MONDAY, July 11, 2011 (HealthDay News) -- Too much salt and too little potassium in your diet may boost your risk for cardiovascular disease and death, a new study shows.
Earlier studies had found an association between high blood pressure and high levels of salt consumption and low levels of potassium intake. The combination of high salt -- sometimes called sodium -- and low potassium appears to convey a stronger risk for cardiovascular disease and death than each mineral alone, the study authors said.
"The combination of high sodium and low potassium is really a double whammy for cardiovascular risk and for mortality," said lead researcher Dr. Frank B. Hu, a professor of medicine at Harvard Medical School.
Although sodium and potassium act independently, high potassium levels can counteract some of the effect of high sodium, Hu said. "But the adverse effects of high sodium cannot be completely offset by a high potassium diet," he said.
For the study, published in the July 11 issue of the Archives of Internal Medicine, Hu's team collected data on 12,267 people who were part of the Third National Health and Nutrition Examination Survey Linked Mortality File, from 1988-2006. In addition to mortality data, this survey contains dietary information.
To find out the role of salt and potassium and the risk of cardiovascular disease and death, the researchers looked at the levels of these minerals and the ratio between them. Over an average of 14.8 years of follow-up, 2,270 people died. Of these, 825 died from cardiovascular disease -- which includes stroke -- and 443 died of heart disease.
After taking into account variables such as gender, race and ethnicity, weight, high blood pressure, education and physical activity, Hu's group found that high salt intake was associated with a 20 percent increased risk of death, while high potassium intake was associated with a 20 percent decreased risk of dying.
What's more, high salt consumption coupled with low potassium intake was a significant risk factor for cardiovascular disease and heart disease, the researchers added.
"We should continue to reduce the amount of sodium in our diet, especially in processed foods," Hu said. "We should also promote high consumption of potassium, especially from fruits and vegetables," he added. "Those things should go hand-in-hand."
While the study uncovered an association between heart disease and the two minerals, it did not prove a cause-and-effect.
Commenting on the study, Lona Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas, said, "The findings are not surprising to me."
The benefits of potassium to counterbalance the effects of salt for controlling high blood pressure have been known for years, but get little attention, Sandon said. "There have been hints in the past research literature that the ratio of the two may be more important than the nutrients individually," she said.
Diets with plenty of fruits and vegetables are associated with better heart health, Sandon said. "Fruits and vegetables are your best natural sources of potassium and they are naturally low in sodium," she explained.
"I agree with the authors that more emphasis should be put on the importance of getting more potassium while lowering sodium intake," Sandon said.
"The DASH (Dietary Approaches to Stop Hypertension) diet does just that and has been around for quite some time now," she stated. "It encourages people to eat more foods high in potassium (fruits, vegetables, low-fat dairy) while eating less sodium-laden foods."
Sandon noted that this is consistent with the 2010 Dietary Guidelines for Americans, which encourage increased fruit and vegetable intake while lowering intake of foods high in sodium.
Those guidelines recommend that Americans limit their daily salt intake to less than 2,300 milligrams (about a teaspoon) for most people, and to less than 1,500 milligrams for people 51 or older, all blacks, and people who have high blood pressure, diabetes or chronic kidney disease, regardless of their age.
For more on ways to reduce salt in your diet, visit the U.S. National Heart, Lung, and Blood Institute.