Dietary onion Prebiotic

 

Ref American Society For Microbiology

(mSystems.) 2024 Dec 23;10(1):e01189-24. doi: 10.1128/msystems.01189-24

The prebiotic potential of dietary onion extracts: shaping gut microbial structures and promoting beneficial metabolites

Yebeen Yoo 1,#, Seongok Kim 1,2,#, WonJune Lee 2, Jinwoo Kim 1,2, Bokyung Son 3, Kwang Jun Lee 4,✉, Hakdong Shin 1,2,✉

Editor: Aviâja Lyberth Hauptmann5

ABSTRACT

Onions are well-known vegetables that offer various health benefits. This study explores the impact of onion extracts on gut microbiome using an in vitro fecal incubation model and metabolome analysis.

 Fecal samples were collected from 19 healthy donors and incubated in the presence or absence of onion 

extracts for 24 h. To reduce inter-individual variability 

in the gut microbiome, we employed enterotyping

 based on baseline fecal microbiota: 14 subjects with a Bacteroides-dominant type (enterotype B) and 5 subjects 

with Prevotella-dominant type (enterotype P). Alpha diversity was significantly reduced in the onion-treated group compared to the non-treated control group in both Bacteroides- and Prevotella-dominant types. However, significant structural differences in bacterial communities were observed based on weighted UniFrac distance. Notably, short-chain fatty acid (SCFA)-producing bacteria, such as Bifidobacterium_388775, Feacalibacterium, and Fusicatenibacter, were overrepresented in response to onion extracts in enterotype B. 

Furthermore, genes related to butyrate production were significantly overrepresented in the onion-treated group within enterotype B. Consistent with the enriched taxa and the predicted metabolic pathways, SCFAs and their related metabolites were significantly enriched in the onion-treated group. Additionally, tryptophan metabolism-derived metabolites, including indolelactate (ILA) and indolepropionate (IPA), were elevated by 4- and 32-fold, respectively, in the onion-treated group compared to the control group. In vitro growth assays showed an increase in lactobacilli strains in the presence of onion extracts.

 These results provide evidence that onion extracts could serve as promising prebiotics by altering gut microbial structure and promoting the production of beneficiary metabolites, including SCFAs( short-chain fatty acid (SCFA)-producing bacteria)

 and indole derivatives, and enhancing the growth of probiotics.