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Microbiome Testing

Gut microbiome testing is a new tool used to define the organisms living in the gut. The gut microbiome is largely based in the colon. It is usually established in the first 2-4 years in life and begins to develop from the moment we are born. The bacteria living in our guts in adulthood often reflect species that were established in our childhood depending upon our mode of delivery (vaginal vs Caesarean) our early nutrition (including breast vs bottle feeding) our geography the biome of those with whom we shared a home (particularly mother but including the pets) and the environment in which we were brought up (did we play in the mud?). It and varies from individual to individual. It also varies over time depending upon our environment, our psychological state, our diet, recent infections and antibiotics. It is also influenced by a host of other drugs and environmental factors. In the early days of research into the human colonic microbiome it was believed that the biome of individuals could be classified into a number of distinct groups, however it has now become clear that there is considerable overlap and within a large population wide spectrum of “biomes” are likely to exist.


The biome has important roles in facilitating the development and control of the visceral and central nervous systems, the immune system and the function of multiple other organs. A number of specific organisms have been demonstrated to have specific metabolic or therapeutic effects. The effects of bacteria are likely to result from there ability to produce certain metabolic products (or chemicals) as a result of the processes they undertake in the bowel. As such the benefits are likely to be limited to particular strains that are able to undertake those processes (or chemical reactions). The benefits we see on individual diseases and disease pathways are therefore likely to be limited to the distinct strains which can undertake the very specific process required to benefit a particular disease or pathway leading to disease.


We know that certain groups of bacteria are associated with higher or lower rates of certain disease. For example certain groups (genera of which there may be 50 in the gut) of bacteria are known to be commoner in patients with normal BMI and those with anorexia compared to those with obesity, however we do not yet know which strains  (of which there may be thousands) may precipitate obesity and which may lead to anorexia within a specific individual. In certain disease it is clear that certain bacteria appear to have a specific role in prevention, precipitation or relapse of disease. In this case it is certainly worthwhile looking for those strains. In other disease we don’t yet know enough about individual strains but large groups of bacteria (lactobacilli, bifidobacterial etc)  may be surrogate markers for relative health> An ecological parallel might be that species diversity within a woodland habitat may give an indication as to the likelihood of finding rarer species that often go unseen. Nevertheless such  unseen species may be important to the overall ecology of the habitat.


Microbiome testing may be of use in defining where your individual biome sits on a spectrum of diversity and organisms, it gives a “snap shot” of where your biome is at that moment.  Testing for specific strains may help identify your particular risk of certain diseases, however our understanding is not yet sufficient to predict how such strains will impact on an individual within a given set of human genes and a particular environment and diet. Numerous factors may change your biome over time including diet, psychological stressors and sleep patterns. It is likely that as our understanding progresses we will be better placed to advise on how to influence particular strains of bacteria and how these strains might impact on an individual.

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