*Amount of salt and percent of daily intake provided by the nutrition facts label displayed on these food products.
as listed on
One slice Fiber
Two tablespoons Kraft
1/2 cup Kemps
What Is Salt?
In chemical terms, salts are ionic compounds. To most people, salt refers to table salt, which is sodium chloride. Sodium chloride forms from the ionic bond- ing of sodium ions and chloride ions. There is one sodium cation (Na+) for every chloride anion (Cl–), so the chemical formula is NaCl (Fig. 1).
The element sodium is very reactive and
can even react explosively with water. For
this reason, it is not found free in nature. In
table salt, sodium is in the form of sodium cat-
ions (Na+), which separate from the chloride
anions (Cl–) when the salt dissolves in water.
Sodium, located at the far left of the third
row of the periodic table, has only one
valence electron. Because its nucleus has
a relatively small effective positive charge, it
readily loses this outer electron. In contrast,
chlorine, at the other end of the same row
of the periodic table, has built up six additional protons and so has a great affinity for
electrons and can readily accept one more
in its valence shell of electrons. Stability is
achieved when sodium’s one valence electron
is transferred to chlorine, producing sodium
U.S. recommended limits for salt ( 2,300 mg
of sodium per day) have more heart trouble
than those consuming more salt. This study
included approximately 150,000 people from
17 countries and was published in the New
England Journal of Medicine.
Scientists challenging the current guidelines
say people should consume at least 3,000
mg of salt per day and up to 6,000 mg per
day. The new research results suggest a low-
sodium diet may stimulate the production of
renin, an enzyme released by
the kidneys. Renin plays a
role in regulating the body’s
water balance and blood
pressure. Too much renin
may harm blood vessels, and
a high-salt diet would help
lower the amount of renin
Why we need
So why do we need salt
in the first place? Salt, espe-
cially the sodium ions (Na+)
present in its NaCl structure,
How much is enough?
Surprisingly little is known about how much
salt we need. U.S. residents consume, on
average, about 3,400 mg of salt per day. For
decades, the U.S. government and organizations such as the American Heart Association
have recommended people consume less
salt. Current dietary guidelines recommend
no more than 2,300 mg of sodium—about
a teaspoon of salt—per day for teens and
adults. No more than 1,500 mg per day is
recommended for groups at higher risk of
heart disease, including African Americans
and everyone over the age of 50.
The U.S. dietary guidelines were established
in the 1970s when relatively little information
was available about dietary salt and health.
The guidelines were the best guess, given the
information available at the time. However, the
guidelines made little difference in people’s
behavior. Between 1957 and 2003, U.S. residents consumed, on average, 3,400 mg of
salt per day.
Also, over the years, salt consumption
remained steady, even though manufactur-
ers added more salt to commercial foods.
This consistency in salt intake suggests that
people may somehow automatically regulate
the amount of salt they eat. If that is true, does
it mean people instinctively choose the right
amount of salt? Or perhaps people used less
salt at the table, in an attempt to follow the
new guidelines, but unknowingly consumed
more salt in their prepared foods.
Some scientists now say that the average
amount of salt U.S. residents eat ( 3,400 mg of
salt per day) is safe and may even be healthier
than the lower government guidelines. In
fact, a study found that people who meet the
12 ChemMatters | FEBRUARY/MARCH 2016 www.acs.org/chemmatters
Figure 1. Table salt, or sodium chloride
(NaCl), consists of equal numbers of
sodium cations and chloride anions
that are arranged in a repeating three-dimensional structure in which the
cations and anions alternate with each
other in all three dimensions.
Do these taste salty to you?