It's a reasonable question and one that needs answers.
Many times, where I live at least in the deep south, African Americans here have large numbers of folks living in poverty. With poverty comes a lot of other things related to poorer health. At least in my area it's hypertension, diabetes, and obesity. Heart disease isn't too far behind.
I'd be curious how white folks in the same economic strata fare compared to their african american countrymen. Is it a racial thing? Is it poverty related? Is it stress? Is it genetic?
I've worked in healthcare and for quite some time it's widely known that african americans in our southernmost communities suffer from worse health outcomes. Miscarriages are a good example with them happening at higher rates for african americans than white women.
Just a lot of things we don't fully understand, but do have enough data to say that in general, health outcomes for the poor and for african americans are generally worse, and when those two things are combined, like they are in high numbers in the south, it's a recipe for poor health outcomes in high volumes.