1. College of Public Health, ETSU
The relationship between Calcium Intake and Hypertension among Obese Adults in the U.S.
College of Public Health, ETSU
Yang Chen, MS
Shimin Zheng, PhD
Liang Wang, MD, DrPH
4/4/2013

2. Contents
Introduction 1
Methods 2
Results 3
Discussion 4
Conclusion 5

3. Introduction Hypertension – 1 in 3 U.S. adults (estimated 68 million)
Increases the risk for heart disease and stroke
leading causes of death in the United States.
Obesity – risk factor for hypertension
Incidence of hypertension is high among obese people
Calcium intake – dietary risk factor for hypertension

4. Introduction Cross-sectional study
Study design
Cross-sectional study
Study objective
Examine the relationship between the calcium
intake and hypertension among obese adults in
U.S. during 1999 to thru 2010

5. Methods – Study population
Participants of National Health and Nutrition Examination Study (NHANES) from 1999 and 2010.
Included criteria Inclusion criteria:
Adult (age≥20 years)
Obesity
Generalized obesity – body mass index(BMI) ≥30 kg/m2
Central obesity – waist circumference ≥102 cm for men and ≥88 cm for women
No pregnancy

6. Methods – Variable measurement
Outcome Risk Factor
Exposure Outcome
Covariates
Calcium intake
Hypertension
Elevated systolic blood pressure (SBP ≥ 140 mmHg)
Elevated diastolic blood pressure (DBP ≥ 90 mmHg)
Demography– age, gender, race, education, poverty
Behavior – smoking, alcohol use
Condition – diabetes
Unit: mg/d
24-hour dietary interview

7. Methods – Statistical Analysis
Sample – stratify by quartiles of calcium intake.
Descriptive
Analysis of variance (ANOVA) tests
Chi-square test
Regression
Simple logistic regression models
Multiple logistic regression models
SAS (version 9.0; SAS Institute Inc, Cary, NC)

9. Results
Fig. 1 Prevalence of hypertension, elevated SBP and DBP among obese adults by calcium intake quartiles in the U.S. (1999–2010)
The color used for bars are too close

10. Results
Table 2. Simple and Multiple logistic regression analysis of hypertension by calcium intake quartiles and other predictors among adults with obesity in the U.S. (1999–2010)

11. Results
Table 3. Simple and Multiple logistic regression analysis of hypertension,
elevated SBP and DBP by calcium intake quartiles among adults with obesity in the U.S. (1999–2010)

12. Discussion
Increasing calcium intake, decreasing probability of hypertension among obese adults. The probability of hypertension among obese adults can decreased by increasing calcium intake.
Inverse relationship between blood pressure status and dietary calcium intake.
The protective effect of calcium on blood pressure can be partly explained by the influence of calcitriol on [Ca2+]i.
An increase of [Ca2+]i in vascular smooth muscle cells can result in vasoconstriction and a consequent rise in blood pressure.

13. Discussion Strengths Limitations Large scale – national wide, 12 years
Focus on obese adults
Adjusted Other covariates adjusted.
Cross-sectional study
Physiological mechanism

14. Conclusion
Inadequate calcium intake may increase the risk of hypertension, high SBP, or high BDP among obese adults.
Hypertension
Calcium intake
Obesity
Increasing the calcium intake in obese adults can be considered as a strategy to prevent hypertension.
Further studies are needed to understand physiological mechanism.

15. References
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Finkelstein, EA, Trogdon, JG, Cohen, JW, and Dietz, W. Annual medical spending attributable to obesity: Payer- and service-specific estimates. Health Affairs 2009; 28(5): w822-w831.
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Daniel EE. Intake of dairy products or calcium and blood pressure. J Hypertens Apr;24(4):633-4
Barger-Lux MJ, Heaney RP. The role of calcium intake in preventing bone fragility, hypertension, and certain cancers. J Nutr. 1994 Aug;124(8 Suppl):1406S-1411S.

16. College of Public Health, ETSU
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College of Public Health, ETSU
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