Effects of a gluten-free diet on gut microbiota and immune function in healthy adult human subjects

• Published in: British journal of nutrition Vol. 102; no. 8; pp. 1154 - 1160
• Main Authors: De Palma, Giada, Nadal, Inmaculada, Collado, Maria Carmen, Sanz, Yolanda
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 28.10.2009
• Subjects: Adult; adults; Bacteria; Bacteria - isolation & purification; Bifidobacterium; Bifidobacterium longum; Biological and medical sciences; biosynthesis; celiac disease; Cells, Cultured; Clostridium; Clostridium lituseburense; Coeliac disease; cytokines; Cytokines - biosynthesis; Diet; Diet, Gluten-Free; E coli; Energy Intake; Enterobacteriaceae; Escherichia coli; Faecalibacterium prausnitzii; Feces; Feces - microbiology; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Gluten; Gluten-free diet; gluten-free foods; Grain; health status; Humans; Immune response; Immune system; Immunity; immunology; In Situ Hybridization, Fluorescence; Intestinal microbiota; intestinal microorganisms; isolation & purification; Lactobacillus; Leukocytes, Mononuclear; Leukocytes, Mononuclear - immunology; Male; methods; Microbiology; Nutrition research; nutritional intervention; Polymerase Chain Reaction; Polymerase Chain Reaction - methods; Probiotics; Proteins; Saccharides; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Young Adult; Gluten-free diet; Coeliac disease; Immunity; Intestinal microbiota; Human; Immunopathology; Healthy subject; Digestive system; Gut; Microflora; Feeding; Vertebrata; Mammalia; Diet; Intestinal malabsorption; Digestive diseases; Intestinal disease; Adult; Gluten
• ISSN: 0007-1145; 1475-2662; 1475-2662
• DOI: 10.1017/S0007114509371767

Diet influences the composition of the gut microbiota and host's health, particularly in patients suffering from food-related diseases. Coeliac disease (CD) is a permanent intolerance to cereal gluten proteins and the only therapy for the patients is to adhere to a life-long gluten-free diet (GFD). In the present preliminary study, the effects of a GFD on the composition and immune function of the gut microbiota were analysed in ten healthy subjects (mean age 30·3 years) over 1 month. Faecal microbiota was analysed by fluorescence in situ hybridisation (FISH) and quantitative PCR (qPCR). The ability of faecal bacteria to stimulate cytokine production by peripheral blood mononuclear cells (PBMC) was determined by ELISA. No significant differences in dietary intake were found before and after the GFD except for reductions (P = 0·001) in polysaccharides. Bifidobacterium, Clostridium lituseburense and Faecalibacterium prausnitzii proportions decreased (P = 0·007, P = 0·031 and P = 0·009, respectively) as a result of the GFD analysed by FISH. Bifidobacterium, Lactobacillus and Bifidobacterium longum counts decreased (P = 0·020, P = 0·001 and P = 0·017, respectively), while Enterobacteriaceae and Escherichia coli counts increased (P = 0·005 and P = 0·003) after the GFD assessed by qPCR. TNF-α, interferon-γ, IL-10 and IL-8 production by PBMC stimulated with faecal samples was also reduced (P = 0·021, P = 0·037, P = 0·002 and P = 0·007, respectively) after the diet. Therefore, the GFD led to reductions in beneficial gut bacteria populations and the ability of faecal samples to stimulate the host's immunity. Thus, the GFD may constitute an environmental variable to be considered in treated CD patients for its possible effects on gut health.