What is the use of vitamin c in the body and how much you need in a day

Calcium is the most abundant mineral in the body, comprising over 1.5% of total body weight (around 1.25Kg or almost 3 pounds for the average adult). Not only is calcium an intergral part of the teeth and bones (where 99% of the calcium in the body is found), but it is also closely associated with, and its absorption is dependent on Vitamin D.

Functions of calcium in the body are: Transmission of electrical impulses along the nerves, Muscle contraction, Blood clotting, Cell structure, Many enzyme reactions , Regulation of blood pressure (increases blood pressure by increasing spasm and vasoconstriction)

Calcium deficiency

A lack of calcium can show up in one or more of many ways, depending on which systems are affected.

Symptoms of calcium deficiency includes; Colon cancer, High blood pressure (hypertension), Irregular heartbeat or palpitations, Loss of muscle tone, Muscle cramps, Osteomalacia and Rickets (children) among others.

Calcium is present in high amounts in a wide variety of foods, although most people get the majority of their calcium from just one group of foods_dairy products, and in particular, cows milk. As calcium often works alongside magnesium, it is useful to obtain calcium from sources  that also include magnesium. This is not the case for milk.

In fact, calcium and magnesium work so closely together that, if there is an excess of one in the body, it will often lead to a reduction in the other, disturbing the natural balance. In addition to the presence of magnesium, it is beneficial that many of the other sources of calcium, such as seeds and nuts also contain essential fatty acids, which are also required for healthy brain, nerve, hormone and immune systems. 

Calcium supplements

Because calcium is so important to so many functions in the body, there must always be plenty to "go round". When insufficient calcium is included in the diet, it is extracted from the bones and teeth. This is particularly common in pregnancy, when the growing foetus makes extra  demands on the mothers calcium stores. If this continual demand for calcium is not met, the eventual result will be osteoporosis (thin, hollow, weak bones that are liable to fracture).

People requiring additional calcium.

Most people will benefit from calcium supplementation of 200-500mg per day, however there are special groups of people whose needs are often greater than others, namely the elderly, people on low fat diets, pregnant women, people suffering from stress (increases excretion) and menopausal women. Doses of up to 1200mg per day may be required.

Which form of calcium to take?

The most commonly used form of calcium is calcium carbonate, which is often contaminated with poisonous lead. Often derived from limestone or oyster shells, this form of calcium is poorly absorbed, especially in the elderly and others with low stomach acid levels. In fact, in many calcium preparations, absorption is as low as 3-5% of the total amount, so a woman taking 1200mg per day for osteoporosis may only absorb 36-60mg - an entirely unsatisfactory situation.

Nowadays, most well formulated calcium supplements, like Calcium Plus use chelated forms of calcium, such as calcium citrate, amino-acid chelates or orotates. the best of these will also include magnesium, phosphorus, potassium and Vitamin D and some iron.

For those taking calcium for osteoporosis, it is important to take sufficient boron either in the diet or as supplementation, as each atom of calcium requires an atom of boron to make bone.
Then, how much calcium do you need?
The human body needs calcium more than any other mineral. A man weighing 70 kg contains one kg of calcium. About 99 per cent of the quantity in the body is used for building strong bones and teeth and the remaining one per cent is used by the blood, muscles and nerves. Calcium performs many important functions. Without this mineral, the contractions of the heart would be faulty, the muscles would not contract properly to make the limbs move and blood would not clot. Calcium stimulates enzymes in the digestive process and coordinates the functions of all other minerals in the body.
Calcium is found in milk and milk products, whole wheat, leafy vegetables such as lettuce, spinach, and cabbage , carrots, watercress, oranges, lemons, almonds, figs and walnuts. A daily intake of about 0.4 to 0.6 grams of calcium is considered desirable for an adult. The requirement is larger for growing children and pregnant and lactating women. Deficiency may cause porous and fragile bones, tooth decay, heart palpitations, muscle cramps, insomnia and irritability.
A large increase in the dietary supply of calcium is needed in tetany and when the bones are decalcified due to poor calcium absorption, as in rickets, oesteomalacia and the malabsorption syndrome. Liberal quantity of calcium is also necessary when excessive calcium has been lost from the body as in hyperparathyroidism or chronic renal disease.