Database FAQs

How does the NCC Food and Nutrient Database compare to other databases?

The NCC Food and Nutrient Database includes more foods and nutrients than other research quality U.S. databases (comparison table).

How does NCC impute nutrients?

One of the features of NDSR that makes it the choice of researchers is the small number of missing nutrient values for foods in the database. This is an essential feature because missing nutrient values for foods are ultimately calculated as zeros in nutrient intake estimates.

To minimize the number of missing values, NCC uses several standardized procedures to impute or logically calculate an estimation. These procedures are described in Procedures for estimating nutrient values for food composition databases. To summarize, one of the following procedures is employed to estimate a nutrient value for a food when an analytic value is not available from the USDA Nutrient Data Laboratory or cannot be found in the literature:

  • Value from a different but similar food is used. (e.g., missing nutrient for wild duck may be judged to be the same as known nutrient in domestic duck)
  • Value for another form of the same food is calculated (e.g., convert from raw to cooked values using retention factors)
  • Calculate values from other components in the same food (e.g., estimate beta-carotene from Vitamin A)
  • Calculate value from household recipes or commercial food product formulations for multicomponent foods (e.g., Manufacturers may provide ingredient listing and macronutrient composition of product. From the macro-nutrients, NCC database scientists estimate the amount of each ingredient. Based on the estimated amounts of the ingredients, micro-nutrients can be imputed for the product.)

Missing values are allowed in the database for foods that are consumed in very small quantities, such as spices, or where there are no data to indicate whether the nutrient exists in the food.

Some nutrients have no missing values, but a high percentage of imputed values. An example is Vitamin A which is calculated from provitamin A carotenoids and retinol.

In future versions of the database, missing and estimated values will be replaced by analytic values as they become available.

How does NCC decide whether to add new nutrients or food components to the database?

The following factors are considered in deciding whether to add a nutrient or other food component to the database:

  • Scientific Interest: Is there demand for it? If there is a nutrient or food component you’d like added to the database please let us know(ndsrhelp@umn.edu).
  • Availability of Food Composition Information: Is there analytic composition information available for a significant proportion of core foods in the NCC Food and Nutrient Database?
  • Quality of Analytic Data: Is the analytic information available of sufficient quality (e.g., obtained using appropriate analytic methods) for use in assigning values to foods in the NCC Food and Nutrient Database?

The database includes several brand name products in some food product categories such as snack crackers but no brand name products in other categories such as canned and frozen vegetables. Why?

Brand name products are included if there are significant differences in the nutrient composition of food products within a category. For example, different brands of potato chips are included in the database because the fatty acid content of chips varies notably across brands. Another reason for including brands relates to how people tend to describe the food. For example, commercial cookies tend to be described by brand name (e.g., Oreo® cookie) rather than by generic food description (e.g., chocolate sandwich cookie).

The nutrient values for brand name food products in the database don't precisely match the values on the product's Nutrition Facts panel. Why?

Nutrient values in the NCC Food and Nutrient Database for brand name foods do not precisely match the information on product Nutrition Facts panels for a number of reasons. One reason is that values in the database are not rounded to the nearest whole number as is allowed on the Nutrition Facts panel. Another reason is the database values may not reflect recent changes in the marketplace. For example, if General Mills reformulates Cheerios® today, the nutrient values in the current database may no longer match those on the product label. Discrepancies between database and Nutrition Facts panel values may be due to use of the nutrient composition of representative foods for some brand name product categories for which the nutrient composition across brands is similar. As an example, although the database includes several brands of pretzel twists, the nutrient values assigned to each are based on a representative pretzel twist. It is important to note that use of a representative food is only done when variation in nutrient content across brands of a product is minimal.