Effects of a Saccharomyces uvarum Cell-Based Preparation on Gut Microbial Ecology and Metabolic Activity in Adults Without Diagnosed Gastrointestinal Disease: A Randomized Placebo-Controlled Crossover Pilot Study.

ATECREM Serius containing Saccharomyces uvarum SERIUS was well tolerated, with no treatment-related adverse events.

• Forty-four volunteers completed the randomized, single-blind, crossover intervention.
• Design: 2 months of ATECREM Serius (TRT1, >10^10 CFU/g) and 2 months of placebo (PLT1), separated by a 2-week wash-out.
• Tolerability was the primary outcome; microbiota effects were secondary exploratory analyses.

The treatment was associated with differences in gut microbial diversity.

• Differences were observed for three out of five α-diversity indices.
• β-diversity differed between TRT1 and PLT1.
• Fecal microbiota was profiled by 16S rRNA gene sequencing.

ATECREM Serius was associated with higher relative abundance and prevalence of Bifidobacteriaceae and Bacteroides compared with placebo.

• Increase in Bifidobacterium abundance compared to placebo was highlighted in the conclusions.
• Both relative abundance and prevalence of these taxa were increased in TRT1.

Enterobacteriaceae and clostridia sensu stricto were limited in the treatment period compared with placebo.

• These taxa were lower in TRT1 relative to PLT1.
• Findings come from exploratory secondary analyses of 16S rRNA data.

Fecal metabolomics showed enrichment of organic acids, particularly short-chain fatty acids (SCFAs), during treatment, while propanoic acid was reduced in placebo.

• Fecal volatile organic compounds were profiled by GC-MS.
• Organic acids, especially SCFAs, were enriched in TRT1.
• Propanoic acid was reduced in PLT1.

Fecal free amino acids tryptophan and histidine decreased during treatment.

• Fecal free amino acids (FAAs) were measured.
• Tryptophan and histidine were lower in TRT1.

Urinary metabolomics showed clearer clustering between TRT0 and TRT1, including a significant decrease of 2,5-dimethylfuran.

• Urinary VOCs were profiled by GC-MS.
• Clustering was between baseline (TRT0) and treatment (TRT1) samples.

The authors characterize the findings as hypothesis-generating requiring confirmation in larger, adequately powered studies.

• The study was a pilot with 44 completers.
• Tolerability was the primary endpoint; microbiota and metabolomic results were secondary exploratory analyses.
• The study was single-blind.