Trial Information

Effect of Vitamin D and Omega-3 Fatty Acids on Blood Pressure and Hypertension

The human toll of hypertension is staggering, and effective preventive measures are needed.
Studies suggest that inadequate vitamin D and omega-3 fatty acid levels may be involved in
the development of hypertension through multiple pathways. Results from several small
clinical trials suggest that these agents may have blood pressure lowering effects, however,
larger trials using higher doses of both vitamin D and omega-3 fatty acids for the
prevention of hypertension among people with normal blood pressure levels are lacking. The
VITamin D and OmegA-3 TriaL (VITAL) provides a cost-effective setting to examine the effects
of both study agents on changes in blood pressure and new diagnoses of hypertension.

VITAL Hypertension will test the following hypotheses: (1) whether vitamin D and fish oil
supplementation lowers 24-hour blood ambulatory blood pressure (ABP) compared to placebo in
a subcohort of 1,000 participants; (2) whether vitamin D and fish oil supplementation
reduces the risk of incident hypertension compared to placebo among all randomized VITAL
participants without baseline hypertension; and (3) whether vitamin D and fish oil
supplementation favorably change hypertension-related biomarkers that are potential
mechanisms linking vitamin D and omega-3 fatty acids with hypertension compared to placebo.

A representative subcohort of 1,000 VITAL participants without hypertension from selected
major metropolitan areas throughout the US will be invited to participate in home-based
study visits at baseline and 2 years follow-up. During these visits, participants will be
asked to wear monitors to record 24-hour ABP measurements, provide fasting bloods, spot
urine samples, and other clinical measurements. The visits will be conducted by Examination
Management Services, Inc. (EMSI), a nationally based, clinical services provider. We will
compare 2-year changes in ABP among those randomized to vitamin D and omega-3 fatty acid
supplements versus those randomized to placebo. In addition, we will assess the 2-year
changes in levels of clinically and mechanistically relevant biomarkers of hypertension
compared the 2 treatment groups.

New diagnoses of hypertension among all VITAL participants will be ascertained on annual
follow-up questionnaires. To strengthen our classification of hypertension status, we will
supplement our questionnaire data with annual updates of hypertension information based upon
outpatient diagnostic codes and medication prescription usage from the Centers for Medicare
& Medicaid Services (CMS) database. Incidence of hypertension among those assigned to each
active agent versus placebo will be compared.

In addition, baseline blood samples from 1,000 participants with new diagnoses of
hypertension will be compared with those from 2,000 participants without hypertension to
determine whether the effect of vitamin D and/or omega-3 fatty acid supplements on the
incidence of hypertension is modified by baseline plasma levels of vitamin D or omega-3
fatty acids.

Results from VITAL Hypertension will provide important evidence to support or refute the
potential preventive roles of vitamin D and omega-3 fatty acids on blood pressure and the
development of hypertension.