Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l.
Level 4 - case-series / case-control
Cross-sectional observational study measuring biomarker concentrations in two traditional cohorts without a control group.
PubMed 22264449 · doi:10.1017/S0007114511007161
What was done
Serum concentrations of 25-hydroxyvitamin D (sum of 25(OH)D₂ and 25(OH)D₃) were measured using liquid chromatography-MS/MS in 35 pastoral Maasai (mean age 34, 43% male) and 25 Hadzabe hunter-gatherers (mean age 35, 84% male) living in Tanzania. Both groups had skin type VI, wore moderate clothing, spent most of the day outdoors, and avoided direct sunlight when possible.
What was found
Mean serum 25(OH)D concentration was 119 nmol/l (range 58–167 nmol/l) in the Maasai and 109 nmol/l (range 71–171 nmol/l) in the Hadzabe, yielding an overall mean of 115 nmol/l. Vitamin D concentrations showed no relationship with age, sex, or BMI.
Why it matters
This study provides an evolutionary reference point for circulating vitamin D concentrations in human populations living under lifelong tropical sunlight conditions.
Limits
Small sample size (total n = 60). Cross-sectional design that did not measure dietary intake, calcium homeostasis, parathyroid hormone, or long-term health outcomes, limiting direct extrapolation of these targets to modern indoor lifestyles.
Cited by
- contradicts Studies of traditional African tribes show natural vitamin D levels over 150 ng/mL.