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

Pratt, Jedd ORCID: https://orcid.org/0000-0002-7410-078X, Acheson, Jordan, Lazaratou, Anna, Greenhalgh, Eve K, Witard, Oliver C, Sale, Craig ORCID: https://orcid.org/0000-0002-5816-4169, Hannaian, Sarkis J, Gritsas, Ari, Churchward-Venne, Tyler A, Hearris, Mark A, Hodson, Nathan ORCID: https://orcid.org/0000-0003-1330-4030 and Morgan, Paul T ORCID: https://orcid.org/0000-0001-7254-4507 (2025) Comparable amino acid & intramuscular signalling responses following consumption of microflora compared to whey protein post-resistance exercise in young adults. The Journal of Nutritional Physiology. 100001. ISSN 3050-6247

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Abstract

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 independently 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 represents a viable alternative protein source of comparable quality to traditional whey protein that may support skeletal muscle remodelling in young healthy adults.