Study links poor diet to pro-inflammatory gut bacteria
New research from a team of Dutch scientists is offering novel insights into the relationship between diet, gut bacteria, and intestinal inflammation. The study, tracking nearly 1,500 people, found consistent associations between pro-inflammatory bacterial species and diets high in fast food, sugar and animal products.
It is certainly no newsflash to suggest a high-fat, high-sugar diet, heavy in processed foods is unhealthy. And a nascent body of research has begun to unpack how disruptions to our gut microbiome can contribute to systemic inflammation and disease. A new study, published in the journal Gut, is offering a robust look at how specific foods can be linked to clusters of gut bacteria known to cause inflammatory responses.
The researchers analyzed stool samples from 1,425 people. Around 550 subjects suffered from either inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS), while the rest of the cohort were healthy. All subjects also completed a questionnaire tracking their dietary habits.
“Processed foods and animal-derived foods were consistently associated with higher abundances of Firmicutes, Ruminococcus species of the Blautia genus and endotoxin synthesis pathways,” the researchers report in the new study. “The opposite was found for plant foods and fish, which were positively associated with short-chain fatty acid-producing commensals and pathways of nutrient metabolism.”
These associations between diet and bacterial clusters were consistent across all cohorts, suggesting a healthy diet, promoting greater volumes of anti-inflammatory bacteria, may help reduce, or at least mitigate, some of the intestinal inflammation common to IBD and IBS.
A particular strength of this new study is its cataloguing of certain bacterial species with specific foods. For example, the research detected associations between increased volumes of Ruminococcus gnavus, Akkermansia muciniphila and Proteobacteria, and diets high in processed meat, sugar and fast food.
These particular bacteria are known to produce endotoxins and damage the gut’s mucus layer. This erosion of the gut barrier is especially prominent when a diet is absent of fiber.
Of course, these kinds of studies are not without their limitations, particularly when trying to determine causality. The researchers make no claims as to whether short-term dietary interventions can directly alter these gut bacteria populations. Further work will be needed to understand the long-term relationships between diet and the microbiome, particularly when considering any clinical recommendations for patients suffering from acute gut inflammation.
“Despite these limitations, we were able to derive dietary patterns that consistently correlate with groups of bacteria and functions known to infer mucosal protection and anti-inflammatory effects,” the researchers conclude in the study. “We believe that the diet-microbiota associations that we described in this manuscript are robust: the results are consistent in the different cohorts and also remained significant after adjusting for additional cohort-specific factors such as medication usage.”
The ultimate conclusion is the suggestion that inflammatory mechanisms mediated by gut bacteria may be minimized by limiting animal products, sugar, processed foods and strong alcoholic drinks. Beneficial gut bacteria providing anti-inflammatory effects may be promoted with a diet focusing more on plant-based proteins, vegetables, fruits, nuts, fish and low-fat fermented dairy.
The new study was published in the journal Gut.