The microbiome is a collection of microbes, mainly made up of bacteria, that live in and on the human body. Far from being a scary concept, these organisms are essential for optimum health. A large percentage of the microbiome is located in the gut where it delivers far reaching benefits.

Here is how the microbiota impact the body:


Much the same way as eating sweet foods makes you feel temporarily happy, gut bacteria can influence emotions (1). Anxiety, stress and negative emotions can be driven by dysbiosis (a state where “bad” organisms outnumber beneficial ones) (2). Conversely, periods of stress can deplete beneficial bacteria and encourage the growth of harmful ones (2).


As the body’s largest organ, the skin forms a protective barrier between the outside world and the body. Some specific nutrients used to nourish this important organ, including biotin, are produced by beneficial bacteria in the gut (3), directly affecting skin health. On the other end of the spectrum, reduced diversity in beneficial gut bacteria are associated with skin conditions such as eczema (4), dermatitis (5) and acne (6) amongst others.

Digestive health

The majority of beneficial bacteria found in the human body reside in the gut (7). Although babies are initially sterile (host no bacteria), microbes colonise the gut during birth and breastfeeding (7). Following colonisation, these gut bacteria enter a mutually beneficial relationship with the host whereby the bacteria have somewhere to live and the host benefits from their presence through increased nutrient availability (8). This mutually beneficial relationship is especially evident when it comes to digestive health. Short chain fatty acids and certain vitamins are provided by beneficial bacteria to the host through the breakdown of otherwise undigestible materials such as fibre (8). Short chain fatty acids in specific help to nourish the gut lining, improve blood flow and encourage healthy repair (9). Significant changes in the gut microbiota have been noted in digestive disorders such as irritable bowel syndrome and inflammatory bowel diseases, whereby certain beneficial bacteria are missing or they have been outnumbered by pathogenic ones (10). Even without a diagnosed disease, microbiota can influence areas of digestive health such as stool frequency or gut motility, gas and bloating (10).

The immune system

Microbiota play an important role in the development of the immune system from early childhood since they assist with the maturation of our defence system as well as train and educate it (11). Beneficial bacteria also discourage the entrance of potentially harmful organisms by producing specific substances to keep them out (12).


Calcium absorption and bone density are influenced by gut bacteria according to the latest research (13). Studies indicate that short chain fatty acids produced through the fermentation of fibres by beneficial bacteria may increase the rate at which calcium is absorbed and retained in bone (14). Animal models also suggest a link between improved bone density, beneficial bacteria and a high fibre diet (13).

If you would like to find out more about the particular types of bacteria in the human microbiome and even get your gut tested please visit


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