In the human body, calcium has two functions are independent of one another. Approximately 99% of total body calcium (about 1.2 Kg) is deposited in the organic matrix of the skeleton such as salts of phosphate rock and provides mechanical stability to the bone.

Meanwhile, about 1% of body calcium is dissolved in blood plasma and cellular fluid, where it carries out several important functions. Among these we may mention that calcium is involved as a messenger to the endocrine glands or a positively charged ion power for the transmission of signals along the nerve pathways and muscle contraction.

These are vital functions, which means that this agency will provide himself a constant level of blood calcium levels constant for the concentration of calcium in cells.
When there is an insufficient supply of calcium in the diet, the level of calcium in the blood is maintained within a normal range at the expense of the deposition of calcium in the skeleton.

In other words, the role of calcium as a messenger and trigger the transmission of electrical signals acquires priority over its support function in the skeleton. The mobilization of calcium from bone loss occurs with the help of a hormone secreted by the parathyroid gland. Therefore, a chronic deficiency of calcium leads to bone loss.

It is known that vitamin D without the intestine can not absorb adequate calcium from food and / or calcium supplements. However, it is very important to note that vitamin D is provided not only in food, or with nutritional supplements, it is also synthesized in the skin from ultraviolet rays of the sun. Therefore, a person receiving adequate amounts of sunlight, is able to synthesize enough vitamin D, according to a secure absorption, optimal amounts of calcium from the intestine.