Although your body absorbs about 30 percent of the calcium from the foods and beverages you consume, the amount can vary. Other factors affect the rate of absorption as well as the amount of calcium the body excretes in sweat, urine and feces. While both calcium and potassium can interact with other electrolytes, potassium aids in maintaining the body's normal blood calcium balance by decreasing the loss of calcium through urine.
Roles of Calcium and Potassium
Not only is calcium an essential component of your bones and teeth, it plays a key role in nerve conduction, muscle contraction and blood clotting. Therefore, you need to consume enough calcium so that calcium levels in the blood do not drop below normal. The body stores calcium in the bones so that it can keep an adequate level of the mineral on reserve. Like calcium, potassium helps to regulate heart function in addition to muscle and nerve activity. Potassium is also involved in kidney function, the body's fluid balance and energy production. You get potassium through dietary sources. What isn't excreted from the body is stored in the muscles and cells.
Vitamins D and K and minerals such as potassium, magnesium and zinc help the body absorb more calcium. How much calcium your body absorbs depends on the amount of calcium you consume. Absorption decreases as you take in more. Age is another factor that affects calcium absorption, which is at its highest during infancy and the early childhood years. Absorption decreases in adulthood and continues to decrease as you age. The foods you eat can also reduce the absorption of calcium. Phytic acid and oxalate acid bind to calcium, reducing its absorption. Whole grains, nuts and seeds are some of the foods high in phytic acid. Sources of oxalic acid include beans, sweet potatoes and rhubarb.
Decreased Calcium Excretion
Adding more potassium to a high-sodium diet can help decrease calcium excretion, particularly in postmenopausal women. According to the National Institutes of Health, women who include enough calcium in their diets may be able to slow the rate of bone loss. Potassium-sparing diuretics can also decrease the amount of calcium excreted in urine, thereby increasing calcium levels in the blood. As a result, a higher intake of potassium may help prevent kidney stones from forming. The chemical stimulant caffeine can increase calcium excretion, reducing absorption, although the effect is minimal. Alcohol also reduces calcium absorption by blocking enzymes in the liver that help convert vitamin D to its active form.
Hyperkalemia – a common cause of cardiac arrhythmias – occurs when the level of potassium in the blood is higher than normal. Symptoms of hyperkalemia include muscle weakness, fatigue, irregular heartbeat or sudden cardiac arrest. Severe hyperkalemia is a medical emergency that can lead to death. Doctors frequently use calcium infusion to help normalize cardiac arrhythmias. Emergency treatment of hyperkalemia generally includes giving calcium intravenously – typically in the form of calcium chloride or calcium gluconate. Administering calcium intravenously is usually the first step in managing hyperkalemia.
- University of Maryland Medical Center: Possible Interactions with Calcium; June 2007
- Linus Pauling Institute; Potassium; Jane Higdon; February 2004
- Arizona Cooperative Extension; Calcium Supplement Guidelines; Linda Houtkooper, et al., January 2011
- Office of Dietary Supplements: Calcium
- Mayo Clinic; Emergency Management and Commonly Encountered Outpatient Scenarios in Patients With Hyperkalemia; Manish Sood, et al., 2007