Gluten-free diet not friendly to gut bacteria

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Gluten-free diet not friendly to gut bacteria

De Palma G, Nadal I, Collado MC, Sanz Y. Effects of a gluten-free diet on gut microbiota and immune function in healthy adult human subjects. Br J Nutr 2009 May 18:1-7.


British Journal of Nutrition Cambridge University Press
Copyright © The Authors 2009
Full Papers
Effects of a gluten-free diet on gut microbiota and immune function in healthy adult human subjects
Giada De Palmaa1, Inmaculada Nadala1, Maria Carmen Colladoa1 and Yolanda Sanza1 c1
a1 Microbial Ecophysiology and Nutrition Group, Institute of Agrochemistry and Food Technology (IATA), Spanish National Research Council (CSIC), PO Box 73, 46100 Burjassot, Valencia, Spain

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-?, interferon-?, 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.
(Received August 13 2008)
(Revised April 03 2009)
(Accepted April 06 2009)

Key Words:Intestinal microbiota; Gluten-free diet; Coeliac disease; Immunity
c1 Corresponding author: Dr Yolanda Sanz, fax +34 963636301, email

Abbreviations: CD, coeliac disease; FISH, fluorescence in situ hybridisation; GFD, gluten-free diet; IFN, interferon; IQR, interquartile range; PBMC, peripheral blood mononuclear cells; qPCR, quantitative PCR; Th, T-helper