As shown in Figure 2-4, more recent data prepared from the NHANES 2003–2006 suggest greater differences in the sodium densities of foods consumed away from home compared to foods consumed at home than seen in the earlier surveys. These data indicate that the sodium density of foods away from home was 1,825 mg/1,000 calories compared to 1,422 mg/1,000 calories for foods consumed at home. To interpret the sodium intake density data in Figure 2-4 with a reference intake of 2,000 calories per day, a density of < 1,150 mg sodium per 1,000 calories is consistent with the Dietary Guidelines for Americans recommendation of < 2,300 mg sodium per day. Within the away-from-home food sources, the rank order of restaurants as the highest and school meals as the lowest continues.

Crepinsek et al. (2009) used menu and recipe data from the Third School Nutrition Dietary Assessment Study to calculate the nutrient contents of nationally representative school breakfasts and lunches. According to their data for calories and sodium as the basis for calculating sodium intake density, school lunches served to students provided an average of 1,901 mg/1,000 calories. In addition, none of the schools offered lunches that met the benchmark for sodium content, which is set at one-third of the maximum daily intake recommended by the 2005 Dietary Guidelines for Americans. However, almost half of the breakfasts offered met the benchmark for sodium content, which is set at one-fourth of the maximum daily intake recommended by the 2005 Dietary Guidelines for Americans.

All of the sources identified above as well as all of the time periods for which data are available suggest that mean intakes are in considerable excess of the Dietary Guidelines for Americans goal. Taken as a whole, these data underscore the difficulty that consumers and meal planners have in meeting sodium guidelines using readily available foods. This is consistent with the concept that consumer taste preference for the saltiness of foods is fairly consistent regardless of where the food is obtained. Finally, these data suggest that all food channels will need significant sodium reductions to meet dietary sodium recommendations, and that sodium reduction strategies may be most effective if they include all food channels.

While sodium densities allow direct compositional comparisons across foods from different food channels, the full impact of these foods on total sodium intake is determined by the total amount of food consumed. The amount of food consumed is affected by several factors including portion size.

Recently, increasing portion sizes of food have received considerable attention as a likely contributor to the emerging obesity epidemic. Larger portion sizes also have the potential to deliver larger quantities of nutrients