Featured Nutrient: Potassium

Joyce Hendley

A vital nutrient that helps keep blood pressure healthy

The word “ubiquitous” comes to mind with potassium, a mineral found in all the body’s cells as well as in the fluid surrounding them. It’s involved in almost every vital body process: maintaining blood pressure, heart and kidney function, muscle contraction, even digestion. And we humans were obviously meant to get plenty of it, since it’s abundant in just about any fresh, whole food—from potatoes and peas to milk and fish.

Why, then, do surveys show that most Americans get less than half the recommended amounts of potassium?

Problem is, say experts, we haven’t been eating many of those whole foods lately. When a food is processed—“whether it’s cooked or put in a can, you lose potassium,” explains R. Curtis Morris, Jr., M.D., a nephrologist at the University of California at San Francisco and a member of the advisory panel on Dietary Reference Intakes. Matters worsen when manufacturers add salt during processing, as they almost always do: when we eat those foods, we deplete our potassium stores to help us handle the excess sodium. Many researchers feel that the resulting sodium-potassium imbalance is one reason why the U.S. incidence of hypertension (high blood pressure) keeps climbing, —and with it, our risk of diseases related to blood pressure, notably stroke.

What would happen if we got enough?

If Americans increased their potassium intake to meet recommendations, says Morris, “we’d readily reduce the likelihood of people expressing hypertension.” For evidence, we need look no farther than the DASH (Dietary Approaches to Stop Hypertension) and Omni Heart trials—major studies in which people with confirmed or near hypertension saw significant drops in their blood pressure after eating a potassium-rich diet that included 9 to 10 daily servings of fruits and vegetables and ample amounts of low-fat dairy products.

More potassium would likely benefit our bones and kidneys too, says Morris, who is one of many who believe that our protein- and cereal-grain-rich western diet produces more acid than our bodies were designed to handle. Excess acid in the blood causes calcium and other minerals to leach out from bones to buffer it, causing bone loss and encouraging the formation of calcium-containing kidney stones. Potassium-rich foods, on the other hand, are alkaline, so eating more of them might help counterbalance this tendency, thus helping to preserve bones and prevent kidney stones.

How much you need—and how to get it

Because of potassium’s health benefits, the recommended adequate intake of potassium for teens and adults is 4,700 milligrams (mg) daily. (The exception are people with kidney disease or severe congestive heart failure, who may have trouble getting rid of the mineral and must limit their intake.) While getting enough potassium through foods is doable, Morris readily admits it takes plenty of fresh fruits, vegetables and “organization” to pull it off. Those who have trouble can ask a doctor to recommend a potassium citrate or malate supplement.