The purpose of the summary system relates to the health outcome that is to be addressed with the system. The purpose of this project was to develop options for summary FOP algorithms that address chronic disease and obesity and to provide accurate and useful information to meet the Dietary Guidelines. We do not consider nutrient-specific FOP systems for this project. The DGA recommend avoiding excess intake of components that are associated with chronic disease and obesity and encourage components that are associated with health and that the population consumes in lower than optimal amounts.
The purpose of the algorithm affects the choice of nutrients or food components. For example, obesity is caused by excess energy intake. Although excess intakes of fat and added sugars result in increased energy intakes, the inclusion of these components in an algorithm is debated. The scientific evidence for chronic disease risk is strongest for "negative" nutrients: saturated fat, trans fat, and sodium. Foods associated with these nutrients are foods that are highly processed and have a high energy density (kcal per gram), except for a small number of energy-dense foods with unsaturated fats (nuts, oils). Nutrients to encourage whose consumption is low according to the 2010 DGA include fiber, vitamin D, calcium, and potassium. Shortfall nutrients from the 2005 DGA also included magnesium and vitamins A, C, and E, and for specific population groups nutrients of concern - vitamin B12, folic acid, and iron. Food-based guidelines are usually based on meeting nutrient requirements. Foods that should be encouraged include fruits, vegetables, whole grains, low-fat milk and milk products, and oils (to replace solid fats, not to increase calories). An algorithm could incorporate the amounts of certain food groups or components themselves instead of nutrients.
Potential goals of summary FOP systems are the following:
- To correspond to the NFP: If the goal is for the FOP label to correspond to the NFP, the system could be limited to the nutrients listed on the NFP or potentially others of interest. Some systems that restricted nutrients or food components to those listed on the NFP have excluded added sugars because they are not listed on the NFP. Some systems use the nutrient values on the NFP to score foods or set criteria based on the label serving sizes.
- To warn consumers of "bad" attributes of foods: An FOP system designed to warn consumers of "bad" attributes of foods would best be served with negative nutrients. Considering summary systems, a threshold-type system (check mark or stars) might be better than an overall scoring system because the icon signifies whether the food meets specified levels of all of the negative nutrients in a simple format.
- To represent the overall nutritional profile of a food: If the goal is to represent the overall nutritional profile of a food, then a combination of negative and positive nutrients is probably most appropriate. In terms of a summary system, an overall score or a threshold system works. An overall score communicates differences between products in a more refined manner than a threshold system; that is, overall numerical scores of 30 and 50 signify a difference between two products, whereas with a threshold system, those same two foods may both meet the criteria for a check mark, and the consumer would not know if one is slightly more nutritious than the other. However, thresholds with transparent criteria may inform the consumer that the product meets specified levels of certain nutrients, whereas the overall score does not communicate to the consumer what nutrients contribute to a difference in the scores.
- To help consumers choose foods within or across food categories: An FOP system can be designed to help consumers choose foods within categories (analogous to comparing foods in the same supermarket aisle) or choose foods across categories (analogous to comparing foods across the supermarket). An overall numerical score is designed for both types of comparisons. In contrast, a threshold system (e.g., check mark or star) is not as refined for either type of comparison. A wide range of nutrient levels may be allowed within the rating for a check mark; therefore, this type of system would have less discriminating power. For example, within the category of fruits and vegetables, all would get the check mark, but an orange has more nutrients than a banana (although a multiple rating system like one to three stars would be more helpful), or across food categories, an orange and a low-fat cookie may meet the thresholds. Threshold systems usually set different criteria for different food categories, which allow for within-category comparisons but do not allow for across-category comparisons, although a graded threshold system could serve this purpose (e.g., one to three stars).