Vitamin D status of older South Africans
Charlton, K.E.; Labadarios, D.; Lombard, C.J.; Louw, M.E.
South African Medical Journal 86(11): 1406-1410
1996
ISSN/ISBN: 0256-9574 PMID: 8980560 Document Number: 455105
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 gtoreq 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-hydroxyvitamin D (25(OH)D) and other biochemical parameters, and to take anthropometric measurements. Results: Seventeen per cent of the subjects (95% CI: 11.4-22.6%) had serum 25(OH)D levels in the deficient range for the elderly ( lt 10 ng/ml); 7.5% (95% CI: 3.6-11.4%) had concentrations in the moderately severe range of deficiency ( lt 8 ng/ml). Sixty-three per cent of the 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 lt 0.05). Mean oral vitamin D intake was low (3.6 (SD = 2.7) mu-g and 2.8 (SD = 1.7) mu-g 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 cross-sectional design of the study. Further investigation is required to determine the potential benefits of intervention in this age group.