Title

The Relationship Between Calcium Intake, Obesity, and Cardiovascular Disease Risk Factors: The Jackson Heart Study

Date of Award

2009

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Nutrition and Food Systems

First Advisor

Kathy Yadrick

Advisor Department

Nutrition and Food Systems

Abstract

Cardiovascular disease (CVD) is a major health risk in the United States. Major indicators of CVD risk include obesity, blood lipids, and blood pressure. Modifiable risk factors associated with CVD include body composition (body mass index and waist circumference), serum lipids, and blood pressure. Data suggest calcium intake may play a role in regulation of weight, serum lipids, and blood pressure. The purpose of this study was to assess relationships of dietary calcium intake with weight status, and cardiovascular disease risks in African American population participating in the Jackson Heart Study. The subjects included 4,267 African American adults ages 21-95 years (mean = 55.1±12.6 years) in the Jackson Heart Study (JHS). Dependent variables included: body mass index (BMI) calculated from measured height/weight (stadiometer/balance scale), waist circumference (WC; measuring tape), serum lipids, and blood pressure (sphygmomanometer). A 158-item food frequency questionnaire (FFQ) was used to assess nutrient intake. Statistical analyses included multiple regression analysis and Pearson correlations using SPSS 16.0 (SPSS Inc. Chicago, IL, USA). There was a significant positive relationship between calcium intake and the body composition measure BMI [F (4, 3982) = 3.26, p = 0.019, ΔR2 = .003] and a significant inverse relationship between calcium intake and WC [F (4, 3982) = 2.43, p = 0.05, ΔR2 = .002]. These relationships were also observed in females only when data were analyzed by gender. There were significant inverse relationships between calcium intake and total cholesterol (TC) [F (4, 4259 = 5.46, p = 0.266, ΔR2 = .002] and LDL-cholesterol (LDL) [F (4, 4225) = 3.218 p = 0.01, ΔR2 = .003]. There were also significant inverse correlations between total cholesterol (TC) and LDL and calcium for males only. There was a significant relationship between calcium intake and HDL-cholesterol [F (4, 4259) = 13.31, p <0.001, ΔR2 = .012], as well as significant a positive relationship between HDL and calcium from supplements and a significant negative relationship between HDL and non-dairy calcium consumption. There was a significant positive relationship between total calcium intake and systolic blood pressure (SBP) [F (4, 3986) = 4.74, p = 0.001, ΔR2 = .004], as well as a significant relationship between calcium intake and diastolic blood pressure (DBP) [F (4, 3986) = 4.84, p = 0.01, ΔR2 = .005]. The direction of this relationship varied with the calcium source. There was no association between calcium intake and triglycerides. While significant negative associations were noted between dietary calcium intake and WC, TC, LDL, and SBP for JHS participants, and significant positive associations between dietary calcium and BMI, HDL, and DBP, the magnitude of the relationships was small. This can be related to several factors including the true predictive power of calcium for CVD risk factor measures (which may be highly multifactoral) and the large sample size. Data from this study suggest the need for additional research in African American populations on the potential relationship between calcium intake and BMI, WC, serum lipids, and blood pressure.