Making peace with your germs, from the February 2016 Harvard Women's Health Watch

Not too long ago, we thought of all germs as enemies to be destroyed with antibacterial soaps and antibiotic drugs. In the last few years, it's become apparent that the war on microbes is not just a futile enterprise, but also one that could be harmful to our health. The more we learn about the human microbiome — the trillions of single-celled organisms that colonize the skin, nose, digestive system, and vagina — the more we realize that the microscopic critters that live on us and in us may be as important to our health as our body cells.

"Knowing which sorts of microbes are normally found in healthy people can help us understand the roles that changes in microbe populations play in disease," says Dr. Curtis Huttenhower, associate professor of computational biology and bioinformatics in the Department of Biostatistics at the Harvard T.H. Chan School of Public Health. Dr. Huttenhower is one of hundreds of scientists contributing to the National Institutes of Health Human Microbiome Project, part of a global effort to identify at least 600 types of the bacteria, fungi, and yeast we carry with us as we go through life. The goal is to distinguish how the microbes differ throughout the body and how changes in the composition of their colonies are associated with the development of diseases.

Microbes function a lot like our body cells. They take in nutrients and break them down to supply the energy they need to grow and reproduce. In the process, they secrete molecules that are taken in by our body cells, and the effects of those molecules can be either harmful or beneficial.

Diversity is the key to beneficial microbe populations. Not only does a wider array of microbes mean a greater variety of bacterial byproducts for body cells to use, it also leaves less territory for disease-causing bacteria to occupy. That's why the new approach to microbes is directed at maintaining a healthy balance of germs throughout the body. Research has determined that microbial colonies vary according to their location on our bodies, our age, where we are in the world, and what we eat.

The article also gives tips for helping beneficial bacteria thrive and hindering the growth of harmful microbes. The full-length article — Making peace with your germs? — is available in the February 2016 issue of the Harvard Women's Health Watch.