Calcium 500 + D3 By 21st Century Overview & Drug Interactions

Vitamin D is a fat-soluble vitamin that plays a crucial role in several bodily processes. It helps the body absorb calcium and phosphorus, which are necessary for healthy bones and teeth. It is also important for immune system function and may help to protect against certain diseases. Vitamin D is found in a variety of foods, including fatty fish, egg yolks, and fortified foods such as milk and cereal. It is also produced by the body when the skin is exposed to sunlight. Vitamin D supplements are available in a variety of forms, including tablets, capsules, and liquids. The recommended daily intake of vitamin D varies depending on age, sex, and other factors, and it is important to follow the dosage recommendations provided by a healthcare professional. There are several different forms of vitamin D available, with the two most popular being ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).

Calcium is a vital nutrient found in various foods such as dairy products, certain vegetables, and many fortified items. Over 99% of the body's calcium is stored in the bones and teeth, predominantly as hydroxyapatite. The remaining calcium circulates in the blood, extracellular fluid, muscles, and other tissues, where it is essential for processes like nerve signaling, muscle contraction, vascular activities, glandular secretion, and maintaining cell membrane and capillary permeability. It also plays critical roles in enzyme reactions, respiration, kidney function, and blood clotting, and is involved in neurotransmitter and hormone release, amino acid uptake, vitamin B12 absorption, and gastrin secretion. Calcium balance changes with age: it is positive during periods of growth, stable in adulthood, and tends to become negative in older age. Calcium loss occurs through feces, urine, sweat, and shedding skin cells. In women, reduced estrogen levels decrease calcium absorption and retention, increase bone turnover, and lead to lower bone mass. Calcium supplements come in various forms, including citrate and carbonate, which differ mainly in their calcium content and absorption rates. Calcium citrate is easily absorbed and can be taken without food, making it suitable for older adults or those with low stomach acid. In contrast, calcium carbonate, which contains a higher percentage of calcium, is best absorbed when taken with meals.