Written by justis berg
20 April 2011

Supplement Performance

By Robbie Durand, M.A.

Casein Hydrosylates Increase Protein Synthesis More Than Casein

Many people have been talking about whey protein hydrosylates, but now there are casein protein hydrosylates. Casein has a long-term effect in suppressing protein breakdown, which your body needs to sustain for 6 to 8 hours during sleep without food. In fact, a total release of amino acids in the bloodstream can last as long as 7 hours after ingestion of casein protein! Casein hydrosylate is a preparation made from the milk protein casein, which is hydrolyzed to break it down into its constituent amino acids.

The ingestion of a protein hydrosylate, as opposed to its intact proteins, has been proposed to facilitate protein digestion and absorption, increase plasma amino acid availability, and thereby increase muscle protein synthesis. A more rapid increase in circulating amino acid concentrations has previously been reported after the ingestion of whey protein hydrosylate, compared to regular whey protein.1 Whey protein hydrosylates have been shown to be superior to whey protein peptides for increasing protein synthesis, but what about casein hydrosylates?

Researchers from the Netherlands examined the effect of casein versus casein hydrosylates on protein synthesis. Subjects received a beverage containing 35 grams of casein or casein hydrosylates. Researchers measured insulin, protein synthesis and protein breakdown in two groups of men.

At the end of the study, researchers reported that ingestion of casein hydrosylate— as opposed to casein— increases the rate of plasma amino acid availability, and tends to increase muscle protein synthesis in humans.8

Researchers also observed a greater increase in plasma amino acid concentrations after ingestion of hydrolyzed casein, compared to its intact protein casein hydrosylates. This study supports an earlier study showing higher peak plasma amino acid concentrations after administration of hydrolyzed casein, compared to its intact protein (i.e., casein).2 The exogenous amino acid phenylalanine’s appearance rate increased to a greater extent after ingestion of the casein hydrosylate, compared to casein protein. During the 6-hour post-feeding period, 25 percent more dietary phenylalanine appeared in the circulation after ingestion of the hydrosylate, compared to the intact protein.

Consequently, this study shows that a hydrolyzed protein is more rapidly digested and absorbed, which results in a greater amino acid delivery. Thus, hydrolyzed casein provides a protein source that is more rapidly digested and absorbed in humans, which improves plasma amino acid availability.

 

Casein Hydrosylates Are Also More Anti-Catabolic

Another interesting finding was that protein breakdown rates tended to be further lowered after ingestion of protein hydrosylate, compared to casein protein, which may be due to the greater insulin release that was observed after protein hydrosylate ingestion.

Elevated insulin concentrations have been shown to inhibit protein breakdown.3,4,5 In contrast, it has been suggested that increases in circulating insulin concentrations are instrumental in stimulating skeletal muscle blood flow— thereby augmenting amino acid delivery to the muscle.6,7 Consequently, both the increase in plasma amino acid availability and the greater plasma insulin response after hydrolyzed casein— compared to casein ingestion (during the initial 3-hour post-feeding period)— might enhance postprandial muscle protein anabolism.

This result indicates that the intake of a casein hydrosylate, as opposed to casein, further stimulates the anabolic response to food intake mainly by inhibiting whole-body protein breakdown.

 

References:

1. Calbet JA, Holst JJ. Gastric emptying, gastric secretion and enterogastrone response after administration of milk proteins or their peptide hydrosylates in humans. Eur J Nutr, 2004;43:127-39.

2. Calbet JA, Holst JJ. Gastric emptying, gastric secretion and enterogastrone response after administration of milk proteins or their peptide hydrosylates in humans. Eur J Nutr, 2004;43:127-39.

3. Gelfand RA, Barrett EJ. Effect of physiologic hyperinsulinemia on skeletal muscle protein synthesis and breakdown in man. J Clin Invest, 1987;80:1-6.

4. Biolo G, Williams BD, Fleming RY, Wolfe RR. Insulin action on muscle protein kinetics and amino acid transport during recovery after resistance exercise. Diabetes, 1999;48:949-57.

5. Fryburg DA, Jahn LA, Hill SA, Oliveras DM, Barrett EJ. Insulin and insulin-like growth factor-1 enhance human skeletal muscle protein anabolism during hyperaminoacidemia by different mechanisms. J Clin Invest, 1995;96:1722-9.

6. Fujita S, Rasmussen BB, Cadenas JG, Grady JJ, Volpi E. The effect of insulin on human skeletal muscle protein synthesis is modulated by insulin-induced changes in muscle blood flow and amino acid availability. Am J Physiol Endocrinol Metab, 2006;291:E745-54.

7. Rasmussen BB, Fujita S, Wolfe RR, et al. Insulin resistance of muscle protein metabolism in aging. FASEB J, 2006;20:768-9.

8. 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 hydrosylate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein. Am J Clin Nutr, 2009.