The Vitamin D Assessment (ViDA) Study: design of a randomized controlled trial of vitamin D supplementation for the prevention of cardiovascular disease, acute respiratory infection, falls and non-vertebral fractures

J Steroid Biochem Mol Biol. 2016 Nov;164:318-325. doi: 10.1016/j.jsbmb.2015.09.010. Epub 2015 Sep 10.


Observational studies have shown that low vitamin D status is associated with an increased risk of cardiovascular disease, acute respiratory infection, falls and non-vertebral fractures. We recruited 5110 Auckland adults, aged 50-84 years, into a randomized, double-blind, placebo-controlled trial to test whether vitamin D supplementation protects against these four major outcomes. The intervention is a monthly cholecalciferol dose of 100,000IU (2.5mg) for an estimated median 3.3 years (range 2.5-4.2) during 2011-2015. Participants were recruited primarily from family practices, plus community groups with a high proportion of Maori, Pacific, or South Asian individuals. The baseline evaluation included medical history, lifestyle, physical measurements (e.g. blood pressure, arterial waveform, lung function, muscle function), and a blood sample (stored at -80°C for later testing). Capsules are being mailed to home addresses with a questionnaire to collect data on non-hospitalized outcomes and to monitor adherence and potential adverse effects. Other data sources include New Zealand Ministry of Health data on mortality, hospitalization, cancer registrations and dispensed pharmaceuticals. A random sample of 438 participants returned for annual collection of blood samples to monitor adherence and safety (hypercalcemia), including repeat physical measurements at 12 months follow-up. The trial will allow testing of a priori hypotheses on several other endpoints including: weight, blood pressure, arterial waveform parameters, heart rate variability, lung function, muscle strength, gait and balance, mood, psoriasis, bone density, and chronic pain.

Keywords: Acute respiratory infection; Cardiovascular disease; Falls; Fractures; Prevention; Randomized controlled trial; Supplement; Vitamin D.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accidental Falls / prevention & control*
  • Affect / drug effects
  • Aged
  • Aged, 80 and over
  • Blood Pressure / drug effects
  • Blood Pressure / physiology
  • Cardiovascular Diseases / metabolism
  • Cardiovascular Diseases / pathology
  • Cardiovascular Diseases / prevention & control*
  • Cholecalciferol / administration & dosage*
  • Dietary Supplements*
  • Double-Blind Method
  • Female
  • Fractures, Bone / metabolism
  • Fractures, Bone / pathology
  • Fractures, Bone / prevention & control*
  • Gait / drug effects
  • Gait / physiology
  • Heart Rate / drug effects
  • Heart Rate / physiology
  • Humans
  • Male
  • Middle Aged
  • Muscle Strength / drug effects
  • Patient Compliance
  • Postural Balance / drug effects
  • Research Design
  • Respiratory Function Tests
  • Respiratory Tract Infections / metabolism
  • Respiratory Tract Infections / pathology
  • Respiratory Tract Infections / prevention & control*
  • Surveys and Questionnaires


  • Cholecalciferol