The mean algorithm scores and distributions of scores of major food groupings using the baseline algorithm are presented in Figures 4-2 and 4-3 on a per 100 kcal basis (NDS1KCAL) and a per RACC basis (NDS1ACC), respectively. Positive scores mean that positive nutrients outweigh negative nutrients included in the algorithm. Likewise, negative scores mean that negative nutrients outweigh positive nutrients. The range of scores is much larger for NDS1KCAL than for NDS1RACC. The mean score of all 570 foods on a per RACC basis was lower than the mean score per 100 kcal.
Figure 4-2. Box Plot of Nutrient Density Scores per 100 Kcal for Baseline Algorithm (NDS1KCAL)
Figure 4-3. Box Plot of Nutrient Density Scores per RACC for Baseline Algorithm (NDS1RACC)
Fruits had the highest mean score among the food groups on a per 100 kcal basis and legumes had the highest mean score on a per RACC basis. Vegetables and eggs had the third and fourth highest mean scores. The mean score of grains was fifth for NDS1KCAL and eighth for NDS1RACC. The grain group contained cookies, cakes, and pastries, which have RACC servings greater than 100 kcal, and the high fat and sugar content resulted in lower scores for these foods. Fats, oils, and dressings scored higher on a per RACC basis because their portion sizes are smaller than 100 kcal portions. The sweets and beverages group had the lowest mean score on a per RACC basis.
Some of the major food groupings contain a diverse variety of foods; therefore, it is useful to examine mean scores of subgroupings for these foods (Tables E-1 and E-2 in Appendix E) and scores of selected foods (Table E-3). In the dairy group, rankings of individual foods were similar between both unit bases (Table E-3). As expected, the milks had decreasing scores with increasing fat content. Chocolate milk, even the low-fat version, scored lower than regular whole milk. Among the yogurts, the nonfat versions scored the highest. The fruit variety of whole-milk yogurt had the lowest ranking for both unit bases but had a more extreme lower score per RACC because the large portion contributes more sugar and fat to the score.
Among legumes and nuts, there were higher scores for nuts on a per RACC basis because the larger RACC serving size, 1 ounce, is greater than 100 kcal, resulting in higher positive nutrient values, particularly for unsaturated fat.
For many of the grain subgroups, similar rankings of foods on a per RACC and per 100 kcal were seen for some subgroups, particularly when the RACC serving size was close to 100 kcal (e.g., breads, cereals, cookies, crackers, and salty snacks). On the other hand, high-calorie and high-fat cakes and mixed foods such as pizza resulted in more extreme lower values on a per RACC basis. For example, a RACC serving of chocolate cake provides 468 kcal, 30% of the daily saturated fat value, and 116% of the daily added sugar value.
The vegetable group had an overall negative mean score. Some foods in this group were condiments that contained a large amount of sodium (e.g., salsa, catsup, pickles). Among the highest scoring vegetables were leafy greens. The NDS1KCAL scores were very high because of the large serving size of 100 kcal portions (e.g., 435 g raw spinach). Pickles had the lowest ranking per 100 kcal because of the large serving (833 g) per 100 kcal and high sodium content. Potato chips are included in the vegetable group and, interestingly, scored higher than baked potatoes regardless of the unit basis. Potato chips have higher unsaturated fat and vitamin E. However, in the nutrient database used for NHANES, baked potatoes have higher sodium than potato chips because the baked potatoes have salt added by default. If the sodium value for baked potatoes without salt were used (5 mg/100 kcal), then the NDS1KCAL score would be 3.11 rather than −1.16 (with salt), which is higher than the score for potato chips (1.93).
Among the fats, oils, and salad dressings group, low-calorie salad dressings had very low scores on a per 100 kcal basis because of high sodium content. For example, the lowest scoring salad dressing was fat-free, reduced-calorie Italian dressing (−33.41), providing 100% of the daily sodium value on a per 100 kcal basis. On a RACC basis, the score was −4.71, which is 14% of the daily sodium value. In contrast, scores for regular Italian dressing were similar with the different unit bases (−8.98 and −7.84 on a per 100 kcal and RACC basis, respectively).
Among beverages, coffee and tea scored very high on a per 100 kcal basis because of their low calorie content, resulting in large portions on a per 100 kcal basis and high potassium values driving the high scores. Sugar-sweetened beverages were similar between both unit bases because a RACC of 240 g is equivalent to ~100 kcal. Sugar-free, calorie-free beverages were assigned a 1 kcal/100 g value to obtain a score on a per 100 kcal basis, which resulted in relatively high nutrient values on a per 100 kcal basis.