Gastrointestinal health in regard to the gut microbiome is a rapidly emerging field and has many key components driving its emergence. Fibre, prebiotics and probiotics are all dietary components that can play a critical role in maintaining a healthy gut microflora. Fibre has long been appreciated for its influential role in cardiovascular disease, glycaemic control and weight management through various physiological mechanisms. Prebiotics have been shown to play an influential role in irritable bowel symptoms/disease, colon cancer, cardiovascular disease and overall digestive health. Together, various types of fibres and prebiotics have been targeted and synthesised to influence the gut microbiome, specifically Lactobacillus and Bifidobacterium populations. Lactobacillus spp. and Bifidobacterium spp. are common markers for gut health because they have been shown to down-regulate inflammation in the gastrointestinal tract, alleviate irritable bowel syndrome symptoms, stimulate immune functions, aid in mineral absorption and produce little, if any, gas or known carcinogenic substances. Probiotics have also been shown to display many of these pro-health components, and include many species of bacteria outside of the commonly utilised Lactobacillus and Bifidobacterium populations. How these dietary components are defined in the scientific and political arenas will play a critical role in the success of the gut health field moving forward. Key changes in administrative definitions and requirements of these dietary components will influence consumption, awareness and understanding of these key influential components. The purpose of this review is to provide current accepted definitions for fibre, prebiotics and probiotics, as well as introduce key scientific studies describing the health benefits of these components, as well as current health claims.