Whey protein concentrate mixed beverages and plasma amino acid response in young males

Whey protein isolate (WPI) and whey protein hydrolysate (WPH) contains more protein than whey protein concentrate. However, to achieve a better taste, most commercial products mix WPI and WPH with whey protein concentrate (WPC). This study aimed to compare postprandial blood amino acids following ingestion of three beverages: WPImixed with WPC (WPI-mixed), WPH-mixed with WPI (WPH-mixed), and placebo. A total of ten healthy men aged between 18 and 30, who regularly engaged in exercise training, were recruited as participants. They each received 350 mL of each beverage on separate days and 6-day apart. Concentrations of plasma essential amino acids (EAA), branched-chain amino acids (BCAA), and leucine (Leu) were measured in blood samples taken from participants every 15 mins for 2 hrs. Plasma concentrations of EAA, BCAA, and Leu increased after ingestion of the WPI-mixed and WPH-mixed beverages versus the placebo beverage (P<0.05). Plasma EAA did not differ between WPI- mixed and WPmixed trials. In contrast, plasma concentrations of BCAA after WPI-mixed were higher than after WPH-mixed at 30 mins. The same was observed for Leu at 30 and 75 mins after ingestion. The higher plasma BCAA and Leu in the WPI-mixed trial versus the WPHmixed trial may have been due to the presence of short-chain peptides, as bioactive peptides, in WPH-mixed, which were absorbed. In conclusion, there was no difference in plasma EAA, but plasma concentrations of leucine and BCAA were higher in the WPImixed trial than WPH-mixed trial. Therefore, future research should investigate bioactive peptides along with plasma amino acids.