Differential effects of pea protein isolate, pea protein concentrate, and whey protein isolate supplementation on gut microbiota and metabolic markers in healthy adults: a 3-arm parallel randomised intervention

Abstract Purpose As origin and quality of dietary protein are key modulators of gut microbiota and host metabolism, characterising health effects of different proteins is increasingly important given the need to shift towards more plant-based protein sources for environmental sustainability. Yet, direct comparisons across protein sources and food matrices in humans remain limited. This randomised, double-blind, 3-arm parallel, dietary intervention study examined the effects of four-week pea protein concentrate (PPC), pea protein isolate (PPI) or whey protein isolate (WPI) supplementation (0.5 g/kg body mass/day) on gut microbiota composition in healthy adults as the main outcome. Methods Faecal samples and lifestyle questionnaires were collected weekly, with fasting blood and 24-h urine samples obtained at baseline, mid- and post-intervention. Proteins were compared using two contrasts – PPC vs. PPI and PPI vs. WPI – investigating differences between plant and animal-based proteins as well as between plant-based proteins with different matrixes. Results Supplementation of PPC and PPI significantly reduced α-diversity and increased β-diversity, partly modulated by BMI. At species level, relative abundances of Anaerobutyricum hallii and Bifidobacterium longum increased significantly in subjects consuming PPC. A similar result was observed for Lactobacillus crispatus and Limosilactobacillus frumenti in subjects consuming PPI. Conclusion Our findings demonstrate that different dietary proteins selectively modulate beneficial gut microbial species, highlighting the importance of investigating individual responses to dietary interventions. Further studies are needed to verify how compositional changes translate into changes in microbial functionality. Trial registration This study is registered at www.clinicaltrials.gov as NCT05611138 (November 02, 2022).