Page Banner

United States Department of Agriculture

Agricultural Research Service

Frequently Asked Questions (FAQs)
headline bar

USDA Nutrient Database:

Nutrition Resources:

Education Resources:

Note:  Although we have made reasonable efforts to assure the accuracy of linked information, the Nutrient Data Laboratory does not assume responsibility for information obtained beyond this point or for interpretations of our data on other sites.  Please remember to click on the BACK Button on your browser to return to this page.


 

How do I reference the USDA National Nutrient Database for Standard Reference?

The suggested citation is:

U.S. Department of Agriculture, Agricultural Research Service. 2013. USDA National Nutrient Database for Standard Reference, Release 26. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/nutrientdata

Note: Release numbers change as new versions are released.

Back to Top


 Is there a copyright on USDA food composition data?

USDA food composition data is in the public domain and there is no copyright. We would appreciate it if you would list us as the source of the data and when possible we would like to see the product which uses the data or be notified of its use.

Back to Top


I multiplied protein, fat and carbohydrate values by 4-9-4 my energy value is different from USDA's. Why?

Calorie values are based on the Atwater system for determining energy values. The factors used in the calculation of energy in the database are given in the food description file of the USDA National Nutrient Database for Standard Reference, Release. The basis and derivation of these factors are described in

Merrill, A.L. and Watt, B.K. 1973. Energy Value of Foods...Basis and Derivation. Agriculture Handbook No. 74. U.S. Government Printing Office. Washington, DC. 105p.

This reference is out of print, but a scanned copy is viewable on our home page.  It may also be available at many university libraries. The Atwater system uses specific energy factors which have been determined for basic food commodities. These specific factors take into account the physiological availability of the energy from these foods. The more general factors of 4-9-4 were developed from the specific calorie factors determined by Professor Atwater and associates. For multi-ingredient foods which are listed by brand name, calorie values generally reflect industry practices of calculating calories from 4-9-4 kcal/g for protein, fat, and carbohydrate, respectively, or from 4-9-4 minus insoluble fiber. The latter method is frequently used for high-fiber foods because insoluble fiber is considered to provide no physiological energy. If the calorie factors are blank or zero for an item in the Database, energy was calculated by recipe from ingredients or was supplied by the manufacturer.

Back to Top


How is Carbohydrate, by difference determined?

Carbohydrate is determined as the difference between 100 and the sum of the percentages of water, protein, total lipid (fat), ash, and, when present, alcohol. Total carbohydrate values include total dietary fiber.

Total carbohydrate by difference = 100 - [water, protein, total lipid, ash and alcohol in g/100g]

Back to Top


Why don’t the individual fatty acid or the fatty acid classes add up to the total lipid (fat)?

The fatty acids are reported as grams of fatty acid per 100 grams of food. They may not add up to the total lipid value provided in a database because the fat value may include some non-fatty acid material, such as, glycerol, phosphate, sugar or sterol. In the case of vegetable oils that are 100% triglyceride, 95.6% is fatty acid and the remaining 4.4% is glycerol. For other fats, the percent of fatty acid will be even lower. Lipid conversion factors for specific fats define the amount of fatty acid (in grams) per gram of fat. The factor is 0.956 for triglycerides and lower for other fats. The factors used in each section of Agriculture Handbook No. 8 were published in an appendix table.  In addition, the individual fatty acids may not add up to their respective total fatty acid classes (saturated, monounsaturated, and polyunsaturated) and in turn, the sum of the total for each class may not add up to the value for total lipid.  

Back to Top


 How do I get a copy of Agriculture Handbook No. 8?

The electronic version of Agriculture Handbook No. 8, the USDA National Nutrient Database for Standard Reference can be downloaded from this Home Page. A program allowing you to search the database is also available. Reports giving the content of each item in the Database are  available online. Printed copies of Agriculture Handbook No. 8, Composition of Foods, are no longer available, though copies may be available at libraries in universities with departments of nutrition or food science. Since there is no copyright, you are free to make additional copies.

Back to Top


What is the status of the USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods?

Recently the USDA’s Nutrient Data Laboratory  (NDL) removed the USDA ORAC Database for Selected Foods from the NDL website due to mounting evidence that the values indicating antioxidant capacity have no relevance to the effects of specific bioactive compounds, including polyphenols on human health.

There are a number of bioactive compounds which are theorized to have a role in preventing or ameliorating various chronic diseases such as cancer, coronary vascular disease, Alzheimer’s, and diabetes.  However, the associated metabolic pathways are not completely understood and non-antioxidant mechanisms, still undefined, may be responsible. ORAC values are routinely misused by food and dietary supplement manufacturing companies to promote their products and by consumers to guide their food and dietary supplement choices.

A number of chemical techniques, of which Oxygen Radical Absorbance Capacity (ORAC) is, one, were developed in an attempt to measure the antioxidant capacity of foods. The ORAC assay measures the degree of inhibition of peroxy-radical-induced oxidation by the compounds of interest in a chemical milieu. It measures the value as Trolox equivalents and includes both inhibition time and the extent of inhibition of oxidation.  Some newer versions of the ORAC assay use other substrates and results among the various ORAC assays are not comparable. In addition to the ORAC assay, other measures of antioxidant capacity include ferric ion reducing antioxidant power (FRAP) and trolox equivalence antioxidant capacity (TEAC) assays. These assays are based on discrete underlying mechanisms that use different radical or oxidant sources and therefore generate distinct values and cannot be compared directly. 

There is no evidence that the beneficial effects of polyphenol-rich foods can be attributed to the antioxidant properties of these foods.  The data for antioxidant capacity of foods generated by in vitro (test-tube) methods cannot be extrapolated to in vivo (human) effects and the clinical trials to test benefits of dietary antioxidants have produced mixed results. We know now that antioxidant molecules in food have a wide range of functions, many of which are unrelated to the ability to absorb free radicals.

For these reasons the ORAC table, previously available on this web site has been withdrawn.

Back to Top


What is the status of the USDA Database for the Added Sugars Content of Selected Foods?

The USDA’s Nutrient Data Laboratory (NDL) recently removed the USDA Database for the Added Sugars Content of Selected Foods from the NDL website due to constant changes in formulations for commercial, multi-ingredient foods, the primary contributor of added sugars to the diet.  Though a reevaluation of these foods, their ingredients and ingredient proportions is integral to our ongoing monitoring program, we are not recalculating added and intrinsic sugars at this point in time.  This is, in part, because brand name market shares and ingredients are changed so rapidly that these estimates are more a temporary cross-section in time than fixed values. No method can analyze for added sugars so their amounts must be extrapolated or supplied by food companies, many of which are not willing to make public such proprietary information.

For these reasons the Added Sugars Table, previously available on this web site, has been withdrawn.

Back to Top


I’m looking for dietary advice. Can you tell me which foods are best for me to eat?

NDL does not provide any kind of dietary advice. The U.S. Department of Agriculture and the Department of Health and Human Services has prepared Dietary Guidelines for Americans, 2010. We recommend nutrition counseling by a qualified professional. The American Dietetic Association maintains a service to find a Registered Dietitian in your area. Other resources include your local dietetic association, health department or hospital.

Back to Top


Where can I get information on Dietary Supplements?

The Nutrient Data Laboratory (NDL) is working with the Office of Dietary Supplements, National Institutes of Health (ODS/NIH) and other federal agencies to plan and develop a Dietary Supplement Ingredient Database (DSID) to estimate levels of ingredients in dietary supplement products. The DSID is funded in large part by the Office of Dietary Supplements and builds on the well-recognized strengths of the USDA ARS in developing databases that support the assessment of nutrient intake from foods. The Office of Dietary Supplements (ODS) conducts research on dietary supplements and has collected information on vitamins, minerals, and botanicals, which is available on the ODS web site. USDA's Food and Nutrition Information Center has also compiled a number of resources on dietary supplements

Since 2009, NDL has been conducting research on the ingredient content of dietary supplements and reporting the results in the DSID. Ingredients in nationally representative adult and children’s multivitamin/mineral (MVM) products have been chemically analyzed and the results compared to labeled levels. Results predicted by regression for the mean percent differences from label and standard errors have been published in the 2012 DSID-2 release. The DSID-2 release includes data tables, data application tables to the National Health and Nutrition Examination Survey data, research summaries and on-line MVM calculators.  New studies are planned to provide analytical measurement and statistical evaluation of ingredients in over-the-counter prenatal MVMs, fish oil and plant oil products and botanically-based supplements. The results from the DSID can be used in population studies to more accurately assess ingredient intake from supplements to determine their impact on public health.  The DSID is available to the public at http://dietarysupplementdatabase.usda.nih.gov

Back to Top


Where can I get information on nutrition?

Nutrition.gov logo, provides easy access to all online federal government information on nutrition. This national resource makes obtaining government information on nutrition, healthy eating, physical activity, and food safety, easily accessible in one place for many Americans.  More nutrition information is available in the 2010 Dietary Guidelines, and on the ChoseMyPlate.gov Web site.  USDA's Food and Nutrition Information Center has compiled a wide variety of links to food and nutrition resources on the Internet.  Some of the resources they have developed contain information on food allergies, food, labeling, food safety, dietary guidance, dietary supplements, nutrition and cancer, vegetarian nutrition and many more.   USDA's Center for Nutrition Policy and Promotion also has information on preparing nutritious meals andother nutrition information.   The American Dietetic Association also has a variety of nutrition information on their Web site.

Back to Top


Do you have a copy of the RDAs on your Web site? In 1996 the Food and Nutrition Board, Commission on Life Sciences, National Research Council began developing Daily Reference Intakes (DRIs) to replace the Recommended Dietary Allowances (RDAs).  These new DRIs are published by the National Academies Press.  Copies of the RDA and DRI  tables are available on the National Agricultural Library's Food and Nutrition Information Center's Web site

In 1973 the FDA developed the U.S. RDA system to replace the minimum daily requirements which had previously been used for nutrition labeling purposes. The U.S. RDAs were based on the Food and Nutrition Board’s RDAs, but were not identical to them. The Daily Values (DV) used on current nutrition labels are based on the U.S. RDAs and can be found in the Code of Federal Regulations, Title 21, Part 101.9.

Back to Top


What is the difference between calories and kilocalories?

In the U.S., energy in foods is expressed in kilocalories (kcal). The scientific definition of a kilocalorie is the amount of energy needed to raise the temperature of 1 kilogram of water one degree Celsius from 15° to 16° at one atmosphere. The true calorie, sometimes referred to as a "small calorie," is the amount of energy needed to raise the temperature of one gram of water one degree Celsius from 15° to 16° at one atmosphere. A kilocalorie is equal to 1000 calories. While the term "calorie" technically applies to the "small calorie," in common usage, such as in reference to food energy, the term "calorie" is actually a kilocalorie. Internationally, most countries express food energy in kilojoules (kJ). One kcal equals 4.184 kJ. The USDA National Nutrient Database for Standard Reference contains values for both kilocalories and kilojoules.

Back to Top


 What are omega-3 and omega-6 fatty acids?

These are types of polyunsaturated fatty acids. Linolenic acid, the shortest chain omega-3 fatty acid, and linoleic acid, the shortest chain omega-6 fatty acid, are essential fatty acids. This means they cannot be synthesized by the body from other fatty acids and must be obtained from food. The most common fatty acids of each class are linolenic (18:3), EPA (20:5), DHA (22:6) for omega-3 and linoleic (18:2) and arachidonic (20:4) for omega-6. Some of the food sources of omega-3 fatty acids are fish and shellfish, flaxseed, walnuts, and canola oil. A computer software package, KIM (Keep it Managed) can be downloaded from http://ods.od.nih.gov/eicosanoids. This software evaluates the balance of omega-3 and omega-6 fatty acids in your diet. A scientific discussion of physiological effects of omega-3 fatty acids can be found on the American Heart Association Web site.

Back to Top


 Where do I get information on nutrition labeling?

USDA's Food Safety and Inspection Service (FSIS) regulates the labeling of meat and poultry. The Food and Drug Administration (FDA) is responsible for all other foods. Information on labeling is available from FDA's Home Page

Back to Top


 My son/daughter has a science fair project. How does he/she analyze a food for a particular nutrient?

Methods for determination of nutrients in foods are published in the "Official Methods of Analysis of AOAC International," The 18th edition comes in 2 volumes. If only earlier editions of the publication can be found, some methods such as the titrimetric method for vitamin C, have not changed in many years. There are also other publications which your child's science teacher can recommend. Caution: Many methods of analysis for foods require the use of strong chemicals, use of specialized equipment and adult supervision. Age and experience of the student should be considered when experiments are planned. Younger students may be encouraged to conduct simple experiments which are planned with the teacher's or parent's guidance.

Back to Top


 Do you have resources for teachers?

ARS's Information Staff has prepared " Science 4 Kids."  which is a series of stories about what scientists do here at the ARS.  They have also prepared the " Whiz Kid" Activity Packet, which is intended for teachers, and is chock-full of fun and clever graphics to introduce agricultural research topics. 

Back to Top


Last Modified: 11/8/2013