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The name "calcium" itself derives from the Latin word calx "lime". [34] Vitruvius noted that the lime that resulted was lighter than the original limestone, attributing this to the boiling of the water. In 1755, Joseph Black proved that this was due to the loss of carbon dioxide, which as a gas had not been recognized by the ancient Romans. [39]
The US Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. [6] See table. The European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg. [10]
For example, for calcium the U.S. Food and Drug Administration set the recommended intake for adults over 70 years at 1,200 mg/day and the UL at 2,000 mg/day. [19] The European Union also sets recommended amounts and upper limits, which are not always in accord with the U.S. [ 20 ] Likewise, Japan, which sets the UL for iodine at 3000 μg ...
Calcium citrate is recommended for patients with achlorhydria and those on medications that decrease stomach acidity. While calcium carbonate is the most common and least expensive form of calcium and contains 40% of elemental calcium, calcium citrate supplements contain only 21% calcium, requiring more tablets for equivalent dosage.
The plasma total calcium concentration is in the range of 2.2–2.6 mmol/L (9–10.5 mg/dL), and the normal ionized calcium is 1.3–1.5 mmol/L (4.5–5.6 mg/dL). [4] The amount of total calcium in the blood varies with the level of plasma albumin, the most abundant protein in plasma, and therefore the main carrier of protein-bound calcium in the blood.
Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue, [1] [2] causing it to harden. Calcifications may be classified on whether there is mineral balance or not, and the location of the calcification. [3]
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The calcium cycle is a transfer of calcium between dissolved and solid phases. There is a continuous supply of calcium ions into waterways from rocks, organisms, and soils. [1] [2] Calcium ions are consumed and removed from aqueous environments as they react to form insoluble structures such as calcium carbonate and calcium silicate, [1] [3] which can deposit to form sediments or the ...