Potassium is considered a major mineral, as well as an electrolyte. Tight control of potassium concentration both inside and outside the cells is required to maintain homeostasis. Potassium plays a vital role in maintaining fluid and electrolyte balance, transmission of nerve impulses, heart function and contraction of both skeletal and smooth muscle. Potassium is a nutrient of concern, as recent research has shown that the average dietary potassium intake for U.S. adults is below the recommended amounts.
Adequate Intake for Potassium
Potassium recommendations are defined in the Dietary Reference Intakes, DRIs. The DRIs are a set of nutrient reference values that are used to plan and assess the dietary intakes of healthy people. The DRIs include Recommended Dietary Allowances, RDA; Estimated Average Requirement, EAR; Adequate Intakes, AI; and Tolerable Upper Intake Levels, UL.
When sufficient scientific evidence is lacking to determine an EAR, an RDA cannot be established, as is the case with potassium. Instead, an AI has been established by the Food and Nutrition Board of the Institute of Medicine. The AI represents an average daily amount of a nutrient assumed to supply nutritional adequacy in a population of healthy individuals. For healthy adults, the AI for potassium is set at 4,700 mg/day, as intakes at this level have been found to reduce salt sensitivity in susceptible populations, lower blood pressure and decrease risk of developing kidney stones. Children and women who are breastfeeding have different recommendations for potassium. If you have been advised to limit your potassium intake by your physician, this AI does not apply to you either.
Consuming a diet rich in fresh fruits and vegetables should allow you to meet the AI for potassium. Potassium-rich fruits and vegetables include baked potatoes with skin, bananas, prunes and prune juice, cooked spinach, raisins, tomatoes and acorn squash. Other high potassium foods include molasses, sunflower seeds, yogurt, clams and almonds. Pre-packaged and processed foods should be limited as they generally are not good sources of potassium. Typically, highly processed foods are higher in sodium and lower in potassium and therefore may increase disease risk.
Importance of Potassium in Disease Prevention
An AI of 4,700 mg/day for adults has been established to encourage a diet rich in potassium, as higher intakes of potassium have been found to be associated with increased bone density, lower blood pressure and decreased risk of stroke and symptomatic kidney stones. Low potassium diets appear to play a role in the development of high blood pressure, as well.
Potassium Toxicity and Supplement Usage
Potassium toxicity, or elevated blood potassium concentration, is known as hyperkalemia. When intake of potassium exceeds the kidneys' ability to eliminate it, toxicity can occur. No UL for potassium intake has been established, since potassium toxicity doesn't typically occur from dietary intake. However, use of potassium supplements poses a potential risk for toxicity. Toxicity symptoms include diarrhea and stomach irritation at low doses, and tingling of the hands and feet, muscle weakness and cardiac arrhythmia at higher doses.
Dietary potassium supplements are typically not needed; a balanced diet, rich in fruits and vegetables, should provide all your necessary potassium. However, if you are considering supplementation, speak with your physician before beginning the usage of potassium supplements.