A new study has produced strong evidence that red meat consumption is a trigger for inflammatory bowel disease (IBD), demonstrating how it alters gut bacteria and immune activity in ways that worsen inflammation. It furthers scientific knowledge of the many pathways involved in inflammation, taking our understanding beyond just association.
Researchers at China's Capital Medical University investigated the effect of different kinds of meat on the gut microbiome, in particular how it could impact the onset and flare-ups of IBD.
In the animal study, mice were fed three types of red meat – pork, beef and mutton – every day for two weeks. Then, the researchers triggered colitis (a model for IBD) using a chemical called dextran sulfate sodium (DSS). Compared to mice on standard diets, those fed red meat developed more severe inflammation in the colon.
Underpinning this ramped-up inflammatory response was a change in the gut's microbial balance. The red meat diets caused a major imbalance in gut bacteria, known as dysbiosis. Analysis showed a significant decrease in good bacteria genera, and a spike in potentially damaging ones.
Specifically, Akkermansia, Faecalibacterium, Streptococcus and Lactococcus species saw a drop-off, compared to the guts of mice on standard diets. Akkermansia helps maintain the gut’s protective mucus layer and calms inflammation, Faecalibacterium produces butyrate, a critical fuel for colon cells and an anti-inflammatory, and Streptococcus and Lactococcus are important for good digestive and immune system health.
Meanwhile, potentially "bad bugs" Clostridium and Mucispirillum became more abundant. We say "potentially" because not all strains impact the body the same way, but some Clostridium species can release toxins and fuel inflammation, while Mucispirillum – which lives in the mucus layer that coats the gut lining, particularly in the colon – is most often seen in abundance in unhealthy or inflamed gut environments.
These microbial shifts can disrupt the gut barrier, heighten immune reactivity and amplify inflammation – especially in people already prone to IBD.
But this wasn't the only change. After the two weeks on the red-meat diet, the mice had a larger amount of immune cells – especially neutrophils and macrophages – in the colon. Under normal circumstances, the colon has a highly regulated immune system, so this increase suggested that immune cells had flooded there to fight injury or irritation. And too many of these two "first responder" cells can trigger a type of biological collateral damage, releasing enzymes and reactive molecules that break down otherwise healthy tissue. This loop then results in a more inflamed and damaged gut lining.
In addition to this, tissue samples taken from the meat-eating mice showed higher levels of pro-inflammatory cytokines in the lining of the colon. While these messenger molecules are important for fighting infections, too much activity means the immune system is in chronic attack mode, which damages surrounding tissue over time.
The tissue samples also showed signs of more widespread colonic damage and sensitivity to DSS – modeling increased sensitivity to colon inflammation. The mice showed signs of increased tissue damage, swelling and signs of pain, and their gut lining broke down more easily.
Essentially, it made the gut simultaneously more fragile and ready for attack, increasing the risk of damage and inflammation in the area.
The results demonstrate that red meat, which was the only variable introduced to the mice, caused a direct and measurable biological change. And the impact was replicated across the three different kinds of meat.
“This study contributes to improving food innervation approaches for inflammatory bowel disease treatment and indicates a close crosstalk among diet, gut microbiota and intestinal immunity,” said co–corresponding author Dan Tian, MD, from Capital Medical University.
However, there were limitations to the study. As well as it being a mice model, it was also a high-exposure study and one that only lasted two weeks. Their gut microbiomes and immune responses don't directly translate to exact human equivalents, and the researchers didn't identify what amount of red meat was a tipping point for these negative health outcomes.
Nearly 10 years ago, a 2016 meta-analysis flagged red meat intake as a possible risk factor in developing IBD, but researchers concluded that more studies were needed to better confirm the link.
An observational study in 2022, which looked at 5,763 individuals from the UK Biobank with IBD, revealed that frequent processed meat consumption (more than four times per week) was associated with a 50-70% higher risk of death in IBD patients – especially those with Crohn’s disease. However, unprocessed red meat was not linked to this increased risk.
Current evidence suggests that people who consume more than 100 – 120 grams (3.5 – 4.2 oz) of red meat a day have a higher risk of developing IBD, and limiting servings to twice a week – especially for those predisposed to IBD – can minimize gut inflammation.
"These results highlight the necessity of dietary optimization, particularly the reduction of red meat consumption, as a preventive strategy against the development of IBD," said the researchers.
The study was published in the journal Molecular Nutrition & Food Research.
Source: Capital Medical University via EurekAlert!
