Documentation

ERS provides data on food and nutrient intake by food source: 

• Three tables provide estimates of food consumption in 2015–18 by food source.
• Two tables provide estimates of nutrient intake in 2015–18 by food source.

About Our Estimates

The National Health and Nutrition Examination Survey (NHANES) measures foods actually eaten by individuals. Since 2003, NHANES has recorded food intake over 2 nonconsecutive days using 24-hour dietary recalls to obtain information about what people eat and where foods are obtained. Each survey is conducted over 2 years, and the 2017–18 data are the most recent data available for research. In this analysis we used the first-day intake data. Survey respondents also reported where food was purchased and where it was eaten.

NHANES collects demographic information, such as household income, race and ethnicity, age, and sex, along with a variety of health data, through household interviews and medical examinations conducted in-person at mobile examination centers. This information makes the data particularly valuable for linking diet and eating habits to health outcomes such as obesity, diabetes, and hypertension. The NHANES data provide background information useful in policy formation, regulation, program planning and evaluation as well as education and research.

Food Consumption Estimates

Food consumption data from NHANES were combined with USDA's Food Patterns Equivalents Database (FPED) to estimate food consumption by food groups as specified in the 2020–2025 Dietary Guidelines for Americans, the Federal Government’s statement of what Americans should eat for a healthy diet (USDA/U.S. Department of Health and Human Services, 2020). The FPED database translates food quantities reported in NHANES into food pattern equivalents as specified in the Dietary Guidelines for Americans. For example, a respondent in NHANES may report having eaten a specific amount of apple pie; such data are then translated into cups of fruit, ounces of grain, grams of oils and solid fat, and teaspoons of added sugar. 

Data on where food is obtained are used to divide food into two main categories—at home and away from home. The latter is further classified as restaurants, fast food places, schools, and other food-away-from-home places.

• Food at home is generally obtained at a retail store such as a supermarket, grocery store, or convenience store.
• Food away from home is generally purchased from foodservice establishments such as full-service restaurants with waitstaff (restaurant), fast food restaurants with limited menus and no waitstaff, and carryout places (fast food), school cafeterias, daycare centers, and summer camps for children age 2–19 (school) as well as from other away-from-home places, such as community food programs, street vendors, vending machines, etc.

Food consumption in terms of the Dietary Guidelines for Americans' groups is reported for all sources as well as by food source for the total U.S. population (aged 2 and older), children age 2–19, adults age 20–64, and seniors age 65 and older, lower income individuals (household income at or falls below 185 percent of the poverty line), middle income (household income falls between 185 and 300 percent of the poverty line) and higher income individuals (household income above 300 percent of the poverty line).

In food consumption table 1, average daily intakes of food groups in 2015–18 are reported. By comparing food consumption data with calorie intake data (reported in the nutrient table 1), food consumption can be expressed in terms of density—the amount of food for each 1,000 calories in a person’s diet. This density measurement is used in USDA's calculation of the Healthy Eating Index. By comparing food consumption density with the benchmark density (a ratio of the recommended consumption amount to calorie intake as specified in the Dietary Guidelines for Americans), insight can be gained about shortfalls in American diets relative to the dietary guidelines. Comparing food consumption density by food source yields a better understanding of the source of American dietary shortfalls. Food consumption density by food source among children, adults, seniors, and households in three income levels are reported in food consumption table 2. The benchmark food density is presented in food consumption table 3.

Either the mean or the ratio approach can be used to estimate food and nutrient density (Lin et al., 2016). Here, ERS used the mean approach, in which first the food or nutrient density was calculated for everyone who reported eating the food or nutrient and then the weighted average density was calculated using the survey sample weight (the number of Americans a survey respondent represents). The mean and ratio approaches often yield similar results, although they may produce different but equally valid results (Lin et al., 2016).

Nutrient Intake Estimates

The Dietary Guidelines for Americans recommend that Americans limit saturated fats, sodium, and dietary cholesterol, and identify underconsumption of calcium, dietary fiber, and iron as a public health concern. Using USDA's nutrient database, food consumption data in NHANES were converted to nutrient consumption data. Average (mean) daily intakes of these nutrients for the U.S. population in total, by age (children age 2–19, adults age 20–64, seniors age 65 and above) and three household income levels (separating by the 185 and 300 percent of the poverty line) are reported by food source in nutrient table 1. Nutrient density (the amount of a nutrient for each 1,000 calories of food consumed) calculated using the mean approach is reported in nutrient table 2.

Mean nutrient intakes are reported by food source in nutrient table 1 and by nutrient density in table 2, providing insight about sources of over- and under-consumption for various nutrients. For example, foods rich in calcium are essential for children's development. According to nutrient table 2, the mean calcium intake for children age 2–19 is 533 and 526 milligrams per 1,000 calories, respectively, for the 2015–16 and 2017–18 periods. Calcium intake by source shows that, for each 1,000 calories, children consumed 590 milligrams of calcium at home in 2017–18, lower than the amount consumed at school (805 milligrams) but higher than the amount consumed at restaurants (331 milligrams) and fast food places (395 milligrams). The increased popularity of eating away from home at restaurants and fast-food places is associated with a deficiency in calcium intake.

References

Lin, B.H., T.D. Anekwe, J.C. Buzby, and J.T. Bentley. 2016. U.S. Food Commodity Availability by Food Source, 1994–2008. ERR-221, U.S. Department of Agriculture, Economic Research Service, December.

U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025. 9th Edition. December 2020. Available at DietaryGuidelines.gov.