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Hydrolyzed pea protein, the new kid in the block that seems cooler. Is it really working to enhance absorption to the body?

Basic facts about protein hydrolysates

Amino acids are the building blocks of protein. Protein are classified into 4 structures: Primary consists of free floating amino acids, secondary pertains to the two-diemnsional folding of a polypeptide chain, tertiary refers to the overall three-dimensional arrangement of its polypeptide chain in space, quarternary refers to the structure of proteins which are themselves composed of two or more smaller protein chains. Protein hydrolysates are produced from purified protein sources by heating with acid or, preferably, addition of proteolytic enzymes, followed by purification procedures. The proteolytic enzymes cleave open the peptide links turning a peptide chain into smaller peptide. Each protein hydrolysate is a complex mixture of peptides of different chain length together with free amino acids.

Hydrolyzed protein vs. protein isolate?

There has not been any published clinical studies that competently investigate and validate the claims that hydrolysis of pea protein facilitates more efficient absorption into the body; perhaps due to the facts that pea protein is still relatively new compared to whey protein.

On another note, there have been a substantial number of studies conducted on whey protein showing that hydrolysis of whey protein does not result in enhanced absorption into the body, which was measured by three parameters: amino acid concentration in blood, rate of gastric emptying of ingested protein, and total urinary and fecal nitrogen.

 Amino acid concentration in blood 

A study by Farnfield et al. examined the plasma amino acid responses to intact whey protein isolate and hydrolyzed whey protein isolate [1]. After an overnight fast, their subjects consumed a 500 ml beverage containing 25 g of protein, and blood was taken at rest and then every 15 min for 2 h post ingestion. The authors reported, quite surprisingly, that intact whey protein results in a rapid absorption of amino acids into the blood compared with the hydrolyzed whey protein.

Rate of gastric emptying of ingested protein 

Another study by Power et al. used extensively hydrolyzed whey protein produced by a major whey protein hydrolysate manufacturer [2]. Sixteen healthy men ingested a 500 ml solution containing either 45 g of intact whey protein or whey protein hydrolysate. When analyzed over the 3 h period, the estimated rate of gastric emptying was not significantly altered by industrial hydrolysis of the protein. In addition, the rate of apperance of branched chain amino acids was not significantly altered by hydrolysis of whey protein.

Total urinary and fecal nitrogen 

A study by Moriarty et al. concluded that the molecular form of protein elicits no difference in nitrogen balance in healthy humans, which is an indicator of utilization of protein by human body [3].



[1] Farnfield MM, Trenerry C, Carey KA, Cameron-Smith D: Plasma amino acid response after ingestion of different whey protein fractions. Int J Food Sci Nutr 2008, 8:1-11.

[2] Power O, Hallihan A, Jakeman P: Human insulinotropic response to oral ingestion of native and hydrolysed whey protein. Amino Acids 2009, 37:333-9.

[3] Moriarty K, Hegarty J, Fairclough P, Kelly M, Clark M, Dawson A: Relative nutritional value of whole protein, hydrolysed protein and free amino acids in man. Gut 1985, 26:694-9.

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