Findings point to AGP’s potent prebiotic activity during in vitro fermentation with higher beneficial bacteria populations noted that include Bifidobacterium and Eubacterium genera.
Further findings also reveal an increase in the concentration of short-chain fatty acids (SCFAs) that have anti-inflammatory effects.
“The most abundant SCFAs, acetate, propionate and butyrate, have been shown to have multiple beneficial effects for the host, the team of UK scientists said.
“For example, by providing dietary energy, and by suppressing the growth of pathogens by decreasing the pH of the intestinal lumen.”
The fermentation process, where colonic microbiota break down carbohydrates to eventually produce SCFAs appears to be particularly important to health benefits of dietary fibre (DF).
Cereal DF components like β-glucan and fructans, are considered prebiotic, while studies demonstrate notable prebiotic activity for wheat flour arabinoxylan (AX).
However, although the AGP concentration in wheat flour is similar to that of water-soluble AX and total β-glucan, its prebiotic potential has not been determined.
The team from the University of Reading and Rothamsted Research in the UK tested AGP prepared from white wheat flour using in vitro fermentation by colonic bacteria in anaerobic stirred batch cultures.
This preparation was compared to fructooligosaccharide (FOS) and AX. Bacterial populations were measured using fluorescence in situ hybridisation (flow-FISH) and short chain fatty acid (SCFA) concentrations were measured using HPLC.
Findings indicated that the fermentation of AGP resulted in a significant bifidogenic activity and increased concentrations of SCFAs, mainly acetate after 24 hours of fermentation.
Further results reveal a combination of AGP and wheat flour arabinoxylan (AX) are potentially more effective as prebiotics than single substrates.
“AGP showed slower bacterial fermentation than FOS, however, this persistence is unlikely to occur when wheat products are consumed as combining AGP with AX resulted in faster utilisation of the substrates,” the study said.
“Since the ratio of water-soluble AX to AGP used in these experiments is similar to that in white wheat flour, their potential to act synergistically is more relevant to the consumption of wheat products than the results obtained with single substrates.”
Bifidobacterium a target
In discussing the finding’s significance, the team pointed to the bacterial genus Bifidobacterium as a common prebiotic target.
This is due to its link with a number of health benefits, including the reduction of colorectal cancer rates and concentration of circulating cholesterol.
Previous studies have identified a decrease in Bifidobacterium levels with conditions such as antibiotic-associated diarrhoea, inflammatory bowel disease, irritable bowel syndrome, obesity and allergies.
“In this study, all substrates demonstrated beneficial effects by significantly increasing the populations of Bifidobacterium from 8 to 24 hours compared to the negative control.
“Unlike the FOS and AGP + AX mixture, which showed the maximum Bifidobacterium growth at 8 hours, proliferation was slower with AGP and AX singly as substrates, reaching the greatest population numbers after 24 hours.”
The team believed bifidobacteria fermented soluble wheat flour AX and AGP at a slower rate than FOS.
The same effect was observed with the populations of the predominant beneficial bacterial group Clostridium coccoides/Eubacterium rectale.
A previous study showed significant increases simultaneously with bifidogenic effects indicating a number of cross-feeding interactions.
Source: European Journal of Nutrition
Published online: doi.org/10.1007/s00394-019-01908-7
“Determination of the prebiotic activity of wheat arabinogalactan peptide (AGP) using batch culture fermentation.”
Authors: Suzanne Harris et al.