Prebiotics are a type of non-digestible carbohydrate found in certain foods, which promote the growth and activity of good bacteria in the gut, explain Alex Parker and Anna Debenham, dietitians at The Biting Truth.
"Because they are able to pass through the stomach and small intestines undigested, they arrive relatively unchanged in the large bowel. Here they become food for the good bacteria living there," says Alex.
Probiotics and prebiotics have a symbiotic relationship, in that when consumed together, they interact in a beneficial way.
Fermented dairy products like yoghurt and kefir for example, are considered beneficial for gut health as they contain both the live bacteria, and the fuel they need to thrive, in the one food.