Understanding the Gut Microbiome

Updated: Nov 10

What is the gut microbiome and why is it important to your health?


In a lot of the research we share, we reference your gut microbiome, but what exactly does that mean and how does your unique gut microbiome affect health outcomes in developing children?


The microbiome is the population of microbes living in and on the body that is acquired from an individual’s environment. This population of microbes is hugely relevant to human health, providing both innate and adaptive immunity to pathogens. The microbiome has been linked to allergy development, the effectiveness of drugs and vaccines, and numerous other factors.




Each person has an entirely unique network of microbiota that is originally determined by one’s DNA. A person is first exposed to microorganisms as an infant, during delivery in the birth canal and through the mother’s breast milk. Exactly which microorganisms the infant is exposed to depends solely on the species found in the mother. Later on, environmental exposures and diet can change one’s microbiome to be either beneficial to health or place one at greater risk for disease.

Over the course of the first year or two of our lives, our gut microbiome changes quickly, but stabilizes by the time we reach the age of three. As we continue to age, our environment, our long-term diet, stress, and the drugs we take, such as antibiotics, continue to play a role in changing our microbiome.


Why has the gut microbiome become such a hot topic in recent years?


In recent years the gut microbiome, in particular, has been linked to a plethora of diseases and conditions, from diabetes to autism and anxiety to obesity.

The gut microbiome has also been linked to how individuals respond to certain drugs, including how cancer patients respond to chemotherapy, and it has even, tentatively, been suggested that it could be linked with how well we sleep.

Meanwhile, a range of studies have raised the importance of other aspects of our microbiome, including that the vaginal microbiome is important in whether an HIV-prevention drug applied to the vagina is effective.


What has the Children’s Environmental Health and Research Center at Dartmouth discovered about the long-term health outcomes associated with our research on the infant gut microbiome?


Using data from the New Hampshire Birth Cohort Study, researchers found that a baby delivered by c-section and wiped with a pad of gauze which was first rested in the vagina would develop a gut microbiome more similar to that of a baby delivered via vaginal birth, indicating that the vaginal environment provides a unique microbiome.

Researchers from Dartmouth also discovered that even relatively low levels of arsenic in drinking water sourced from private wells in New Hampshire had a significant association with infant gut microbiome composition.

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