Vitamin D status and its predictors in New Zealand aged-care residents eligible for a government-funded universal Vitamin D supplementation programme

Abstract

Objective The provision of prescribed vitamin D to all aged-care residents has been implemented in New Zealand as part of a government-led falls prevention programme. To our knowledge, there has been no evaluation of this universal programme on vitamin D status and functional and health outcomes. Thus, we aimed to determine 25-hydroxyvitamin D (25(OH)D) concentrations and their predictors in aged-care residents across the country and to investigate whether the government-funded programme was associated with adequate vitamin D status. Design Cross-sectional survey of sociodemographic, biochemical, anthropometric, dietary and health characteristics. Blood samples were analysed for serum 25(OH)D and other biochemical measures. Multiple regression was used to examine predictors of vitamin D status. Setting Sixteen residential aged-care facilities throughout New Zealand. Subjects Residents aged ≥60 years with residency duration >12 weeks (n 309). Results Mean serum 25(OH)D was 89·9 (95 % CI 85·2, 94·5) nmol/l and monthly supplements (1250 g (50 000 IU)) were taken by 75 % of all residents. Of those not taking a funded supplement, 65·3 % had serum 25(OH)D <50 nmol/l compared with only 1·5 % of supplement users. Being female, residing at lower latitude, increasing duration of aged-care residency and raised serum α1-acid glycoprotein were positively associated with higher 25(OH)D concentrations. Supplemental vitamin D from all sources was the strongest predictor, increasing serum 25(OH)D levels by more than 70 nmol/l. Furthermore, 25 % of participants had serum 25(OH)D levels >125 nmol/l. Conclusions Residents taking supplemental vitamin D had adequate vitamin D status; however monitoring of long-term supplementation should be considered, due to the high proportion of participants with high serum 25(OH)D levels.