Real ileal amino acid digestibility of pea protein compared to casein in healthy humans, a randomized trial.

Background It is necessary to propose plant alternatives to animal proteins that are of good nutritional quality. Pea is a good candidate owing to its high protein content and its well-balanced amino acid (AA) profile. Objective This study aimed at assessing the real ileal AA and nitrogen digestibility (RIDAA and RIDN) of pea protein isolate as compared to milk casein in humans. It also aimed to evaluate their nutritional quality through calculation of the digestible indispensable amino acid score (DIAAS) and to determine the net postprandial protein utilization (NPPU). Methods Fifteen healthy volunteers were included in a randomized, single-blinded, 2-arms parallel design, trial. They were equipped with a naso-ileal tube. They ingested the test meals, which consisted of nine successive portions of mashed potatoes containing either pea protein or casein, intrinsically labelled with 15N. Ileal content, plasma and urine samples were collected regularly over an 8 h postprandial period. Results Mean RIDAA was 93.6 ± 2.9% for pea protein and 96.8 ± 1.0% for casein, with no difference between the sources (P = 0.22). Leucine, valine, lysine and phenylalanine were significantly less digestible in pea than in casein. The RIDN was 92.0 ± 2.7% and 94.0 ± 1.7% for pea protein and casein, respectively, and was not different (P = 0.11). The DIAAS was 1.00 for pea protein and 1.45 for casein. The NPPU was 71.6 ± 6.2% and 71.2 ± 4.9% for pea protein and casein, respectively (P = 0.88). Conclusion Although some AAs are less digestible in pea protein than in casein, the RID and the NPPU were not different. The DIAAS of 1.00 obtained for pea protein demonstrated its ability to meet all AA requirements. This study shows the potential of pea isolate as a high quality protein. This study was registered at clinicaltrials.gov as NCT04072770.