Bioconversion-Based Postbiotics Enhance Muscle Strength and Modulate Gut Microbiota in Healthy Individuals: A Randomized, Double-Blind, Placebo-Controlled Trial.

KP supplementation significantly increased dominant-hand grip strength after 12 weeks.

• Participants consumed either KP (6 g/day) or placebo in a 12-week, randomized, double-blind, placebo-controlled trial.
• The improvement was described as a 'modest within-group improvement in grip strength.'
• Non-dominant grip strength showed no significant changes.
• Lean mass also showed no significant changes with KP supplementation.

KP supplementation significantly increased plasma irisin concentrations after 12 weeks.

• Irisin is a myokine associated with muscle health and metabolic regulation.
• IGF-1 concentrations showed no significant changes with KP supplementation.
• The increase in irisin was observed alongside improvements in dominant-hand grip strength.
• Irisin changes were implicated as part of a gut-muscle axis modulation mechanism.

KP supplementation significantly reduced IL-1β concentrations after 12 weeks.

• IL-1β is a pro-inflammatory cytokine, and its reduction suggests an anti-inflammatory effect of KP.
• The reduction in IL-1β was identified as part of a potential anti-inflammation pathway contributing to muscle health benefits.
• The postbiotics were prepared using Lentilactobacillus kefiri DH5 with Cucumis melo L. and whey protein.

KP supplementation enriched several gut microbial taxa including Bifidobacterium adolescentis, Latilactobacillus sakei, Lentihominibacter hominis, Mediterraneibacter gnavus, Streptococcus anginosus, and Phocaeicola plebeius.

• Gut microbiota profiling was conducted using 16S rRNA sequencing of fecal samples.
• Six bacterial taxa showed increased relative abundance following KP supplementation.
• Concomitant reductions were observed in Lachnospira eligens, Roseburia inulinivorans, Ruthenibacterium lactatiformans, and Vescimonas fastidiosa.
• Correlations between microbial taxa and muscle-related biomarkers were assessed.

Relative abundance of Faecalibacterium prausnitzii was positively correlated with plasma irisin concentration.

• This correlation suggests a potential mechanistic link between gut microbiota composition and muscle-related biomarkers via the gut-muscle axis.
• Faecalibacterium prausnitzii is a well-known beneficial gut bacterium often associated with anti-inflammatory properties.
• The finding was described as 'notable' by the authors.
• This correlation supports the proposed mechanism of gut-muscle axis modulation involving irisin pathways.

The postbiotics (KP) were produced by bioconversion of polyphenol-rich Cucumis melo L. extract and whey protein using Lentilactobacillus kefiri DH5.

• KP stands for 'Kefir lactic acid bacteria-derived postbiotics.'
• The daily supplementation dose was 6 g/day.
• The trial duration was 12 weeks.
• Bioconversion of polyphenol-rich extract and whey protein by kefir lactic acid bacteria is described as an emerging approach for producing postbiotics that modulate gut microbiota and muscle health.