A Primer on Potassium

What? Potassium can lessen the impact of sodium on my  blood pressure?How does potassium affect my heart health?

Potassium is a mineral that our bodies need to stay healthy. Eating foods with potassium is important in controlling blood pressure because potassium blunts the effects of sodium. The more potassium we eat, the more sodium we pass out of the body through urine. Potassium also helps relax blood vessel walls, which helps lower blood pressure.

“More and more, we’re realizing how important potassium plays a role in lowering blood pressure,” said Rachel K. Johnson, Ph.D., M.P.H., R.D., an AHA spokeswoman, AHA Nutrition Committee Chair, and Bickford Professor of Nutrition at the University of Vermont.

But not so fast. Even though potassium can help blunt the blood pressure-raising effects of sodium, eating more potassium isn’t an excuse to slack off in your efforts to break up with that excess salt.

How much potassium should I eat?

The recommended potassium intake for an average adult is 4,700 milligrams (mg) per day. Most of us aren’t getting nearly that much. On average, adult males eat almost 3,200 mg/day, and adult females eat about 2,400 mg/day.

But potassium is only part of an overall heart-healthy eating pattern. Other dietary factors that may affect blood pressure include amount and type of dietary fat; cholesterol; protein and fiber; calcium and magnesium, and of course, sodium.

For example, the DASH (Dietary Approaches to Stop Hypertension) diet study found that a diet rich in fruits, vegetables, fat-free or low-fat (1 percent) milk and milk products, whole-grain foods, fish, poultry, beans, seeds and unsalted nuts reduced blood pressure compared to a typical American diet. The DASH eating plan also had less sodium; sweets, added sugars and sugar-containing beverages; saturated and trans fats; and red meats than the typical American diet.

What foods have potassium?

Many of the elements of the DASH diet — fruits, vegetables, fat-free or low-fat (1 percent) dairy foods and fish — are good natural sources of potassium. For example, a medium banana has about 420 mg of potassium, and half a cup of plain mashed sweet potatoes has 475 mg.

Other potassium-rich foods include:

  • Potatoes
  • Greens
  • Spinach
  • Mushrooms
  • Lima beans
  • Peas
  • Tomatoes, tomato juice and tomato sauce
  • Oranges and orange juice
  • Cantaloupe and honeydew melon
  • Grapefruit and grapefruit juice (talk to your healthcare provider if you’re taking a cholesterol-lowering drug)
  • Prunes and prune juice
  • Apricots and apricot juice
  • Raisins and dates
  • Fat-free or low-fat (1 percent) milk
  • Fat-free yogurt
  • Halibut
  • Tuna
  • Molasses

Is it possible to have too much potassium?

Too much potassium can be harmful in older people and those with kidney disorders. Potassium affects the balance of fluids in the body. As we get older, our kidneys become less able to remove potassium from our blood. So, before taking any over-the-counter potassium supplement, talk to your healthcare provider.

Certain salt substitutes have a lot of potassium and very little sodium. They are not expensive and may be used freely by most people, unless you have certain medical conditions (such as kidney disease) or take certain medications. Talk to your healthcare provider about whether a particular salt substitute is right for you.