Dietary recommendations and r and omized trials on vitamin D supplementation should evaluate whether increases in circulating 25-hydroxyvitamin D levels match expectations -- for instance , the average increases obtained by trials on vitamin D3 without concomitant calcium supplements
CONTEXT Few studies in subjects over 50 yr of age have evaluated the influence of variable doses of vitamin D supplementation on serum 25-hydroxyvitamin D levels .
OBJECTIVE We performed a meta- analysis of changes in circulating 25-hydroxyvitamin D level associated with vitamin D supplementation in Caucasian subjects over 50 yr old .
How Much Vitamin D3 Do the Elderly Need?
Background : Vitamin D insufficiency poses a problem in many parts of the world , the elderly being an especially vulnerable group . This insufficiency results from an inadequate amount of sunshine and a low dietary intake of vitamin D. Typically , insufficiency is accompanied with high intact parathyroid hormone , ( S-iPTH ) concentrations . Aims of the Study : We studied how serum 25-hydroxy vitamin D ( S-25-OHD ) concentrations respond to different doses of vitamin D3 supplementation . Secondly to determine the smallest efficient dose to maintain serum 25-OHD concentration above the insufficiency level . We also studied which dose would be efficient in decreasing S-iPTH concentration in these subjects . Subjects and Methods : Forty-nine 65- to 85-year-old women participated . The women were r and omly assigned into one of four groups receiving 0 ( placebo ) , 5 , 10 or 20 μg of vitamin D3 daily for 12 weeks . Fasting morning blood was drawn at the beginning of the study , and thereafter every second week . Calciotropic variables were assessed from serum and urine sample s. Results : The S-25-OHD concentration increased significantly ( p < 0.001 ) in all supplemented groups [ 5 μg : by 10.9 ( 8.5 ) nmol/L , 10 μg : by 14.4 ( 6.9 ) nmol/L , 20 μg : by 23.7 ( 11.9 ) nmol/L ] , whereas it decreased in the placebo group by 8.3 ( 13.2 ) nmol/L. Equilibrium in S-25-OHD concentration was reached in all groups after 6 weeks of supplementation at 57.7 ( 8.9 ) nmol/L , 59.9 ( 8.9 ) nmol/L and 70.9 ( 8.9 ) nmol/L in the groups with increasing vitamin D supplementation . The dose-response to supplementation decreased with increasing vitamin D status at baseline , r = −0.513 , p = 0.002 . S-iPTH tended to decrease in those with highest dose response to supplementation . Conclusions : A clear dose response was noted in S-25-OHD to different doses of vitamin D3 . The recommended dietary intake of 15 μg is adequate to maintain the S-25-OHD concentration around 40–55 nmol/L during winter , but if the optimal S-25-OHD is higher than that even higher vitamin D intakes are needed . Interestingly , subjects with lower vitamin D status at baseline responded more efficiently to supplementation than those with more adequate status
Dietary recommendations and r and omized trials on vitamin D supplementation should evaluate whether increases in circulating 25-hydroxyvitamin D levels match expectations -- for instance , the average increases obtained by trials on vitamin D3 without concomitant calcium supplements
CONTEXT Few studies in subjects over 50 yr of age have evaluated the influence of variable doses of vitamin D supplementation on serum 25-hydroxyvitamin D levels .
OBJECTIVE We performed a meta- analysis of changes in circulating 25-hydroxyvitamin D level associated with vitamin D supplementation in Caucasian subjects over 50 yr old .