VITAMINA D: ACCIONES NO CLÁSICAS

Abstract

Vitamin D es a steroidal hormone, essential for the development, growth, and maintenance of the

skeleton. Adequate levels of this vitamin are obtained through the diet and especially through

exposure to sunlight. After intestinal absorption of ingested vitamin, or following photoproduction in

the skin, it is metabolized in the liver to 25-hydroxyvitamin D3 [25(OH)D3], and then in the kidney to

1,25-dihydroxyvitamina D3 [1,25(OH)2D3]. The latter interacts with its nuclear receptor (VDR) in gut

and bone, thus contributing to calcium homeostasis. The VDR is present also in several cells and

tissues, including striated muscle, lymphocytes, heart, pancreas, skin, brain, gonads, etc. The

interaction of 1,25(OH)2D3 with these receptors is responsible for several recently identified

physiological responses. Some tissues such as breast, prostate, colon, and skin have the enzyme 1α-

hydroxilase and can produce 1,25(OH)2D3 locally. Mounting epidemiological evidence demonstrates

the association of living at high latitudes and an increased risk of several diseases. Such associated

appears to be linked to decreased generation of vitamin D3 in the skindue to less exposure to

ultraviolet B radiation. The pathophysiological mechanisms of these entities have begun to be

revealed in recent years. Deficiency of vitamin D is quite prevalent in the general population, with

several high-risk subpopulations, such as lactating infants, people living at high latitudes, and the elderly. Hypovitaminosis D is frequently underdiagnosed. It can induce rickets in children,

osteomalacia and osteoporosis in adults, and can have untowards effects on general health in the long

run. Possible consequences are: autoimmune diseases (diabetes, multiple sclerosis), hypertension, and

some types of cancer (prostate, breast, colon).