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Study Puts New Focus on Health Risks of Getting Too Much Salt
By Charlene Laino
WebMD Health News
Reviewed by Laura J. Martin, MD
Feb. 9, 2011 (Los Angeles) -- Fewer than 2 teaspoons of salt a day may raise your risk of stroke.
In a study of over 2,600 people, those who got more than 4,000 milligrams of sodium a day were about two-and-one-half times more likely to have a stroke than those who got less than 1,500 milligrams a day.
One teaspoon of salt contains 2,300 milligrams of sodium.
Interestingly, the results held true regardless of whether a person had high blood pressure, says study researcher Hannah Gardener, ScD, an epidemiologist at the University of Miami Miller School of Medicine.
Salty diets have been linked to high blood pressure, a major stroke risk factor.
The findings were presented at the American Stroke Association International Stroke Conference (ISC).
How Much Salt Is Healthy?
The study doesn't prove cause and effect. People who eat a lot of salt may share some other characteristic that places them at increased risk for stroke.
Still, "it looks like even small changes in salt intake can make a difference in stroke risk," says Steven Greenberg, MD, PhD, vice chair of the ISC meeting committee and professor of neurology at Harvard Medical School.
So how much salt should you have? The American Heart Association recommends 1,500 milligrams of sodium a day. And the U.S. Dietary Guidelines for Americans call for less than 2,300 milligrams a day for most people; 1,500 milligrams a day for those over 50 or who have hypertension, diabetes, or chronic kidney disease.
If the new findings are any indication, we're not doing too well at meeting those goals. A staggering 88% of participants said they got more than 1,500 milligrams of sodium a day and 21% got more than 4,000 milligrams a day.
Measuring Salt Intake
The study involved 2,657 participants in the Northern Manhattan Study. At the start of the study, they were asked to fill out a questionnaire that included questions about how much salt they consumed.
Over the next 10 years, 227 participants suffered an ischemic stroke, the most common type of stroke. It occurs when a clot blocks blood flow to a region of the brain.
Results showed that for every 500-milligram increase of sodium per day, the risk of ischemic stroke increased 18%.
The analysis took into account a host of stroke risk factors, including age, sex, race, education, alcohol use, exercise, daily caloric intake, smoking status, diabetes, high cholesterol, high blood pressure, and previous heart disease.
One drawback of the study is that participants were only asked about their salt intake at one time point, Gardener says.
Morton Satin, vice president of the Salt Institute, a trade association representing the salt industry, tells WebMD that studies with designs such as this are limited "because of the lack of control over a host of variables."
While Satin says he is unfamiliar with the new findings, he notes that a recent study shows that since the 1960s, salt consumption in the U.S. has remained flat.
As a result, it's only logical to conclude "that salt is not linked to the rising or falling rates of anything: hypertension, cardiovascular disease, obesity, etc.," he writes in an email.
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.
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