^ and this belongs with the post and graph above.
It is hugely significant; it is the only measure I have seen so far of vitamin D levels of groups living as they have for thousands of years, and in dark skinned people who have the equivalent of a factor 15 or more sunscreen built into their skins.
Notwithstanding the very powerful natural sun screen their vitamin D level average 115nmol/l, (and from memory the levels in pregnant women were higher 149nmol/l - there must be another part to this paper, not referenced here).
This dispels the often cited view that people with dark skins do not need as much vitamin D, (and would have significant implications for levels in pregnancy - I will try and find the reference).
http://www.vitamindcouncil.org/blog/...abe-of-africa/
http://www.ncbi.nlm.nih.gov/pubmed/22264449
Br J Nutr. 2012 Nov 14;108(9):1557-61. doi: 10.1017/S0007114511007161. Epub 2012 Jan 23.
Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l.
Luxwolda MF1, Kuipers RS, Kema IP, Dijck-Brouwer DA, Muskiet FA.
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Abstract
Cutaneous synthesis of vitamin D by exposure to UVB is the principal source of vitamin D in the human body. Our current clothing habits and reduced time spent outdoors put us at risk of many insufficiency-related diseases that are associated with calcaemic and non-calcaemic functions of vitamin D. Populations with traditional lifestyles having lifelong, year-round exposure to tropical sunlight might provide us with information on optimal vitamin D status from an evolutionary perspective. We measured the sum of serum 25-hydroxyvitamin D₂ and D₃ (25(OH)D) concentrations of thirty-five pastoral Maasai (34 (SD 10) years, 43 % male) and twenty-five Hadzabe hunter-gatherers (35 (SD 12) years, 84 % male) living in Tanzania. They have skin type VI, have a moderate degree of clothing, spend the major part of the day outdoors, but avoid direct exposure to sunlight when possible. Their 25(OH)D concentrations were measured by liquid chromatography-MS/MS. The mean serum 25(OH)D concentrations of Maasai and Hadzabe were 119 (range 58-167) and 109 (range 71-171) nmol/l, respectively. These concentrations were not related to age, sex or BMI. People with traditional lifestyles, living in the cradle of mankind, have a mean circulating 25(OH)D concentration of 115 nmol/l. Whether this concentration is optimal under the conditions of the current Western lifestyle is uncertain, and should as a possible target be investigated with concomitant appreciation of other important factors in Ca homeostasis that we have changed since the agricultural revolution.