A systematic review and meta-regression analysis of the vitamin D intake-serum 25-hydroxyvitamin D relationship to inform European recommendations.

Br J Nutr. 2011 Oct 14:1-11.
Cashman KD k.cashman at ucc.i.e. , Fitzgerald AP, Kiely M, Seamans KM.
School of Food and Nutritional Sciences, University College Cork, Cork, Republic of Ireland.

The present study used a systematic review approach to identify relevant randomised control trials (RCT) with vitamin D and then apply meta-regression to explore the most appropriate model of the vitamin D intake-serum 25-hydroxyvitamin D (25(OH)D) relationship to underpin setting reference intake values.

Methods included an updated structured search on Ovid MEDLINE; rigorous inclusion/exclusion criteria; data extraction; and meta-regression (using different model constructs). In particular, priority was given to data from winter-based RCT performed at latitudes >49·5°N (n 12).

A combined weighted linear model meta-regression analyses of natural log (Ln) total vitamin D intake (i.e. diet and supplemental vitamin D) v. achieved serum 25(OH)D in winter (that used by the North American Dietary Reference Intake Committee) produced a curvilinear relationship (mean (95 % lower CI) serum 25(OH)D (nmol/l) = 9·2 (8·5) Ln (total vitamin D)). Use of non-transformed total vitamin D intake data (maximum 1400 IU/d; 35 ?g/d) provided for a more linear relationship (mean serum 25(OH)D (nmol/l) = 0·044 × (total vitamin D)+33·035).

Although inputting an intake of 600 IU/d (i.e. the RDA) into the 95 % lower CI curvilinear and linear models predicted a serum 25(OH)D of 54·4 and 55·2 nmol/l, respectively, the total vitamin D intake that would achieve 50 (and 40) nmol/l serum 25(OH)D was 359 (111) and 480 (260) IU/d, respectively.

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. The model used to describe the vitamin D intake-status relationship needs to be considered carefully when setting new reference intake values in the Europe.
PMID: 22000709
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930 IU would achieve 20 ng/ml for 95% of the population

Of course would need much more Vitamin D to get 30, 40, or 50 ng/ml

Wonder if their models considered additional Reasons for Vitamin D Deficiency

• Obese: a majority of the vitamin D does not get to their blood
• People with adsorption problems
• People drinking cola (which uses up Calcium and thus vitamin D)
• People who get very little vitamin D from the sun:
  • wearing excessive clothing,
  • those in most senior homes or otherwise indoors a lot
  • those who are paranoid about skin cancer (5X less likely to get skin cancer if you do not get a sunburn)
• Have a condition which prevents conversion to active vitamin D
• Have a condition called pregnancy (many studies show a need for 4,000 to 6,400 IU)
  • Especially black and pregnant

See also Vitamin D Life

• Overview of How Much Vitamin D
• Is 50 ng of vitamin D too high, just right, or not enough
• All items in category How much D 218 items June 2012
• 800 IU vitamin D resulted in 20 ng, 3200 IU resulted in 45 ng – RCT March 2012
• Four reasons why vitamin D levels should be higher than 30 ng – Aug 2011
• Cadavers with good skeletons had 30 ng of vitamin D – Feb 2010
• Germany increases vitamin D to 800 IU - Jan 2012
• Published Recommendations of Vitamin D which includes the following graph