The 2020-2025 Dietary Guidelines for Americans (DGAs), slated for launch in December, spotlight the special nutrient concerns at each life stage. The second of five major overarching guidelines is “Focus on variety, nutrient density and amount.”
There is no standard definition for nutrient density, and it’s not the primary consideration in most consumer food choices. A 2019 IFIC survey, https://foodinsight.org/consumer-research-nutrient-density/, found that only 15% of consumers ranked nutrient density as a primary factor driving food purchase, lagging behind taste, 58%, price, 45%, and healthfulness, 35%. As most dairy products are nutrient-dense, it behooves the industry to explore ways to promote nutrient density.
Defining nutrient density
Nutrient density is considered to be a measure of the amount of selected nutrients per reference amount of food. The reference amount can be 100 kilocalories, 100 grams or a serving size.
There is no standard list of positive nutrients, with scoring patterns using from six to 15 nutrients. Some patterns ignore positive nutrients entirely and base their score solely on the absence of sugar, sodium and saturated fat. The lack of a standard scoring system may explain why the majority of consumers don’t embrace nutrient density as a food purchasing tool.
One popular scoring model is the Nutrient Rich Food (NRF) Index. There are several variations, but all use a set of nutrients to encourage (perhaps protein, fiber, calcium, iron potassium, magnesium and vitamins A, C and E) and nutrients to limit (typically saturated fats, sugars and sodium). The pattern is based on 100 kilocalories of food. The NRF 6.3 system rates raw broccoli at 77, calcium-fortified skim milk at 73 and whole-milk plain yogurt at 7.
A hybrid model
However, as the latest DGAs note, “Just as nutrients are not consumed in isolation, foods and beverages are not consumed separately either. Rather, they are consumed in various combinations over time — a dietary pattern.” A 2019 paper, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6489166/, proposes a hybrid nutrient-density score that includes nutrients and food groups to better align with dietary guidance. The basic scoring formula is: NR (qualifying nutrient to encourage) + FR (qualifying food groups to encourage) – LIM (disqualifying nutrients to limit) × 100. This model boosts the score of many dairy foods.
Unfortunately, current nutrient-profiling concepts do not incorporate issues such as bioavailability, nutrient interactions or nutrient balance. Nutrient-density scores should be based on scientific, objective and transparent criteria. A 2020 IFIC report found that six in 10 consumers surveyed would find “nutrient-dense” labeling helpful for informing food choices.