Calcium is found in or added to foods and some medications and is the body’s most plentiful mineral. The body is not able to make calcium and thus this mineral must be acquired within the diet and/or via supplementation. When calcium levels are low, the body is able to strip its calcium stores to maintain a healthy blood calcium level.
Functions
- Bone strength: Bones, comprised largely of calcium, store 99% of the body’s supply of the mineral. Because the body is unable to produce its own calcium, the bone’s storage of calcium is integral to proper body function. The presence of calcium increases bone strength by increasing bone density and allowing for the constant remodeling of bone throughout the lifespan.
- Muscular action: Calcium is essential in the movement of muscles as it reacts with regulatory proteins to stimulate the muscle fibers to contract.
- Cardiovascular function: The body stores 1% of its calcium in the blood which allows for blood clotting. Blood pressure is also regulated by calcium stores as blood vessels tighten and relax based on the amount of calcium in the blood.
- Nervous system function: Calcium enables the transduction of nerve impulses within the body. It also instructs neurons to carry out communicative action and synaptic transmission.
Sources
Dairy products, including yogurt, cheese, and milk, are excellent sources of calcium. Calcium is also present in plant sources including greens such as spinach. However, the presence of phytic acid in spinach decreases the bioavailability of calcium and therefore the body is only able to absorb about 5% of the calcium consumed in spinach. Tofu and sardines are also sources of calcium for the diet.
Supplementation
The recommended daily allowance (RDA) for calcium is 1000mg for both men and women. Of note, calcium is better absorbed when consumed in conjunction with vitamin D. Additionally, calcium and magnesium work closely and are often supplemented together.
Deficiencies
Low calcium levels put people at risk for many bone-related health complications. These include osteoporosis (porous, fragile bones), osteomalacia (softened bones), and rickets (abnormal mineralization of cartilage in children). Symptoms of low calcium levels, or hypocalcemia, include numbness, tingling, poor appetite, muscle weakness, and cramping.
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