Cardiology study looks at sodium and potassium in diet

By Dr. Ananya Mandal, MDJul 11 2011

A new study suggests that in addition to cutting the amount of sodium in their diets to improve heart health, Americans should also increase consumption of a key mineral found in many fruits and vegetables, potassium.

This comes from researchers at the Centers for Disease Control and Prevention (CDC) who studied 12,267 adults who participated in a federal nutrition study. It tracked their diets and followed them for nearly 15 years to observe rates of cardiovascular disease, heart attacks and death. The study was published in this week's Archives of Internal Medicine.

The authors write that sodium, a key component of salt, has been shown to raise blood pressure, which in turn raises the risk of heart disease, but studies have shown inconsistent results as to whether high-sodium diets actually boost the risk of heart-related problems. Potassium has been found to offset sodium's impact on blood pressure.

The team looked at sodium and potassium intake and found that higher sodium intake was associated with a higher risk of premature death from any cause, while higher potassium intake was associated with a lower risk of dying prematurely. Looking at heart-related deaths alone, sodium itself wasn't associated with an increased risk, but researchers said higher potassium intakes were linked with lower heart-related death rates.

The authors termed it as sodium-potassium ratio. A high sodium-potassium ratio means a person consumes more sodium relative to potassium. Sodium-potassium ratios could be improved by either lowering sodium intake or raising potassium intake, or both.

Results revealed that those who had highest ratios were more than twice as likely to die from a heart attack compared with those with the lowest ratios. They also were 46% more likely to die from a heart-related death compared with those with the lowest ratios. (Looking at all causes of death, people with high ratios saw a 46% higher risk.)

Elena Kuklina, an epidemiologist at the CDC's division for heart disease and stroke prevention said, “When you have a more imbalanced diet, you are more at risk.” To remedy this is to eat more fruits and vegetables, researchers said. About 80% of the sodium consumed by Americans comes from processed or restaurant foods, making it harder to lower sodium intake than it is to raise potassium intake.

The most recent U.S. dietary guidelines, released earlier this year, recommend adults consume 4,700 milligrams of potassium a day. The guidelines called on Americans to reduce their daily sodium intake to less than 2,300 milligrams or about a teaspoon of salt. People who are 51 and older, African-American or have hypertension, diabetes, or chronic kidney disease, recommendations call for no more than 1,500 milligrams a day. The average American adult consumes 3,400 milligrams of sodium a day.

Potassium rich foods are potatoes, spinach, bananas, prune juice, broccoli, peas, lima beans, tomatoes, sweet potatoes, winter squashes, citrus fruits, cantaloupe, kiwi, apricots, milk, plain yogurt and fish. People who consume a largely plant-based diet naturally get less sodium and more potassium. But few Americans follow such a diet. Instead high-salt, low-potassium levels are often found in popular processed foods and snacks, say the authors of an editorial accompanying the study. Dr. Lynn D. Silver and Dr. Thomas A. Farley, of the New York City Department of Health and Mental Hygiene, in their editorial write, “It is crucial that we understand the interplay of sodium and potassium in the diet and how to optimize intake in an increasingly processed food supply without generating harm.”