lvysaur
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This post is intended to debunk the common claim that people of African descent are severely low in vitamin D.
This is because vitamin D, like most hormones, has a binding globulin that attenuates its absorption. Estro/Androgens have SHBG. Vitamin D has vitamin D binding protein (VDBP). More VDBP makes Vitamin D less available.
Levels of VDBP are half as high in blacks as in whites (168 vs. 337 ug/mL)
79.4% of the variation in VDBP levels is due to 2 mutations, even discounting for race entirely.
Both of these mutations are nearly fixed (90%+) for pure Africans, but are less common (50-70%) in Indo-Caucasoids.
rs4588 - SNPedia
rs7041 - SNPedia
Vitamin D–Binding Protein and Vitamin D Status of Black Americans and White Americans
The Myth of chronic Black Vitamin D deficiency
Therefore, an African person with a vitamin D level that is 50% that of a white person, is nowhere nearly as bad as clinicians think--he might even be sufficient. However, a minority of Africans, a minority which gets larger among black Americans due to admixture, has the "Asian" phenotype of high VDBP, and would need higher D levels.
Also, low VDBP among Africans may pose challenges for winter vitamin D levels, as VDBP may act as a form of vitamin D "storage". Vitamin D usually can't be made in winter, regardless of skin color.
Dark-skinned NON-African people still have the Eurasian risk. For example, Southern Indian people have genotype frequencies that are similar to Arabs/Europeans, despite dark skin--meaning that these people have high VDBP and thus need higher D levels (just like Europeans) to compensate.
This is because vitamin D, like most hormones, has a binding globulin that attenuates its absorption. Estro/Androgens have SHBG. Vitamin D has vitamin D binding protein (VDBP). More VDBP makes Vitamin D less available.
Levels of VDBP are half as high in blacks as in whites (168 vs. 337 ug/mL)
79.4% of the variation in VDBP levels is due to 2 mutations, even discounting for race entirely.
Both of these mutations are nearly fixed (90%+) for pure Africans, but are less common (50-70%) in Indo-Caucasoids.
rs4588 - SNPedia
rs7041 - SNPedia
Vitamin D–Binding Protein and Vitamin D Status of Black Americans and White Americans
The Myth of chronic Black Vitamin D deficiency
Therefore, an African person with a vitamin D level that is 50% that of a white person, is nowhere nearly as bad as clinicians think--he might even be sufficient. However, a minority of Africans, a minority which gets larger among black Americans due to admixture, has the "Asian" phenotype of high VDBP, and would need higher D levels.
Also, low VDBP among Africans may pose challenges for winter vitamin D levels, as VDBP may act as a form of vitamin D "storage". Vitamin D usually can't be made in winter, regardless of skin color.
Dark-skinned NON-African people still have the Eurasian risk. For example, Southern Indian people have genotype frequencies that are similar to Arabs/Europeans, despite dark skin--meaning that these people have high VDBP and thus need higher D levels (just like Europeans) to compensate.
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