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Every 400 IU increase of vitamin D3 increases serum level about 8 ng– Systematic Review Aug 2012

A Systematic Review: Influence of Vitamin D Supplementation on Serum 25-Hydroxyvitamin D Concentration

Philippe Autier, Sara Gandini and Patrick Mullie
International Prevention Research Institute (P.A., P.M.), 69006 Lyon, France; and European Institute of Oncology (S.G.), 20139 Milano, Italy
Address all correspondence and requests for reprints to: Philippe Autier, M.D., International Prevention Research Institute (iPRI), 95 Cours Lafayette, 69006 Lyon, France. E-mail: philippe.autier at i-pri.org.

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.

Data Sources: We conducted a systematic search in literature databases and in references of past reviews.

Study Selection: Randomized placebo or open-label trials that evaluated the influence of vitamin D supplementation on clinical outcomes were included in the study.

Data Extraction: We reviewed trial characteristics and serum 25-hydroxyvitamin D concentrations at baseline and during the trial.

Data Synthesis: Seventy-six trials published from 1984 to March 2011 included 6207 subjects allocated to 101 intervention groups that tested supplement doses ranging from 5 to 250 ?g/d (median, 20 ?g/d). For similar doses, trials could obtain increases in 25-hydroxyvitamin D three to four times lower than other trials.

A meta-regression showed that in the absence of concomitant use of calcium supplements, the average increase in serum 25-hydroxyvitamin D concentrations was 0.78 ng/ml (1.95 nmol/liter) per microgram of vitamin D3 supplement per day.

Compared to the vitamin D3, the vitamin D2 was associated with significantly lower increases (P = 0.03).
Concomitant use of calcium supplementation and high 25-hydroxyvitamin D concentration at baseline was nonsignificantly associated with lower increases in 25-hydroxyvitamin D concentrations.

Conclusions: Dietary recommendations and randomized 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.

Received January 27, 2012, Accepted May 15, 2012, Copyright © 2012 by The Endocrine Society
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This linear relationship differs from previous analysis which have found relationships which:

  1. which are non-linear
  2. varies with weight
  3. varies with age
  4. increase as cofactors (Magnesium, Vitamin K2, Boron, etc) are taken

See also VitaminDWiki

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