Effects of incrementally increased plant-based protein intake on gut microbiota and inflammatory-metabolic biomarkers in healthy adults.

Fecal calprotectin levels significantly increased only in a subset of participants during pea protein supplementation.

• The study included 29 male and female healthy adults in an exploratory intervention design.
• A 4-week pre-intervention period was followed by 4 weeks of pea protein supplementation.
• The calprotectin increase was accompanied by higher fecal water cytotoxicity in vitro in the affected subset.
• Not all participants showed this response, indicating differential effects on gut inflammatory markers.

Short-chain fatty acids (SCFAs) mainly rose in participants who maintained stable calprotectin levels during the intervention.

• SCFA changes were observed in the subset of participants without significant calprotectin increases.
• Fecal samples were collected weekly throughout both the pre-intervention and supplementation periods.
• This finding suggests a divergent gut response pattern between participant subgroups.

Relative abundances of Limosilactobacillus frumenti, Odoribacter splanchnicus, and Lactobacillus crispatus increased significantly in the total study population during the intervention.

• These increases were observed across all 29 participants during the 4-week pea protein supplementation period.
• Gut microbiota composition was assessed via fecal samples collected weekly.
• These three bacterial species showed statistically significant relative abundance increases.

Relative abundances of Bifidobacterium longum and Bifidobacterium catenulatum decreased significantly in the total study population during pea protein supplementation.

• Both Bifidobacterium species showed decreased relative abundances across the full participant group (N = 29).
• These are generally considered beneficial bacterial strains, and their decrease occurred alongside increases in other beneficial strains.
• Changes were monitored over the 4-week supplementation period with weekly fecal sample collection.

The pea protein isolate was administered in weekly incrementally increasing doses ranging from 0.25 g per kg body mass per day to 1.00 g per kg body mass per day.

• Week 5: 0.25 g/kg body mass/day; Week 6: 0.50 g/kg body mass/day (implied by weekly increments); Week 7: 0.75 g/kg body mass/day (implied); Week 8: 1.00 g/kg body mass/day.
• Protein source was described as a 'well-characterized pea protein isolate' derived from yellow pea.
• Biological samples (fecal, fasting blood, 24-hour urine) and questionnaire data were collected weekly.
• Questionnaire data and biological sample data 'confirmed a healthy study population and compliance.'

Yellow pea protein isolate is widely used as a main ingredient in meat alternatives, but its biological effects on gastrointestinal health remain incompletely understood.

• The study was motivated by the global dietary shift toward plant-based proteins and the need to understand their gastrointestinal effects.
• Surrogate markers investigated included fecal short-chain fatty acids, gut microbiota composition, fecal calprotectin, and fecal water cytotoxicity.
• Blood and urine biomarkers described as 'inflammatory-metabolic biomarkers' were also assessed.