Most research has linked high sodium consumption
with greater risks of stroke and cardiovascular disease. Evidence
has shown that men and women age 51 or older, African Americans or
those with hypertension, diabetes or chronic kidney disease face
especially high risks.
But when several studies produced findings suggesting diets could be
too low in sodium, the U.S. Institute of Medicine (IOM) asked
experts to review studies on the health effects of sodium.
The data "weren't entirely convincing," said Nancy Cook, lead author
of the current study published in the journal Circulation, and a
member of that expert panel.
Cook is a statistician at the Brigham and Women's Hospital and
Harvard Medical School in Boston.
In an attempt to resolve the conflicting information, Cook and her
team analyzed data from a previous large study called the Trials of
Hypertension Prevention (TOHP) designed to look at high blood
pressure. The TOHP followed the field's "gold-standard" technique of
measuring salt consumption in 24-hour urine samples.
Other salt consumption studies have used single urine collections or
overnight samples, neither of which provide as much consistency and
accuracy as samples that participants collected throughout an entire
day and night.
"The quality of the sodium measures (in TOHP) is probably better
than any other study out there," Cook said.
"We found there were no adverse effects with lower amounts of sodium
and benefits continued to be seen at the lowest sodium levels," she
said. The findings match up with most evidence available.
"People should realize — and it may be difficult to do with all of
the conflicting information in the press — that quality differs from
study to study," Cook said. "When you get down to the details, some
studies are more reliable than others."
The average American still eats about 3,400 mg of salt per day — about
1 1/2 teaspoons — despite public health awareness
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In a study published last year, Cook along with another group of
researchers projected that up to 500,000 deaths could be avoided in
the U.S. each year if more Americans reduced salt in their diets
(see Reuters Health story of February 14, 2013 here: http://reut.rs/1g7ZMxi.
Main food culprits containing high sodium include bread, cured meat,
pizza, poultry, soup, cheese and snacks, wrote Lyn Steffen of the
University of Minnesota School of Public Health in Minneapolis in an
editorial that accompanied the new study.
On the nutritional facts panel on food packaging, if the sodium
amount per serving is 5 percent daily value, then that is a
low-sodium product, Steffen said. Products with 20 percent daily
value are high-sodium.
Even though modern lifestyle is busy, Dr. Graham MacGregor of Queen
Mary University and chairman of the World Action on Salt and Health
lobby group, suggested a solution: "If you cook fresh vegetables,
potatoes, pasta and rice with fresh meat or fish, make more than you
can consume, you can then put portions in the freezer and use this
on different occasions so that the food can be instantly ready."
In restaurants, the challenge to eat less salt can be greater. "You
can request that no salt be added," Cook said.
"If you suddenly cut all sodium from your meals, then things will
taste bland," Cook said. "So it's important to lower sodium
gradually and get accustomed to lower amounts of salt."
As the body adjusts to lower sodium levels, then foods with high
sodium may be less appealing, she said.
Circulation, online Jan. 10, 2014.
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