Background: To be successful, dietary guidance needs to identify foods that are nutrient rich, affordable, and appealing. Analyses of dietary surveys on "what we eat in America" can now be supplemented by analyses of nutrient density as well as nutrient cost.
Objective: To explore the relative contribution of 9 food groups to energy and nutrient intakes and to assess the relative cost of selected nutrients by major food group.
Method: Dietary intake data were provided by the 4 cycles of the continuous National Health and Nutrition Examination Survey (NHANES 2001-2002, 2003-2004, 2005-2006, and 2007-2008). Research on the nutritive value and cost of U.S. foods was made possible by the merging of the U.S. Department of Agriculture (USDA) Food and Nutrition Database for Dietary Studies (FNDDS 2.0) with the USDA food prices database. Nutrient densities were calculated per 100 kcal. Nutrient costs were calculated as the dollar cost of meeting 10% daily value for a given nutrient.
Results: Despite their low energy contribution (10%-13% of energy), milk and milk products contributed 47% of calcium, 42% of retinol, and 65% of vitamin D to the diets of children and adults. Milk and milk products were among the top sources of riboflavin, phosphorous, and vitamin B(12). Cost analyses showed that milk and milk products were by far the lowest-cost source of dietary calcium and were among the lowest-cost sources of riboflavin and vitamin B(12). Vegetables and fruit were the lowest-cost sources of vitamin C, whereas dry beans and legumes were the lowest-cost sources of fiber.
Conclusion: The nutrients-per-calorie and nutrient cost metrics can help identify affordable nutrient-rich foods.