Prevalence and Predictors of Vitamin D Deficiency among African Immigrants Living in Australia

Abstract

Vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) concentrations <50 nmol/L) is a public health issue in Australia and internationally. Those with darker skin require a greater dose of ultraviolet B radiation from sunlight than those with paler skin to synthesise adequate amounts of vitamin D. Using data from the 2011–2013 Australian Health Survey, we investigated the prevalence and predictors of vitamin D deficiency in African immigrants aged ≥18 years living in Australia (n = 236). Serum 25(OH)D was measured using a liquid chromatography–tandem mass spectrometry method that is certified to international reference measurement procedures. Poisson regression was used to investigate independent predictors of vitamin D deficiency. A total of 36% of adults were vitamin D deficient (35% of men, 37% of women). The prevalence ratio (PR) of vitamin D deficiency decreased by 2% per year of age (PR 0.98; 95% CI (0.97, 0.99); p = 0.004) and was 1.6 times higher in those with low/sedentary, compared to moderate/high, physical activity levels (PR 1.64; 95% CI (1.12, 2.39); p = 0.011). The greatest risk was for those assessed during winter/spring compared with summer/autumn (PR 1.89; 95% CI (1.33, 2.64); p < 0.001). Culturally appropriate messaging on safe sun exposure and dietary vitamin D is warranted in order to promote vitamin D sufficiency in African immigrants living in Australia.