The Effect of Gluten-Free Diet on Health and the Gut Microbiota Cannot Be Extrapolated from One Population to Others

Abstract

Gluten-related disorders (GRD) affect millions of people worldwide and have been related to the composition and metabolism of the gut microbiota. These disorders present differently in each patient and the only treatment available is a strict life-long gluten-free diet (GFD). Several studies have investigated the effect of a GFD on the gut microbiota of patients afflicted with GRD as well as healthy people. The purpose of this review is to persuade the biomedical community to think that, while useful, the results from the effect of GFD on health and the gut microbiota cannot be extrapolated from one population to others. This argument is primarily based on the highly individualized pattern of gut microbial composition and metabolic activity in each person, the variability of the gut microbiota over time and the plethora of factors associated with this variation. In addition, there is wide variation in the composition, economic viability, and possible deleterious effects to health among different GFD, both within and among countries. Overall, this paper encourages the conception of more collaborative efforts to study local populations in an effort to reach biologically and medically useful conclusions that truly contribute to improve health in patients afflicted with GRD.

First Insights into the Gut Microbiota of Mexican Patients with Celiac Disease and Non-Celiac Gluten Sensitivity

“…This study has limitations that are relevant to future studies. First, this and other studies lack a large enough sample size to generalize phenomena and even with bigger samples sizes the results cannot be extrapolated from one population to others [ 17 ]. Second, gluten-free diets vary widely around the world and these may or may not lead to a microbial state more similar to healthy controls [ 13 ].…”

“…Growing evidence suggests that the gut microbiota is closely related to GRDs, particularly CD [ 8 , 12 ]; however, a disease-specific microbial signature of GRDs has not yet been defined and there is a lack of consensus with respect to the specific changes involved in these disorders with or without dietary gluten [ 12 , 13 , 14 , 15 ], partly due to the well-known high interindividual variation of the gut microbiota [ 16 , 17 ]. One study used culture techniques to investigate the effect of GFD on fecal Bifidobacterium and showed that CD patients have a lower load of this microorganism [ 18 ].…”

“…In México, CD has a prevalence of ~1% (~1.2 million people) [ 22 ], yet we know very little about CD in terms of its genetic predisposition, clinical presentation, treatment and involvement of the gut microbiota in Mexican patients [ 17 , 23 , 24 , 25 , 26 , 27 ]. The purpose of this research is to investigate the gut microbiota composition and predicted functional profile in Mexican patients with GRDs.…”

The role of diet in irritable bowel syndrome: implications for dietary advice

“…The changes seen may be because gluten or fructans exert a prebiotic action, with their exclusion provoking change in gut microbial composition . However, caution should be taken when interpreting these findings, as individuals have highly unique microbiota, and findings may not be able to be extrapolated from one population to another .…”

Mood Disorders and Gluten: It’s Not All in Your Mind! A Systematic Review with Meta-Analysis

“…Despite this, recent RCTs suggest that a low-FODMAPs diet can further reduce the severity of depressive symptoms in those with NCGS [ 29 ] and CD [ 78 ] already on a GFD, although further research is needed in this area. In addition, while it has been suggested that altered gut microbiota may contribute to the psychiatric effects of a GFD [ 29 , 79 , 80 ], results should not be extrapolated from one population to another, due to the highly individualised pattern of gut microbial composition [ 81 ]. In any case, future studies should be mindful of the shortcomings of only considering mean scores of the sample as a whole, and closer attention should be paid to patients who may be unresponsive to a GFD in research and practice.…”