How salt intake may lead to sudden death

The World Health Organisation (WHO)
recommends that adults should consume
less than 2 g of sodium per day. But a new
study finds that sodium intake above this
recommendation accounts for almost 1 in
10 cardiovascular deaths globally each
year.
Researchers estimate that 1 in 10
cardiovascular deaths each year are
attributable to sodium intake above the
WHO recommendations of 2 g per day.
The research team, led by Dr. Dariush
Mozaffarian of the Friedman School of
Nutrition Science and Policy at Tufts
University in Medford, MA, recently
published their findings in The New England
Journal of Medicine.
Sodium is an element that occurs naturally
in most foods, such as table salt, milk,
beets and celery. It is also added in high
amounts to processed foods, including
bread and processed meats.
Too much dietary sodium can increase
blood pressure, and high blood pressure is
a major risk factor for cardiovascular
diseases, such as heart disease and
stroke.
“However,” says Dr. Mozaffarian, “the
effects of excess sodium intake on
cardiovascular diseases globally by age,
sex, and nation had not been well
established.”
To gain a better insight into how excess
dietary sodium influences cardiovascular
health on a global scale, the research team
analysed data from 205 surveys of sodium
intake representing approximately 75% of
the world’s adult population.
They also assessed global nutrition data in
order to see how sodium intake varies by
sex, age and country. Furthermore, they
conducted pooled meta-analyses to
measure the effects of sodium on blood
pressure, and separately, the effects of
blood pressure on cardiovascular
diseases.
The team’s findings were applied to current
global rates of cardiovascular diseases,
and they used this information to estimate
how many deaths are caused by sodium
intake above 2 g per day.
Results of the study revealed that the
average worldwide sodium intake in 2010
was 3.95 g per day - almost double the
daily recommendation set by the World
Health Organisation (WHO).
All worldwide regions had sodium intakes
above the WHO recommendation. These
ranged from 2.18 g per day in sub-Saharan
Africa to 5.51 g per day in Central Asia.
This excess sodium intake was attributable
to 1.65 million cardiovascular-related
deaths worldwide - the equivalent to 1 in 10
deaths from cardiovascular causes.
The researchers found that four out of five
global deaths attributable to excess sodium
intake occurred in low- and middle-income
countries.
The average daily sodium intake in the US
was almost 80% higher than the WHO
recommendation, at 3.6 g, and significantly
higher than the 2.3 g per day intake
recommended by the federal government’s
Dietary Guidelines for Americans.
In addition, the researchers found that daily
sodium intake above 2 g accounts for
around 58,000 cardiovascular-related
deaths in the US each year.
Commenting on the results, study author
John Powles, of the department of public
health and primary care at the University of
Cambridge in the UK, says:
“These new findings inform the need for
strong policies to reduce dietary sodium in
the United States and across the world.”
From their meta-analyses, the researchers
found that reducing sodium intake lowered
blood pressure in all adults, particularly
among blacks, older adults and those who
already had high blood pressure.
“Programmes to reduce sodium intake
could provide a practical and cost-
effective means for reducing premature
deaths in adults around the world,” adds
Powles.
The team notes that their study is subject
to some limitations. For example, estimates
of sodium intake were based on urine
samples, which could have underestimated
actual sodium consumption.