The Vitamin D and Omega-3 Trial (VITAL): Effects on Bone Structure and Architecture Study, Baseline Clinical Characteristics, Bone Density and Body Composition

Presentation Number: SAT 346
Date of Presentation: April 2nd, 2016

Amy Y Yue*1, Trisha Copleand2, Nancy R Cook3, Julie E Buring3, JoAnn E Manson3 and Meryl S LeBoff4
1Brigham and Women's Hospital, Boston, MA, 2Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 3Department of Epidemiology, Harvard School of Public Health, Boston, MA, 4Harvard Medical School, Boston, MA

Abstract

While vitamin D is widely used to promote bone health, previous epidemiological studies and meta-analyses on effects of supplemental vitamin D alone on bone outcomes have been conflicting. Randomized clinical trials (RCT) provide the highest quality results, but the prior RCTs have been limited by inclusion of supplemental calcium with vitamin D in the intervention and vitamin D doses at or below 1000 IU/d. In addition, with the high prevalence of obesity, the relationships between body composition, bone health, and supplemental vitamin D remain to be clarified.

We are conducting an ancillary study to the VITamin D and OmegA-3 TriaL (VITAL) to test effects of 2000 IU/d of supplemental vitamin D3 (cholecalciferol) alone on bone health outcomes. VITAL is a randomized, placebo-controlled trial among 25,874 U.S. men and women, aged ≥50 and ≥55 respectively that is examining the effects of supplemental vitamin D and/or omega-3 fatty acids for the primary prevention of cancer and cardiovascular disease. In the VITAL: Effects on Bone Structure and Architecture study, we performed detailed skeletal assessments in a VITAL sub-cohort. Between November 2012 and March 2013, we enrolled 776 randomized participants in the New England area in this study and completed in-person, baseline visits at the Harvard Catalyst Clinical and Translational Science Center. Clinical characteristics and an in-depth medical history were obtained. We measured pre-randomization, bone mineral density (BMD; spine, hip, whole body) and body composition (fat and lean tissue and visceral adiposity [VAT]) by dual energy x-ray absorptiometry, trabecular bone score, bone structure and architecture by peripheral quantitative computed tomography, bone turnover biomarkers and physical performance measures. Participants were approximately equal numbers of women and men (48%/52%) with 24% aged 50-59 years (yrs), 57% aged 60-69 yrs, and 18% aged 70+ yrs. Baseline BMD at the spine, femoral neck, total hip, and whole body were 1.028±0.171 g/cm2, 0.772±0.133 g/cm2, 0.931±0.144 g/cm2, and 1.166±0.152 g/cm2, respectively. The mean body mass index (BMI) was 28.3±5.1 kg/m2 and 30.7% were obese. Baseline body composition measures included fat mass index (10.3±3.9 kg/m2), total fat mass (29.2±10.3 kg), percent body fat (36.4±8.5%), total lean mass (47.8±10.5 kg), VAT (863±382 cm3), appendicular lean mass (ALM) (20.3±5.2 kg), and BMI-adjusted ALM (0.73±0.18). Relationships between baseline clinical characteristics in this VITAL ancillary study and bone health and body composition measurements will be presented. Ongoing follow-up studies at 2 yrs post-randomization are in progress. These investigations will clarify the effects of moderately high-doses of supplemental vitamin D and/or omega-3 fatty acids on skeletal outcomes and will inform clinical practice regarding the role of supplemental vitamin D alone on bone health.

 

Nothing to Disclose: AYY, TC, NRC, JEB, JEM, MSL