It is only in the last 11 years or so that official forms (like the Census) have allowed individuals in America to identify as being from more than one race. A couple of sociologists argue that this multiracial identification impacts self-reported health:
Bratter and Bridget Gorman, associate professor of sociology at Rice, studied nearly 1.8 million cases, including data from more than 27,000 multiracial adults, from the Behavioral Risk Factor Surveillance System (BRFSS) questionnaire…
The new study found that only 13.5 percent of whites report their health as fair to poor, whereas most other single-race or multiracial groups were more likely to report those health conditions: 24 percent of American Indians, 19.9 percent of blacks and 18.4 percent of others. Single-race Asians were the least likely to report fair-to-poor health – only 8.7 percent did so.
While differences in self-rated health exist between single-race whites and multiracial whites, the percentage of single-race blacks who rated their health as fair to poor is nearly identical to that of multiracial blacks. The same is true for single-race and multiracial Asians.
“Our findings highlight the need for new approaches in understanding how race operates in a landscape where racial categories are no longer mutually exclusive yet racial inequality still exists,” said Bratter, director of Race Scholars at Rice, a program within the Kinder Institute for Urban Research. “This extends beyond health data to other measurements of well-being, income, poverty and so much else.”
The key question here seems to be whether multiracial individuals experience the same health outcomes as single race individuals. From this description, it sounds like this study suggests that being multiracial and white has different health outcomes compared to whites while being black or multiracial black has the same health outcomes. This would make sense given what we know about health differentials by race (more than genetics and extending to areas like life expectancy).