Policy Research for Front of Package Nutrition Labeling: Developing and Testing a Summary System Algorithm. 4.1.1 Calculation of NDS Scores for Food Items


Scores were calculated for all food items reportedly consumed by participants in NHANES 2005-2008. The first dietary interview day was used. Individuals were excluded if they were under 2 years of age, pregnant, or lactating or had unreliable records. Dietary intake records from 16,587 individuals were included.

Nutrient values corresponding to foods consumed in NHANES were from the USDA Food and Nutrient Database for Dietary Studies (FNDDS) Version 3.0 (for NHANES 2005-2006) and Version 4.0 (for NHANES 2007-2008) (U.S. Department of Agriculture, 2008; U.S. Department of Agriculture, 2010b). Adjustments to the available nutrient values were made. Vitamin D values were not available in FNDDS 3.0 and thus were calculated using data from the USDA Standard Reference, Release 22 database (U.S. Department of Agriculture, 2009) and FNDDS 4.0. The amount of the food components added sugar and whole grains were obtained from the MyPyramid Equivalents Database, 2.0 for USDA Survey Foods, 2003-2004 (Bowman, Friday, & Moshfegh, 2008), and values for new foods in 2005-2008 were determined by Nutrition Impact, LCC, primarily by matching to similar foods. Added sugar is provided in teaspoon equivalent units and was converted to grams using a factor of 4.2 grams per teaspoon.

Standard serving sizes or RACCs were assigned to all foods using FDA guidance in the CFR (Code of Federal Regulations, 2010b). Reference amounts in units other than grams (cup, teaspoon, piece, etc.) were converted to grams using conversions in FNDDS 4.0 or earlier versions. Some judgments had to be made for foods, such as frozen meals or mixed dishes that are specified in the regulation as 1 cup if measurable with a cup or 140 g if not measurable with a cup. The data file provided to ASPE includes RACC serving sizes.

The baseline algorithm (Figure 3-1) calculates a score based on the nutrient value of foods per 100 kcal divided by the daily recommended value of the nutrient, summing these values for all of the positive nutrients and dividing by the number of positive nutrients (eight), and subtracting the sum of the negative nutrients divided by the number of negative nutrients (three). The equation for the baseline algorithm as depicted in Figure 3-1 is [(Protein g per kcal/50 g + Fiber g per kcal/25 g + Vitamin E IU per kcal/30 IU + Vitamin D IU per kcal/400 IU + Calcium mg per kcal/1,000 mg + Iron mg per kcal/18 mg + Potassium mg per kcal/3,500 mg + Unsaturated fat g per kcal/44 g) * 100/8] − [(Saturated fat g per kcal/20 g + Added sugars g per kcal/50 g + Sodium mg per kcal/2,400 mg) * 100/3]. The rationale for nutrient selection was discussed in Section 3.2.