Age and Gender Differences in the Prevalence and Correlates of Vitamin D Deficiency

Background: Vitamin D deficiency is a public health concern. This study's objective was to measure the prevalence of vitamin D deficiency and determine its correlates among Saudi adults in Riyadh, Saudi Arabia.

Methods: A cross-sectional study was conducted with 2835 Saudi males and females aged 30-75 years in 18 different primary health care centers (PHCC) in Riyadh. Detailed interviews on sociodemographic and lifestyle factors and anthropometric measurements were conducted. Serum calcium, phosphorus, parathyroid, alkaline phosphatase, and 25(OH) vitamin D were measured. Multiple logistic regression analyses were conducted.

Results: The mean age (SD) of male and female participants was 43.0 (± 11.7) and 42.8 (± 10.3) years, respectively. Serum 25(OH) vitamin D assays for participants revealed that 72.0% (n = 695) of males and 64.0% (n = 1191) of females had levels < 50 nmol/L (deficiency), whereas 17.3% (n = 166) and 19.4% (n = 362), respectively, had levels of 50-75 nmol/L (insufficiency). Multivariate analyses for males revealed that lack of use of vitamin D supplements [adjusted odds ratio (aOR) = 4.0, 95% CI 1.7, 9.4], younger age [30-40 years aOR = 3.6, 95% CI 1.7, 7.3 and 41-50 years aOR = 4.2, 95% CI 2.0, 8.8], low milk intake [aOR = 1.7, 95% CI 1.0, 2.8], consumption of cola drinks [aOR = 2.0, 95% CI 1.1, 3.9], and central obesity [aOR = 1.8, 95% CI 1.0, 3.4] were associated with low vitamin D. In females, lack of use of vitamin D supplements [aOR = 3.7, 95% CI 2.8, 4.9], younger age [30-40 years aOR = 3.4, 95% CI 2.0, 5.8 and 41-50 years aOR = 2.8, 95% CI 1.6, 4.7], central obesity [aOR = 1.4, 95% CI 1.0, 2.2], and seasonal variation [aOR = 1.6, 95% CI 1.3, 2.1] had higher odds for vitamin D deficiency. Significantly lower levels were observed for men than women for mean serum 25(OH) vitamin D [42.6 (± 24.1) vs. 46.8 (± 30.5)], parathyroid hormone [5.3 (± 2.9) vs. 5.9 (± 2.7)], and phosphorus [1.1 (± 0.2) vs. 1.2 (± 0.2)], respectively; alkaline phosphatase levels [106 (± 32.8) vs. 99 (± 27.8)] [p < 0.01] were significantly higher in males than females.

Conclusion: Vitamin D deficiency was highly prevalent, particularly among young adults and those with central obesity. Proper fortification policy, health education, and regular screening PHCCs may help prevent and treat vitamin D deficiency.