Twenty-one days of consuming arabinoxylan-oligosaccharides-enriched breads boosted bifidobacteria levels in feces and increased fermentation end products such as the short chain fatty acid butyrate, according to findings published in the Nutrition Journal.
“AXOS-enriched breads were well tolerated and gave rise to a butyrogenic effect, which is of potential benefit to the consumer,” wrote the authors, led by Reading’s Gemma Walton.
“The effects on fermentation end-products, that were not observed following the placebo breads, indicate that AXOS-bread consumption elicited a potentially beneficial shift in fermentation characteristics.”
Prebiotics are defined as: "Non-digestible substances that provide a beneficial physiological effect on the host by selectively stimulating the favorable growth or activity of a limited number of indigenous bacteria".
Commenting on the study's findings, Prof Glenn Gibson, a leading global prebiotic expert from the University of Reading and co-author of the study, told NutraIngredients-USA: "This study was done to look at an emerging prebiotic (arabinoxylan oligosaccharides) but in an authentic food. namely bread.
"The product was very well tolerated. The aim we had was to look at increasing bifidobacteria but it looks like there were ingredients in the non supplemented bread that caused this anyway. We did see increased butyrate in the volunteers stools with the intervention. This was good news, as this is seen to be a very positive microbial metabolite."
Walton and her co-workers used enzymes called endoxylanases to modify arabinoxylans found naturally in cereal to produce arabinoxylan-oligosaccharides (AXOS) at high levels. Placebo breads were prepared using the same ingredients but no endoxylanases were used.
Forty healthy adults were then recruited to participate in a double-blind, placebo controlled human intervention study. Volunteers were randomly assigned to consume ‘placebo’ breads or test breads containing 2.2 g arabinoxylan-oligosaccharides for 21 days. This was followed by a 21 day ‘washout period’ before the volunteers were crossed over to the other group.
Results showed that bifidobacteria levels increased following consumption of the AXOS bread, whereas both AXOS and placebo breads were associated with increases in Lactobacilli levels.
In addition, the AXOS bread was associated with beneficial shifts in fermentation products like butyrate, and a reduction in compounds associated with protein fermentation, which is “considered to be a non-beneficial process within the colon”, said the researchers.
Importantly, the researchers also reported no adverse effects on gastrointestinal symptoms for the AXOS-bread.
“In situ enrichment of AXOS in breads provides an enhanced approach to straightforward fortification,” explained the researchers. “This process utilises naturally occurring AX – furthermore xylanases are already used within the baking industry.
“The production of these breads may be subject to some variations, e.g. as rye and wheat composition may vary amid intrinsic and extrinsic factors. However, providing the level of AX within the grain is in excess of 2%, acceptable levels of AXOS generation would still be possible.
“Therefore, it is unlikely that changes in grain will pose a problem in production of AXOS enriched breads.”
Source: Nutrition Journal
“A randomised, double-blind, placebo controlled cross-over study to determine the gastrointestinal effects of consumption of arabinoxylanoligosaccharides enriched bread in healthy volunteers”
Authors: G.E. Walton, C. Lu, I. Trogh, F. Arnaut, G.R. Gibson