The VITamin D and OmegA-3 TriaL (VITAL; NCT 01169259) was a randomized clinical trial in 25,871 U.S. men and women investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or fish oil (1 gram of omega-3 fatty acids) reduces the risk of developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. This ancillary study is being conducted among participants in VITAL-CTSC cohort and will examine whether vitamin D or fish oil supplementation has beneficial effects on cellular aging.

This project is an ancillary study based on the parental study "the VITamin D and OmegA-3 TriaL (VITAL; NCT 01169259)" at the Harvard Clinical and Translational Science Centre (CTSC) and Brigham and Women's Hospital. Our research focuses on the separate and synergistic effects of vitamin D and omega -3 supplements on telomere length, a cellular aging marker, using de-identified samples from VITAL-CTSC cohort.

Aims: 1) To test the hypothesis that vitamin D supplementation decreases leukocyte telomere length attrition. The investigators will determine the effect of vitamin D supplementation on telomere length attrition over time (Baseline, Year 2, and Year 4); 2) To test the hypothesis that marine omega-3 fatty acid supplementation decreases LTL attrition. The investigators will determine the effect of marine omega-3 fatty acid supplementation on telomere length attrition over time (Baseline, Year 2, and Year 4); 3) To determine to what extent the effects of vitamin D or omega-3 supplementation on inflammatory cytokines and CVD risk factors are mediated by telomere length attrition over time; 4) To explore the synergistic effects vitamin D and omega-3 fatty acid supplementation.

Inclusion Criteria:

The subcohort of 1,054 participants in VITAL (NCT 01169259) who are receiving detailed health assessments at a Clinical and Translation Science Center at Boston are eligible to participate in this ancillary study:

-

Exclusion Criteria: None

-

The investigators recognize and fully support the principles of resource and data sharing that have been endorsed by the NIH. Since VITAL is a randomized, double-blind, placebo-controlled trial, the investigators will not be able to share any unblinded data involving randomized treatments with internal or outside investigators while the trial in ongoing (with the exception of the Independent Data and Safety Monitoring Board). However, the investigators will maintain our strong commitment to the full communication of important study results to participants and the scientific community through rapid publication of primary findings, presentations at major meetings, as well as through appropriate lay interviews and lay publications.