Food manufacturers have recently been adding summary nutrition information on the fronts of packages in addition to the back or side panel Nutrition Facts Panel (NFP). In addition, some supermarkets have added summary information or symbols on shelf labels. The Department of Health and Human Services (HHS), Office of the Assistant Secretary for Planning and Evaluation (ASPE) and the Food and Drug Administration (FDA) are interested in ensuring that nutrition criteria that manufacturers use to make broad front-of-package (FOP) or shelf-label claims concerning the nutritional quality of a food are based on evidence and are not misleading to consumers. It is recognized that multiple FOP labeling schemes can cause confusion for consumers and that a uniform system based on current science may be optimal.
A summary FOP or shelf system rates the overall nutritional quality of a food with an overall numeric score, a multiple category rating, or a single icon to indicate whether a food meets specified nutrient criteria (Figure 1-1). Summary systems are one of two general types of FOP systems; the other type is a nutrient-specific system that displays a few nutrients and their amounts per serving and sometimes includes the percentage of a daily recommended value. On the one hand, nutrient-specific systems can help consumers identify key nutrients in a food but do not provide an overall assessment of the product. Therefore, the consumer may focus on a single nutrient (e.g., calories) and not get a sense of the overall nutritional quality of the food. On the other hand, summary systems can provide an overall assessment of the nutritional quality of a food but do not tell the consumer why the food received the score or rating (e.g., high calcium and low saturated fat content of low-fat milk). This report considers only summary systems.
Figure 1-1. Examples of Summary FOP or Shelf Nutrition Labels
Example of a numerical scoring shelf-label
system (NuVal; reprinted with permission
from NuVal, LLC, U.S.)
Example of a threshold multiple category rating
shelf-label system (Guiding Stars; reprinted with
permission from the Guiding Stars Licensing
Example of a threshold system FOP icon system (Australian/New Zealand National Heart Foundation
Tick; reprinted with permission from the National Heart Foundation of Australia)
The science of ranking foods based on their nutrient content is referred to as "nutrient profiling." A nutrient profile is a ranking, either on a continuous scale (e.g., 1 to 100) or categorical (such as low, medium, and high). Nutrient profiling is the basis for summary FOP and shelf-label systems. Some systems use nutrient criteria or thresholds to determine whether a food receives an icon signifying a healthy or nutritious food. Most systems are based on similar dietary recommendations, such as the 2005 Dietary Guidelines for Americans (2005 DGA) (U.S. Department of Health and Human Services & U.S. Department of Agriculture, 2005), which encourage the consumption of nutrient-dense foods to meet recommended nutrient intakes. The 2005 DGA note particular nutrients of importance that are consumed in less than optimal amounts by the population, such as fiber; vitamins A, C, and E; and calcium, magnesium, and potassium, and nutrients to limit, such as saturated fat, added sugars, and sodium. FDA criteria for nutrition labeling regulations and claims are often used in summary FOP systems, particularly threshold-based systems. For example, a "healthy" food as defined by FDA has to contain at least 10% of the daily value of one or more of these six nutrients: protein, fiber, vitamin A, vitamin C, calcium, or iron per reference amount. In addition, it has to be low in total fat (<3 g), saturated fat (<1 g), cholesterol (<60 mg), and sodium (<480 mg) per reference amount. Many other summary FOP systems use these FDA threshold criteria.
Some key factors must be considered in developing an FOP labeling scheme:
- selection of the nutrients to include in the algorithm
- weighting of nutrients
- assignment of an overall rating score, a category rating, or a symbol (e.g., check mark)
- validation of the ability of the system to rank foods and predict diet quality
FOP labeling systems use algorithms containing selected nutrients to calculate an overall score of nutritional quality or to determine if a food meets specified criteria. Nutrient selection involves the choice of "positive" or "negative" nutrients:
- Positive nutrients are those associated with health effects and are to be encouraged.
- Negative nutrients are related to obesity and chronic disease when consumed in excess and should be limited.
Nutrient profiling systems can use either positive, negative, or both kinds of nutrients. Some systems use additional nonnutrient components such as whole grains or glycemic load (Katz et al., 2009).
Nutrient density is a basis for some nutrient profiling systems and typically refers to the amount of nutrient per kcal (or some multiple of kcal, for example, 100 kcal). Nutrient criteria for calculating a nutrient density index have been examined using various combinations of nutrients to encourage and nutrients to limit. One nutrient density system found that a combination of nine nutrients to encourage and three nutrients to limit best predicted an overall measure of dietary quality (Fulgoni, Keast, & Drewnowski, 2009).
Weighting factors can be applied to nutrients in a scoring system, where some nutrients are assigned higher weights than others. Weighting can be based on bioavailability, biological quality, or presence in the food supply. For example, iron in meat is more bioavailable than iron from plant foods. Animal protein is higher quality (defined by amino acid content) than plant protein. Some nutrients are only present in selected foods, such as vitamin B12, which is only present in animal foods. Few systems actually use weighting factors because the optimal method to weigh nutrients within algorithms is uncertain; however, this remains a topic of interest for nutrient profiling research.
Numerous FOP labeling schemes assign a rating, symbol, or icon only if a food meets certain nutrient criteria. For example, the American Heart Association assigns a check mark to foods meeting criteria for total fat, saturated fat, trans fat, cholesterol, sodium, and fiber. Guiding Stars assigns one, two, or three stars to foods meeting different criteria for vitamins A and C, calcium, iron, zinc, fiber, whole grains, saturated fat, trans fat, cholesterol, added sugars, and sodium.
There is no gold standard to measure the performance of nutrient-based FOP labeling systems in ranking foods by nutritional quality. Often the developers of these systems have asked nutrition experts to rank the foods based on their subjective expert opinion. Different FOP labeling systems can be compared by selecting specific foods and comparing the ranking of the food using the various systems. Current opinion among nutrient profile researchers for validating FOP labeling systems is to compare the total rankings of all foods consumed by individuals in a dietary survey against an overall measure of dietary quality using the same dietary intake survey data. The best-performing system can be assessed by the degree of variance explained by the system in regression analyses. We used this methodology to test our algorithms in this project.
Numerous issues must be considered when evaluating FOP labeling systems with the ultimate goal of identifying or developing a single system for the United States. The best nutrient-based system will only be effective if the consumer understands and uses the system to make healthier choices. Critical evaluation of both the consumer and nutritional aspects of FOP labeling systems is necessary to inform the development of effective policy.