Calcium is one of about 20 minerals that are essential for your health, and it is the most abundant mineral in your body. Calcium concentration in your bloodstream and in the fluids surrounding your cells must be maintained within a narrow range for normal physiologic function. Your body possesses mechanisms for controlling serum calcium concentrations, but calcium supplements can increase your calcium level under certain circumstances. Your physician or a nutritionist can guide you in your use of calcium supplements.
Functions
If your serum calcium level is too high -- a condition called hypercalcemia -- it can interfere with the metabolic activities of your cells and disrupt the function of several vital organ systems. Aside from its structural role in your bones and teeth, calcium acts as a cofactor for a number of enzymes such as those that control blood clotting or synthesize neurotransmitters; it is intimately involved in generating the electrical currents that allow your heart, muscles and nerves to function normally.
Regulation
Vitamin D and parathyroid hormone, or PTH, regulate calcium concentrations in your bodily fluids. Falling serum calcium levels prompt the release of PTH from your parathyroid glands, which in turn triggers the production of active vitamin D in your kidneys. Vitamin D then stimulates calcium absorption from your intestine. In addition, PTH and vitamin D work together to increase reabsorption of calcium from your urine and mobilize calcium from your bones. As your serum calcium level increases, PTH secretion ceases. The inappropriate use of calcium supplements can disrupt your body's ability to "fine-tune" calcium concentrations.
Milk-Alkali Syndrome
A study in the February 2011 issue of "Indian Journal of Pharmacology," indicates that high intake of calcium and "absorbable alkali" -- sodium bicarbonate, for example -- increases your blood calcium level while simultaneously interfering with your kidneys' ability to eliminate excess calcium. This so-called milk-alkali syndrome, characterized by hypercalcemia, alkaline blood and reduced kidney function, was fairly common when calcium-containing antacids were the primary therapy for ulcers. With the advent of modern medications for treating ulcers, milk-alkali syndrome is less commonly seen.
Considerations
Recommended daily intakes for calcium vary from 200 mg daily for infants to 1,300 mg for growing children, adolescents and pregnant women. Dietary sources of calcium have never been implicated as a cause of hypercalcemia, but supplemental calcium -- in widely variable doses of 1.5 to 16.5 g daily for 2 days to 30 years -- has been associated with milk-alkali syndrome, according to the Linus Pauling Institute. Symptoms of hypercalcemia include loss of appetite, nausea, vomiting, constipation, abdominal pain, lethargy and confusion. Ask your doctor if your calcium needs are being met before you take additional calcium.
Member Comments