. "Appendix E: Background on the National Health and Nutrition Examination Surveys and Data Analysis Methods." Strategies to Reduce Sodium Intake in the United States. Washington, DC: The National Academies Press, 2010.
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Strategies to Reduce Sodium Intake in the United States
ESTIMATION OF TIME TRENDS FORSODIUM INTAKE FROM NHANES
Trends in mean sodium intake have been reported for age/gender subgroups from age 1 year through 74 years from 1971–1974 to 1999–2000 (Briefel and Johnson, 2004). NHANES collected single 24-hour dietary recalls in 1971–1974 and estimated mean sodium intake from foods by age group and gender for the household-based population ages 1 year through 74 years. The age range was expanded to 2 months and older with no upper age cutoff in NHANES III (1988–1994), and from birth on starting in NHANES 1999. Nutrient intake is not reported for breastfeeding infants.
To update the Briefel and Johnson analysis (2004) and allow for comparison to current estimates of intake, estimated 1-day mean sodium intake from foods9 in NHANES 2003–2006 was derived using analytic techniques comparable to those used in the earlier analysis. A table was then generated to compare intake estimates from NHANES 2003–2006 to the existing time trend analysis (Briefel and Johnson, 2004).
APPROACH TO CHARACTERIZING SOURCESOF SODIUM IN NHANES 2003–2006
The food category analysis used data from NHANES 2003–2006 and relied on the food categorization scheme used in a previous NHANES analysis by Cole and Fox (2008). In brief, all foods reported in the 24-hour dietary recalls are grouped into 11 major categories and into 154 food groups. Nearly 4,000 unique food codes were used to code foods reported in NHANES 2003–2004 (n = 3,894 foods). The estimates of sodium from foods include salt used in cooking and food preparation, but not salt added at the table. Further, foods are not disaggregated at the ingredient level, and salt that was used in recipes is also included in the sodium content of the food “as prepared.” Foods are recorded as reported by consumers, for example, as an apple, a mixed dish, or a sandwich. In some cases, individual components were reported, and it was not always possible to aggregate or disaggregate all reported foods at the same level.
One-day dietary recall data were used to estimate food sources of sodium and mean daily sodium and sodium density by home versus away food source using the population proportion method as described by Krebs-Smith and colleagues (1989). For this report, the committee classified food sources as “Home,” “Away,” and “Other” based on the food source categories listed in Box E-1. “Home” sources are those foods obtained from the store and assumed to be consumed at home. “Away” sources include restaurants (which include those with waiter service, fast food and pizza
This estimate includes salt used in cooking and in food preparation.