Browsing by Author "Knight, Kimberley"

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    Determinants of serum 25-hydroxyvitamin D levels in healthy young adults living in the Western Cape
    (Stellenbosch : Stellenbosch University, 2018-03) Knight, Kimberley; Visser, Janicke; Blaauw, Renee; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Global Health. Human Nutrition.
    ENGLISH SUMMARY : Background: The prevalence of vitamin D deficiency is fast emerging as a global pandemic. In South Africa, however, few studies have been conducted to determine the vitamin D status of the healthy population. While the effects of vitamin D on the body have been known for centuries, vitamin D has recently garnered great attention, with new evidence surrounding vitamin D and health emerging at a rapid rate. Previously thought to only be important for bone health, new research into the role of vitamin D in the body has revealed the importance of sufficient vitamin D levels for overall health. Aim: The main aim of this study was to investigate the vitamin D status of adults in the Western Cape. Objectives sought to determine whether skin tone, gender, basic anthropometrical measurements, diet, and lifestyle factors had an effect on serum 25(OH)D levels. Methods: This descriptive, cross-sectional study investigated the vitamin D status of healthy, undergraduate students (mean age: 20.41 ± 2.29 years) at Stellenbosch University. Serum 25(OH)D was collected and analysed, along with basic anthropometrical measurements (weight, height, BMI and waist circumference). A food frequency questionnaire was used to estimate dietary vitamin D intakes. Skin tone was measured using the Fitzpatrick Skin Type (FST) Classification, and a skin reflectometry device was used to measure dermal melanin content. Results: A total of 242 undergraduate students (with equal gender representation) were included in this study during September 2016. The results showed a mean serum 25(OH)D of 63.80 ± 41.35 ng/ml and a high prevalence of vitamin D sufficiency (90% of participants). The relationship between gender and serum 25(OH)D was found to be significant (p<0.01), with more females experiencing suboptimal vitamin D levels than males (18% vs. 5%). Just over half of the participants identified themselves as skin type IV when using the FST classification, and participants with lighter skin tones had higher levels of 25(OH)D than those with darker skin tones (p=0.02). The majority of the participants (60.74%) had normal BMIs, although the relationship between BMI and serum 25(OH)D was not statistically significant (p=0.09). Total mean dietary vitamin D intake was 7.99 ± 13.81mcg, with 87.2% of participants consuming less than the recommended daily intake of vitamin D (15mcg). The relationship between total vitamin D intake and serum 25(OH)D was found to be weak, but statistically significant (p=0.003). Sun exposure and lifestyle factors were not found to have an effect on serum 25(OH)D levels in this study. Conclusion: This study found a low prevalence of vitamin D deficiency amongst young adults, despite low dietary vitamin D intakes. Significant relationships were found between serum Stellenbosch 25(OH)D and gender, skin tone, and vitamin D intake. While this study population was homogenous, it encompassed a very specific group of young, healthy undergraduate students and further studies need to be done before the results are applied to the greater public.