What Is the Function of Potassium in Humans?

Fruits and vegetables are excellent sources of potassium.
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That morning banana is an easy breakfast food, but you may not realize that the potassium it contains powers many of your vital functions. The third most abundant mineral in your body, potassium promotes muscle and nerve function, water balance and blood pressure control. Most adults do not eat enough of this valuable nutrient, but you can easily meet your needs by following a well-balanced diet.

Muscles and Nerves

    After a long workout, your body needs to replenish electrolytes, substances that conduct electrical currents in your body. Potassium is an electrolyte needed for nerve function and contraction of your skeletal muscles, heart and stomach. Vomiting, excessive use of diuretics and eating disorders can cause low potassium levels, leading to irregular heart beat, muscle spasms and temporary paralysis.

Blood Pressure

    A balance of sodium and potassium in your body promotes electrical activity and water balance. Your body spends 20 to 40 percent of its resting energy maintaining sodium and potassium balance in your cells. You feel bloated after a salty meal, because sodium makes the body retain water. Extra fluid in your blood increases your blood pressure and forces your heart to pump harder. To maintain healthy blood pressure, eat plenty of potassium-rich foods and eat less than 2,300 milligrams of sodium per day.

Other Functions

    Enzymes in your body need potassium to convert the carbohydrates you eat into energy. Potassium also facilitates healthy growth and repair of body tissues and creates protein that builds muscles. One sign of low potassium in the body is muscle damage and weakness.


    For good health, eat 4,700 milligrams of potassium per day. Fruits and vegetables are good sources of potassium. These include bananas, root vegetables, citrus fruits, dark leafy greens and vine fruits, such as grapes and blackberries. The U.S. Department of Agriculture recommends eating 1 1/2 cups of fruits and 2 1/2 cups of vegetables each day. Milk and yogurt are also excellent sources of potassium. For good health, have 3 cups of dairy each day.

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