Postprandial Aminoacidemia And Exercise-induced Skeletal Muscle Remodelling With Recombinant Bovine β-lactoglobulin In Young Adults

PURPOSE: Given increasing concerns surrounding the long-term environmental impact of animal- and plant-derived protein production, investigations of more sustainable alternative protein sources and their efficacy for supporting skeletal muscle anabolism are critical. Herein, the postprandial amino acid bioavailability of a novel form of supplemental protein derived from recombinant bovine β-lactoglobulin (rBLG) was determined, alongside the muscle adaptive response to resistance exercise (RE) with rBLG supplementation, where responses were compared with dairy-derived whey (WHEY). METHODS: 8 healthy adults (M:F = 3:5; age: 24 ± 4 years; BMI: 23.5 ± 2.1 kg·m2) participated in a participant-blind randomised crossover study in which they ingested 0.3 g·kg-1·mass-1 of rBLG or WHEY with arterialised blood samples collected in the fasted state and over 240 min postprandially for measurement of plasma amino acid concentrations via UPLC-MS. In a separate double-blind randomised parallel group design, 24 healthy recreationally active adults completed thrice-weekly lower-body RE for 8 weeks, with twice daily supplementation of 0.3 g·kg-1·mass-1 rBLG (n(M:F): 12(5:7); age: 23 ± 6 years; BMI: 25.6 ± 3.4 kg·m2) or WHEY (n(M:F): 12(6:6); age: 25 ± 6 years; BMI 25.1 ± 3.1 kg·m2). Training-induced changes in muscle strength and DEXA-derived lean body mass (LBM) were assessed. RESULTS: Plasma essential amino acid (EAA) concentration increased following protein ingestion (P < 0.001), but did not differ between trials (P = 0.554). Mean plasma leucine incremental area under curve (iAUC) was greater following rBLG compared to WHEY (mean diff(95%CI) 10727 (7738 to 13716) μmol·240 min·L-1; P < 0.001). Leg LBM and leg press 1RM increased following training (P < 0.05), with no differences between the rBLG and WHEY groups (P < 0.05). Total training volume performed and total energy and protein intake over the 8-week training period did not differ between the rBLG and WHEY groups (P > 0.05 for all). CONCLUSION: These data highlight recombinant bovine β-lactoglobulin, a more sustainable, precision-engineered mimetic of dairy-derived whey as a novel protein source with the capacity to support skeletal muscle anabolism and exercise-induced remodelling that is comparable to dairy-derived whey.