Dietary Fibres Differentially Impact on the Production of Phenolic Acids from Rutin in an In Vitro Fermentation Model of the Human Gut Microbiota

Abstract

Polyphenols are often ingested alongside dietary fibres. They are both catabolised by, and may influence, the intestinal microbiota; yet, interactions between them and the impact on their resultant microbial products are poorly understood. Dietary fibres (inulin, pectin, psyllium, pyrodextrin, wheat bran, cellulose—three doses) were fermented in vitro with human faeces (n = 10) with and without rutin (20 µg/mL), a common dietary flavonol glycoside. Twenty-eight phenolic metabolites and short chain fatty acids (SCFA) were measured over 24 h. Several phenolic metabolites were produced during fibre fermentation, without rutin. With rutin, 3,4-dihydroxyphenylacetic acid (3,4diOHPAA), 3-hydroxyphenylacetic acid (3OHPAA), 3-(3 hydroxyphenyl)propionic acid (3OHPPA) and 3-(3,4-dihydroxyphenyl)propionic acid (3,4diOHPPA; DOPAC) were produced, with 3,4diOHPAA the most abundant, confirmed by fermentation of 13C labelled quercetin. The addition of inulin, wheat bran or pyrodextrin increased 3,4diOHPAA 2 2.5-fold over 24 h (p < 0.05). Rutin affected SCFA production, but this depended on fibre, fibre concentration and timepoint. With inulin, rutin increased pH at 6 h from 4.9 to 5.6 (p = 0.01) but increased propionic, butyric and isovaleric acid (1.9, 1.6 and 5-fold, p < 0.05 at 24 h). Interactions between fibre and phenolics modify production of phenolic acids and SCFA and may be key in enhancing health benefits.

Interactions between dietary fibre and the gut microbiota

“…These differences may be related to age and sex (70,71) . The response to fibre and polyphenol intake also varies considerably between individuals (29) . Individuals could also have inherent differences in gut physiology such as gut muscle tone, receptor profiles and pain perception leading to differences in tolerance of fibre doses and gas production, and/or digestive symptoms.…”

“…Individuals could also have inherent differences in gut physiology such as gut muscle tone, receptor profiles and pain perception leading to differences in tolerance of fibre doses and gas production, and/or digestive symptoms. Bacterial metabolite profiles differ among individuals fed the same diets and subsequent physiological responses to those metabolites may also vary (29,72) . The factors which determine this individual variability need further research.…”

“…More fermentable fibres such as inulin and resistant maltodextrin had the greatest impact on bacterial catabolism of rutin increasing the production of bioactive phenolic acids e.g. 3,4-dihydroxyphenylacetic acid in vitro (29) . Individual polyphenols may have a key role in determining composition of the microbiota as some have potential anti-bacterial properties (30) but others may act as probiotics (31,32) .…”

“…Individual polyphenols may have a key role in determining composition of the microbiota as some have potential anti-bacterial properties (30) but others may act as probiotics (31,32) . Little effect of polyphenols on SCFA production from fibre in vitro has been reported (28,29) . It is becoming more common for fibres to be present in our diet as additional ingredients in processed food products (33) .…”

The Improvement of Parturition Progress by High Intake of Dietary Fibre in Late Gestation is Associated with the Altered Gut Microbiome and Metabolome in Sows

“…The gut microbiome is associated with various physiological aspects of host and largely affected by diet [5]. A plethora of studies have associated intake of dietary bre with the change of composition and function of gut microbiome [6][7][8]. The production of symbiotic metabolites by gut microbiome had been proposed to play roles in gut microbiome affecting host physiology [9].…”