THURSDAY, Sept. 25, 2003 (HealthDayNews) --If you're like many Americans, you scour food labels for the sodium content of what lies beneath.
Researchers now say it's time to broaden your search.
A new study finds that while salt may boost blood pressure, this effect appears to be worsened by meager intake of calcium, potassium, magnesium and other beneficial nutrients.
The researchers looked at diet and high blood pressure in tens of thousands of Americans participating in a series of national health and nutrition surveys between 1980 and 2000.
In the surveys, sodium intake didn't have a major impact on blood pressure --though calcium consumption drove it down. People who reported eating more calcium, potassium and magnesium tended to have lower blood pressure than those who ate less of these nutrients.
When salt does have an impact on blood pressure, the researchers say, it appears to reflect poor intake of the other nutrients.
The findings were reported Sept. 25 at a meeting of the American Heart Association in Washington, D.C.
Dr. Daniel Jones, dean of the School of Medicine at the University of Mississippi and a spokesman for the American Heart Association, says more convincing evidence in other studies points to a stronger effect of salt on blood pressure. "The best data available from clinical trials simply tells us something different," Jones says. "This shouldn't sway medical practice."
A quarter of all American adults, and two-thirds of those over age 65, have high blood pressure -- considered a reading of at least 140/90 millimeters of mercury. Elevated pressure is linked to strokes, heart attacks, kidney failure and a host of other serious health problems.
Obesity, stress, alcohol abuse and lack of exercise each raises the risk of high blood pressure. Heavy salt intake also is linked to the condition, though the effect appears to be greater in certain people with a genetic susceptibility to salt.
Marlene Most, a dietitian at Louisiana State University's Pennington Biomedical Research Center has studied the impact of nutrition on blood pressure. The latest work, Most says, mirrors what she and colleagues have found in previous research.
One such study compared the effects on blood pressure of different diets with varying amounts of salt. It found that while reducing sodium intake did seem to lower blood pressure, increased consumption of potassium, calcium and magnesium did, too.
"It seems to be the combination of those nutrients, working in concert," that keeps blood pressure in check, Most says. "My feeling is that there might be other things in food that we don't know about" that also control pressure -- unstudied chemicals in vegetables, for example.
So why not load up on diet supplements to drive down blood pressure? "It won't work," Most says. "You need this multitude of minerals or perhaps these other components from food" to get the effect.
To get these nutrients in your diet, load up on fruits and vegetables. Milk and other dairy products are excellent sources of calcium.
The National Institutes of Health recommends people eat a maximum of 2,400 milligrams of salt a day, or about two teaspoon's worth. Ideally, experts say, salt intake should be about 1,500 milligrams a day, or about two-thirds of a teaspoon.
Although it may be relatively easy to stop salting food at the table, the trick is avoiding sodium in packaged and processed items such as soups and frozen dinners.
"Excess sodium is offered to us every day. It's impossible to eat a diet that's too low in sodium in this country," Jones says.
More information
For more on the dangers of high blood pressure, visit the National Heart, Lung, and Blood Institute or the American Heart Association.
