represent two common sources of protein.
Both have been described as fast acting because they are digested and absorbed faster than
protein. However, there have been few studies that directly compared the absorption of whey and soy in the same subjects. Protein hydrolysates are pre-digested forms of proteins and therefore should result in faster appearance of
into the blood compared to the intact protein. However, few studies have tested this for whey and soy. Japanese researchers had healthy subjects consume 4 different protein meals each containing 12.5 grams protein with no carbohydrate. The meals were intact whey, hydrolyzed whey, intact soy, and hydrolyzed soy. Blood samples were collected for 2 hours after ingestion to determine amino acids and insulin levels. There was a more rapid and greater increase in total amino acids following whey than soy. This was also the case for total essential and
branched chain amino acids
. For both whey and soy, the hydrolyzed forms of protein resulted in more rapid increases in amino acids than the intact protein. The same pattern was seen for plasma insulin with whey showing a greater response than soy and hydrolyzed protein showing a greater effect than intact protein. These findings highlight the unique effects of whey hydrolysates as evidenced by very fast absorption, rapid increases in plasma amino acid levels, and higher insulin responses compared to other proteins.
is a high quality protein source that uses whey hydrolysates to rapidly elevate plasma amino acids and insulin for
.Morifuji M, Ishizaka M, Baba S, Fukuda K, Matsumoto H, Koga J, Kanegae M, Higuchi M. Comparison of Different Sources and Degrees of Hydrolysis of Dietary Protein: Effect on Plasma Amino Acids, Dipeptides, and Insulin Responses in Human Subjects. J Agric Food Chem. 2010 Jul 8.