Fermented and non-fermented pickles modulate gut microbiota in older adults with dysphagia: A pilot crossover study

Dysphagia is common among older adults and often leads to dietary restrictions, reduced appetite, malnutrition, and decreased quality of life. Although pickles are widely enjoyed by older adults, dysphagia-friendly pickles are often avoided owing to their texture. Moreover, many dysphagia-friendly foods are non-fermented and lack live lactic acid bacteria, and it remains unclear whether texture-modified, non-fermented pickles can favorably influence the gut microbiota. Therefore, this exploratory, microbiotal-focused study examined preliminary, taxon-level gut microbiotal signals associated with dysphagia-adapted non-fermented versus fermented pickles.

In this pilot, single-blind, 2 × 2 crossover study, participants were alternately allocated to receive non-fermented or fermented pickles (finely shredded sauerkraut cut into 1-mm strips) first, with a 2-week washout between periods. Fecal samples were collected before and after each intervention. The gut microbiotal composition was analyzed using 16S rRNA gene amplicon sequencing and bioinformatic processing via QIIME2. Microbial diversity and taxonomic changes were analyzed using Wilcoxon's signed-rank test. Finally, α-diversity (Shannon, Chao1, Simpson), β-diversity (Bray-Curtis permutational multivariate analysis of variance), and taxon-level relative abundances for prespecified taxa (e.g., Bifidobacterium, SCFA-associated taxa) were evaluated.

Thirteen participants were enrolled. There were no significant post-intervention changes in α-diversity (e.g., shannon p = 0.273, 0.414) and β-diversity (p = 0.993, 0.999). However, consumption of non-fermented pickles significantly increased the abundance of Actinobacteriota, including Bifidobacteriales, Bifidobacteriaceae, and Bifidobacterium (p = 0.012). In contrast, consumption of fermented pickles significantly increased the abundance of several short-chain fatty acid-associated taxa, including [Eubacterium] coprostanoligenes group and Marvinbryantia genus.

Texture-modified pickles and fermented pickles can be safely provided and feasibly consumed by older adults with dysphagia risk. Their consumption induced modest, taxon-specific shifts in gut microbial composition, without altering global diversity. These exploratory pilot findings demonstrate feasibility and suggest taxon-level trends requiring confirmation in larger, randomized trials with functional and clinical endpoints.

UMIN-CTR UMIN000046319 (Japan).