This clinical trial was designed to determine the efficacy of vitamin D supplementation on plasma 25-hydroxyvitamin D [25(OH)D] and intact parathyroid hormone (PTH) concentrations of Malaysian female adults of child-bearing age after daily intake of vitamin D supplements containing either 0 IU, 600 IU, 1200 IU or 4000 IU vitamin D for 16 weeks.

After being informed regarding the study protocol and requirements, participants given informed consent were interviewed using a questionnaire for collection of background data and medical history as a screening process. Eligible participants were randomly assigned in a double-blind manner to receive daily 500 mg of calcium with either 0, 600 IU, 1200 IU or 4000 IU vitamin D supplement for 16 weeks. Questionnaires and anthropometric measurements were collected at baseline and post 16 weeks supplementation trial. Primary outcomes of plasma 25(OH)D and intact PTH were measured via fasting intravenous blood samples at baseline and post 16 weeks trial.

Inclusion Criteria:

• three major ethnic groups (Malay, Chinese, Indian)
• age 20-45 years

Exclusion Criteria:

• any diseases or conditions that may affect vitamin D metabolism, such as diabetes, cardiovascular diseases, bone diseases, autoimmune diseases, had major gastrointestinal surgery and diagnosed primary hyperparathyroidism
• medications that might affect vitamin D metabolism, such as insulin, thiazide diuretics, prednisolone, biphosphonates, tamoxifen and phenytoin
• pregnant and lactating women

Data cannot be shared publicly because of shared IPs. Data are available from the International Medical University Institutional Data Access (contact via khor.geoklin@gmail.com) for researchers who meet the criteria for access to confidential data