Explain Absorption and Metabolism of Minerals?
All minerals in the diet are not equally absorbed. Also different compounds and complexes of same mineral are absorbed with different degree of efficiency. The fraction of the dietary intake of minerals absorbed and utilized for specific functions is defined as the bioavailability of the minerals. In addition to the chemical form in which minerals are present in the diet, factors such as age, sex, general health, and other constituents of the diet affect bioavailability of minerals. Upon absorption across the intestinal mucosa, minerals enter their metabolic pool. They are transported in the blood by specific transport protein(s) to their storage site or to the active physiologic/biochemical site. The physiologic effects of minerals depend on the level of intake.
There is a range of intake, known as safe and adequate range which provides optimal function. If the intake is progressively below this range there is a gradual decrease in the respective function of minerals until overt signs of deficiency appear. On the other hand when the intake exceeds the upper limit of safety (i.e. upper tolerable limit) signs of toxicity begin to appear. In fact, all the essential minerals are toxic if consumed in excess; however the concentration at which toxicity occurs varies widely. It must be emphasized here that as long as a mixed diet is the only source of minerals, toxicity is most unlikely to occur. In our subsequent sections we will learn in detail about the metabolism, functions, requirements, food sources etc of calcium, phosphorus, magnesium, iron, sodium, potassium and chloride. Let us begin with one of the most crucial element for maintaining bones and our skeletal system i.e., calcium and learn why is this mineral so important for us?