Third National Health and Nutrition Examination Survey - NHANES III

Description:

Role of serum antioxidants in hypertension.

Hypothesis:

Role of serum antioxidants in hypertension.

Study Design

Study Design:

Patients Screened: Not given
Patients Enrolled: 13,415

Patient Populations:

U.S. non-institutionalized civilians ≥18 years of age

Exclusions:

Antihypertensive medication

Primary Endpoints:

Serial blood pressure measurements; serum antioxidant levels

Drug/Procedures Used:

Standard medical questionnaire/survey; nutrient intake assessed by 24-hour dietary recall; 6 blood pressure measurements obtained by trained observers using a standard sphygmomanometer; serum antioxidant vitamin levels.

Principal Findings:

This analysis of NHANES data examined the relationship of serum antioxidants (vitamin C, α-carotene, β-carotene, vitamin A, and vitamin E) to blood pressure in a representative sample of the U.S. general population. Linear regression analysis was used to explore the relationship between antioxidant vitamins and blood pressure. Data evaluated included age, sex, body mass index, alcohol use, and dietary intake of total energy, polyunsaturated-to-saturated fat ratio, fiber, sodium, and potassium, with the data adjusted in multivariate regression models.

The study population included 3,679 African-Americans, 4,132 Mexican-Americans, and 5,605 Caucasians The characteristics of study participants were well-matched at baseline, except the Caucasians tended to be older compared to the other two groups (52 years vs. 40 years for the other two groups). Age- and sex-adjusted systolic index ranged from 120 mmHg to 125 mmHg.

Multivariate analysis revealed that mean serum levels of vitamin C (in African-Americans), as well as a-carotene and b-carotene levels (in all 3 races) were independently, significantly, and inversely associated with systolic blood pressure. Serum vitamin A and vitamin E were significantly and positively associated with systolic blood pressure in all 3 races. Similar statistically significant relationships were noted between serum antioxidant levels and diastolic blood pressure.

Interpretation:

Antioxidants may be important in the etiology of hypertension. These findings warrant further investigation on possible mechanisms of antioxidant vitamins on regulation of blood pressure.

References:

1. Circulation 1998;98(Suppl I):I-657. Antioxidants and blood pressure

Clinical Topics: Prevention, Diet, Hypertension

Keywords: Carotenoids, Multivariate Analysis, Vitamin E, beta Carotene, Sodium, Potassium, Body Mass Index, Sphygmomanometers, Vitamin A, Energy Intake, Questionnaires, Regression Analysis, Nutrition Surveys, Hypertension


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