Baseline characteristics of participants in the VITamin D and OmegA-3 TriaL (VITAL)

Contemp Clin Trials. 2016 Mar;47:235-43. doi: 10.1016/j.cct.2015.12.022. Epub 2016 Jan 6.


Evidence for a role of supplemental vitamin D and marine omega-3 fatty acids in preventing cancer and cardiovascular disease (CVD) remains inconclusive and insufficient to inform nutritional recommendations for primary prevention. The VITamin D and Omega-A 3 TriaL (VITAL) is an ongoing nationwide, randomized, double-blind, placebo-controlled clinical trial designed to fill this knowledge gap. The study population consists of 25,874 U.S. adults without cancer or CVD at baseline, who were selected only on age (men aged ≥50 and women aged ≥55), with an oversampling of African Americans (n=5,107). In a 2 × 2 factorial design, participants were randomized to one of four supplement groups: [1] active vitamin D3 (cholecalciferol; 2000 IU/d) and active marine omega-3 fatty acids (Omacor® fish oil, eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA], 1g/d); [2] active vitamin D and omega-3 placebo; [3] vitamin D placebo and active marine omega-3 fatty acids; or [4] vitamin D placebo and omega-3 placebo. The mean length of the randomized treatment period will be 5 years. The randomization was successful, as evidenced by similar distributions of baseline demographic, health, and behavioral characteristics across treatment groups. The similar distribution of known potential confounders across treatment groups strongly suggests that unmeasured or unknown potential confounders are also equally distributed. VITAL is expected to provide important information on the benefit-risk balance of vitamin D and omega-3 fatty acid supplementation when taken for the primary prevention of cancer and CVD.

Trial registration: NCT01169259.

Keywords: Cancer; Cardiovascular disease; Omega-3 fatty acids; Primary prevention; Randomized clinical trial; Vitamin D.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cardiovascular Diseases / prevention & control*
  • Cholecalciferol / therapeutic use*
  • Clinical Protocols
  • Dietary Supplements*
  • Docosahexaenoic Acids / therapeutic use*
  • Double-Blind Method
  • Drug Combinations
  • Eicosapentaenoic Acid / therapeutic use*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neoplasms / prevention & control*
  • Patient Selection
  • Primary Prevention / methods*
  • Research Design
  • Vitamins / therapeutic use*


  • Drug Combinations
  • Vitamins
  • Cholecalciferol
  • Docosahexaenoic Acids
  • Eicosapentaenoic Acid
  • Omacor

Associated data