Acute microbial protease supplementation increases net postprandial plasma amino acid concentrations after pea protein ingestion in healthy adults: a randomized, double-blind, placebo-controlled trial

Background Digestibility is a primary factor in determining the quality of dietary protein. Microbial protease supplementation may be a strategy for improving protein digestion and subsequent postprandial plasma amino acid availability. Objective To assess the effect of co-ingesting a microbial protease mixture with pea protein on postprandial plasma amino acid concentrations. Design A mixture of three microbial protease preparations (P3) was tested for proteolytic efficacy in an in vitro static simulation of gastrointestinal digestion. Subsequently, in a randomized, double-blind, placebo-controlled crossover trial, 24 healthy adults (27 ± 4 y; 12F, 12M) ingested 25 g pea protein isolate (20 g protein, 2.2 g fat) with either P3 or maltodextrin placebo (PLA). Blood samples were collected at baseline and throughout a 0‒5 h postprandial period and both the early (0–2 h) iAUC and total (0–5 h) iAUC were examined. Results Plasma glucose concentrations decreased in both conditions (P<0.001), with higher concentrations after P3 ingestion vs. PLA (P<0.001). Plasma insulin concentrations increased for both conditions (P<0.001) with no difference between conditions (P=0.331). Plasma total amino acid (TAA) concentrations increased over time (P<0.001) with higher concentrations observed for P3 vs. PLA (P=0.010) during the 0‒5 h period. There was a trend for elevated essential amino acid (EAA) concentrations for P3 vs. PLA (P=0.099) during the 0‒5 h postprandial period, but not for leucine (P=0.282) or branched-chain amino acids (BCAA, P=0.410). The early net exposure (0‒2 h iAUC) to amino acids (leucine, BCAA, EAA, and TAA) was higher for P3 vs. PLA (all, P<0.05). Conclusion Microbial protease co-ingestion increases plasma TAA concentrations (0–5 h) and leucine, BCAA, EAA, and TAA availability in the early postprandial period (0‒2 h) compared to ingesting pea protein with placebo in healthy adults.