Vitamin D status of older South Africans

Objective. To determine the vitamin D status of older 'coloured' South Africans who had not sustained a fracture. Design. Cross-sectional analytic study. Methods. A random sample of 200 non-institutionalised subjects in Cape Town aged 65 years was drawn using a two-stage cluster design. Trained fieldworkers interviewed subjects to obtain demographic, dietary and lifestyle data, to draw fasting blood samples for the analysis of serum 25-hydroxyvilamin 0 (25(OH)O) and other biochemical parameters. and to take anthropometric measurements. Results. Seventeen per cent of the subjects (95% Cl: 11.4 - 22.6%) had serum 25(OH)D levels in the deficient range for the elderly « 10 nglml); 7.5% (95% Cl: 3.6- 11.4%) had concentrations in the moderately severe range of deficiency « 8 nglml). Sixty-three per cent of Ihe subjects had raised serum alkaline phosphatase concentrations. Regression modelling showed neither a sex difference in 25(OH)D levels nor a sex-age interaction; however, a negative association with age was found (r = -0.18; P < 0.05). Mean oral vitamin D intake was low (3.6 (SO =2.7) and 2.8 (SO =1.7) for men and women, respectively), but no association between dietary vitamin D intake and serum 25(OH)D was found. Conclusions. The prevalence of suboptimal vitamin D status was high. However, the interpretation of the data, with regard to bone health, is limited by the crosssectional design of the study. Further investigation is required to detennine the potential benefits of intervention in this age group.