Calcium

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File:CalciumSample.png
A sample of elemental calcium

Introduction[edit | edit source]

Calcium is a chemical element with the symbol Ca and atomic number 20. Classified under the alkaline earth metals group in the periodic table, it is a soft, grayish metal that is essential for living organisms.

PouringMilk.jpg

Physical and Chemical Properties[edit | edit source]

Calcium is known for its reactivity with water and its ability to form stable compounds with other elements. The metal reacts with water, producing calcium hydroxide and hydrogen gas. It also forms oxides and nitrides upon exposure to air. In its compound state, calcium often takes a divalent form (Ca^2+), making it a crucial component in numerous materials.

Biological Importance[edit | edit source]

In the realm of biology, calcium plays an indispensable role in various physiological and structural processes in organisms:

Bone Structure: Most notably, calcium is a primary component of bones and teeth in vertebrates. The mineral provides structural rigidity and strength. Cellular Processes: At the cellular level, calcium ions (Ca^2+) function as a secondary messenger in various cell signaling pathways. Muscle Contraction: Calcium ions are vital for muscle contraction, including the rhythmic contraction of heart muscles. Blood Coagulation: The coagulation process of blood also depends on calcium. Dietary calcium is crucial for maintaining optimum health, especially for the strength and functionality of bones and teeth. Dairy products, green leafy vegetables, and certain fish are rich sources of calcium.

A deficiency of calcium in the diet can lead to conditions like osteoporosis, where bones become brittle and prone to fractures.

Industrial Applications[edit | edit source]

Beyond its biological importance, calcium finds a range of applications in industries:

It's used as a reducing agent in the extraction of other metals like thorium, uranium, and zirconium. Calcium compounds, especially calcium carbonate, are used in building materials, such as cement and concrete. In the realm of agriculture, calcium is utilized in the form of lime for soil treatment to neutralize acidic soils.

History[edit | edit source]

Calcium was first isolated in its elemental form by Sir Humphry Davy in 1808 through the electrolysis of a mixture of lime and mercuric oxide. The name "calcium" originates from the Latin word calx or calcis, meaning "lime".

Frequently asked questions:Calcium[edit | edit source]

What is calcium?[edit | edit source]

Calcium is a mineral and is one of the most abundant mineral in the body.

Where is it found?[edit | edit source]

In our body, it is found in bones, teeth and other connective tissues. Calcium makes up much of the structure of bones and teeth and allows normal bodily movement by keeping tissue rigid, strong, and flexible

What is ionized calcium?[edit | edit source]

The small ionized pool of calcium in the circulatory system, extracellular fluid, and various tissues mediates blood vessel contraction and dilation, muscle function, blood clotting, nerve transmission, and hormonal secretion

How is calcium absorbed?[edit | edit source]

Calcium from foods and dietary supplements is absorbed by both active transport and by passive diffusion across the intestinal mucosa. Active transport is responsible for most absorption when calcium intakes are lower, and passive diffusion accounts for an increasing proportion of calcium absorption as intakes rise [1,3].

Where is most of our bodies calcium stored?[edit | edit source]

Almost all (98%) calcium in the body is stored in the bones, and the body uses the bones as a reservoir for, and source of, calcium to maintain calcium homeostasis

What form of calcium is found in our body?[edit | edit source]

  • More than 99% of calcium in the body is in the form of calcium hydroxyapatite, an inorganic matrix of calcium and phosphate that is stored in the bones and teeth.
  • Unlike teeth, bone undergoes continuous remodeling, with constant resorption and deposition of calcium into new bone.
  • Bone remodeling is required to change bone size during growth, repair damage, maintain serum calcium levels, and provide a source of other minerals.

What is the relationship between intake and absorption?[edit | edit source]

  • An inverse relationship exists between calcium intake and absorption.
  • Absorption of calcium from food is about 45% at intakes of 200 mg/day but only 15% when intakes are higher than 2,000 mg/day.

What is the recommended intake?[edit | edit source]

Recommended Dietary Allowances (RDAs) for Calcium
Age Male Female Pregnant Lactating
0-6 months* 200 mg 200 mg
7–12 months* 260 mg 260 mg
1–3 years 700 mg 700 mg
4–8 years 1,000 mg 1,000 mg
9–13 years 1,300 mg 1,300 mg
14–18 years 1,300 mg 1,300 mg 1,300 mg 1,300 mg
19–50 years 1,000 mg 1,000 mg 1,000 mg 1,000 mg
51–70 years 1,000 mg 1,200 mg
>70+ years 1,200 mg 1,200 mg
  • Adequate Intake (AI)

What are some good sources of calcium[edit | edit source]

  • Milk, yogurt, and cheese are rich natural sources of calcium
  • Nondairy sources include canned sardines and salmon with bones as well as certain vegetables, such as kale, broccoli, and Chinese cabbage (bok choi).
Calcium regulation.png

Are grains a poor source of calcium?[edit | edit source]

Yes. Most grains do not have high amounts of calcium unless they are fortified.

Does calcium absorption vary based on food?[edit | edit source]

Calcium absorption varies by type of food. The absorption of calcium from dairy products and fortified foods is about 30%

What factors decrease calcium absorption?[edit | edit source]

Certain compounds in plants (e.g., oxalic acid, phytic acid) can decrease calcium absorption by forming indigestible salts with calcium, decreasing its absorption

What foods are high in oxalic acid?[edit | edit source]

The absorption of calcium is only 5% for spinach, whereas it is much higher, at 27%, for milk. Other foods with high levels of oxalic acid include collard greens, sweet potatoes, rhubarb, and beans

Does caffein play a role?[edit | edit source]

Net absorption of dietary calcium is also reduced to a small extent by intakes of caffeine and phosphorus and to a greater extent by low status of vitamin D.

How much calcium do dietary supplements have?[edit | edit source]

  • Calcium is available in many dietary supplements, including multivitamin/mineral products and supplements containing calcium only or calcium plus vitamin D.
  • Amounts of calcium in supplements vary widely; multivitamin/mineral supplements commonly contain about 200 to 300 mg, and common amounts in calcium or calcium plus vitamin D supplements are 500 or 600 mg.

What are the different types of calcium?[edit | edit source]

Is calcium citrate a better choice?[edit | edit source]

  • Calcium citrate is less dependent on stomach acid for absorption than calcium carbonate, so it can be taken without food.

Do you absorb calcium better when taken with food?[edit | edit source]

  • nYes. In general, absorption of calcium supplements is greater when they are taken with food, regardless of whether the user’s gastric acid is low.

What are some other forms of calcium supplements?[edit | edit source]

Does the amount of calcium vary by type of supplement?[edit | edit source]

  • Yes. The forms of calcium in supplements contain varying amounts of elemental calcium. For example, calcium carbonate is 40% calcium by weight, whereas calcium citrate is 21% calcium.

What is elemental calcium?[edit | edit source]

  • Elemental calcium is listed in the Supplement Facts panel, so consumers do not need to calculate the amount of calcium supplied by various forms of calcium in supplements.

Are there any side effects to calcium supplements?[edit | edit source]

  • Some individuals who take calcium supplements might experience gastrointestinal side effects, including gas, bloating, constipation, or a combination of these symptoms.

Does calcium carbonate Calcium carbonate cause more side effects?[edit | edit source]

  • Yes. When compared to calcium citrate, especially in older adults who have lower levels of stomach acid, calcium carbonate causes more side effects.

How to reduce side effects?[edit | edit source]

  • Symptoms can be alleviated by switching to a supplement containing a different form of calcium, taking smaller calcium doses more often during the day, or taking the supplement with meals.

Medicines[edit | edit source]

  • Because of its ability to neutralize stomach acid, calcium carbonate is contained in some over-the-counter antacid products, such as Tums and Rolaids.
  • Depending on its strength, each chewable pill or soft chew provides about 270 to 400 mg of calcium.

What is calcium deficiency?[edit | edit source]

  • Calcium deficiency can reduce bone strength and lead to osteoporosis, which is characterized by fragile bones and an increased risk of falling.
  • Calcium deficiency can also cause rickets in children and other bone disorders in adults, although these disorders are more commonly caused by vitamin D deficiency.
  • In children with rickets, the growth cartilage does not mineralize normally, which can lead to irreversible changes in the skeletal structure.

See also[edit | edit source]

Calcium Resources

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