Potassium is an essential mineral that your body uses mainly as an electrolyte, which is an element that becomes electrically charged in fluid. Positively-charged potassium interacts with other electrolytes, such as sodium and chloride, to allow for the movement of water in and out of cells as well as the electrical conductance of nerve messages. The condition of low blood potassium, which is called hypokalemia, is unusual among Americans, because most people's diets have enough of the nutrient. However, some conditions and diseases greatly increase its likelihood.
Electrolytes such as such as potassium are essential for water balance, blood pressure, pH balance, heart function and muscle contraction. About 98 percent of the potassium in your body is found inside your cells, where it works with sodium outside your cells. Small changes in potassium levels outside your cells significantly impact the function of your nerves, heart and skeletal muscles. Your kidneys normally control potassium levels by excreting excess amounts into urine. A lack of dietary potassium is relatively rare in the United States, although kidney dysfunction, over-use of diuretics, excessive sweating from exercise, severe vomiting or chronic diarrhea may lead to low potassium levels.
The amount of potassium needed by most adults range from 2,000 to 3,000 milligrams each day, depending on a person's body size and activity levels. Normal potassium blood levels range from 3.6 to 4.8 milliequivalents per liter, so levels below 3.6 are too low and classified abnormal by your doctor. However, most symptoms related to hypokalemia are not noticeable until levels drop below 3.1 milliequivalents. Symptoms of severe hypokalemia and greatly increased risk of death occur below 2.5 milliequivalents.
Symptoms of Hypokalemia
Initial symptoms of hypokalemia include constipation, fatigue, muscle weakness, muscle twitching and dry skin. As potassium levels continue to drop and hypokalemia gets worse, high blood pressure and elevated heart rate develop. Advanced symptoms may include irregular heart rhythm, excessive perspiration, muscle paralysis and nausea. Severe hypokalemia ultimately leads to congestive heart failure.
Good Sources of Potassium
If your potassium levels are a little on the low side, then consider adding some potassium-rich foods to your diet. Fish and seafood are very good sources of potassium, but so are chicken, bananas, melons, most tropical fruits, oranges, tomatoes, avocados, white potatoes, sweet potatoes, carrots, prunes, spinach, some beans and most dairy products.
Potassium supplements are widely available, but taking too much over a period of many days or weeks could disrupt your kidney function and lead to swelling and reduced heart rate. Talk to your doctor about appropriate levels of potassium supplementation. Depending on how low your potassium levels are and the the kinds of symptoms you have, your doctor may recommend quickly increasing blood levels intravenously, which involves placing a needle in your arm.
- Human Physiology: An Integrated Approach; Dee Silverthorn and William Ober
- Textbook of Functional Medicine; David S. Jones
- Encyclopedia of Human Nutrition; Benjamin Caballero et al.
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.