It is worth reading the article properly - a pdf of the study itself is also available from PNAS.
The rise in mortality is not reflected in Europe, and is not diet related. It is related to increased drug and alcohol use. There is a high use of prescription painkillers by whites with lower educational achievements, and far higher proportion of imported heroin (eg from Mexico) is being sold to the white population, rather than the black or hispanic, than in the past.