Calcium plays a crucial role in the human body and is often referred to as a "macromineral" due to the significant amount needed for various physiological functions.
Calcium is a mineral most often associated with healthy bones and teeth, although it also plays an important role in blood clotting, helping muscles to contract, and regulating normal heart rhythms and nerve functions. About 99% of the body’s calcium is stored in bones, and the remaining 1% is found in blood, muscle, and other tissues.
The body gets the calcium it needs in two ways. One is by eating foods or supplements that contain calcium, and the other is by drawing from calcium in the body. If one does not eat enough calcium-containing foods, the body will remove calcium from bones. Ideally, the calcium that is “borrowed” from the bones will be replaced at a later point. But this doesn’t always happen, and can’t always be accomplished just by eating more calcium.
Food Sources
Calcium is widely available in many foods, not just milk and other dairy foods. Fruits, leafy greens, beans, nuts, and some starchy vegetables are good sources.
» Dairy (cow, goat, sheep)
» Plant-based milks (almond, soy, rice)
» Cheese
» Yogurt
» Calcium-fortified orange juice
» Winter squash
» Edamame (young green soybeans); Tofu, made with calcium sulfate
» Canned sardines, salmon (with bones)
» Almonds
» Leafy greens (collard, mustard, turnip, kale, spinach)
Here's a detailed overview of the role of calcium in the body:
Bone Health:
Perhaps the most well-known role of calcium is in maintaining strong and healthy bones. About 99% of the body's calcium is stored in the bones and teeth, providing structural support and strength. Calcium is continuously being deposited and withdrawn from bones in a process known as "bone remodeling." Adequate calcium intake is essential during periods of growth (such as childhood and adolescence) to build optimal bone density and prevent conditions like osteoporosis in later life.
Muscle Contraction:
Calcium is vital for muscle contraction, including both skeletal muscles (those attached to bones) and smooth muscles (like those in blood vessels and the digestive tract). When a muscle receives a signal from the nervous system to contract, a release of calcium ions from specialized storage sites triggers muscle fiber contraction. Once the signal ends, calcium is actively pumped back into storage, leading to muscle relaxation.
Nervous System Function:
Calcium ions also play a crucial role in transmitting nerve impulses throughout the nervous system. They are involved in releasing neurotransmitters at synapses, the junctions between nerve cells, allowing for efficient communication between neurons.
Blood Clotting:
In the process of blood clotting (coagulation), calcium ions are necessary for the activation of certain clotting factors. These factors help in forming a stable blood clot to prevent excessive bleeding when there's an injury.
Cell Signaling:
Calcium acts as a second messenger in many cellular signaling pathways. It is involved in regulating a wide range of cellular processes, including gene expression, cell growth, and apoptosis (programmed cell death).
Enzyme Activation:
Several enzymes require calcium as a cofactor to function properly. These enzymes are involved in various biochemical reactions within the body, including those related to energy production, metabolism, and digestion.
Hormone Secretion:
Calcium is necessary for the secretion of various hormones, including insulin, which regulates blood sugar levels, and hormones released by the parathyroid glands, which play a role in maintaining calcium balance in the body.
Blood Pressure Regulation:
Calcium is involved in blood vessel contraction and relaxation, which impacts blood pressure regulation. It also plays a role in the function of cells that help regulate blood pressure, known as smooth muscle cells.
The Bottom Line
Calcium is not only essential for maintaining strong bones and teeth but also plays a critical role in muscle function, nerve transmission, blood clotting, cell signaling, enzyme activation, hormone secretion, and blood pressure regulation. It's important to ensure an adequate intake of calcium through a balanced diet, as the body cannot produce its own calcium and relies on dietary sources to meet its needs. Good sources of calcium include dairy products, leafy greens, fortified foods, nuts, and seeds.
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