Alexandra Brewster: retired naturopath, nurse, functional medicine doctor and the GUT... let's chat!

The microbiome is the collection of all microbes, such as bacteria, fungi, viruses, and their genes, that naturally live on our bodies and inside us. Although microbes are so small that they require a microscope to see them, they contribute in big ways to human health and wellness. They protect us against pathogens, help our immune system develop, and enable us to digest food to produce energy.

Because the microbiome is a key interface between the body and the environment, these microbes can affect health in many ways and can even affect how we respond to certain environmental substances. Some microbes alter environmental substances in ways that make them more toxic, while others act as a buffer and make environmental substances less harmful.

How can the microbiome affect health?
The critical role of the microbiome is not surprising when considering that there are as many microbes as there are human cells in the body. The human microbiome is diverse, and each body site – for example, the gut, skin, and oral and nasal cavities – has a different community of microbes.

A person’s core microbiome is formed in the first years of life but can change over time in response to different factors including diet, medications, and environmental exposures.

Differences in the microbiome may lead to different health effects from environmental exposures and may also help determine individual susceptibility to certain illnesses. Environmental exposures can also disrupt a person’s microbiome in ways that could increase the likelihood of developing conditions such as diabetes, obesity, cardiovascular and neurological diseases, allergies, and inflammatory bowel disease. For example, specific changes in the gut microbiome have been linked to liver health. NIEHS-funded researchers and collaborators developed a rapid, low-cost tool that uses stool samples to detect microbial changes that can accurately diagnose liver fibrosis and cirrhosis.