Determinants of serum 25-hydroxyvitamin D levels in healthy young adults living in the Western Cape, South Africa
Date
2019-10-28
Journal Title
Journal ISSN
Volume Title
Publisher
South African Academy of Family Physicians
Abstract
Background: Vitamin D deficiency is fast emerging as a global pandemic. In South Africa few studies have been conducted to determine the vitamin D status of the healthy population.
Methods: This prospective study with an analytical component investigated vitamin D status of healthy undergraduate students at two time points (winter and summer) at Stellenbosch University. Serum 25(OH)D was determined, anthropometric measurements taken and dietary vitamin D intake estimated (food-frequency questionnaire). Skin tone was determined (Fitzpatrick skin type classification), and a skin reflectometry device used to measure dermal melanin content.
Results: Results of 242 students indicated a mean serum 25(OH)D of 63.80 ± 41.35 ng/ml and a high prevalence of vitamin D sufficiency (88%). Significantly more females experienced suboptimal vitamin D levels than males (18 vs. 5%; p < 0.01). Participants with lighter skin tones had higher levels of 25(OH)D than those with darker skin tones (chi-square = 24.02; p = 0.02). The majority (60.74%) had a normal BMI, although there was no significant relationship between BMI and serum 25 (OH)D (Spearman’s r=–0.11; p = 0.09). Total mean dietary vitamin D intake was 7.99 ± 13.81 mcg, with 87.2% having inadequate intake (< 15 mcg). The relationship between total vitamin D intake and serum 25(OH)D was found to be significant in winter (p < 0.001) and summer (p = 0.01). Serum vitamin D levels were significantly higher in the winter phase (p < 0.001).
Conclusions: A low prevalence of vitamin D deficiency was found amongst healthy young adults, despite low dietary vitamin D intakes. Significant relationships were found between serum 25(OH)D and gender, skin tone and vitamin D intake. Further studies need to be conducted, especially in high-risk groups, before results are applied to the greater South African public.
Description
CITATION: Visser, J. et al. 2019. Determinants of serum 25-hydroxyvitamin D levels in healthy young adults living in the Western Cape, South Africa. South African Family Practice, 61(4):150–158. doi:10.4102/safp.v61i4.4951
The original publication is available at https://safpj.co.za/index.php/safpj
The original publication is available at https://safpj.co.za/index.php/safpj
Keywords
Vitamin D in the body -- Seasonal variations -- Western Cape (South Africa), Vitamin D in the body -- Adults -- Western Cape (South Africa), Vitamin D in human nutrition, Vitamin D deficiency
Citation
Visser, J. et al. 2019. Determinants of serum 25-hydroxyvitamin D levels in healthy young adults living in the Western Cape, South Africa. South African Family Practice, 61(4):150–158. doi:10.4102/safp.v61i4.4951