Abstract

Background: Serum hydroxyvitamin D [25(OH)D] has been well-accepted as not an ordinary vitamin but a pro-hormone that has many benefits beyond its well-known effects on bone. Cardiovascular risk factors such as hypertension remain a huge health burden and Blacks have been recognized to have higher prevalence of hypertension compared to non-Hispanic Whites. Despite increasing evidence of the benefits of vitamin D on blood pressure control, there is much more to be learned about the relationship of serum 25(OH)D to blood pressure among different ethnicities.

Purpose: The goal of this study was to determine whether vitamin D serum 25(OH)D levels were related to blood pressure among two ethnic groups: Blacks and Whites and if these relationships exist after controlling for potential confounders.

Methods: The study was based on a cross-sectional design involving participants of the calibration substudy of the Adventist Health Study (AHS-2) cohort. 284 White and 284 Black calibration study participants were required to attend a clinic during which weight, height, blood pressure were measured, a food-frequency questionnaire was completed and fasting blood samples were obtained in 2003-2007. To determine the association between serum hydroxyvitamin D and blood pressure, multivariable regression analyses were performed. Age, BMI, gender, waist circumference, % body fat, ethnicity, sun exposure, type of diet, use of medications, calcium and vitamin D/ supplementation, and UV season were examined as covariables. The modifying effect of being diagnosed with hypertension was also studied.

Results: There was an inverse relationship between systolic blood pressure and serum25(OH)D in Whites but not in Blacks after controlling for age, BMI, gender, use of BP medications, waist circumference, and % body fat (β-coefficient -0.23, 95% CI -0.42, -0.02). No association was found for Blacks for both systolic and diastolic blood pressures. Further, 25(OH)D levels did not predict hypertension status in both ethnicities.

Conclusion: Systolic BP is inversely associated with serum 25(OH)D levels in non-diabetic White persons. This relationship was not seen in Blacks. Vitamin D may not be a major contributor to the White-Black differential in systolic BP.

School

School of Public Health

First Advisor

Serena Tonstad

Second Advisor

Gary Fraser

Third Advisor

Ella Haddad

Fourth Advisor

Karen Jaceldo-Siegl

Degree Name

Doctor of Public Health (DrPH)

Degree Level

Ph.D.

Year Degree Awarded

2011

Date (Title Page)

6-2011

Language

English

Library of Congress/MESH Subject Headings

Vitamin D -- therapeutic use; Vitamin D Deficiency; 25-hydroxyvitamin D [Supplementary Concept]; Blood Pressure -- drug effects; Hypertension -- prevention & control; Ethnic Groups; African Americans; Caucasoid Race

Type

Dissertation

Page Count

xiii; 126

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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