What's the role of potassium in your body?

Potassium is a mineral that controls the amount of fluid inside the cells. Foods highest in potassium include dried fruits, lentils and other legumes, potatoes, spinach, and bananas.
Potassium is a mineral that controls the amount of fluid inside the cells. Foods highest in potassium include dried fruits, lentils and other legumes, potatoes, spinach, and bananas.

Potassium is an often overlooked nutrient. Until 2018, nutrition labels didn't have to list the potassium content. Today, there's a growing awareness of its importance. For good health, you should know about potassium sources and benefits.

Potassium belongs to several key groups:

  • Electrolytes. Electrolytes are ions that conduct electricity, and they interact with your cells to do certain physiological functions.
  • Minerals. Minerals are solid, naturally occurring substances, which are necessary for maintaining your health.
  • Micronutrients. Micronutrients are nutrients that your body needs in a tiny amount.

Sodium and potassium work together in the body — sodium regulates the fluid outside the cells, while potassium controls the amount of fluid inside the cells.

Our ancestors ate a diet rich in potassium and low in sodium. But, today, most Americans get twice as much sodium as potassium. Many people could benefit from eating less sodium and more potassium.

How much potassium do you need?

Scientists around the world disagree on how much potassium humans need. One number that’s often cited is 4700 milligrams per day. Very few Americans reach that level.

Doctors rarely recommend potassium supplements to their patients because too much potassium is toxic to humans. It's much safer to get potassium from food.‌

Too much or too little potassium can cause serious health problems, especially if potassium levels go very high or very low. Certain illnesses can cause high or low potassium.

  • Hypokalemia (low potassium). When potassium in the body gets too low, a condition called hypokalemia can occur. Hypokalemia is usually the result of vomiting and diarrhea or the overuse of diuretics. Abnormal heart rhythms can result. The remedy is potassium taken by mouth.
  • Hyperkalemia (high potassium). If potassium is too high, hyperkalemia can happen. Kidney disease is the most common cause of high potassium. If you have low kidney function, you may have to restrict your potassium intake. Hyperkalemia can cause heart problems. Extremely high potassium levels can cause the heart to stop. Treatment for hyperkalemia depends on its cause. 

Benefits of potassium

Good potassium levels can improve health, especially in those with certain conditions:

  • High blood pressure. Low-sodium high-potassium diets may lower blood pressure, which reduces your chance of stroke.
  • Bone loss. Too little potassium can cause loss of calcium from the bones. Increasing the potassium you get from food sources can improve bone density.
  • Kidney stones. When calcium leaves the bones, it goes into the urine. It can settle in the kidneys, where it can cause painful kidney stones.

Perhaps you've heard that a lack of potassium causes muscle cramps — especially those intense leg cramps that occur at night. Scientific proof for this belief is lacking, though.

Doctors are unsure what causes most leg cramps. If you only get them occasionally, you can safely ignore them. If they happen often, talk to your doctor.

Eating more bananas or other potassium-rich food is unlikely to help.

Potassium sources in food

Your body absorbs potassium from food sources very well. It uses about 85 to 90 percent of what's available. You can get potassium from many foods and drinks, including coffee and tea. Beef and salmon are good food sources of potassium, and so are dairy products like milk and yogurt.

The very best sources are fruits and vegetables. Not only do they top the list of potassium-rich foods but they also provide other health benefits.

Dried fruits

Dried apricot is the potassium champ with about one-quarter of your daily need in one serving. Raisins and prunes are also high on the list.

Besides potassium, dried fruit offers healthy antioxidants and fiber. Dried fruit is a calorie-dense food. Don't eat too much, and check labels for added sugar.

Lentils and other legumes

Lentils are another good source of potassium with about 15 percent of your daily need per cup. Kidney beans and soybeans are excellent as well.

These foods belong to the category known as legumes. Legumes are nutritional powerhouses, containing protein, fiber, complex carbohydrates, vitamins, and minerals. They are also inexpensive — especially when you buy the dried ones. 

Potatoes

If you need an excuse to dig into a delicious baked potato, here's one. It's a rich source of potassium.

You may think of potatoes as unhealthy, but that's mainly true if you fry them or add fatty condiments. Simply prepared, they have vitamin C, a lot of fiber, and even a little protein, all along with potassium.

Spinach

Spinach's reputation as a superfood is well earned. It’s an excellent source of six vitamins and six minerals, including potassium. It has anti-inflammatory qualities and is low in calories but high in fiber. Unlike some vegetables, spinach keeps most of its nutrients when cooked, especially when cooked quickly. 

Bananas

Bananas have a reputation as the best source of potassium. They are a good source, but one banana provides only about 10 percent of your daily need.

Bananas are also a good source of fiber, vitamin C, vitamin B6, magnesium, and manganese. With 15 grams of natural sugar, they are not a low-calorie food. Still, unless you are on a strict diet for diabetes or weight control, feel free to enjoy  an occasional banana.

QUESTION

According to the USDA, there is no difference between a “portion” and a “serving.” See Answer

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Medically Reviewed on 10/4/2021
References
SOURCES:

American Family Physician: "Nocturnal Leg Cramps."

European Food Information Council: "The Nutritional Value of Potatoes."

Harvard Health Publishing: "Is eating dried fruit healthy?" "The importance of potassium."

Harvard T.H. Chan School of Public Health: "Bananas," "Legumes and Pulses," "Potassium."

Merck Manual Consumer Version: "Hyperkalemia," "Hypokalemia."

National Institutes of Health: "Potassium: Fact Sheet for Consumers."

Nutrition Today: "What Is the Evidence Base for a Potassium Requirement?"

PennState Extension: "Potassium, an Often Forgotten Nutrient."

World's Healthiest Foods: "Spinach."