Heat-killed postbiotic EF-2001® improves gastrointestinal health in overweight adults: A randomized, double-blind, placebo-controlled trial

A diverse, functionally resilient gut microbiome supports metabolic, immune, and gastrointestinal (GI) health. This trial evaluated heat-killed Enterococcus faecalis EF-2001 (EF-2001®) on GI symptoms, quality of life, and gut microbiome composition in adults with excess weight and mild-to-moderate GI discomfort. In this 84-day randomized, double-blind, placebo-controlled, parallel-group trial, 209 adults aged 18–45 years were randomized (1:1:1) to receive EF-2001® (≥30 billion cells/day), beLP1® (reported separately), or placebo once daily after breakfast. Per-protocol analyses included 49 participants in the EF-2001® group and 54 in the placebo group. The primary endpoint was change in gastrointestinal symptoms assessed by the Gastrointestinal Symptom Rating Scale (GSRS). Secondary endpoints included perceived stress (PSS), digestion-associated quality of life (DQLQ), serum TNF-α, lipid parameters, body composition (DEXA), and gut microbiome composition assessed by metagenomic next-generation sequencing. By Day 84, EF-2001® significantly reduced total GSRS scores compared with placebo (mean decrease 9.92 [SD 7.16] units; p = 0.0167). Significant improvements were also observed in perceived stress (PSS decrease 3.45 [SD 6.40] units; p = 0.0163) and digestion-associated quality of life (DQLQ decrease 1.25 [SD 1.90] units; p = 0.0114). Shotgun metagenomic analysis identified exploratory shifts in the gut microbiome, with directional increases in Lactobacillus , Megamonas , and Bifidobacterium and reductions in Escherichia and Klebsiella . However, no taxa reached significance after FDR correction. Serum TNF-α showed a small reduction, while lipid parameters changed minimally. EF-2001® supplementation for 84 days improved GI symptoms, perceived stress and digestion-associated quality of life, while exploratory microbiome analyses identified directional changes in selected taxa.