EAA.
• Whey protein resulted in a greater insulin response than EAA, possibly through increases in GIP.
• Cysteine found in whey has anabolic actions not found in EAA.
• Whey has potent immune-stimulating properties not found in EAA.

Ø     Christos S. Katsanos, David L. Chinkes, Douglas Paddon-Jones, Xiao-jun Zhang, Asle Aarsland, Robert R. Wolfe. Whey protein ingestion in elderly persons results in greater muscle protein accrual than ingestion of its constituent essential amino acid content. Volume 28, 2008. Pages 651-65.