Volume 88, Issue 2, August (2002), pp. 133-139 © The Author 2002

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Changes with malnutrition in the concentration of plasma vitamin D binding protein in growing rats

Christopher J. Laing^*, David R. Fraser
Faculty of Veterinary Science, University of Sydney 2006, Australia

 (Received 12 June 2001–Revised 5 March 2002–Accepted 17 March 2002)

The work presented here examines the possible effects of nutritional deficiencies on the characteristics of the plasma transport protein for vitamin D and its metabolites (vitamin D binding protein, DBP) in the growing rat. Deficiencies in both dietary protein intake and dietary energy intake may decrease the concentration of DBP in the circulation, although plasma DBP was not affected by dietary Ca deficiency. None of the dietary factors examined appears to influence the affinity of DBP for its major ligand, 25-hydroxycholecalciferol (25(OH)D₃). Protein-deficient rats seemed to have difficulty in maintaining adequate concentrations of 1,25-dihydroxycholecalciferol (1,25(OH)₂D₃) in the circulation. The sensitivity of DBP to dietary protein and energy intake may constitute a novel mechanism that may help to explain the observed associations between malnutrition and the development of metabolic bone disease, through alterations to the cellular availability of vitamin D ligands to DBP.

Keywords:
Plasma vitamin D binding protein: Cholecalciferol: Malnutrition