Supplementation of probiotic strains can enhance the absorption of amino acids from protein in the gut. The purpose of this study was to assess if supplementation of a multi-strain probiotic or a postbiotic, consisting of the same strains, would alter the absorption of individual and total amino acids following ingestion of a plant-based meal. Sixteen male participants consumed either probiotic (PRO) or postbiotic (cells inactivated by γ-irradiation
POST), both consisting of L. paracasei LP-DG® (CNCM I-1572) plus L. paracasei LPC-S01 (DSM 26760), or a placebo (PLA) for 2 weeks in a randomized, double-blind, crossover design study separated by a 4-week washout period. During the testing session, blood samples were taken at baseline, 30-, 60-, 120-, and 180-min post-ingestion of a plant-based vegan burger patty. Plasma amino acid levels were analyzed, and percent changes from baseline were assessed using linear mixed-effects models, with the PLA condition as the reference group. There was statistically significant POST condition-by-time interactions for percent changes in alanine, asparagine, citrulline, cystine, glycine, methionine, proline, and total amino acids (p <
0.05, for all). Additionally, there was a statistically significant condition (PRO) by time interactions for cystine (p = 0.02). Two weeks of POST supplementation resulted in significant improvements in amino acid absorption profiles for various individual amino acids and total amino acids compared to PLA. This is the first study to report improved amino acid absorption from a mixed macronutrient meal following a period of postbiotic supplementation.