Protein-fermentation biomarkers in plasma and urine differ between bovine plasma protein and whey protein isolate in a randomized fully controlled dietary intervention.
Roseanne Minderhoud, Edoardo Capuano, Sonja de Vries et al.
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In 30 seconds
This randomized, controlled crossover dietary intervention compared bovine plasma protein (BPP) with whey protein isolate (WPI) in 15 healthy adults. Participants consumed 30 g/day of each protein source for 7 days, with a washout between periods. BPP consumption was associated with higher concentrations of several aromatic amino acid-derived microbial metabolites: plasma p-cresyl sulfate was 41.0 ± 27.4 compared with 28.5 ± 19.6 during WPI consumption (P < 0.01). Urinary concentrations of several metabolites were also higher with BPP. The authors suggest amino acid composition, rather than digestibility, may explain the differences.
Key findings
- Plasma p-cresyl sulfate was higher with BPP than WPI: 41.0 ± 27.4 compared with 28.5 ± 19.6 (P < 0.01).
- Plasma phenyl sulfate, phenylacetyl-L-glutamine, and indoxyl sulfate were also higher during BPP consumption.
- Urinary p-cresyl sulfate, phenyl sulfate, and phenylacetyl-L-glutamine concentrations were higher with BPP than WPI.
- Protein source did not affect fecal ammonia, branched-chain fatty acids, or microbial diversity.
Why it matters
The findings indicate that protein source can influence circulating and urinary markers of microbial protein fermentation, even when postprandial amino acid responses are similar. This adds evidence that protein composition may matter when considering gut-derived metabolites, while the study does not establish whether the observed biomarker differences affect health outcomes.
What to keep in mind
The intervention involved 15 healthy adults and lasted 7 days per protein source; the reported outcomes were biomarkers rather than clinical health outcomes.