Abstract
ScopeAn underexplored topic is the investigation of health effects of dietary fibers via modulation of human small intestine (SI) microbiota. A few previous studies hint at fermentation of some dietary fibers in the distal SI of humans and pigs. Here the potential of human SI microbiota to degrade dietary fibers and produce metabolites in vitro is investigated.Methods and ResultsFructans, galacto‐oligosaccharides, lemon pectins, and isomalto/malto‐polysaccharides are subjected to in vitro batch fermentations inoculated with ileostomy effluent from five subjects. Fiber degradation products, formation of bacterial metabolites, and microbiota composition are determined over time. Galacto‐ and fructo‐oligosaccharides are rapidly utilized by the SI microbiota of all subjects. At 5h of fermentation, 31%–82% of galacto‐oligosaccharides and 29%–89% fructo‐oligosaccharides (degree of polymerization DP4‐8) are utilized. Breakdown of fructo‐oligosaccharides/inulin DP ≥ 10, lemon pectin, and iso‐malto/maltopolysaccharides only started after 7h incubation. Degradation of different fibers result in production of mainly acetate, and changed microbiota composition over time.ConclusionHuman SI microbiota have hydrolytic potential for prebiotic galacto‐ and fructo‐oligosaccharides. In contrast, the higher molecular weight fibers inulin, lemon pectin, and iso‐malto/maltopolysaccharides show slow fermentation rate. Fiber degradation kinetics and microbiota responses are subject dependent, therefore personalized nutritional fiber based strategies are required.
Highlights
There is a strong interest in optimizing human health through the consumption of dietary fibers, due to their direct and indirect health benefits.[1,2,3] Dietary fibers are present as natural constituents of leguminous seeds, fruits, vegetables, and cereals
The microbiota profiles in the ileostomy effluents used in this study showed high variation (R = 0.37 ± 0.22) among subjects, and included taxa that are often found in the human small intestine (SI) (Figure S2, Supporting Information)
We investigated the potential of human SI microbiota to degrade dietary fibers in vitro, using ileostomy effluent samples
Summary
There is a strong interest in optimizing human health through the consumption of dietary fibers, due to their direct and indirect health benefits.[1,2,3] Dietary fibers are present as natural constituents of leguminous seeds, fruits, vegetables, and cereals. SCFAs have been suggested to play a key role in the prevention and treatment of metabolic syndrome.[7,8] Soluble galacto-oligosaccharides (GOS), fructans including inulin and fructooligosaccharides (FOS), and more complex fibers such as pectins, and a novel fiber type isomalto/maltopolysaccharides (IMMP), are known to stimulate the growth of a number of microbial species in the intestinal tract such as Bifidobacterium spp.[9,10] Part of the health benefits of fibers are thought to be mediated by changing the gut microbiota
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