Comparable amino acid & intramuscular signalling responses following consumption of a novel microflora compared to whey protein post-resistance exercise in young adults

<h2>Abstract</h2> There is growing interest in alternative protein sources to reduce the intake of animal foods, although the quality of non-animal-based proteins has been questioned. In a double-blind, crossover, randomised and counter-balanced trial, we investigated the anabolic potential of a microflora (bacterial) protein designed to mimic ‘high-quality' whey protein. Twelve, physically-active young adults (sex: M = 6, F = 6; age: 21.1 ± 3.0 years; body fat: 21.1 ± 7.3%; fasting glucose: 4.3 ± 0.4 mmol L⁻¹) consumed 0.3 g kg⁻¹ (of body mass) of either whey protein (WHEY; dose: 27.7 ± 7.5 g) or microflora protein (MIC; dose: 29.8 ± 7.3 g) concentrate in an overnight postabsorptive state immediately following single-leg resistance exercise (∼80% of 1 repetition maximum). The amino acid (AA) composition of protein supplements was analysed by mass spectrometry. Postprandial plasma AA concentrations (0–4 h, by liquid chromatography mass spectrometry) and intramuscular signalling responses (1 h postprandial, by Western Blot) to exercise were determined. Diet and physical activity were monitored prior to each experimental visit and replicated in a cross-over fashion. A comparable pattern of AA composition was observed between sources. Postprandial plasma AA, glucose and insulin concentrations and intramuscular signalling responses (i.e., p-mTOR, p-4E-BP1, p-Akt, p-RPS6) were largely not different between WHEY and MIC (p > 0.05) with the exception of leucine whereby significantly higher plasma concentrations were observed with MIC across the postprandial period (p = 0.024). Therefore, MIC may represent a viable alternative protein source of comparable quality to traditional whey protein that may support skeletal muscle remodelling in young healthy adults.