title: Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l.
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.
authors.affiliation: Laboratory Medicine, University Medical Center Groningen, Groningen, The Netherlands. m.luxwolda@umcg.nl
authors.forename: Martine F
authors.initials: MF
authors.lastname: Luxwolda
authors.forename: Remko S
authors.initials: RS
authors.lastname: Kuipers
authors.forename: Ido P
authors.initials: IP
authors.lastname: Kema
authors.forename: D A Janneke
authors.initials: DA
authors.lastname: Dijck-Brouwer
authors.forename: Frits A J
authors.initials: FA
authors.lastname: Muskiet
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood; D000293:Adolescent; D000328:Adult; D000368:Aged; D044383:Black People; D002112:Calcifediol / Q000097:blood*; D003020:Clothing; D003906:Developing Countries; D005260:Female; D006801:Humans; D008019:Life Style / Q000208:ethnology*; D008297:Male; D008875:Middle Aged; D009751:Nutritional Requirements; D012423:Rural Health / Q000208:ethnology; D012880:Skin Pigmentation; D013472:Sunlight; D013636:Tanzania / Q000453:epidemiology; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology / Q000208:ethnology / Q000517:prevention & control*; D055815:Young Adult
chemical_list: D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol