Page 29 - Spring2012

SALT IS AN ESSENTIAL NUTRIENT unfortunate that consumers are not aware of all It is
In clinical studies, salt is calculated in mil- the other negative consequences that occur as a
limoles (mmol) of sodium, where 100 mmol of result of dietary salt reduction. unfortunate
sodium amounts to 2300 mg or the equivalent of that
one teaspoon of salt. PUBLIC PRESSURE TO REDUCE SALT consumers
If we do not consume sufficient sodium, In the late 1980s, in response to the notion
our metabolism, driven by specific feedback that sodium had a major impact on a population's are not aware
mechanisms, goes into a sodium-sparing mode blood pressure, an international study (Intersalt) of all the

so that the circulatory system can maintain os- was carried out to determine the impact of salt negative
motic balance and adequate blood pressure. This consumption on blood pressure. As it turned
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has several important consequences for us. A out, the per capita consumption of sodium in the consequences
reduced intake of sodium is characterized by the majority of countries ranged between 130-210 that occur
stimulation of the renin-angiotensin-aldosterone mmol sodium or the equivalent of 1.3 to two as a result of
hormonal system (RAAS). Renin, the first en- teaspoons of salt per day. The results indicated
zyme taking part in the RAAS was clearly shown that there was no clear pattern between the dietary salt
in a dose-response curve to increase as sodium level of salt intake and blood pressure. However, reduction.
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intakes fell below 150 mmol sodium (or 1.5 tea- there were four populations among the fifty-two
spoons of salt) per day. At a point of intake below groups that showed very low salt intakes and far
110 mmol sodium per day renin begins to rise lower than average blood pressures. The low-
rapidly. The RAAS feedback mechanism is the est consumption population in this group was
most transparent measure of our dose response the primitive Yanomami Indians, who live in
to salt intake and is a fundamental indicator of the Brazilian rain forest. Normally, data points
sodium intake sufficiency. that are very far from the rest of the pattern are
Although this cascade of reactions is de- referred to as outliers and are generally omitted
signed to sustain osmotic balance and blood from the analysis. In this case, the outliers were
pressure, chronically elevated levels of renin and included and a line drawn from them to the rest
aldosterone have significant negative effects on of the population in order to show that a pattern
the condition of the circulatory system and may relating salt consumption to blood pressure did
stimulate inflammatory agents within the body. exist. (See Figure 1.)
Included among the negative outcomes of chroni- While the advisability of making com-
cally elevated levels of renin and aldosterone are parisons between modern Western societies
insulin resistance, metabolic syndrome, cardio- and those that have vastly different lifestyles,
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vascular disease, cognition loss, and others.
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SALT AND BLOOD PRESSURE
The overwhelming public interest in salt
consumption derives from the concern over
its perceived universal impact on blood pres-
sure (BP). Unfortunately, this has long been a
subject of significant myth-information. The
cross-population blood pressure response to
salt reduction is heterogeneous. With major
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reductions in salt (more than half of our current
consumption), about 30 percent of the popula-
tion will experience a slight drop (2-6 mm) in
systolic BP, while about 20 percent will see a
similar increase in BP, and the remaining 50
percent of the population will show no effect
at all. Considering the relatively small impact FIGURE 1.
of major salt reduction on blood pressure, it is InterSalt Study
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