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Gwenn Smith Olson, Facebook asked:
Can we please address the American, Brit, Canadian, et cetera of African descent and vitamin D deficiencies issue?Ē
Elina - Skin colouration is the most important personal characteristics which is affecting how likely you are to be Vitamin D deficient or how efficiently you can produce vitamin D by your skin.
So for example, we were looking at this cohort of 45-year-old individuals and if among the white skinned individuals, we had less than 10% who were severely vitamin D deficient, so that by severe, I mean people who were at increased risk of rickets or bone deformities. In individuals who were from non-Caucasian ethnic groups there was 40% of them. So itís a massively strong risk factor for vitamin D deficiency.
Chris - What about the other cultural aspect of this, people who are not necessarily very darkly skinned, but choose to cover themselves from head to foot in very dark fabrics so they don't see the sun? What about that practice?
Elina - Yeah, that's of course is a combination of different things and you can't produce vitamin D by your skin without exposing some of your skin to the sunlight.
Chris - So, what should people who are in these risk groups do? Should they go and get a vitamin D test then?
John - Yes, I think you raised the very important point of the additional cultural burden of concealment if you like from the sun which of course means that particularly, families of Muslim extraction are at increased risk, and clearly, the common sense thing is to add a dietary supplement of vitamin D Ė itís very straightforward. But I think itís also worth just generally picking up this point about our evolution.
Itís very clear that as we migrated out of Africa, we got paler the further north we went and that had to have been a Darwinian selection process and almost certainly, now that we know so much about vitamin D, the strong argument is that as we got further away from the equator, we had to get paler to remain healthy because our vitamin D levels were at risk. So, I think that both in terms of the genetic predisposition if you like to vitamin D problems and the cultural problems being that anyone from ethnic minorities should think very seriously about taking a vitamin D supplement.