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Am J Clin Nutr. 2017 Oct;106(4):1005-1019. doi: 10.3945/ajcn.117.158816. Epub 2017 Sep 13.

Quantity and source of dietary protein influence metabolite production by gut microbiota and rectal mucosa gene expression: a randomized, parallel, double-blind trial in overweight humans.

Author information

1
Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France.
2
Microbial Ecology, Nutrition and Health Research Unit, Institute of agronomy and food technology - Spanish National Research Council, Valencia, Spain.
3
Department of Gastroenterology, Avicenne Hospital, Public Assistance-Hospital of Paris, Bobigny, France.
4
Research Centre in Food Toxicology, University of Toulouse, INRA, Toulouse National Veterinary School, Polytechnic National Institute - Purpan, Paul Sabatier University, Toulouse, France.
5
Genomic Platform, Cochin Institute, Paris, France; and.
6
Department of Food and Nutritional Sciences, University of Reading, Reading, United Kingdom.
7
Department of Food and Nutritional Sciences, University of Reading, Reading, United Kingdom francois.blachier@agroparistech.fr s.p.claus@reading.ac.uk.
8
Mixed research unit Nutrition Physiology and Ingestive Behavior, AgroParisTech, French National Institute for Agricultural Research (INRA), University of Paris-Saclay, Paris, France; francois.blachier@agroparistech.fr s.p.claus@reading.ac.uk.

Abstract

Background: Although high-protein diets (HPDs) are frequently consumed for body-weight control, little is known about the consequences for gut microbiota composition and metabolic activity and for large intestine mucosal homeostasis. Moreover, the effects of HPDs according to the source of protein need to be considered in this context.Objective: The objective of this study was to evaluate the effects of the quantity and source of dietary protein on microbiota composition, bacterial metabolite production, and consequences for the large intestinal mucosa in humans.Design: A randomized, double-blind, parallel-design trial was conducted in 38 overweight individuals who received a 3-wk isocaloric supplementation with casein, soy protein, or maltodextrin as a control. Fecal and rectal biopsy-associated microbiota composition was analyzed by 16S ribosomal DNA sequencing. Fecal, urinary, and plasma metabolomes were assessed by 1H-nuclear magnetic resonance. Mucosal transcriptome in rectal biopsies was determined with the use of microarrays.Results: HPDs did not alter the microbiota composition, but induced a shift in bacterial metabolism toward amino acid degradation with different metabolite profiles according to the protein source. Correlation analysis identified new potential bacterial taxa involved in amino acid degradation. Fecal water cytotoxicity was not modified by HPDs, but was associated with a specific microbiota and bacterial metabolite profile. Casein and soy protein HPDs did not induce inflammation, but differentially modified the expression of genes playing key roles in homeostatic processes in rectal mucosa, such as cell cycle or cell death.Conclusions: This human intervention study shows that the quantity and source of dietary proteins act as regulators of gut microbiota metabolite production and host gene expression in the rectal mucosa, raising new questions on the impact of HPDs on the large intestine mucosa homeostasis. This trial was registered at clinicaltrials.gov as NCT02351297.

KEYWORDS:

bacterial metabolites; dietary protein; gut microbiota; high-protein diet; large intestine mucosa; overweight humans; protein source; transcriptome

PMID:
28903954
DOI:
10.3945/ajcn.117.158816
[Indexed for MEDLINE]

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