I suspect it's not a decline in general health, it's more the fact that people not used to consuming large amounts of alcohol will have more trouble processing it...
There is, I recently read about the enormous quantities of alcohol that the average American drank in the 1800s. They didn't live as long (but not by that much, considering they didn't have modern medicine), but they were physically active, had healthier social ties, and weren't exposed to the myriad of other poisons most of us are nowadays.
