In the age-old debate of nature versus nurture, the question is which aspects of our mental and physical traits are written into our genetic code, and which are a product of the environment around us.
When it comes to our health, we tend to focus on genetics, says Albert-László Barabási, Robert Gray Dodge Professor of Network Science and University Distinguished Professor of physics at Northeastern. But environmental factors drive as much as 70 to 80 percent of our risk for various non-communicable diseases, such as heart disease.
To understand how and why people get sick, researchers need to take a deep dive into the molecules around us.
“We are actually exposed to over 20,000 different molecules every time we eat, through the food’s composition,” Barabási says. “And there’s quite a number of other chemicals that we are exposed to through air, as well as simply by contact.”
In a paper to be published on Friday in Science, Barabási and colleagues at Columbia University, Utrecht University, and the University of Luxembourg lay out the case for increased study of all these environmental factors, which researchers call ‘the exposome.’
“Our genes are not our destiny, nor do they provide a complete picture of our risk for disease,” says Gary Miller, a senior author on the paper and professor of environmental health sciences at Columbia. “Our health is also shaped by what we eat and do, our experiences, and where we live and work.”
This includes the pollutants and other chemicals that make it into our bodies through our food, water, and air, as well as those that are products of microbes, inflammation, infections, and stress.
“The exposome concept is trying to capture everything—all the chemicals that we humans are exposed to on a daily basis—to understand which, how, in what quantities, and in what circumstances they have an effect on health,” Barabási says.
Some of these chemicals do very little. Others can alter cell behavior or interact with different molecules to set off a series of reactions, which could be helpful or harmful. But studying them individually won’t give us an accurate picture of how they affect our health.
“We have a very complex chemical world around us,” says Roel Vermeulen, an environmental epidemiologist at Utrecht University and the lead author on the paper. “We have to change the way that we have been looking at these problems, which has been one disease, one chemical at a time. We need to move to much more of a system approach.”
Network science offers a way to map how various molecules connect to our cells and their eventual biological impact, Barabási says. Understanding the interactions between chemicals and their cumulative effects on our health could eventually provide new ways to prevent diseases from developing.
“Being exposed to the exposome, which we are on a daily basis, is the equivalent of taking a huge number of pills,” Barabási says. “Some of these pills don’t enter the bloodstream, so they don’t affect our health. Others, however, do. Distinguishing from the many, many chemicals those that are harmful, and how they are harmful, is the key, because that’s where regulation needs to step in to eliminate those from the environment.”
Barabási’s lab at Northeastern is currently working on a project to catalogue and map all the chemicals in our food. Other researchers are tracking chemicals in the air using wearable technologies or using new analytical tools to evaluate water and soil samples.
“There is no single expertise that could solve this problem alone,” Barabási says. “There are so many routes through which we are exposed to chemicals. Many different communities will have to come together.”