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Protein hydrolyzate

Protein is by all standards the most important nutrient when it comes to bodybuilding and muscular adaptations. The body will protect protein better than fat or carbohydrates during periods of high stress, which shows how important protein is. However, not all proteins are created equal. Meat protein has a higher value than most plant proteins because it is a more complete protein. Whey protein differs from casein in that whey protein is digested faster than casein and therefore provides higher amino acid levels over a shorter period of time. Hydrolyzed protein has attracted a lot of attention recently, but is all this attention justified?

Hydrolyzed protein

Hydrolyzed protein is protein that has undergone a process of hydrolysis. Whole proteins are quite large molecules that the body cannot use except under very specific circumstances. In order for whole proteins to be used by the body, these complex protein molecules must first be broken down into smaller molecules. In order to be absorbed by the body, protein must be in the form of either di- or tripeptides or free amino acids. The hydrolysis of proteins does the work for the body and breaks down whole proteins into smaller peptides including di- and tripeptides. In theory, this should mean that hydrolyzed protein can be absorbed by the body faster than intact protein and provide quicker access to the protein needed to build muscle mass. Numerous studies (2,3) have shown that this is indeed the case. In these studies, the rate of protein synthesis was also higher when hydrolyzed protein was used than when intact protein was used. Due to the faster absorption compared to intact proteins, the use of protein hydrolysates, and hydrolyzed whey protein in particular, can make the most of the critical time window around training by providing muscles with the amino acids needed for muscle adaptations more quickly (4).

Hydrolyzed protein compared to free amino acids

Since the body can absorb di- and tripeptides just as well as free amino acids, wouldn't it be okay to just use free amino acids? On a physiological basis, studies have shown that di- and tripeptides are absorbed more easily and at a higher rate than free amino acids (2,5). This is due to the fact that di- and tripeptides use a different transport system to enter the bloodstream. The presence of a large amount of free amino acids, on the other hand, leads to competition for the free amino acid transporters that transport these amino acids from the digestive tract into the bloodstream, resulting in a delay in the delivery of free amino acids to structures of the body including muscle. The absorption of free amino acids is also controlled by the sodium levels in the body and the acidity of the environment in the digestive tract. This does not apply to the absorption of di- and tripeptides. Other studies have observed higher protein retention in the body when using peptides than when using free amino acids (6).

What other benefits does hydrolyzed protein have?

As mentioned above, hydrolyzed protein is absorbed faster by the body than intact protein and free amino acids. This means that the body is able to use these proteins more quickly as they are more readily available. Hydrolyzed peptides are also able to increase nitrogen retention more compared to intact proteins (7) and free amino acids (8). Higher nitrogen retention means a continuous positive nitrogen balance, which is a key factor in promoting an anabolic environment in the body. Even though the studies that showed these qualities of hydrolyzed protein were animal studies, these results should be transferable to humans since the transport methods for peptides and proteins are the same in humans and animals. To satisfy the critics, I would like to take a closer look at some of the effects of hydrolyzed proteins in humans. One study (9) showed that the consumption of hydrolyzed whey protein led to better recovery after exhaustive eccentric training compared to non-hydrolyzed whey protein isolate. Two other studies (10, 11) were able to show that hydrolyzed protein with carbohydrate was able to increase insulin levels by almost 100% more than carbohydrate alone. Insulin is an amazing anabolic hormone and is important during training and recovery to transport glycogen into the muscles.

Other studies have shown that hydrolyzed protein is effective in promoting and enhancing gains in skeletal muscle mass (1), improving strength gains (13) and stimulating protein synthesis (14) during exercise. In addition, protein hydrolysates may also be beneficial for young children. Infants fed exclusively hydrolyzed protein instead of cow's milk formulas showed normal weight gain. Increased weight gain in the early years of life increases the risk of conditions such as obesity and diabetes later in life. The best option will always be breast milk, but if this is not an option, a formula with hydrolyzed protein may prove to be better and less allergenic.

Protein quality for bodybuilders

Having shown the benefits of hydrolyzed protein, the next question is how to choose the right hydrolyzed protein for your individual goals. The degree of hydrolysis is an important factor to consider. The fact is that hydrolysis simply creates smaller proteins. These can be dipeptides, tripeptides or larger peptides. A good hydrolyzed protein should contain a high proportion of dipeptides and tripeptides, as these proteins are more easily absorbed by the body. Many supplement manufacturers use fillers to increase the volume of their product, which decreases the percentage of di- and tripeptides.

The method of hydrolysis is also an important factor to consider. Hydrolysis of protein can be accomplished either by using a strong acid or base or by using enzymes. Enzymatic hydrolysis is better when it comes to maintaining the amino acid profile of the product, as hydrolysis using acid usually oxidizes key amino acids, lowering the protein quality and biological value of the final product (15). Unfortunately, most supplement companies do not specify the process by which the protein hydrolysate was produced. It may therefore be useful to check with the manufacturer before purchasing such a product.

Conclusion

Even though hydrolyzed protein is absorbed faster than free amino acids and intact proteins, the effects of this quality of hydrolyzed protein on muscle protein synthesis and muscle adaptation, as well as on training and athletic performance, have not yet been conclusively clarified and further studies are required. The fact is that rapidly digestible protein such as whey protein is digested and absorbed within 45 to 60 minutes, which is still within the critical post-workout time window in which protein has the greatest ability to stimulate positive muscular adaptations including muscle growth. Both protein supplements (and especially whey protein) and free amino acids are already absorbed quite quickly anyway. Whether the additional time advantage that hydrolyzed protein provides actually has long-term benefits for healthy people is not yet clear. Many studies suggesting benefits of hydrolyzed protein focus on protein in general rather than directly comparing hydrolyzed and non-hydrolyzed protein. Further research comparing hydrolyzed and non-hydrolyzed protein and different types of hydrolyzed protein will help to provide a better overall picture. As things stand, hydrolyzed protein with high levels of di- and tripeptides could be a useful addition to regular protein powders and could also be combined with other supplements to help get the most out of training.

References

  1. Koopman R, Crombach N, Gijsen AP, Walrand S, Fauquant J, Kies AK, Lemosquet S, Saris WH, Boirie Y, van Loon LJ. 'Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein.' Am J Clin Nutr. 2009 Jul;90(1):106-15. Epub 2009 May 27.
  2. Di Pasquale, M.G. 'Amino acids and proteins for the athlete: The anabolic edge.' (1997) Boca Raton, FL: CRC Press.
  3. Meredith JW, Ditesheim JA, Zaloga GP. 'Visceral protein levels in trauma patients are greater with peptide diet than with intact protein diet.' J Trauma. 1990 Jul;30(7):825-8; discussion 828-9.
  4. Tipton KD, Rasmussen BB, Miller SL, et al. Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise.Am J Physiol Endocrinol Metab. Aug 2001;281(2):E197 - 206.
  5. Adibi SA. 'Intestinal phase of protein assimilation in man.' Am J Clin Nutr. 1976 Feb;29(2):205-15.
  6. Poullain MG, Cezard JP, Roger L, Mendy F. 'Effect of whey proteins, their oligopeptide hydrolysates and free amino acid mixtures on growth and nitrogen retention in fed and starved rats.' JPEN J Parenter Enteral Nutr. 1989 Jul-Aug;13(4):382-6.
  7. Boza JJ, Martínez-Augustin O, Baró L, Suarez MD, Gil A. 'Protein v. enzymic protein hydrolysates. Nitrogen utilization in starved rats.' Br J Nutr. 1995 Jan;73(1):65-71.
  8. Yamamoto S, Korin T, Anzai M, Wang MF, Hosoi A, Abe A, Kishi K, Inoue G. 'Comparative effects of protein, protein hydrolysate and amino acid diets on nitrogen metabolism of normal, protein-deficient, gastrectomized or hepatectomized rats.' J Nutr. 1985 Nov;115(11):1436-46.
  9. Buckley JD, Thomson RL, Coates AM, Howe PR, DeNichilo MO, Rowney MK. 'Supplementation with a whey protein hydrolysate enhances recovery of muscle force-generating capacity following eccentric exercise.' J Sci Med Sport. 2010 Jan;13(1):178-81. epub 2008 Sep 2.
  10. van Loon LJ, Saris WH, Verhagen H, Wagenmakers AJ. 'Plasma insulin responses after ingestion of different amino acid or protein mixtures with carbohydrate.' Am J Clin Nutr. 2000 Jul;72(1):96-105.
  11. van Loon LJ, Kruijshoop M, Verhagen H, Saris WH, Wagenmakers AJ. 'Ingestion of protein hydrolysate and amino acid-carbohydrate mixtures increases postexercise plasma insulin responses in men.' J Nutr. Oct 2000;130(10):2508 - 2513.
  12. Manninen, AH. 'Protein hydrolysates in sports and exercise: A brief review.' Journ. Of Sports Sci. And Med. (2004) 3, 60-63
  13. Cribb PJ, Williams AD, Carey MF, Hayes A. 'The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine.' Int J Sport Nutr Exerc Metab. 2006 Oct;16(5):494-509.
  14. Beelen M, Koopman R, Gijsen AP, Vandereyt H, Kies AK, Kuipers H, Saris WH, van Loon LJ. 'Protein coingestion stimulates muscle protein synthesis during resistance-type exercise.' Am J Physiol Endocrinol Metab. 2008 Jul;295(1):E70-7. Epub 2008 Apr 22.
  15. Bucci, L.R. and Unlu, L. 'Protein and amino acid supplements in exercise and sport. In: Energy yielding macronutrients and energy metabolism in sports nutrition.' (2000) Eds: Wolinsky, I., Driskell, J.A. Boca Raton, FL: CRC Press. 191-212.