month are combined to estimate a daily amount of sodium from supplements per person. Antacids are included in the estimates of sodium intake from dietary supplements.
As part of describing current sodium intake, means and distributions of usual intake from foods and from all dietary sources in NHANES 2003–2006 were compared to the Dietary Reference Intakes (DRIs) (IOM, 2005)—that is, the Adequate Intake (AI) and the Tolerable Upper Intake Level (UL) for sodium. If the usual mean intake exceeds the AI, the group is assumed to have adequate intake levels (Murphy, 2003). The proportion of the population that exceeds the UL is determined to be at risk of adverse effects from an excessive intake (Murphy, 2003). The statistical method for estimating the proportion below or above defined DRI cutoff values developed at Iowa State University was used (Carriquiry and Camano-Garcia, 2006).
The NHANES collects information on race/ethnicity on the basis of self-reported categories as follows: non-Hispanic whites, non-Hispanic African Americans, and Mexican Americans. Income for the survey is also reported on a category basis and is analyzed consistent with standards for reporting nutrition and statistical data for the evaluation of nutrition assistance programs: low-income is defined as an annual household income level of 130 percent of poverty or less, the income eligibility for the Supplemental Nutrition Assistance Program, formerly called the food stamp program; higher-income is defined as an annual household income above 185 percent of poverty, the eligibility cut-off for free- or reduced-price school meals and the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC); and intermediate income is between 130 and 185 percent of the poverty line. Mean sodium intake from foods is highest among low- and higher-income adults ages 19–30 years and higher-income adults ages 31–50 years (Appendix F, Table F-6). Hypertension was defined as an elevated blood pressure (systolic pressure ≥ 140 mm Hg and diastolic pressure ≥ 90 mm Hg) and/or the taking of antihypertensive medications at the time of the individual’s medical examination in the NHANES Medical Examination Center (NCHS, 2009).