Comparison of Label and Laboratory Sodium Values in Popular Sodium-Contributing Foods in the United States

What is already known?

Food labels can help consumers make healthful food choices. More than 50% of consumers read labels before purchasing a food for the first time. About one third of consumers use digital tools that are based on nutrient label information for tracking their food and health-related activities. In addition, information based on nutrition labels is used to monitor the nutrient content of foods, to inform policies and programs for improving public health.

The main aim of this study was to compare the label and laboratory (analytical) values for sodium, total fat, saturated fat, and total sugars in popular sodium-contributing foods. This study also examined agreement between label and laboratory values by brand type (national or private label), the location where the food was purchased (store or restaurant), and restaurant type (fast-food or sit-down).

What does this article add?

We do not know of a recent published comprehensive analysis comparing label and laboratory sodium values for foods in the United States or examining agreement between label and laboratory values among brand types (national or private label) or source (store or restaurant).

The U.S. Department of Agriculture’s (USDA) Nutrient Data Laboratory sampled 125 popular sodium-contributing foods from supermarkets and fast-food and casual dining restaurants from up to 12 counties or cities nationwide.

In this study, an underdeclaration was defined as a laboratory value that was higher than 120% of the label value. An overdeclaration was defined as a laboratory value that was at or below 80% of the label value.

  • A comparison of label and laboratory sodium values for 1,390 composites (one or more samples of the same food) of 114 foods showed that the majority of the values were in agreement.
  • Overall, when label and laboratory values for sodium were compared:
    • 5% of labels underdeclared.
    • 14% of labels overdeclared.
  • When sodium label and laboratory values were compared by brand and source:
    • 22% of private-label brand labels overdeclared.
    • 12% of national brand labels overdeclared.
    • 3% of store labels underdeclared.
    • 11% of restaurant labels underdeclared.
      • 37% of sit-down restaurants overdeclared sodium, compared with 9% of fast-food restaurants.
  • The proportions of labels that did not match laboratory values (either underdeclaring or overdeclaring values) differed by source—store (16%) or restaurant (25%) and by type of restaurant—fast-food (19%) or sit-down (48%).

What are the implications of these findings?

Overall, for the majority of foods sampled, label and laboratory sodium values agree, and underdeclaration of label values is limited. However, there are some discrepancies between label and laboratory values, particularly for restaurants.

Periodic monitoring of the nutrient content of foods through laboratory analyses establishes the validity of food labels and helps identify foods and food categories where the label and laboratory values do not compare well. Routine laboratory analyses of labels may be needed to support the accuracy of nutrient databases.

Citation

Ahuja JKC, Li Y, Nickle MS, Haytowitz DB, Roseland J, Nguyen Q, et. al. Comparison of label and laboratory sodium values in popular sodium-contributing foods in the United States.External J Acad Nutr Diet 2019;119(2):293-300.e17. https://doi.org/10.1016/j.jand.2018.08.155External