Association Between Vitamin D Level and Z-Score Changes of Bone Density in College-Age Saudi Girls: A Cross-Sectional Study

OBJECTIVE: Vitamin D (VD) deficiency is a worldwide health problem. VD plays a crucial role in calcium homeostasis, phosphorus metabolism and bone health. Still much remain to understand the effect of VD deficiency on bone mass. This study aimed to evaluate the relationship between VD levels and bone mass density (BMD) among college-age Saudi females. METHODS: In a cross-sectional study, 460 females with a median age of 21 years, were enrolled, completed a comprehensive, structured questionnaire which was validated by experienced endocrinologist, a dietician, and a statistician. Body mass indexes (BMI) were calculated, and BMD was estimated through quantitative ultrasound to ankle. Serum VD, calcium, phosphate, parathyroid hormone, and alkaline phosphatase were measured using chemiluminescent immunoassay technique. RESULTS: VD deficiency reached up to 83.3% (66.9% insufficiency and 16.4% deficiency). Lower than normal BMD was detected in 18.3% of subjects, with only 1.1% having a non-age-matched high risk for osteoporosis. The significant independent predictors of Z-score were age of menarche, menstrual irregularities, dairy products consumption, physical activity, BMI, alkaline phosphatase, and history of previous VD supplementation. CONCLUSION: VD deficiency and low BMD are highly prevalent among college-age Saudi females. Low BMD is not linked to serum level of VD but to its previous use as a supplementation. Early lifestyle changes, attention to gynecological problems, and prevention of VD deficiency are all needed to support BMD among these girls.