Possible Microbiome Alterations:
i. Diet- Diet can alter the gut microbiome because there could be microbes on or in the food that you are potentially introducing to your already established environment, but also because the food you eat is also the food your microbes are going to eat. Reasonably then, we can assume if you eat a lot of a particular nutrient but then switch your diet to one where that nutrient is now scarce, your microbes will react and dysbiosis could occur. A change in diet could be positive, if introducing probiotics or negative, if diet somehow alters the Firmicutes to Bacteriodetes ratio, increasing the odds of GI tract pathologies.
ii. Antibiotics- Taking antibiotics will alter your gut microbiome, likely negatively. The function of antibiotics is to get rid of microbes so the diversity of microbes in your gut will probably be decreased. Lower diversity has been shown overall to lead to negative effects, which makes sense as destroying helpful gut bacteria will obviously not be good.
iii. Stress- Stress is known to have many physical manifestations if allowed to become chronic. An increase in stress would likely be harmful to your microbiome, as the sustained release of cortisol can alter metabolism which could also then lead to stress for your microbes.
iv. Environment- Changing environment could lead to a change in the microbial community due to different conditions spawning different microbes. The change in your microbiome likely correlates with how dramatic the change in environment is. For example, IBS incidence is higher in North America and very low in Africa with IBS etiology though to be linked to gut microbiome. Another example, Helicobacter pylori is found in much lower numbers in Australia than Africa. This indicates that environment has some effect on gut microbiome.