The definition of microbiome is the collection of microorganisms that inhabit a particular environment; and so the term “gut microbiome” obviously refers directly to the gut.


The condition of one’s gut microbiome has the ability to impact many health outcomes and can influence the pathogenesis of conditions such as cancer, inflammatory bowel disease, non-alcoholic fatty liver disease and metabolic syndrome.

We are becoming more aware of the effect that what we eat, how we exercise and our sleeping patterns have on the health of the gut microbiome, and how this may relate to the development of these conditions.  


What we eat has an influence over the type and number of microorganisms colonising the gut.

Prebiotics are non-digestible food stuffs that stimulate the growth and activity of microorganisms in the gut. They do so by being metabolised into short chain fatty acids which are a fuel source for the microorganisms. Consumption of a variety of prebiotics allows for a more diverse gut microbiome. Prebiotics are found in vegetables, legumes and fruit. Psylium husk is a rich source of prebiotics and can be used as a dietary supplement.

Probiotics are live microorganisms which are thought to exert a positive effect on the gut.  Bifidobacterium and Lactobacillus are the two most commonly researched strains. Probiotics help to maintain the integrity of the lining of the gut and help produce immune-modulating and anti-microbial substances. Some studies have found significant positive effects when probiotics have been used in conditions such as ulcerative colitis and non-alcoholic fatty liver disease, while some studies in other areas have not. However, the clinical benefits observed when using probiotics is strong enough to warrant further studies.


The gastrointestinal tract, as with other organs, works on a 24-hour circadian rhythm and so different functions, such as gastric acid production, nutrient absorption and colonic motility occur depending on if it is day or night. Processes related to immunity also occur according to the circadian rhythm via communication between the central nervous system and the immune system.

Prolonged sleep restriction and the accompanying stress response invokes the production of proinflammatory cytokines, which results in a low-grade chronic inflammatory state. Epidemiologic studies have established the best amount of sleep to target as approximately 7 hours. This is the range that best correlates with lower prevalence of cardiovascular disease. Studies have also highlighted the relationship between sleep disruption and the increased flare ups in those with ulcerative colitis.



There seems to be a positive relationship between exercise and gut microbiota, indicating that exercise can positively affect the health of the gut. Exercise helps to modulate vagal tone, which is important in maintaining the brain-gut axis (i.e. keeps healthy communication between the gut and the brain). Contraction of skeletal muscle, which occurs during exercise, causes the release of anti-inflammatory cytokines, which strengthens the immune system.


The effects of prebiotics, probiotics and other nutrients on the health of the gut remains to be a hot-topic in the nutritional sciences, with a lot of evidence pointing toward the fact that the health of the gut does have some role to play in the development of various systemic diseases, and the health of the gut can be improved and maintained using certain dietary changes.

The role of sleep and exercise on gut health are areas that need further research in order to specifically define in which ways these activities may enhance gut health. However, you don’t have to be a rocket scientist to understand that sleeping 7 – 8 hours every night and getting regular exercise improves one’s health, vitality and longevity.