Calcium

Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Calcium shopping experience:

1. Compare - without doubt the biggest advantage that the Calcium offers shoppers today is the ability to compare thousands of Calcium at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Calcium? Wrong! If the Calcium is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Calcium then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Calcium? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Calcium and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Calcium wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Calcium then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Calcium site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Calcium, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Calcium, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.

Calcium (International Phonetic Alphabet: ) is the chemical element in the periodic table that has the symbol Ca and atomic number 20. It has an atomic mass of 40.078. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element in the Earth's crust. It is essential for living organisms, particularly in Cell (biology) physiology, and is the most common metal in many animals. Notable characteristics Calcium is a rather soft (though harder than lead), gray, metallic element that can be extracted by electrolysis from fused calcium chloride.Pauling, Linus General Chemistry p. 627, 1970 ed. Dover Publications It burns with a yellow-red flame and forms a white nitride coating when exposed to air. It reacts with water, displacing a hydrogen atom from the structure, then forming calcium hydroxide.

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 occurs most commonly in sedimentary rocks in the minerals calcite, dolomite and gypsum. It occurs in igneous rocks and metamorphic rocks chiefly in the silicate minerals: plagioclase, amphiboles, pyroxenes and garnets.

See also :Category:Calcium minerals.

Applications Some uses are:

as a reducing agent in the extraction of other metals, such as uranium, zirconium, and thorium.
as a deoxidizer, desulfurizer, or decarbonizer for various Iron and nonferrous alloys.
as an alloying agent used in the production of aluminium, beryllium, copper, lead, and magnesium alloys.
in the making of cements and Mortar (masonry) to be used in construction.

Calcium compounds

Calcium Carbonate (CaCO3) used in manufacturing cement and mortar, agricultural lime, limestone (usually used in the steel industry); aids in production in the glass industry, also has chemical and optical uses as mineral specimens in toothpastes for example.
Calcium arsenate (Ca3(AsO4)2) is used in insecticides.
Calcium carbide (CaC2) is used: to make acetylene gas (for use in acetylene torches for welding) and in the manufacturing of plastics.
Calcium chloride (CaCl2) is used: in ice removal and dust control on dirt roads, in conditioner for concrete, as an additive in canned tomatoes, and to provide body for automobile tires.
Calcium cyclamate (Ca(C6H11NHSO4)2) was used as a sweetening agent but is no longer permitted for use because of suspected cancer-causing properties.
Calcium gluconate (Ca(C6H11O7)2) is used as a food additive and in vitamin pills.
Calcium hypochlorite (Ca(OCl)2) is used: as a swimming pool disinfectant, as a bleaching agent, as an ingredient in deodorant, and in algicide and fungicide.
Calcium permanganate (Ca(MnO4)2) is used in liquid rocket propellant, textile production, as a water sterilizing agent and in dental procedures.
Calcium phosphate (Ca3(PO4)2) is used as a supplement for animal feed, fertilizer, in commercial production for dough and yeast products, in the manufacture of glass, and in dental products.
Calcium phosphide (Ca3P2) is used in fireworks, rodenticide, torpedoes and flare (pyrotechnic)s.
Calcium stearate (Ca(C18H35O2)2 is used in the manufacture of wax crayons, cements, certain kinds of plastics and cosmetics, as a food additive, in the production of water resistant materials and in the production of paints.
Calcium sulfate (CaSO4·2H2O) is used as common blackboard chalk, as well as, in its hemihydrate form being more well known as Plaster of Paris.
Calcium tungstate (CaWO4) is used in luminous paints, fluorescent lights and in X-ray studies.

H and K lines In the visible portion of the spectrum of many stars, including the Sun, show strong Spectral lines of singly-ionized Calcium. Prominent among these are the H-line at 3968.5 Ångstrom and the K line at 3933.7 Å of singly-ionized Calcium, or Ca II. For the Sun and stars with low temperatures, the prominence of the H and K lines can be an indication of strong magnetic activity in the chromosphere. Measurement of periodic variations of these active regions can also be used to deduce the rotation periods of these stars.{{cite web| author=Staff | year=1995 | url =http://www.mtwilson.edu/hk/ | title =H-K Project | publisher =Mount Wilson Observatory | accessdate = 2006-08-10 -->

History Calcium (Latin calx, meaning "limestone") was known as early as the first century when the Ancient Rome prepared lime as calcium oxide. It was not isolated until 1808 in England when Humphry Davy Electrolysis a mixture of lime and mercuric oxide. Davy was trying to isolate calcium; 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.

Other compounds include Calcium carbonate (CaCO3), one of the common compounds of calcium. It is heated to form quicklime (CaO), which is then added to water (H2O). This forms another material known as slaked lime (Ca(OH)2), which is an inexpensive base material used throughout the chemical industry. Chalk, marble, and limestone are all forms of calcium carbonate.

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 (masonry) 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 calcium nitrate, calcium sulfide, calcium chloride, calcium carbide, calcium cyanamide, and calcium hypochlorite.

Isotopes Calcium has four stable isotopes (40Ca and 42Ca through 44Ca), plus two more isotopes (46Ca and Calcium-48) 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 Earth's 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 geology 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 Potassium-Ca age dating.

Nutrition {| class="wikitable" align="right"|+ Recommended Adequate Intake by the IOM for Calcium: Dietary Supplement Fact Sheet: Calcium|-! Age! Calcium (mg/day)|-| 0–6 months| 210|-| 7–12 months| 270|-|1–3 years|500|-|4–8 years|800|-|9–18 years|1300|-|19–50 years|1000|-|51+ years|1200|}

Calcium is an important component of a healthy diet. A deficit can affect bone and tooth formation, while overretention can cause hypercalcemia (elevated levels of calcium in the blood), impaired kidney function and decreased absorption of other minerals.Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington DC: The National Academies Press, 1997 High calcium intakes or high calcium absorption were previously thought to contribute to the development of kidney stones. However, more recent studies show that high dietary calcium intakes actually decrease the risk for kidney stones.Curhan G, Willett WC, Rimm E, Stampher MJ. A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones. N Engl J Med 1993;328:833-8 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 Indo-European descent, are Lactose intolerance, leaving them unable to consume dairy products. Others, such as vegans, avoid dairy products for ethical and health reasons. Fortunately, many other good sources of calcium exist. These include seaweeds such as kelp, wakame and hijiki; nuts and seeds (like almonds and sesame); blackstrap molasses; beans; oranges; amaranth; collard greens; okra; rutabaga; broccoli; dandelion leaves; kale; sardines; and fortified products such as orange juice and soy milk. The calcium content of most foods can be found in the USDA National Nutrient Database. USDA National Nutrient Database

Calcium is essential for the normal growth and maintenance of bones and teeth, and calcium requirements must be met throughout life. Long-term calcium deficiency can lead to osteoporosis, in which the bone deteriorates and there is an increased risk of fractures. Calcium has also been found to assist in the production of lymphatic fluids.

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

Dietary calcium supplements Calcium supplements 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 because the percent of calcium absorbed decreases as the amount of calcium in the supplement increases. It is recommended to spread doses throughout the day, with the last dose near bedtime. Recommended daily calcium intake varies from 1000 to 1500 mg, 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 50s gained 5 pounds less in a period of 10 years by taking more than 500 mg 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 "going out on a limb" to suggest calcium supplements as a weight-limiting aid.{{cite web | title=Calcium May Help With Weight Loss | accessdate=2007-07-10 | url=http://www.rxalternativemedicine.com/headlines_news.php#headline77|author=Anne Harding -->

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. It is recommended to take this supplement with food to aid in absorption. In some calcium supplements based on calcium carbonate, vitamin D is added 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.
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 about 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 difficult to digest and are more expensive than calcium carbonate
Calcium chelation have been chemically bonded with an agent that the body recognizes as food. This form is generally known to be better absorbed by the human body than all other forms of calcium due to the bond.

The National Nutritional Food Association — NNFA (Newport Beach, Calif.) defines a chelate very specifically, and several criteria must be met in order for chelation to actually occur. Some of the claimed "chelates" on the market are the various Citric acid cycle chelates, such as citrate, malate, and aspartate. Dicalcium malate (chelated with malic acid) is a newer form of a true calcium chelate. It contains a high amount of elemental calcium (30%).

Do calcium supplements prevent fractures due to osteoporosis? Randomized controlled trials found both positive and negative benefit. The different results may be explained by doses of calcium and underlying rates of calcium supplementation in the control groups.

Do calcium supplements prevent cancer? A meta-analysis by the international Cochrane Collaboration of two randomized controlled trialsfound that calcium "might contribute to a moderate degree to the prevention of adenomatous colonic polyps".

More recent studies were conflicting:

A randomized controlled trial found that 1000 mg of elemental calcium and 400 IU of vitamin D3 had no effect on colorectal cancer
A randomized controlled trial found that 1400–1500 mg supplemental calcium and 1100 IU vitamin D3 reduced aggregated cancers with a relative risk of 0.402.
An observational cohort study found that high calcium and vitamin D intake was associated with "lower risk of developing premenopausal breast cancer"