Background: More than 100 studies now link racism to worse health. Many people of color experience a wide range of serious health issues at higher rates than do whites, including breast cancer, heart disease, stroke, diabetes, hypertension, respiratory illness and pain-related problems. On average, African Americans, Native Americans, Pacific Islanders and some Asian American groups live shorter lives and have poorer health outcomes than whites. But why?

According to the Centers for Disease Control, African American men die on average 5.1 years sooner than white men (69.6 vs. 75.7 years), while African American women die 4.3 years sooner than white women (76.5 vs. 80.8 years). Vietnamese American and Korean American women suffer some of the highest rates of cervical cancer in the nation; Vietnamese American men die from liver cancer at a rate seven times that of non-Hispanic white men.

Class certainly plays a role. Because of historical discrimination and structural racism, people of color are likely to be less wealthy, to have less education and to live in segregated communities with underfunded schools, insufficient services, poor transportation and housing, and higher levels of exposure to toxic and environmental hazards. A wide body of evidence has shown that wealth predicts health: the higher you are on the class pyramid, the better your health. Every step down corresponds to slightly worse health, from top to bottom. Inequitable distribution of resources helps explain why.

Yet socioeconomic status doesn't account for the whole picture. In many instances, African Americans and other groups fare worse than whites at the same income levels. In fact, infant mortality rates among babies born to college-educated African American women are higher than those of white Americans who haven't finished high school. Recent Latino immigrants, though typically poorer, are healthier than the average American; yet the longer they're here, the more their relative health status declines even as their socioeconomic situation improves. Racism has proven to be a factor affecting health "upstream" and independent of class.

Could there be a genetic reason? Researchers funded by the National Institutes of Health, for example, have spent 40 years and several millions of dollars studying Native Americans in southern Arizona, trying to discover a biological reason for their high rates of Type 2 diabetes. Yet their findings remain inconclusive. Hypotheses like the "salt retention gene" explanation for high rates of hypertension among African Americans have also long been debunked scientifically, although they continue to hold currency in the popular press and public imagination.

In fact, studies comparing birth outcomes among white and Black American women showed that more low birth-weight babies are born to African Americans, but birth outcomes among white Americans and African-born immigrants to America were comparable. Moreover, the daughters of the African immigrants gave birth to low birth-weight babies at the same rate as African Americans.

One risk factor researchers are investigating is how the lived experience of racism can increase chronic stress levels and thus worse health among people of color. According to their thinking, addressing unequal birth outcomes, for example, requires more than just better prenatal care; it also requires that we change the social conditions that produce negative experiences over a lifetime. African Americans have among the worst hypertension rates not because of their genes but because of difficulties they face in their lives.

As sociologist Troy Duster explains, the impact of race on disease is not biological in origin but in effect. Anxiety, anger, or frustration from racist experiences trigger the body's stress response, which over time, creates wear and tear on the body's organs and systems. Dr. Camara Jones, a leading expert on racism and health at the Centers for Disease Control, puts it this way: "It's like gunning the engine of a car, without ever letting up. Just wearing it out, wearing it out without rest. And I think that the stresses of everyday racism are doing that." Dr. Jones and others are studying three kinds of racism - institutional, interpersonal and internalized - and how each contributes to health.

Whether it takes the form of overt discrimination or structural disadvantage, racism continues to influence how people are treated, what resources and jobs are available, where we are likely to live, how we perceive the world and our place in it, what environmental exposures we face, and what chances we have to reach our full potential. Important policies to address racism and its impact on health include more equitable school funding, better enforcement of anti-discrimination laws, housing mobility programs, better transportation, affirmative action, tax policy and land use, as well as economic revitalization, business investment and wealth accumulation in communities of color.