(OR14-04-26) Intracellular Amino Acid Bioavailability of Postbiotic Cultured Protein, Pea and Whey Protein Using a Novel Stable Isotope Pulse Method

Objectives: Consumption of non-animal plant-based proteins has gained interest for its palatability, affordability, and sustainability, but protein quality is lower than dairy protein. Postbiotic Cultured Protein (Superbrewed ®) was developed to create a higher-quality non-animal protein. We investigated whether differences exist in the anabolic response and essential amino acid (EAA) bioavailability, comparing whey (WP), Pea (PP), and postbiotic cultured protein (PCP) in healthy adults using a novel stable-isotope pulse approach¹.

Methods: Ten adult participants (5m/5f), age 31.4, BMI: 25.2, protein intake: 1.3 (0.4g/kg bw/d), participated in a randomized crossover design over four non-consecutive days. Participants consumed an oral mixture via sip feeding every 20 minutes for 5 hours containing isonitrogenous PCP (45g), WP, and PP. At 3 hours into feeding, a stable isotope pulse was given intravenously containing o.a. 10 labeled EAA to assess postprandial amino acid kinetics and intracellular anabolic responses. Blood samples were collected before and after the IV pulse, and tracer enrichment analyzed by LC-MS/MS. EAA utilization (disposal rate) was calculated by dividing intracellular amino acid production by the amount given in the meal. Data are mean [95% CI], stats by GLMM.

Results: Large variability caused the net anabolic response to be not different between WP (65% [30-100%]), PP (47% [22, 72%]), and PCP (53% [22-83%]). Bioavailability was around 75% for all proteins. Intracellular EAA utilization was lower for isoleucine (PP: p< 0.001), leucine (PP: p< 0.001, PCP: p=0.002), tryptophan (PP and PCP: p< 0.001), but lysine was comparable, suggesting lysine to be the key limiting amino acid in WP, PP, and PP. All proteins showed a comparable large deficiency of lysine and methionine. EAA utilization shows that more EAAs need to be added to PP than PCP to improve the protein quality.

Conclusions: All proteins exhibited amino acid-specific limitations, indicated by increased demand for those amino acids from other endogenous pools. We conclude that targeted amino acid formulation strategies are needed to enhance anabolic capacity and optimize plant-based proteins to support muscle health and functional independence.

¹ Deutz et al CN2025

Funding Sources: This work was supported by funding from Superbrewed.