Prebiotics occur naturally in our diet and prebiotic fibres can be found in Jerusalem artichokes, garlic, chicory, and onions amongst other things. One may have to eat large quantities of these foods to have a ‘bifidogenic’ effect – that is to increase the levels of friendly bacteria in our intestines. For this reason many people find it easier to take a prebiotic supplement, or a combination probiotic and prebiotic supplement (called a synbiotic) to ensure they are feeding their levels of friendly bacteria.