Image Credits: left: Photo by cottonbro studio via Pexels; right: Photo by Polina Tankilevitch via Pexels
Those with coeliac disease need to avoid gluten, but those with gastrointestinal complaints may also choose to follow a gluten free diet. However, gluten free diets can adversely impact the gut microbiome. In studies, coeliac patients, on a gluten free diet, showed a decrease in beneficial bacteria Bifidobacterium and Lactobacillus, a decrease in microbial diversity and an increase in potential pathogenic bacteria such as from the Enterobacteriaceae and E. coli family in their guts. (1) (2). In one study these changes were found in 13 weeks and in another study diminished Bifidobacterium were observed at 4 weeks after starting a gluten free diet, which means that these adverse changes can happen even in the short-term. (2) (3) This could be due to the absence of fructans (found in wheat) and the lack of prebiotic function from gluten in gluten free diets. (1) There seems to be a direct correlation between wheat intake and the amount of Bifidobacterium found in people’s guts. More traditional diets lead to low or absent Bifidobacterium compared to industrialised parts of the world, where diets tend to be enriched with wheat. (3)
A Danish study compared the effects of low and high gluten diets. In the gluten free diet when compared with the high gluten diet there was:
- a reduction in butyrate-producing E. hallii and A. hadrus bacteria
- a decrease in hydrogen-producing Dorea
- a reduction in hydrogen-consuming, acetate-producing Blautia
- an adverse impact on the cross feeding of these interrelated species between Bifidobacterium and butyrate-producing bacteria taking into account Blautia’ ability to produce acetate and utilise hydrogen during fibre fermentation and the ability of Dorea longicatena to produce hydrogen
- a reduction in fasting and post-meal hydrogen exhalation and multiple changes in the by-products found in urine suggesting a change in intestinal fermentation. This correlated with a previous study where coeliac disease patients on gluten free diets had significantly lower breath hydrogen concentrations than coeliac disease patients not on gluten free diets. It is unclear whether improvements in well-being and bloating observed in the gluten free compared to the high gluten diets were related to these changes in intestinal fermentation or placebo effects and as such remain unresolved
Components of cereal grains called arabinoxylan and arabinoxylan-oligosaccharides, which are non-starch polysaccharides, promote Bifidobacterium in the gut. In the study, gluten free products showed lower concentrations of arabinose compared with high gluten products. This correlated with the lower abundance of Bifidobacterium with gluten free diets. (3)
Interestingly, during the 8 weeks of the study, no changes in short chain fatty acids (SCFA) were observed. There were no health implications of the reduction in Bifidobacterium and butyrate-producing species, although long term effects are unknown. Additionally, there was no impact on white blood cell counts, blood markers of inflammation or measures of intestinal inflammation and permeability with the gluten free diet. (3)
There is an interesting article here regarding someone returning to gluten after being gluten free (4).
Some people avoid gluten since they think it may help their IBS. However, it tends to be the fructans, a FODMAP, in wheat, that some IBS sufferers are sensitive to and not specifically the gluten itself. Unless you have coeliac disease and/or are fructan intolerant, being gluten free isn’t necessarily a healthy choice. Many gluten free products can be considered ultra-processed foods since you would not be able to recreate the product in your kitchen due to additives. They often contain less healthful fibre than wholegrain wheat products. The best form of simple bread would be a home-made loaf with few ingredients (water, olive oil, sugar, yeast and wholemeal flour) that can be made in a bread maker. The best type of wholemeal flour for this purpose would be a stoneground version (even better organic), which would have a lower glycaemic index (less impact on blood sugar levels) than highly milled flours. Wholegrain sourdough breads are also a possibility though some may find the acidic content of the bread to be too harsh on the digestive system or exacerbate reflux, though some report sourdough should help reflux.
Having said that, some IBS suffers may have non-celiac gluten sensitivity. In a study non-celiac gluten sensitivity was related to elevated levels of anti-gliadin IgG antibodies and human leukocyte antigen DQ2 (HLA-DQ2) gene expression. In fact, those who tested positive for HLA-DQ2/8 were found to have heightened intestinal permeability, and frequency of gastrointestinal movements with gluten consumption. Additionally, some components of wheat such as wheat-germ agglutinin and amylase trypsin inhibitors, may play a role in both intestinal and extra-intestinal symptoms in some people (6). However, in all cases patients should be tested for the possibility of celiac disease, which can only be tested whilst the patient is continuing to consume gluten. (5)
IBS Researcher 