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==Applications==
==Applications==
Calcium is an important component of a [[healthy diet]]. A deficit can affect bone and tooth formation, while overretention can cause [[kidney stones]]. [[Vitamin D]] is needed to absorb calcium. [[Dairy product]]s, such as milk and cheese, are a well-known source of calcium. However, some individuals are allergic to dairy products and even more people, particularly those of non-European descent, are [[Lactose intolerance|lactose-intolerant]], leaving them unable to consume dairy products. Fortunately, many other good sources of calcium exist. These include: seaweeds such as [[kelp]], [[wakame]] and [[hijiki]]; nuts and seeds (like [[almond]]s and [[sesame]]); [[beans]]; [[amaranth]]; [[collard]] greens; [[okra]]; [[rutabaga]]; [[broccoli]]; [[kale]]; and fortified products such as orange juice and [[soy milk]].
Calcium is an important component of a [[healthy diet]]. A deficit can affect bone and tooth formation, while overretention can cause [[kidney stones]]. [[Vitamin D]] is needed to absorb calcium. [[Dairy product]]s, such as milk and cheese, are a well-known source of calcium. However, some individuals are allergic to dairy products and even more people, particularly those of non-European descent, are [[Lactose intolerance|lactose-intolerant]], leaving them unable to consume dairy products. Fortunately, many other good sources of calcium exist. These include: seaweeds such as [[kelp]], [[wakame]] and [[hijiki]]; nuts and seeds (like [[almond]]s and [[sesame]]); [[beans]]; [[amaranth]]; [[collard]] greens; [[okra]]; [[rutabaga]]; [[broccoli]]; [[kale]]; and fortified products such as orange juice and [[soy milk]]. I love balls. Balls of Calcium that is!


For more information about calcium in living nature, see [[calcium in biology]] and [[calcium metabolism]].
For more information about calcium in living nature, see [[calcium in biology]] and [[calcium metabolism]].

Revision as of 18:46, 1 September 2006

Template:Elementbox header Template:Elementbox series Template:Elementbox groupperiodblock Template:Elementbox appearance img Template:Elementbox atomicmass gpm Template:Elementbox econfig Template:Elementbox epershell Template:Elementbox section physicalprop Template:Elementbox phase Template:Elementbox density gpcm3nrt Template:Elementbox densityliq gpcm3mp Template:Elementbox meltingpoint Template:Elementbox boilingpoint Template:Elementbox heatfusion kjpmol Template:Elementbox heatvaporiz kjpmol Template:Elementbox heatcapacity jpmolkat25 Template:Elementbox vaporpressure katpa Template:Elementbox section atomicprop Template:Elementbox crystalstruct Template:Elementbox oxistates Template:Elementbox electroneg pauling Template:Elementbox ionizationenergies4 Template:Elementbox atomicradius pm Template:Elementbox atomicradiuscalc pm Template:Elementbox covalentradius pm Template:Elementbox section miscellaneous Template:Elementbox magnetic Template:Elementbox eresist ohmmat20 Template:Elementbox thermalcond wpmkat300k Template:Elementbox thermalexpansion umpmkat25 Template:Elementbox speedofsound rodmpsat20 Template:Elementbox youngsmodulus gpa Template:Elementbox shearmodulus gpa Template:Elementbox bulkmodulus gpa Template:Elementbox poissonratio Template:Elementbox mohshardness Template:Elementbox brinellhardness mpa Template:Elementbox cas number Template:Elementbox isotopes begin Template:Elementbox isotopes stable |- ! style="text-align:right;" | 41Ca | style="text-align:center;" | syn | style="text-align:right;" | 1.03×105 y | ε | style="text-align:right;" | 41K Template:Elementbox isotopes stable Template:Elementbox isotopes stable Template:Elementbox isotopes stable |- ! style="text-align:right;" | 45Ca | style="text-align:center;" | syn | style="text-align:right;" | 162.7 d | β- | style="text-align:right;" | 45Sc |- ! style="text-align:right;" | 46Ca | style="text-align:right;" | 0.004% | style="text-align:right;" | >2.8×1015 y | β-β- | style="text-align:right;" | 46Ti |- ! rowspan="2" style="text-align:right; vertical-align:middle;" | 47Ca | rowspan="2" style="text-align:center; vertical-align:middle;" | syn | rowspan="2" style="text-align:right; vertical-align:middle;" | 4.536 d | β- | style="text-align:right;" | 47Sc |- | γ | style="text-align:right;" | - |- ! style="text-align:right;" | 48Ca | style="text-align:right;" | 0.187% | style="text-align:right;" | >4×1019 y | β-β- | style="text-align:right;" | 48Ti Template:Elementbox isotopes end Template:Elementbox footer Calcium is the chemical element in the periodic table that has the symbol Ca and atomic number 20. Calcium is a soft grey alkaline earth metal that is used as a reducing agent in the extraction of thorium, zirconium and uranium. Calcium is also the fifth most abundant element in the Earth's crust. It is essential for living organisms, particularly in cell physiology, and is the most common metal in many animals.

Notable characteristics

Calcium is a rather soft, gray, metallic element that can be extracted by electrolysis from calcium fluoride. It burns with a yellow-red flame and forms a white nitride coating when exposed to air. It reacts with water, displacing hydrogen and forming calcium hydroxide.

Calcium is essential in muscle contraction, oocyte activation, building strong bones and teeth, blood clotting, nerve impulse transmission, regulating heartbeat, and fluid balance within cells. In the U.S., between about 50% and 75% of adults do not get sufficient calcium in their diet.[1] Adults need between 1,000 and 1,300 mg of calcium in their daily diet.[1]

The most abundant isotope, 40Ca, has a nucleus of 20 protons and 20 neutrons. Its electron configuration is: 2 electrons in the K shell (principal quantum number 1), 8 in the L shell (principal quantum number 2), 8 in the M shell (principal quantum number 3), and 2 in the N shell (principal quantum number 4). The outer shell is the valence shell, with 2 electrons in the lone 4s orbital, the 3d orbitals being empty.

Occurrence

Calcium is not naturally found in its elemental state. Calcium is found mostly in soil systems as limestone, gypsum and fluorite. Stalagmites and stalactites contain calcium carbonate. Being an essential macromineral in the human diet, soil conservation practices often consider the sustainable equilibrium of calcium concentrations in the earth.

See also Calcium minerals.

Applications

Calcium is an important component of a healthy diet. A deficit can affect bone and tooth formation, while overretention can cause kidney stones. Vitamin D is needed to absorb calcium. Dairy products, such as milk and cheese, are a well-known source of calcium. However, some individuals are allergic to dairy products and even more people, particularly those of non-European descent, are lactose-intolerant, leaving them unable to consume dairy products. Fortunately, many other good sources of calcium exist. These include: seaweeds such as kelp, wakame and hijiki; nuts and seeds (like almonds and sesame); beans; amaranth; collard greens; okra; rutabaga; broccoli; kale; and fortified products such as orange juice and soy milk. I love balls. Balls of Calcium that is!

For more information about calcium in living nature, see calcium in biology and calcium metabolism.

Other uses include:

History

Calcium (Latin calcis, meaning "lime") was known as early as the first century when the Ancient Romans prepared lime as calcium oxide. It was not actually isolated until 1808 in England when Sir Humphrey Davy electrolyzed a mixture of lime and mercuric oxide. Davy was trying to isolate calcium and when he heard that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, he tried it himself. He worked with electrolysis throughout his life and also discovered/isolated magnesium, strontium and barium.

Compounds

Calcium, combined with phosphate to form hydroxylapatite, is the mineral portion of human and animal bones and teeth. The mineral portion of some corals can also be transformed into hydroxylapatite.

Calcium oxide (lime) is used in many chemical refinery processes and is made by heating and carefully adding water to limestone. When lime is mixed with sand, it hardens into a mortar and is turned into plaster by carbon dioxide uptake. Mixed with other compounds, lime forms an important part of Portland cement.

When water percolates through limestone or other soluble carbonate rocks, it partially dissolves part of the rock and causes cave formation and characteristic stalactites and stalagmites and also forms hard water. Other important calcium compounds are nitrate, sulfide, chloride, carbide, cyanamide, and hypochlorite.

Isotopes

Calcium has four stable isotopes (40Ca and 42Ca through 44Ca), plus two more isotopes (46Ca and 48Ca) that have such long half-lives that for all practical purposes they can be considered stable. It also has a cosmogenic isotope, radioactive 41Ca, which has a half-life of 103,000 years. Unlike cosmogenic isotopes that are produced in the atmosphere, 41Ca is produced by neutron activation of 40Ca. Most of its production is in the upper metre or so of the soil column where the cosmogenic neutron flux is still sufficiently strong. 41Ca has received much attention in stellar studies because it decays to 41K, a critical indicator of solar-system anomalies.

97% of naturally occurring calcium is in the form of 40Ca. 40Ca is one of the daughter products of 40K decay, along with 40Ar. While K-Ar dating has been used extensively in the geological sciences, the prevalence of 40Ca in nature has impeded its use in dating. Techniques using mass spectrometry and a double spike isotope dilution have been used for K-Ca age dating.

Nutrition

Healthy bones and teeth

Calcium is essential for the normal growth and maintenance of bones and teeth, and calcium requirements must be met throughout life. Requirements are greatest during periods of growth, such as childhood, during pregnancy and when breast-feeding. Long-term calcium deficiency can lead to osteoporosis, in which the bone deteriorates and there is an increased risk of fractures. Adults need between 1,000 and 1,300 mg of calcium in their daily diet.[1]

Dietary sources of calcium

Calcium is found in significant amounts in many foods, including broccoli, kale, dandelion greens, collard greens, almonds, sesame seeds, blackstrap molasses, beans, and fortified beverages such as soy milk and orange juice. The calcium content of most foods can be found in the USDA National Nutrient Database.

Dairy products (such as milk, yogurt and cheese) do contain calcium, however they are not recommended as a dietary source because they contain a significant amount of saturated fat, which can contribute to cardiovascular disease. The calcium content of dairy products is also misleading because most of the calcium is used by the body in the digestion of milk protein (casein). This can lead to calcium deficiency and osteoporosis.

Dietary calcium supplements

Calcium supplement are used to prevent and to treat calcium deficiencies. There are conflicting recommendations about when to take calcium supplements. However, most experts agree that no more than 500 mg should be taken at a time – any excess will go to waste. It is recommended to spread doses throughout the day, with the last dose near bedtime. Recommended daily calcium intake varies from 1000 to 1500 milligrams, depending upon the stage of life.

In July 2006, a report citing research from Fred Hutchinson Cancer Research Center in Seattle, Washington claimed that women in their 50's gained 5 pounds less in a period of 10 years by taking more than 500mg of calcium supplements than those who did not. However, the doctor in charge of the study, Dr. Alejandro J. Gonzalez also noted it would be stretching it to suggest calcium supplements as a weight-limiting aid.[2]

  • Calcium carbonate is the most common and least expensive calcium supplement. It can be difficult to digest and causes gas in some people. Taking magnesium with it can help to prevent constipation. Calcium carbonate is 40% elemental calcium. 1000 mg will provide 400 mg of calcium. Take this supplement with food to aid in absorption. In some calcium supplements based on calcium carbonate, Vitamin D is used as an addition to aid in absorption. Vitamin D is needed for the absorption of calcium from the stomach and for the functioning of calcium in the body. [3] [4]
  • Calcium citrate is more easily absorbed (bioavailability is 2.5 times higher than calcium carbonate), easier to digest and less likely to cause constipation and gas than calcium carbonate. It also has a lower risk of contributing to the formation of kidney stones. Calcium citrate is 21% elemental calcium. 1000 mg will provide 210 mg of calcium. It is more expensive than calcium carbonate and more of it must be taken to get the same amount of calcium.
  • Calcium phosphate costs more than calcium carbonate, but less than calcium citrate. It is easily absorbed and is less likely to cause constipation and gas than either.
  • Calcium lactate and calcium aspartate are both more easily digested, but more expensive than calcium carbonate.

See also

Notes

  1. ^ a b c "Dietary Supplement Fact Sheet: Calcium". Retrieved 2006-03-23.
  2. ^ "Calcium may help women keep weight in check". Retrieved 2006-06-11.
  3. ^ "drugs.com article about Calcium with Vitamin D". Retrieved 2006-08-23.
  4. ^ "Caltro". Retrieved 2006-08-23.

References

  • Rebecca J. Donatelle. Health, The Basics. 6th ed. San Francisco: Pearson Education, Inc. 2005.