In the March 28th, 2013 issue of the NEJM, a review of sorts
entitled "Salt in Health and Disease - A Delicate Balance" by Kotchen et al can be
found. My interest in this topic stems
from my interest in the question of association versus causation, my personal predilection for salt, my observation that I lose a good deal of sodium in outdoor activities
in the American Southwest, and my concern for bias in the generation of and especially
the implementation of evidence in medicine as public policy.
This is an important topic, especially because sweeping
policy changes regarding the sodium content of food are proposed, but it is a
nettlesome topic to study, rife with hobgoblins. First we need
a well-defined research question: does reduction
in dietary sodium intake: a.) reduce
blood pressure in hypertensive people? in
all people? b.) does this reduction in
hypertension lead to improved outcomes (hypertension is in some ways a
surrogate marker)? In a utopian world,
we would randomize thousands of participants to diets low in sodium and "normal"
in sodium, we would measure sodium intake carefully, and we would follow the
participants for changes in blood pressure and clinical outcomes for a
protracted period. But alas, this has
not been done, and it will not likely be done because of cost and logistics,
among other obstacles (including ideology).
