Calcium Monograph 2013

Calcium is the most abundant mineral in the human body and has several important functions. More than 99% of total body calcium is stored in the bones and teeth where it supports the structure. The remaining 1% is found throughout the body in blood, muscle, and the intracellular fluid. Calcium is needed for muscle contraction, blood vessel constriction and relaxation, the secretion of hormones and enzymes, and nervous system signaling. A constant level of calcium is maintained in body fluid and tissues so that these vital body processes function efficiently.

The body gets the calcium it needs in two ways. One method is dietary intake of calcium-rich foods including dairy products, which have the highest concentration per serving of highly absorbable calcium, and dark, leafy greens or dried beans, which have varying amounts of absorbable calcium. Calcium is an essential nutrient required in substantial amounts, but many diets are deficient in calcium.

The other way the body obtains calcium is by extracting it from bones. This happens when blood levels of calcium drop too low and dietary calcium is not sufficient. Ideally, the calcium that is taken from the bones will be replaced when calcium levels are replenished. However, simply eating more calcium-rich foods does not necessarily replace lost bone calcium, which leads to weakened bone structure.

The Surgeon General’s 2004 report “Bone Health and Osteoporosis” stated that calcium has been singled out as a major public health concern today because it is critically important to bone health, and the average American consumes levels of calcium that are far below the amount suggested. Vitamin D is important for good bone health because it aids in the absorption and utilization of calcium. There is a high prevalence of vitamin D insufficiency in nursing home residents, hospitalized patients, and adults with hip fractures.

Calcium supplements are widely used to reduce bone resorption in osteoporosis, and many studies support this use. Calcium supplementation is also used as an antacid, for building bone mineral density, for hyperphosphatemia, hypocalcemia, renal failure, magnesium toxicity, black widow spider bite, fracture prevention, gastrointestinal tract and colorectal cancer prevention, hyperkalemia, hypertension, lead toxicity, osteomalacia (bone softening)/rickets, postsurgical side effects (rectal epithelial hyperproliferation), preeclampsia, premenstrual syndrome (PMS), seizures, arrhythmias, bone diseases, breast cancer prevention, cardiovascular risk reduction, cystic fibrosis, endometrial cancer prevention, fall prevention, growth, childbirth (preterm birth prevention), circulation, hyperparathyroidism, mortality, muscle strength, myocardial infarction, osteoporosis (drug-induced), ovarian cancer prevention, postnatal depression, type 2 diabetes, weight loss, cardiopulmonary resuscitation (CPR), and vaginal disorders. Calcium’s use for calcium channel blocker overdose is investigational.