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Nutrient Data Laboratory - Frequently Asked Questions
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.
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I multiplied protein, fat and carbohydrate values by 4-9-4, but 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 Nutrient Database for Standard Reference, Release 13. 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.
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Why don’t the individual fatty acids 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.
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How do I get a copy of Agriculture Handbook No. 8?
The electronic version of Agriculture Handbook No. 8, the USDA 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. The database is also available on CD-ROM and may be purchased from the Government
Printing Office (Stock No.001-000-04679-9). 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.
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