Calcium
Year of discovery: 1808 | Humphrey Davy
Calcium is the most abundant mineral in the body. Ninety-nine percent of the body's calcium is found in the bones and teeth. Calcium is an integral part of the structure of the bones, which are necessary to form the skeleton that supports the body upright and allows movement. Calcium in the bones also serves as a storehouse from which the body can draw calcium to compensate for low calcium intake. The remaining 1% of calcium in the body is found in body fluids. There, calcium helps properly regulate blood pressure and muscle movement. The body needs calcium for healthy bones. Bones are constantly taking in and depleting various elements in a cycle of constant remodeling. Calcium forms crystals on a matrix of protein collagen. This process is called mineralization. During mineralization, as the crystals become denser, they give the bones their strength and stiffness. In most people, peak bone mass occurs before the age of 20, and dense bones will best protect against age-related bone loss and fractures. Calcium is important at all stages of life, especially during periods of even growth, infancy, childhood and adolescence, as well as pregnancy and lactation. Calcium in the blood helps maintain normal blood pressure. Calcium also participates in the regulation of muscle contractions, the transmission of nerve impulses, the secretion of hormones and the activation of certain enzymatic reactions.
Main sources of calcium
Milk and dairy products, small fish (with bones), calcium-based tofu (bean curd), legumes, spinach, Chinese cabbage, kale, broccoli.
Bioavailability of calcium
The body's absorption of calcium increases due to the presence of vitamin D and decreases in the presence of oxalic and phytic acid in food. Therefore, foods high in calcium that are also rich in oxalic acid (e.g., spinach, sweet potatoes, rhubarb and beans) or phytic acid (e.g., seeds, nuts, cereals) result in lower calcium absorption compared to foods without inhibitors, such as milk and dairy products. Diets high in sodium or phosphorus (e.g., cola drinks) also negatively affect calcium levels in the bones.
Risks associated with insufficient calcium intake
Calcium is crucial in terms of muscle contractility and nerve impulse transmission, and the body closely regulates blood calcium levels. If calcium intake is low, the body will draw calcium from the bones. Low calcium intake over a long period of time causes osteomalacia, a condition in which bones become weak due to a lack of calcium. Insufficient calcium in the bones can also result from an inadequate supply of vitamin D, which is necessary for calcium absorption and deposition in the bones. Therefore, an adequate intake of calcium and vitamin D is essential for bone integrity and bone growth.