Abstract
- Background
Onions serve as a primary dietary reservoir of health-promoting flavonols renowned for their significant disease-preventive and bioactive properties. To evaluate the physiological fate of novel food preservation technologies, onions treated by high-pressure processing (HPP-treated onion) were subjected to an advanced dynamic gastrointestinal digestion and colon fermentation simulator (DGID-CF). This study aimed to investigate the precise impact of chronic simulated dietary intake—administered at a regimen of 27 g/day for 14 consecutive days—on gut microbiota metabolism and catabolic profiles across the three distinct anatomical regions of the colon: the ascending colon (AC), transverse colon (TC), and descending colon (DC).
- Methods
HPP-treated onion samples were characterized for initial flavonol content and introduced into the DGID-CF system simulating chronic feeding dynamics. High-performance liquid chromatography and advanced spectroscopic techniques tracked the stability and regional delivery of primary flavonols (specifically quercetin-3,4'-diglucoside and quercetin-4'-glucoside) throughout the simulated gastrointestinal tract. Microbial fermentation kinetics, production rates of short-chain fatty acids (SCFAs including acetic, propionic, and butyric acids), population shifts in beneficial gut microbiota (Bifidobacterium spp. and Lactobacillus spp.), and the generation of phenolic catabolic metabolites across the AC, TC, and DC compartments were systematically quantified. Multivariate statistical approaches, including principal component analysis (PCA), were utilized to discern regional metabolic clustering based on precursor and phenolic metabolite compositions.
- Results
Analytical evaluations confirmed that HPP-treated onions retain a high concentration of quercetin-3,4'-diglucoside and quercetin-4'-glucoside, a large proportion of which successfully reached the ascending colon structurally unaltered. In the transverse and descending colons, total phenolic metabolites progressively increased by 2.5-fold relative to day 2, predominantly comprising 3-hydroxyphenylacetic, 4-hydroxyphenylacetic, 3-(4-hydroxyphenyl)-propionic, and 3,4-dihydroxyphenylpropionic acids. Furthermore, chronic simulated feeding stimulated the proliferation of beneficial colonic bacteria (Bifidobacterium spp. and Lactobacillus spp.) and drove substantial increases in total SCFA production by 9-fold in the AC, 2.2-fold in the TC, and 4.4-fold in the DC compared to baseline levels on day 1. Principal component analysis (PCA) demonstrated a distinct biochemical separation among the three colonic regions driven by their unique phenolic precursor and metabolite profiles.
- Conclusions
HPP-treated onion effectively modulates human gut microbiota metabolism, promoting the proliferation of beneficial bacterial taxa, enhancing short-chain fatty acid production, and generating bioactive phenolic metabolites across the colonic regions. Furthermore, the DGID-CF simulator proves to be a robust, reliable in vitro system for modeling complex colonic biotransformations.
https://pmc.ncbi.nlm.nih.gov/articles/PMC8145356/