The Effect of Monthly 50,000 IU or 100,000 IU Vitamin D Supplements on Vitamin D Levels in Pre-menopausal Middle Eastern Women Living in Auckland - Middle Eastern Women's Health Study-Phase II

We know that potential consequences of vitamin D deficiency extend beyond bone health. Vitamin D deficiency is implicated in some diseases such as CVD, type 2 diabetes and depression. We previously found a disturbingly high prevalence of vitamin D deficiency/insufficiency in Middle Eastern women living in Auckland, despite some women using prescribed vitamin D supplements (50,000 IU/month). In this survey, 100% of women had low vitamin D concentrations with 75% being deficient.The adequate dose for improving vitamin D status of this population to at least 50 nmol/L (the current minimum for adequacy) is unknown. The aim of this study is to investigate the adequacy of supplementation with monthly 50,000 IU and 100,000 IU vitamin D3 for 6 months in increasing serum 25(OH)D concentrations greater than or equal to 50 nmol/L in Middle Eastern pre-menopausal women living in Auckland, and to investigate the effect of supplementation with these dosages for 6 months on Parathyroid Hormone (PTH) concentrations. Sixty-six pre-menopausal women of Middle Eastern origin, living in Auckland, will be recruited. Participants will randomly receive monthly 50,000 IU, 100,000 IU or placebo for 6 months. Blood samples will be tested for serum 25(OH)D, calcium, and PTH concentrations at baseline, 3-months, and 6-months. The change in serum 25(OH)D and PTH concentrations in response to vitamin D supplementation will be assessed.