Decades have passed without a resolution [to the controversy
over the putative benefits of salt reduction] because the epidemiologic
tools are incapable of distinguishing a small benefit from no benefit
or even from a small adverse effect. This has led to a literature so
enormous and conflicting that it is easy to amass a body of
evidence -- what Stamler calls a "totality of data" -- that appears to
support a particular conviction definitively, unless one is aware of
the other totality of data that doesn't.
-- Gary Taubes
"The (Political) Science of Salt", Science
Volume 281, Number 5379, (14 Aug 1998) pp. 898-907.