Calcium is a mineral necessary for life and an important component of a healthy diet. It plays an important role in building stronger, denser bones early in childhood as well as later in life. Approximately ninety-nine percent of the body's calcium is stored in the bones and teeth.
Calcium also plays an important role in neurotransmitter release, muscle contraction and the electrical conduction system of the heart.
Long-term calcium deficiency can lead to rickets and poor blood clotting and in case of a menopausal woman, it can lead to osteoporosis, in which the bone deteriorates and there is an increased risk of fractures or bone breakage.
Some studies have also found that calcium may contribute to the prevention of adenomatous colonic polyps, and another that high calcium and vitamin D intake was associated with lower risk of developing premenopausal breast cancer.
Proper vitamin D status is important as it is needed to absorb calcium. Calcium also has a complementary relationship with magnesium – contraction of the heart muscle requires magnesium, and calcium is required when the heart opens.
Over-retention of calcium can cause hypercalcemia (elevated levels of calcium in the blood), impaired kidney function and decreased absorption of other minerals.
Dairy products, such as milk and cheese, are a good sources of calcium. While vegans and those who are lactose intolerant can run the risk of consuming insufficient calcium, many other sources of the mineral exist, including: seaweeds (kelp, wakame, hijiki), nuts and seeds (almonds and sesame), blackstrap molasses, beans, oranges, figs, quinoa, amaranth, collard greens, okra, rutabaga, broccoli, dandelion leaves, kale, and many fortified products such as orange juice and soy milk. As a general rule, cultivated vegetables have less calcium than wild plants.
Research has found an association between diets high in animal protein and increased urinary calcium loss from the bones. Similarly, diets high in candy were found to result in lower bone density in both men and women. A diet high in fruit, vegetables and cereals was demonstrated to result in greater bone mineral density in older men, in comparison to a range of other diets.