Vitamin D: A Molecular Approach

Danilo BARRAL, Adna Conceição BARROS, Roberto Paulo Correia de ARAÚJO

Abstract


Introduction: The expression Vitamin D is a denomination employed to designate several compounds that have the property of preventing and healing rickets. The most important are ergocalciferol (D2) and cholecalciferol (D3), though approximately ten compounds express vitamin D activity. All compounds are vital to the maintenance and control of calcium and phosphorus homeostasis. They are formed from their pro-vitamins in the organism by the action of sunlight ultraviolet (UV) radiation. 7-dehydrocholecalciferol is converted in D3 vitamin. The active form is 1,25-dihydroxycholecalciferol or calcitriol, which has either exogenous or endogenous origin and act as sterolic hormone. Important activities of vitamin D, particularly in the intestines, kidneys and bones, make it an essential hormone for the maintenance of calcium phosphate homeostasis. The existence of receptors for this hormone in the human tissues is a relevant finding that justifies the other actions attributed to it, regardless of its specific activity on the mineral metabolism. D vitamin has an endogenous route of formation – action of sunlight UV radiation on skin cholesterol – though its exogenous supply is an important factor for the maintenance of levels considered as ideal. Alterations or deficiencies in its mechanism of activation and absorption control result in organic disturbances and may evolve to important pathologies like rickets and osteomalacia. Objective: To analyze the relevance of vitamin D, currently considered as a sterolic hormone, for the maintenance of human homeostasis. Conclusion: Regular exposures to sun radiation are needed and even prescriptions of food supplements are required in cases of defective absorption of vitamin D or its conversion into its active form.

Keywords


Calcitriol; Vitamina D 3; 1,25-diidroxicolecalciferol; Raquitismo; Osteomalácia; Osteoporose; Calcitriol; Cholecalciferol; 1,25-dihydroxycholecalciferol; Raquitism; Osteomalacia; Osteoporosis.



DOI: http://dx.doi.org/10.4034/pboci.v7i3.181

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