First, Singh and Miller's reporton immigrants to America had some unexpected findings.
Whereas U.S.-born black men have a life expectancy of 64, their immigrant counterparts live to an average age of 73; and whereas U.S.-born Hispanic men live to 73, on average, their immigrant counterparts have a life expectancy of around 77. This gap—which prevails even though immigrants are poorer, less likely to have health insurance, and less likely to visit doctors than the general population—may reflect the tendency of immigrants to be among the healthier people in their country of origin; immigrants also have better dietary habits than the U.S. population as a whole, and they smoke and drink less.
These healthy habits -- and their effect on longevity -- erode with time. The exorbitant American lifestyle takes its toll (the "accumulation hypothesis"), but isn't it part of the reason immigrants chose to come here?
It's a trade-off, like any other choice. But I hope immigrants hold on to enough of their own culture to keep themselves healthy, and teach the natives a thing or two.