Vitamin D insufficiency in a sunshine-sufficient area: southern Ethiopia

Background. Although the photosynthesis and bioavailability of vitamin D are influenced by various factors, vitamin D is produced in the skin by ultraviolet B (UVB) radiation from sunlight. However, vitamin D insufficiency is being recognized as a common problem, even in areas with abundant sunshine.

This study assessed vitamin D status by measuring plasma 25(OH)D concentrations in rural women in southern Ethiopia living in the Rift Valley at 7 degree3' N latitude. Methods. Nonpregnant women (n = 202) living in three adjacent rural communities volunteered to participate in this cross-sectional study. Demographic, socioeconomic, health, and food frequency data were acquired by questionnaire. Anthropometric measurements and a fasting venipuncture blood sample were obtained by qualified professionals. Body mass index (BMI) was calculated. ELISA kits from ImmunoDiagnostic Systems were used to determine concentrations of 25(OH)D with external quality control standards from UTAK Laboratories.

The self-reported mean +/- SD age was 30.8 +/- 7.8 years. The mean number of pregnancies was 4.7 +/- 2.7, household size was 6.0 +/- 2.6, and BMI was 20.0 +/- 2.2. None of the participants reported ever consuming vitamin D-rich foods, fortified foods, or dietary supplements. Only 15.8% of the participants had 25(OH) D levels above 50 nmol/L, and 14.8% were below 30 nmol/L, which represents risk of deficiency relative to bone health.

Vitamin D insufficiency is a serious problem in the study population, and living near the Equator does not assure adequate vitamin D status.