Inclusion of 95 % range in the model to account for inter-individual variability increased the predicted intake of vitamin D needed to maintain serum 25(OH)D ≥ 50 nmol/l to 930 IU/d .
Vitamin D supplementation in elderly nursing home residents increases 25(OH)D but not 1,25(OH)2D.
Vitamin D metabolism in elderly individuals can be compromised by several mechanisms . We previously described reduced concentrations of 1,25-dihydroxyvitamin D [ 1,25(OH)2D ] in 30 % of elderly nursing home residents . The present study assesses the effect of vitamin D supplementation on 25-hydroxyvitamin D [ 25(OH)D ] and 1,25(OH)2D . We performed a double-blind study in which 30 elderly nursing home residents were r and omly given either 50 micrograms vitamin D or a placebo daily for 6 wk . Vitamin D metabolites , immunometrically assayed parathyroid hormone ( IRMA-PTH ) , ionized calcium , and bone Gla hormone ( BGP ) were measured in serum at baseline and biweekly for 6 wk . Serum 25(OH)D concentrations increased significantly ( P less than 0.0001 ) over the 6 wk in the treatment group but were unchanged in the placebo group . Serum 1,25(OH)2D , ionized calcium , BGP , and PTH were not significantly altered by the supplement . We conclude that vitamin D supplementation results in an increase in circulating 25(OH)D but not 1,25(OH)2D ; however , the long-term effect on bone mineral metabolism remains unclear
Inclusion of 95 % range in the model to account for inter-individual variability increased the predicted intake of vitamin D needed to maintain serum 25(OH)D ≥ 50 nmol/l to 930 IU/d .