30 percent of variation of vitamin D levels were associated with just 3 variables – March 2013

Determinants of Vitamin D Status in Fair-Skinned Women of Childbearing Age at Northern Latitudes

PLoS ONE 8(4): e60864. doi:10.1371/journal.pone.0060864
Linnea Hedlund, Petra Brembeck, Hanna Olausson

Background and Objective: Poor vitamin D status during pregnancy has been associated with unfavorable outcomes for mother and child. Thus, adequate vitamin D status in women of childbearing age may be important. The aim of this study is to investigate the determinants of 25-hydroxyvitamin D (25(OH)D) serum concentrations in women of childbearing age living in Sweden, at latitude 57–58° north.

Method: Eighty four non-pregnant, non-lactating, healthy, fair-skinned women aged between 25–40 years were included. All subjects provided blood samples, four day food records and answered questionnaires about sun exposure and lifestyle. Total serum 25(OH)D was analyzed using Roche Cobas® electrochemoluminiescent immunoassay.

Results: Mean 25(OH)D was 65.8±19.9 nmol/l and 23% of the subjects had concentrations <50 nmol/l. Only 1% had concentrations <25 nmol/l. Determinants of 25(OH)D concentrations were recent sunbed use, recent travel to southern latitude, season, estrogen contraceptive use and use of supplementary vitamin D (R2 = 0.27).

Conclusion: Every fifth woman had 25(OH)D concentrations <50 nmol/l.
About 30% of the variation in vitamin D status was explained by

• sun exposure,
• use of vitamin D supplements and
• use of estrogen contraceptives.

Cutaneous vitamin D synthesis seems to be a major contributor to vitamin D status, even at northern latitudes.
Thus, recommendations on safe UV-B exposure could be beneficial for vitamin D status.

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See also VitaminDWiki

• Overview Deficiency of vitamin D
• Unable to make a model to predict vitamin D deficiency – Sept 2011
• Predicted vitamin D levels during pregnancy were sort of similar to those measured – Jan 2013
• All items in category Predict Vitamin D 82 items
• How to predict response to a vitamin D dose – RCT April 2014