NUTRIENT PROFILING: THE NEED FOR EVIDENCE-BASED FOOD CHOICES

Chronic, non-communicable diseases are the leading cause of premature death and disability globally. These diseases are frequently linked to poor diet, defined commonly by excess caloric intake alongside high salt, refined sugar, and saturated fat intake, which are the hallmarks of some ultra-processed food products.¹ Amidst the extreme volume and consistent marketing of these food products, consumers face the challenge of navigating food choices and comparing products as a part of a healthy diet in a prevailing unhealthy food environment. This situation warrants the application of new tools for comprehensive, standardized, and transparent guidance on food and dietary intake for consumers and health practitioners.

Nutrient profiling systems (NPSs) are “the science of classifying or ranking foods according to their nutritional composition for reasons related to preventing disease and promoting health.”² Metrics evaluate and compare nutritional information and ingredient makeup of food products to assess their dietary benefits or risks upon consumption.^3,4 More basic NPSs evaluate thresholds met or exceeded for a focused few nutrients of public health concern (e.g., sodium, saturated fat), while more comprehensive scoring algorithms describe the presence and value of a wider range of beneficial food attributes (e.g., vitamins, minerals, healthy lipids, fiber, etc.) in contrast to discouraged attributes (e.g., sodium, added sugar, trans fats, etc.).^5,6

NPSs are increasingly used to evaluate foods for government policies such as taxation, front-of-package labels (FOPLs) which may include warning labels for excess content of nutrients to reduce, and to rate company product portfolios.⁷ NPS metrics and indices are intended to provide quantitative, evidence-based recommendations to improve consumer food choices and reduce their risk of non-communicable disease. Like any index, the content and scoring methodology depends on the selection, justification, and validation of scored metrics. Selection often follows dietary/nutritional guidelines from authoritative bodies such as the World Health Organization (WHO), the U.S. Department of Agriculture (USDA), the National Academy of Medicine (NAM), and the U.S. Food and Drug Administration (FDA). However, variable standards for justifying and validating metrics introduce limitations in the application of this decision-making tool. Below, we describe important features of NPSs while highlighting limitations for their use to inform healthy food and dietary intake choices.

NPSs: Features and Limitations

NPSs depend on transparent and complete reporting of food product ingredients and contents, information which may come from the Nutrition Facts panel or other publicly available data, or private databases maintained by producers. After extracting profiles on key product nutrients, NPSs perform comparisons among food groups, food products, ingredients, and brands. Metric precision and accuracy depend on the consistency, timeliness, and availability of product reporting. However, the variety of food products and brands available for consumption, particularly when ingredient and formulation information is held within proprietary or otherwise restricted databases, limit the comprehensiveness and completeness of NPS algorithms.⁷  

NPSs may evaluate food products based on units of mass, serving size, and/or energy, which presents another variable in the algorithm that can alter the final food score as well as its interpretation and comparability.⁵ A mass-based unit, such as 100g or 100ml, is most common and generally allows for comparability across products of similar food type; however, such a basis complicates appraisal across food groups or even between raw and cooked versions of the same food, where differences in water content or caloric density make direct comparison unreliable.⁸ This issue can inflate scores for energy-dense processed or pre-prepared foods, while deflating scores for bulkier fruits and vegetables. Similarly, while serving size may be more readily understood by consumers, the lack of standardized serving sizes makes the score vulnerable to fluctuation or manipulation. Scoring by unit of energy, typically 100kcal, calculates nutrient density in a consistent manner not affected by water content; this facilitates comparability across a diverse range of food items and may also be scaled up for meal or diet assessment.⁸  

Finally, NPS metrics can provide flexibility for quantifying both healthy and unhealthy attributes within a single food product, and are therefore often the basis for FOPLs.⁹ This type of product profile provides a more balanced formula for guidance around tradeoffs between food choices and provides an evidence-based tool for health practitioners to encourage and reinforce dietary recommendations. Furthermore, as food companies reformulate and rebrand old and new products for marketability and sales, FOPL placement as a visual representation of nutritional quality can encourage modifications, such as reduction in salt or sugar content, and help improve the healthfulness of a product’s portfolio.¹⁰ However, practitioners and consumers must be cognizant that FOPLs are not uniformly applied or regulated. As a result, FOPLs are often curated by food companies and emphasize positive food attributes to boost product sales.¹¹ For example, use of micronutrient fortification, non-nutritive sweeteners, and synthetic fibers in ultra-processed foods might achieve positive NPS ratings without being products to be encouraged.¹²

Next Steps: Building Transparency and Validity

As we strive toward better public health nutrition, NPSs have grown in popularity and complexity.^5,13-15 However, a review of 78 NPS models demonstrated that less than half underwent any formal evaluation of validity.^5,16,17 These omissions inhibit the reproducibility and generalizability of conducted research and question the reliability of NPSs for accurate assessment or grading of foods and product portfolios.

Developed by governmental bodies, academic/research institutions, health-oriented nonprofit organizations, or food companies, NPS and related food assessment metrics are in widespread circulation in public and private food and health domains. Some examples by global region include:

• North America (Guiding Stars, Food Compass Score)
• South America (Pan American Health Organization system, NOVA)
• European Union (Nutri-Score, Keyhole)
• Middle East (Waqeya)
• Africa (South Africa NP Model)
• Asia (Healthier Choice Symbol)
• Australia and New Zealand (Health Star Rating)
• Internationally (WHO Nutrient Profile Model).^18-26

Among the most recent is the Food Compass Score (FCS), developed by a Tufts University team (including an author of this article), which is designed for expansive and objective assessment across a multitude of food choices.⁸ The FCS scores foods according to 54 attributes across 9 domains representing nutrient, non-nutrient, and food-based ingredient characteristics, as well as added components and processing parameters. These attributes were selected based on the strength of the scientific evidence for their average impact on human health, which was further incorporated into the scoring system through a weighted algorithm. While the FCS is intended to be applied uniformly across food categories, scoring across thousands of foods, beverages, and mixed meals may work more consistently for some aspects of diet quality than others. NPSs in general should be considered within the context of a person’s overall dietary patterns, helping individuals select foods within their overall preferences which contribute nutrients to their health and well-being. 

NPSs have varied roles in nutrition science, public health nutrition programming, consumer awareness and choice, and the commercial food industry. However, all of these roles rely on fundamental validity of the NPSs in scope, structure, and interpretation, which does not come without limitations.²⁷ Appropriate food selections are based on a multitude of factors which go beyond a single score evaluation and may further vary due to specific health and biological traits of the individual. Nonetheless, they can provide quick and useful assessment criteria for comparative judgements of food choices and general nutrition guidance for the population. Future research must emphasize methodological transparency, such as clear, comprehensive, and standardized reporting of data source extraction; metric selection; score validation; and sensitivity analyses to other NPS algorithms.