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Dark skin does not generate as much vitamin D from the same amount of UV – Nov 2011

Am J Clin Nutr. 2011 Nov;94(5):1219-24. Epub 2011 Sep 14.
Farrar MD, Kift R, Felton SJ, Berry JL, Durkin MT, Allan D, Vail A, Webb AR, Rhodes LE.
Dermatological Sciences, Inflammation Sciences Research Group, School of Translational Medicine, University of Manchester, United Kingdom.

BACKGROUND: The cutaneous synthesis of vitamin D is dependent on UVB from sunlight, but melanin reduces the penetration of UVB and thus contributes to vitamin D insufficiency in individuals with darker skin. The national guidance provided on amounts of sunlight exposure in the United Kingdom is for the light-skinned population, and in the absence of dedicated information, darker-skinned people may attempt to follow this guidance.

OBJECTIVES: We determined the relative effect of a simulation of UK recommendations of summer sunlight exposure on the vitamin D status of individuals of South Asian ethnicity compared with that of whites.

DESIGN: In a prospective cohort study, simulated summer sunlight exposures were provided under rigorous dosimetric conditions to 15 adults (aged 20-60 y) of South Asian ethnicity, and serum 25-hydroxyvitamin D 25(OH)D was measured weekly. Dietary vitamin D intake was estimated. Outcomes were compared with those of 109 whites (aged 20-60 y) treated with the identical UV-radiation exposure protocol.

RESULTS: At baseline (winter trough),

  • all South Asians were vitamin D-insufficient [25(OH)D concentrations <20 ng/mL], and
  • 27% of South Asians were vitamin D-deficient [25(OH)D concentrations <5 ng/mL];

although 25(OH)D concentrations increased postcourse (P < 0.0001), all South Asians remained vitamin D-insufficient.
The mean increase in 25(OH)D was 4.3 compared with 10.5 ng/mL in the South Asian and white groups, respectively (P < 0.0001), and 90% of the white group reached vitamin D sufficiency postcourse. The median dietary vitamin D intake was very low in both groups.

CONCLUSIONS:Sunlight-exposure recommendations are inappropriate for individuals of South Asian ethnicity who live at the UK latitude. More guidance is required to meet the vitamin D requirements of this sector of the population. This study was registered at www.isrctn.org as ISRCTN 07565297.

PMID: 21918215
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With the same UV exposure:
South Asians 4.3 ng, Whites 10.5 ng
South Asians gained only 40% as much as whites
Abstract does not indicate: wonder if the percentage gained by each was the same

Blacks 10X more likely  to be deficient -2008

Blacks 10X more likely to be vitamin D deficient ( < 17.8 ng)

The health disparity for dark skinned people is almost the same as whites having a low level of vitamin D

Black vs WhiteWhite: low D vs high D
breast cancer 1.34 1.26
colorectal cancer 1.43 1.44
cardiovascular disease1.29 1.27
all-cause mortality 1.26 1.26

CLICK HERE for details, Dr. Grant

See also VitaminDWiki

in wikipage: http://www.vitamindwiki.com/tiki-index.php?page_id=1660

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