The trillions of microbes, including bacteria, fungi, and viruses, in one environment (for example your gut), are collectively known as a microbiome. These microbes may be commensal, symbiotic, or pathogenic.
Researchers estimate the microbiome to account for one to three percent of the human body mass, which can total as high as three pounds. Bacterial DNA was once considered to outnumber human DNA by nearly 10 times; however, today that number is estimated to be around 3 times. So if you think about it, you are more bacteria than you are human!
Your first reaction to this information might be disgust; however, there is a common misconception surrounding bacteria and their potential for disease. Many of the bacteria and other microbes in and on the human body are actually considered commensals, which means that there is no harm to the human host. In addition, a majority of the microbes may also play symbiotic roles, which is a mutually beneficial relationship for the microbe and human host. The balance of gut microbes playing a role in our health is a revolutionary idea that is literally changing the medical field and how we think about and treat disease.
The human gut microbiome is considered one of the most important microbial environments in regards to the role it plays in human health; however, we still have a lot to learn. Research on the gut microbiome only began in the late 1990s. Some scientists have hailed the gut microbiome as a new organ, and believe it plays a major role in immune health. Some disease states, including obesity, diabetes, asthma, autism, and many more, have been linked to specific balances of microbes, or dysbiosis.