In recent years there has been an impressive increase in the number of scientific articles related to the metabolism of calcium and vitamin D. We have gained a much deeper knowledge of many patho-physiological aspects. However, and in spite of this, a series of fraudulence, myths and legends have been developed in parallel on both calcium and vitamin D, many of them absolutely unjustified, and others derived from a misunderstanding of some scientific articles. Since this can lead to the abandonment of treatments or taking them in the wrong way, we have developed this article in order to clarify, with scientific evidence, some of these aspects.
Review of the physiology of calcium and vitamin D.
Calcium absorption depends on vitamin D and is a saturable mechanism. From a certain amount and reach the optimum level of absorption, all calcium that is ingested is not absorbed and is eliminated by feces.
Between 100 and 200 mg of calcium are removed by the kidney on a daily basis under normal conditions. Also, between 800 to 900 mg of calcium is lost by stool, as a result of the secretion of bile salts and pancreatic juices. These are known as “mandatory calcium losses” and together they constitute about 1,000 mg (Figure 1). Calcium cannot be synthesized by any metabolic route and, therefore, must be taken by diet .