When Tomi Akinyemiju, PhD, came from Nigeria to Michigan for college in 2001, she realized that she had drastically underestimated the cold. “It was the first snowstorm of the winter,” she said. “I arrived in Michigan wearing a cute little hoodie, thinking I was all bundled up.” Her brother, who had been living in the state for a while, brought her a winter jacket.

Another culture shock — when she applied for a part-time job, the application asked her to check a box to indicate her race. In Nigeria, where she had lived since she was three years old, she had never had to think about it.

“Why does it matter what race I am?” she thought.

It matters a lot. “The more time I spent in the United States, the more I understood that there are complex historical, structural, and systemic factors that shape everyday interactions,” she said. “The moment you step outside your door, one of the first things people notice is your race.

And with that comes a series of unspoken and complex social cues to negotiate and navigate any preconceived assumption and implicit association, and to get to present your true self. Sometimes it is an uphill battle.

Race, and how people are treated differently because of it, leads to major differences in health outcomes. As a bit of an outsider, Akinyemiju (pronounced Ah-keen-yah-MEE-jew) saw this aspect of culture and health as something to be examined and dissected. She has built her career doing that.

She meticulously studies what drives cancer outcomes, trying to understand why some groups of people fare worse than others, and what can be done to erase those disparities.

The biological and social intersect in an idea called allostatic load, which is biological wear and tear caused by a state of chronic stress.

The idea was developed in 1993 by a researcher at Rockefeller University, Bruce McEwen, PhD. “Before that, it was clear that the social context in which people lived affected people’s health. But the concept of allostatic load allowed us to measure how that happens,” Akinyemiju said.

Allostatic load is calculated by looking at markers of strain on several of the body’s organs and systems, including the heart, the immune system, and the neuroendocrine system (hormones that respond to the nervous system). High allostatic load indicates that the body is in a state of over-reaction or hyper-reactivity, Akinyemiju said.

“Everybody has a normal stress response, right? We all get stressed out, then we adjust,” Akinyemiju said. “Our bodies know how to modulate themselves. But the more adversity you experience, the more your body has to keep reacting. It's fight or flight, but always being in fight mode. Things wear and tear faster.”

In general, allostatic load increases as people age. But when Akinyemiju’s team analyzed data from a Centers for Disease Control survey that tracked more than 50,000 people over 30 years, they saw that higher allostatic load scores began at younger ages for African American and Hispanic/Latinx participants, and the scores stayed higher over time, compared to white people. This work was published in June 2021 in the journal Preventive Medicine.

In a different study that looked at healthy people over time, Akinyemiju’s team again found that African Americans in the study had higher levels of allostatic load, and these higher levels were statistically linked to higher risk of death overall and higher risk of death from cancer. Other studies have linked high allostatic load to increased risk of death from heart disease.

Akinyemiju says that treatments to address some of the elements of high allostatic load, such as high blood pressure or high blood sugar, can help, but the underlying issues must also be addressed. “Ideally, we are intervening to prevent the fundamental cause of this, which is the societal structure that continues to disadvantage a whole group of individuals,” she said. “So there's a bigger societal conversation we need to have about those deeply entrenched issues.”