A recent study from Spain [Br J Nutr. 2009 May 18:1-7. (Epub ahead of print)] looked at the effects of a gluten-free diet on the microbiota (microorganisms) that live in the gut. Both helpful and harmful microorganisms live in the gut and diet is known to influence the overall composition. According to study researchers, the purpose of this study was to “analyze the impact of a gluten-free diet on the composition and immune function of the microbiota in healthy subjects to gain further insights on interactions between diet and gut microbes.”

Ten people without celiac disease or history of digestive disease participated in the study. They followed a gluten-free diet for one month by replacing the gluten-containing foods they usually ate with certified gluten-free foods (no more than 20 parts per million of gluten). Three-day food records were kept before the start of the study and again after one month. Food records were analyzed for calories and macronutrients. Gut microbiota were assessed through fecal samples collected before and after following a gluten-free diet for 1 month.

Researchers found that polysaccharide (complex carbohydrate) intake was significantly reduced while study subjects were following a gluten-free diet as compared to a gluten-containing diet. Polysaccharide intake decreased from an average intake of 117 grams while study subjects were following a normal diet to 63 grams when they were following a gluten-free diet. They also found significant differences in the composition of fecal microorganisms before and after following a gluten-free diet. In short, there was a reduction in certain helpful bacteria and an increase in certain potential pathogens. Researchers speculated that this change in composition in fecal microorganisms might be due to decreased intake of polysaccharides.

According to study researchers “these findings indicate that this dietary therapy may contribute to reduce beneficial bacteria group counts and increase enterobacterial counts, which are microbial features associated with the active phase of CD and therefore it would not favor completely the normalization of the gut ecosystem in treated CD patients.”

Dr. Yolanda Sanz, head of the research study, graciously agreed to answer some questions for us about the study.

Can you explain why a diet low in polysaccharides or complex carbohydrates might cause a decrease in good gut bacteria and an increase in potential gut pathogens?

Complex carbohydrates (polysaccharides) ...    Continue

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