Vitamin D in the 21st century. Beyond osteoporosis
Interest in vitamin D has increased dramatically in recent years. As shown in figure 1, the number of journal articles published and indexed in the PubMed database has multiplied almost by 4 from 2000 to 2016.
Vitamin D, which maintains its name by habit or history related to its discovery, is actually a complex hormonal system [1], its structure being very similar to that of steroid hormones.
Hormone D, as it should actually be termed [2], began to be studied and related to bone mineral metabolism. It is well known that its deficiency produces a skeletal disease in children referred to as rickets and osteomalacia in adults [3]. Subsequently and already in the 20th century, it was verified that practically all the cells of the organism have receptors for this hormone. Thus our knowledge was expanding into other pathophysiological and clinical aspects, including osteoporosis [3-5] as in other bone diseases. The relationship of vitamin D to these processes has been termed “extra-bone effects of vitamin D” [3,6-9].
Nowadays we have a better understanding of vitamin D’s relation with muscle and falls [1], with diabetes mellitus, both type 1 and 2 [10], with arterial hypertension and ischemic heart disease [11], immune system and autoimmune diseases [12], respiratory infections [13], Bronchial asthma [14] or cancer [3,7,8,15], to name some of the relationships on which an increasing number of articles have been published.