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vascular disease. Again, while no continual dose around the world. During the Anglo-American When
response relationship is implied, the risks appear War of 1812, despite its high cost, salt rations
to outweigh the benefits when reducing sodium amounted to three teaspoons per day. Ameri- refrigeration
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consumption below 3,450 mg (1.5 teaspoons) per can prisoners of war, incarcerated in Britain’s displaced salt
day. Dartmoor prison, bitterly complained that the 1.5 as the main
Consistent with the NHANES studies, 25-27 teaspoons of salt per day they received was part
the paper demonstrated significant increases of “…scanty and meager diet for men brought means of
in cardiovascular mortality as consumption of up in the land of liberty, and ever used to feast food
sodium dropped from a high of 260 mmols (just on the luscious fruits of plenty…” Declassified preservation
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over 2.5 teaspoons of salt) down to a low of 107 World War II documents regarding rations fed to
mmols (a bit more than one teaspoon). American prisoners of war show a ration of one salt
Finally, based on a long-term study with a hundred forty grams per week or 3.3 teaspoons consumption
large cohort, the O’Donnell paper sets out a J- per day. in the U.S.
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shaped response curve with the range of lowest After World War II, when refrigeration be-
risk between a daily consumption of 1.3 and three gan to displace salt as the main means of food dropped
teaspoons of salt per day. preservation, salt consumption in the U.S. (and dramatically
If the data from the above studies are com- somewhat later in other countries) dropped dra- and has
piled, it is apparent that the range of sodium matically to about half that rate, or nine grams
intake at which there is least negative health (1.5 teaspoons) per day and, based on twenty-four remained flat
outcome impact is anywhere above approxi- hour urinary sodium data, has remained flat for for the last
mately 3,000 mg per day or the equivalent of the last fifty years. During that time, rates of fifty years.
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1.3 teaspoons of salt. This also happens to be hypertension have increased, thus casting doubt
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the range that most people around the world on any linkage between the two.
consume. These data are not based on surrogate It is telling that this sudden drop took place
end points, but on hard outcomes (mortality) and without pressure or influence from any govern-
dose responses involving measurable feedback ment Dietary Guidelines, public health institu-
responses (renin, aldosterone, catecholamines, tions or strident warnings from salt-reduction
cholesterol and triglycerides) that, in the words advocates. The massive reduction was the result
of the DRIs, are not subject to “imprecision in of an effortless shift to a palatable, cold-chain-
blood pressure measurement.” based food supply. It is further interesting that
These results support the idea that sodium this abrupt drop halted at one level of consump-
is consumed in a fairly narrow hygienic range, tion fifty years ago and descended no further. It
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which has more recently been approximated as is equally extraordinary that, without guidance
2,691-4,876 mg or between 1.2 and 2.13 tea- or pressure of any kind, the consumption of salt
spoons of salt per day. around the world, for more than two centuries
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Considering the available evidence, it is has remained in the range of 1.5 to three tea-
difficult to determine a practical maximum for spoons per day, which, from all the available
salt because the data suggest that such a level data, appears to hold the lowest risk for us. It
is outside our current consumption range; i.e., lends support to the notion of the “wisdom of the
greater than 7,000 mg sodium or the equivalent body” at work through a mechanism that may not
of three teaspoons of salt per day. In other words, be as obvious as the typical sodium appetite so
our taste response to salt may be self-limiting. common in most other mammalian species, but
effective nevertheless.
HISTORICAL RATES OF Regardless of the evidence, we now must
SALT CONSUMPTION face a certain reality resulting from the two
It is of great interest that available data sug- decades long campaign to reduce salt. Because
gest Western societies consumed between three the Dietary Reference Intakes for salt were pro-
and 3.3 grams of salt per day from the early 1800s mulgated by the Institute of Medicine, they were
until the end of World War II, based on military immediately adopted without question by most
archives for prisoner-of-war and soldier rations public health agencies around the world. This
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