Calcium is a chemical element, typically found as a solid in its elemental form. It has the chemical symbol Ca, atomic number (number of protons) Z = 20, and a standard atomic weight of 40.078 grams per mole.
Calcium is considered to be a member of the "alkaline earth metal" class of element. At a pressure of 101.325 kPa, it has a boiling point of 1,484 °C, and a melting point of 842 °C.
Calcium is essential for life, particularly in cell physiology, where movement of the calcium ion Ca2+ into and out of the cytoplasm functions as a signal for many cellular processes, including neuromuscular contractions. It is also a major material used in mineralization of bones, teeth and shells.
Calcium may increase the rate of myocardial infarctions according to a meta-analysis by Bolland  A more recent cohort study agrees.
Regarding all cardiovascular events, Bolland reported in a meta-analysis of 6 randomized controlled trials an insignificant increase in cardiovascular events(pooled relative risk, 1.12 (CI, 0.97 to 1.30])). A meta-analysis by Wang of 3 randomized controlled trials with a total of approximately 300 patients reports an insignificant increase in cardiovascular events (pooled relative risk, 1.14 (CI, 0.92 to 1.41])).This increase was also found in a more recently analyzed randomized controlled trial. A more recent cohort study agrees.
Regarding mortality, Bolland reported in a meta-analysis of 6 randomized controlled trials an insignificant increase in mortality (pooled relative risk, 1.07 (CI, 0.95 to 1.19])).
- ↑ 1.0 1.1 1.2 Bolland MJ, Avenell A, Baron JA, Grey A, MacLennan GS, Gamble GD et al. (2010). "Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis.". BMJ 341: c3691. DOI:10.1136/bmj.c3691. PMID 20671013. PMC PMC2912459. Research Blogging. Review in: Ann Intern Med. 2010 Nov 16;153(10):JC5-7 Review in: Evid Based Med. 2010 Dec;15(6):181
- ↑ 2.0 2.1 Li K, Kaaks R, Linseisen J, Rohrmann S (2012). "Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition study (EPIC-Heidelberg).". Heart 98 (12): 920-5. DOI:10.1136/heartjnl-2011-301345. PMID 22626900. Research Blogging.
- ↑ Wang L, Manson JE, Song Y, Sesso HD (2010). "Systematic review: Vitamin D and calcium supplementation in prevention of cardiovascular events.". Ann Intern Med 152 (5): 315-23. DOI:10.1059/0003-4819-152-5-201003020-00010. PMID 20194238. Research Blogging.
- ↑ Bolland MJ, Grey A, Avenell A, Gamble GD, Reid IR (2011). "Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women's Health Initiative limited access dataset and meta-analysis.". BMJ 342: d2040. DOI:10.1136/bmj.d2040. PMID 21505219. PMC PMC3079822. Research Blogging. Review in: Ann Intern Med. 2011 Aug 16;155(4):JC2-3 Review in: Evid Based Med. 2012 Feb;17(1):16-7