How the microbiome shapes our health

Dr. Irah King explains the role of the microbiome in health and how we might be able to harness it to prevent disease.

The word bacteria often summons images of unwiped countertops and nasty infections. It makes most of us reach for the hand sanitizer. A new area of study is challenging our perception of microbes by demonstrating the ways they can be beneficial to our health.

Dr. Irah King, Associate Professor of Microbiology and Immunology at McGill University and Canada Research Chair in Barrier Immunity, is an expert in the study of the microbiome. The microbiome is the collection of micro-organisms—bacteria, viruses or fungi—that live on and inside us. Though this idea may give you the heebie-jeebies, our microbiomes are critical to our health and help shape who we are.

“Everybody has a unique microbiome living on our skin, in our intestine, our lungs. Though these microbes can contribute to disease, they are also critical to our health,” says Dr. King.

The microbiome forms as soon as we are born. As babies emerge from the birth canal, they are inundated with trillions of bacteria living in and on their mothers. Dr. King describes the formation of our microbiome as a school for our immune system.

“The microbes we pick up as babies educate our immune systems. They set the tone of how we respond to infections or wounds we may experience later in life,” says Dr. King.

The microbiome is so influential in our health that researchers believe it plays a role in the development of illnesses from heart disease to depression. An exciting area of Dr. King’s research is focusing on how the microbiome can be manipulated to prevent the development of Alzheimer’s disease.

“We are studying whether we can harness bacteria to eat a certain kind of cholesterol that circulates in the blood. This cholesterol contributes to the development of Alzheimer’s disease and also cardiovascular disease. We’re hoping that if we can shape the microbiome by identifying bacteria that inhibits the body’s absorption of cholesterol, we can then prevent these diseases,” says Dr. King.

Microbiome research has the potential to unlock a vast array of new knowledge about our health. Scientists want to understand what makes up a healthy microbiome, how it affects our physical and mental health, and how we can harness it to prevent disease.

“The microbiome is not only affecting whether we develop a disease, but also how we respond to the medical treatments for that disease. I think we need to focus on both of those things if we’re going to maximize the impact of the microbiome and improve our health,” says Dr. King.

As the field develops, scientists are sure to gain new insights about the microbiome that will change out health and health care for the better.

Dr. King is part of the McGill Interdisciplinary Initiative in Infection and Immunity (MI4), a group of over 250 scientists working to better understand and prevent infectious and immune diseases. To learn more about MI4’s lifesaving work, visit

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