The human microbiome is the collection of microorganisms (such as bacteria viruses and fungi) which live on and inside humans (on the skin, in the saliva and mouth, in the eyes, and in the gut and the rest of the gastrointestinal tract). Foreign microbes outnumber human cells in the body a wide margin; humans have about 100 trillion cells, and carry ten times as many microorganisms in the intestines alone. We know that some of these organisms are useful for humans. However, most have no known effect; they are just symbionts and are referred to as the normal ‘flora.’ Studies in 2009 asked whether our health is damaged if we reduce this biota (collection of … Continue reading →