Most of the bacteria that live in your bowel are relatively harmless. In fact, they help with digestion, produce vital vitamins and help to repair damaged cells. But some bacteria are harmful. We are normally protected from harmful bacteria by our immune system and by other bacteria. Unfortunately, lifestyle factors such as high-fat diets, smoking and stress can cause chronic inflammation. Under these conditions the good bacteria struggle to survive, while some harmful, or “pathogenic”, bacteria thrive and multiply. High numbers of pathogenic bacteria means higher risk of a dangerous infection.
High numbers of E. coli have been found under inflammatory conditions. Some types of E. coli can be beneficial and used to treat disease; these can be found in most healthy people. However, inflammation increases the number of pathogenic E. coli and this can lead to disease. Patients with inflammatory bowel disease and bowel cancers have been found with huge numbers of pathogenic E. coli living inside tumours. That’s because these E. coli can stick to and invade the cells lining our bowels and replicate inside them. To make things worse, these E. coli are capable of producing a toxic substance called colibactin that damages the DNA of bowel cells making them cancerous, and can help cancers to spread.