Eating less salt may not lower risk of heart disease
Contrary to what medical experts have been saying for years, a new
study suggests salt may not be as bad for the heart as commonly
believed.
Researchers from the Universities of Exeter and Plymouth in Exeter,
UK reviewed data from seven studies with nearly 6,500 participants who
reduced their salt intake and found that while eating less salt did
lower blood pressure, it did not reduce the risk of dying or of having
heart disease.
But this finding doesn't mean people can eat as much salt as they
want. The authors caution that they don't have enough data to come to
any firm conclusions about salt intake and heart disease.
"We would require some 2,500 cardiovascular events in over 18,000
trial participants to detect a small reduction in relative risk," they
wrote. They also said that the study subjects only moderately lowered
their sodium intake, so the effect on blood pressure and heart disease
was small.
Numerous experts who were not involved with this research weighed in
on the findings, and their opinions are mixed.
They agree more data are needed to provide a better explanation of
the findings and that there are other limitations to the study design,
but debate how big a role sodium plays in the development of heart
disease.
"I had been long concerned that the bold and strident public health
recommendations of trying to reduce salt intake in Western societies was
not based on robust data and may be premature," said Dr. Salim Yusuf,
professor of medicine at McMaster University in Hamilton, Ontario,
Canada. The studies reviewed by the authors, he said, suggest the
relationship between salt consumption and cardiovascular disease is
complex and requires more research. This research should be a priority,
he added.
Weak data
"I have always viewed the data for salt shortening life as being very
weak," said Dr. Ken Fujioka, director of the Nutrition and Metabolic
Research Center at Scripps Health in San Diego.
But other experts say salt does contribute to heart disease and other
life-threatening conditions, which can lead to an untimely death in the
long term.
"There is extensive evidence that excessive salt intake places many
individuals at risk for hypertension and cardiovascular disease. These
long-term effects may not result in death for many years," said Dr.
Pascal Imperato, dean of SUNY Downstate Medical Center's School of
Public Health in Brooklyn, NY.
"Reducing blood pressure does reduce the risk of cardiovascular
disease and related mortality," said Dr. Redford Williams, director of
the Behavioral Medicine Research Center at Duke University in Durham,
NC.
"We do know that high blood pressure, while associated with all forms
of cardiovascular disease, is particularly associated with risk for
stroke," said Dr. Merle Myerson, director of the Cardiovascular Disease
Prevention Program at St. Luke's-Roosevelt Hospital in New York.
Dr. Clyde Yancy, chief of the Division of Cardiology at Northwestern
University's Feinberg School of Medicine, said prior research does
support the conclusion that restricting sodium can lead to "fewer deaths
and much less money spent on health care for blood pressure-related
diseases."
Bad diet
"If someone gets large amounts of salt in their diet, it may be an
indicator of a bad diet," said Keith Ayoob, associate professor of
pediatrics at the Albert Einstein College of Medicine in the Bronx, NY.
"Foods that are staples in the US tend to be high in both sodium and
fat. Reducing the intake of many of these foods would reduce body
weight, which would have a significant effect on blood pressure and
[cardiovascular disease]," said Carla Wolper, an obesity researcher at
St. Luke's-Roosevelt Hospital. "If Americans really reduced salt
consumption, they would most likely also be lowering fat intake and thus
caloric intake."
Experts recommend taking these findings with a grain of salt and
focusing efforts on other ways to prevent cardiovascular disease, such
as eating more fruits and vegetables and exercising. They do, however,
suggest avoiding excessive salt consumption. "The data are not strong
enough to recommend marked sodium restriction for the entire country,
but I also do not believe that these data negate the overall
recommendations to at least avoid excessive salt," said Dr. Carl Lavie,
medical director of Cardiac Rehabilitation and Prevention at the John
Ochsner Heart and Vascular Institute in New Orleans. The US Dietary
Guidelines recommend no more than 1,500 milligrams of sodium a day for
all African Americans and other adults older than 50, but some believe
this is overly restrictive.
Low-sodium diet
"1,500 mg/day is actually lower than the typical hospital's
'low-sodium diet' of 2,000 mg/day," Ayoob said.
"I do generally recommend lowering salt intake, but don't push it too
hard, and focus more on calories and exercise," said Dr. Christopher
Cannon, a physician at Brigham and Women's Hospital in Boston. "People
get treated for their blood pressure with medicine now," said Dr. Louis
Aronne, clinical professor of medicine at NY-Presbyterian/Weill Cornell
Medical Center. "There are so many medicines that are effective, with so
few side effects, it makes me wonder if dietary restriction is useful."
Some people, such as the approximately one in four who are not
sensitive to the effects of salt as well as those who are healthy and
don't have high blood pressure should focus on other methods of
preventing heart disease.
- abcnews
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