Dietary Fiber from Coffee Beverage:  Degradation by Human Fecal Microbiota

Abstract

Arabinogalactans and galactomannans from coffee beverages are part of the dietary fiber complex. Chemical structures and fermentability of soluble dietary fiber obtained from a standard filter coffee beverage (Coffea arabica, origin Colombia, medium roasted) by human intestinal bacteria were investigated. One cup (150 mL) of filter coffee contained approximately 0.5 g of soluble dietary fiber (enzymatic-gravimetric methodology), 62% of which were polysaccharides. The remainder was composed of Maillard reaction products and other nonidentified substances. Galactomannans and type II arabinogalactans were present in almost equal proportions. Coffee dietary fiber was readily fermented by human fecal slurries, resulting in the production of short-chain fatty acids (SCFA). After 24 h of fermentation, 85% of total carbohydrates were degraded. In general, arabinosyl units from the polysaccharide fraction were degraded at a slower rate than mannosyl and galactosyl units. In the process of depolymerization arabinogalactans were debranched and the ratio of (1-->3)-linked to (1-->6)-linked galactosyl residues decreased. Structural units composed of (1-->5)-linked arabinosyl residues were least degradable, whereas terminally linked arabinosyl residues were easily utilized. The impact of coffee fiber on numerically dominant population groups of the intestinal microbiota was investigated by fluorescence in situ hybridization combined with flow cytometry (FISH-FC). After 24 h of fermentation, an increase of about 60% of species belonging to the Bacteroides-Prevotella group was observed. The growth of bifidobacteria and lactobacilli was not stimulated.

Letter: gut microbiota modulation contributes to coffee's benefits for non‐alcoholic fatty liver disease – authors’ reply

“…Dr Shen argues that one of the potential mechanisms by which coffee consumption may reduce the risk of non-alcoholic fatty liver disease (NAFLD) is through beneficial modifications of the bacterial community resident in the lower gastrointestinal tract. We entirely agree with Dr Shen's intriguing hypothesis, which is further supported by the findings of Gniechwitz et al, 3 who demonstrated that arabinogalactans and galactomannans from coffee beverages determined an increase of about 60% of species belonging to the Bacteroides group. Recently, a shift in distal gut microbiota towards a lower percentage of Bacteroides in NAFLD patients has been observed, with a decrease in the relative abundance of Bacteroides as the severity of NAFLD increased.…”

Characterization of high molecular weight coffee fractions and their fermentation by human intestinal microbiota

“…Fresh fecal samples were prepared as described elsewhere [1]. The OD at 600 nm was adjusted to a final value of l1.7.…”

“…The experiments presented here build upon our previous study in which we investigated the degradation of coffee dietary fiber prepared from medium roasted coffee [1]. The objective of the present study was to investigate the in vitro fermentability of different high M r fractions (3 -10, 10 -50, 50 -100, and A100 kDa) prepared by ultrafiltration from coffee brews of three different degrees of roast (light, medium, and dark).…”

“…Galactomannans and type II arabinogalactans were shown to be major components of the coffee dietary fiber fraction, which is effectively metabolized by human intestinal bacteria in vitro [1]. Since high M r melanoidins are presumably not absorbed in the small intestine [2], they serve as potential substrates for the colonic microbiota and influence the microbial composition [3].…”

Linking Smoking, Coffee, Urate, and Parkinson’s Disease – A Role for Gut Microbiota?

“…Dietary fiber contained in coffee has marked effects on gut microbiota. It is rapidly metabolized into SCFAs and causes a marked expansion of Bacteroides/ Prevotella bacteria [60]. In vivo, one study found a decrease of Bacteroides after coffee consumption while another did not find changes of Bacteroides/ Prevotella [61,62].…”