HUNDREDS of different species of bacteria live in the gut in a community estimated to contain 40 trillion cells. Previous studies have established the links between the diet and gut microbiome, but whether specific foods and dietary patterns might affect the composition of the gut microbiome and resultant inflammatory responses in the gut remains unclear.
A group of researchers from The University Medical Center Groningen, Groningen, the Netherlands, explored the direct effect of the microbiome on pro-inflammatory and anti-inflammatory responses in the gut by focusing on dietary intake and microbial features that induce intestinal inflammation. The new study enrolled 1,425 people with either Crohn’s disease, ulcerative colitis, irritable bowel syndrome, or a healthy gut. Each person provided a stool sample for microbial analysis and filled in a Food Frequency Questionnaire (FFQ) for a measure of average daily nutrient intake. Specific food items were classified into 25 food groups measured in grams per day.
Data analysis revealed 38 associations between dietary intake and specific bacterial clusters; a particular strength of this new study was the identification of certain bacterial species with specific foods: “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 reported. These particular bacteria produce endotoxins and damage the gut’s mucus layer. This erosion of the gut barrier is especially prominent when a diet is absent of fibre. “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 four 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 gastrointestinal diseases.
The researchers confirmed 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.
Overall, inflammatory mechanisms mediated by gut bacteria may be minimised 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.