The Human Microbiome, Diet, and Health Workshop Summary (2013) / Chapter Skim
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4 Influence of the Microbiome on the Metabolism of Diet and Dietary Components
4 Influence of the Microbiome on the Metabolism of Diet and Dietary Components
Pages 69-80
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From page 69... ...
This chapter summarizes the workshop presentations and discussion that were focused on the influence of the microbiome on diet and dietary components. DIET, OBESITY, AND THE GUT MICROBIOME1 When the tremendous amount of undigested polysaccharides, lipids, and peptides that pass through the small intestine unabsorbed enter the large intestine, they serve as the perfect medium for growing a rich gut microbiota.
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From page 70... ...
. Researchers observed about twice as much gain in body fat in mice receiving microbiota transplanted from either ob/ob or diet-induced obese donors, compared to mice receiving microbiota from lean donors (see
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From page 71... ...
These results suggest that microbial communities derived from obese versus lean mice impact the energy balance of their new hosts in different ways. Human twin data provide additional evidence to support the hypothesis that the microbiome impacts host energetics.
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From page 72... ...
conducted an extensive set of diet shift comparisons using a "humanized" mouse model, that is, an initially germ-free mouse that was colonized with a human microbiome. They compared 16S rRNA sequences in humanized mice that were fed conventional mouse chow versus humanized mice fed a "Western" diet (i.e., high fat)
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From page 73... ...
For example, gut microbiomes in carnivores tend to be enriched with amino acid catabolism genes. Implications of the Association Between Diet and the Microbiome Evidence collected by Turnbaugh and others suggests that the human ability to extract and store calories from food as fat is at least partially impacted by gut microbes.
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From page 74... ...
(2010) identified a number of host metabolic pathways handled by gut microbes, many of which are involved with carbohydrate or amino acid metabolism or xenobiotic biodegradation.
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From page 75... ...
Various mechanisms have been proposed to explain the association, including decreased inflammation and oxidative stress, induced cell differentiation and apoptosis, and improved carcinogen metabolizing capacity. From a human dietary perspective, one of the challenges to deriving chemopreventive benefit from cruciferous vegetables is that isothiocynate, the active component that actually imparts the protective benefit, is difficult to access.
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From page 76... ...
To determine whether any specific microbial communities are associated with the capacity to produce equol, Hullar and Lampe (unpublished) identified individuals as equol producers or nonproducers based on a soy protein challenge, collected fecal samples, and analyzed 16S rRNA as part of what Lampe described as a "quick and dirty" evaluation of the gut microbiome.
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From page 77... ...
He noted that samples have been collected from various places along the length of the human GI tract and that they reveal both longitudinal and axial differences in both 16S rRNA and metagenomic microbial sequences. Peter Turnbaugh remarked that based on his observations in mice, while
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From page 78... ...
showing that microbial communities can be matched to individuals regardless of whether the microbial sequencing data came from biopsy or fecal samples. Turnbaugh speculated that some biogeographic structure probably exists, but at a finer scale.
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From page 79... ...
2010. Organismal, genetic, and transcriptional variation in the deeply sequenced gut microbiomes of identical twins.
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