Potassium is a mineral and the world's seventh most abundant metal. It is an essential nutrient in the human body and functions in numerous bodily systems. Your body uses an estimated 20 to 40 percent of resting energy just to move potassium through cells. This much energy expenditure would only be for a nutrient that is necessary to sustaining your life.
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Potassium is absorbed from food in the gastrointestinal tract by the mucosal cells of the colon, where it then moves into the bloodstream. Your kidneys work to maintain the proper balance of potassium. Most of the potassium in your body is inside of cells, while most of the sodium is outside of the cells. Potassium and sodium are essential electrolytes; they are able to conduct electricity. The movement of potassium into the cell and sodium out of the cell creates an electrochemical gradient called the membrane potential.
Potassium is essential for maintaining the cell's membrane potential, which enables nerve impulse transmission. This is an electrical charge that travels along the nerve in response to stimuli, such as pressure, cold or pain. Membrane potential is required for muscles, including the heart, to be able to contract. The peristaltic movement of the intestines requires potassium as well. Cellular enzymes, including pyruvate kinase, require potassium to be able to function. Potassium is also important for maintaining osmotic balance, which preserves proper blood pressure.
Rather than a recommended dietary allowance, the Food and Nutrition Board of the Institute of Medicine suggests an adequate intake level, or AI, for potassium. The AI for potassium is 4,700 mg/day, and this amount should meet the needs of 90 to 95 percent of the population. The "What We Eat in America," or WWEIA, survey asks Americans what they ate in the past 24 hours. Using information from this survey, it is possible to calculate if the average American is meeting the AI for potassium. The data collected by WWEIA from 2007 to 2008 indicate that adults consume between 2,189 mg to 3,026 mg of potassium per day -- suggesting that the average American does not get enough potassium from their diet. Good sources of potassium include meat, vegetables, fruit, nuts and dairy products. If you are concerned about your potassium intake, talk with your doctor or dietitian.
Low levels of potassium can cause sodium sensitivity and an increase in blood pressure. Potassium also affects insulin levels. When potassium levels are low, there is a reduction in insulin secretion. A very low level of potassium causes a condition called hypokalemia. Symptoms of this condition reflect the importance of potassium in nerve transmission and muscle contraction. A patient with hypokalemia might have constipation, abnormal heart rhythms, muscle weakness and fatigue, muscle spasms and even paralysis. Hypokalemia can be life threatening. Risk factors for hypokalemia include diuretic medications, prolonged diarrhea or vomiting and certain antibiotics. Some kidney diseases can negatively affect potassium regulation, including hyperaldosteronism and Cushing syndrome.