USDA Nutrient Database for Standard Reference, Release 14

Introduction
Specific Changes
Data Files
Reports
File Content
   Food Description File
   Refuse
   Nutrients
      Proximates
      Minerals
      Vitamins
      Lipid Components
      Amino Acids
   Weights and Measures
   Footnotes
   References
Explanation of File Format
   Relational File
      Food Description File
      Food Group Description File
      Nutrient Data File
      Nutrient Definition File
      Source Code File
      Derivation Code File
      Gram weight file
      Footnote file
      Reference file
   Abbreviated
   Update Files
References 
Appendix A. Abbreviations Used in Short Descriptions
Appendix B. Other Abbreviations

U.S. Department of Agriculture, Agricultural Research Service, USDA Nutrient Data Laboratory. 2001. USDA Nutrient Database for Standard Reference, Release 14.

USDA Nutrient Data Laboratory home page, http://www.nal.usda.gov/fnic/foodcomp

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Issued July 2001

The USDA Nutrient Database for Standard Reference (SR) is the major source of food composition data in the United States. It provides the foundation for most food composition databases in the public and private sectors. As information is updated, new versions of the database are released. This version, Release 14 (SR14), contains data on 6,039 food items and up to 113 food components. It replaces SR13, issued in February 2000.

This is the first release from NDL's new Nutrient Databank System (NDBS). We have changed some formats and have added fields to improve the descriptive information for food items and the statistical information about the nutrient values. While data in previous releases have been migrated into the new NDBS, they have not been processed through the complete system. Consequently, many of these new fields contain data for only a few items and it will take a number of years before they are populated for a majority of food items in the database.

SR14 includes data for all the food groups and nutrients published in the 21 volumes of Agriculture Handbook No. 8 (U.S. Department of Agriculture 1976-88), and its four supplements (U.S. Department of Agriculture 1990-93), which, in turn superseded the 1963 edition (Watt and Merrill 1963). Since 1992, updated data have been published electronically on NDL's Web site. This SR14 release supersedes all previous releases including the printed version in the event of any differences.

Data were compiled from published and unpublished sources. Published sources include the scientific and technical literature. Unpublished data are from the food industry, other government agencies, and research conducted under contracts initiated by the Agricultural Research Service (ARS). Values in the database may be based on the results of laboratory analyses or calculated by the use of appropriate factors or recipes, which is indicated by the source code in the Nutrient Data File. Every food item may not contain a complete nutrient profile.

• New fields to improve descriptive information on foods were added.(common name, manufacturer name, and survey indicator). For more details on these fields see page 2.
• New fields to expand statistical information to better describe the mean (number of studies, minimum and maximum value, degrees of freedom, lower and upper error bounds, and statistical comments). For more details on these fields see page 3
• Modified Gram Weight file replaces the Gram Weight file and Measure Description File.
• Nutrient values have been rounded to a set number of decimal places for each nutrient
• In addition to total folate, values are reported for food folate, folic acid, and folate as dietary folate equivalents (DFE).

• Values are reported for starch, individual sugars, individual tocopherols, individual phytosterols, and several additional fatty acids (including trans fatty acids) for a limited number of foods.

• Brand name items for which we did not have current data were removed from the database.

The data files for SR14 are presented in ASCII format. An abbreviated file, with fewer nutrients, is also provided. A description of each field in these files and the relationships between each is provided below. We have also made available a MS Access 2000 database. This database contains all the SR14 files and relationships, with a few sample queries and reports. The abbreviated file in MS Excel 2000 is also available.

The data in SR14 are also available as reports in two different presentations. The first is for all items in SR14 as page images, containing all the data for each food. These data are separated into files according to food groups. The second is for selected foods and nutrients in SR14. These reports are sorted either by food description or in descending order by nutrient content in terms of common household measures. The food items and weights in these reports are adapted from those in the upcoming revision of Home and Garden Bulletin No. 72, Nutritive Values of Foods

The Adobe Acrobat viewer is needed to see these files. These is a link to the internet site where it can be downloaded for free.

File Content

As mentioned, the database consists of several separate data files. Details about the information in each is provided in the sections below. More extensive details on many specific foods are available in the printed Agriculture Handbook No. 8 sections (U.S. Department of Agriculture 1976-88).

The four principal files are the Food Description File, Nutrient Data File, Gram Weight File, and Footnote File. The five support files are the Nutrient Definition File, Food Group Description File, Source Code File, Derivation Code File, and References File.

Food Description File

This file includes descriptive information about the food items. Food descriptions for brand name items are in upper case. A full description and a short description (containing abbreviations) are provided. Abbreviations used in creating short descriptions are given in appendix A. In creating the short description, the first word in the long description was not abbreviated. Also, if the long description was 25 characters or less, the short description contains no abbreviations. Abbreviations used elsewhere in the tables are given in appendix B. Scientific names, amounts of refuse, and refuse description are provided where appropriate. The factors used to calculate protein from nitrogen are included, as well as those used to calculate calories. There are no factors for items prepared using the recipe program of the Nutrient Data Bank System or for items where protein and calories are calculated by the manufacturer. Three new fields have been added to this file:

• Common name field will allow us to include local or regional names for various foods, i.e. soda or pop for carbonated beverages.
• Manufacturer name field will allow us to indicate the company which manufactured the product, when appropriate.
• Survey field indicates if the food item is used in a National Food and Nutrition Survey and has a complete nutrient profile for a specified set of nutrients.

The refuse and refuse description fields contain amounts and descriptions of inedible material (for example, seeds, bone, skin) for applicable foods. These amounts are expressed as a percentage of the total weight of the item as purchased, and they were used to compute the weight of the edible portion. Refuse data were obtained from USDA sponsored contracts and Agriculture Handbook Nos. 102 and 456 (Adams 1975, Matthews and Garrison 1975). To calculate "Amount in edible portion of 1 pound as purchased" use the following formula:

Y = V*4.536*[(100-R)/100]

where

Y = nutrient value per 1 pound as purchased
V = nutrient value per 100 g (Nutr_Val in the Nutrient Data File), and
R = percent refuse (Refuse in the Food Description File).

For meat cuts containing bone and connective tissue, the amount of connective tissue is included in the value given for bone. Separable fat is not shown as refuse if the meat is described as separable lean and fat. Separable fat generally refers to seam fat and intramuscular fat. Separable lean refers to muscle tissue that can be readily separated from the intact cut; it includes any fat striations (marbling) within the muscle. For boneless cuts, the refuse values apply to connective tissue or connective tissue plus separable fat. The percentage yield of cooked, edible meat from 1 pound of raw meat with refuse can be determined from the following formula:

Y = (W_c / 453.6)*100

where

W_c = weight of cooked, edible meat.

Nutrient values per 100 g are contained in the Nutrient File, along with fields to further describe the mean value. Nutrient values have been rounded to a specified number of decimal places for each nutrient. Number of decimal places for each nutrient are listed in the Nutrient Definition File (p.20). With the implementation of the new Nutrient Databank System, we have added a number of statistical attributes to better describe the mean. These include:

• Number of Studies - The number of analytical studies used to generate a mean. A study is a discrete research project on the analysis of foods. A study can be the analysis of one nutrient in one food; one nutrient in many foods; or many nutrients in many foods.
• Minimum value - the smallest observed value in a range of values
• Maximum value - the largest observed value in a range of values
• Degrees of freedom - the number of values that are free to vary after we have placed certain restrictions on the data. Used in probability calculations.
• Lower and upper error bounds - represent a range of values the mean is expected to fall within, given a pre-specified Confidence Level. For the Standard Reference Database 14 and related releases, the Confidence Level is 95%.
• Statistical comments give additional details about certain assumptions made during statistical calculations. The definition of each comment is given in the discussion of the Nutrient Value file under File Formats.

A few additional fields were added to expand the information on how the values are generated:

• Derivation code - a code giving more information about how a value was calculated or imputed. Procedures for imputing nutrient values were described by Schakel et al. (1997).
• Reference NDB number - NDB number of the food item that was used to impute a nutrient value for another food. This field has not been populated for this release.
• Added nutrient marker - a check in this field indicates that a mineral or vitamin was added for enrichment or fortification purposes. This field has not been populated for this release.
• Confidence code - a code indicating the quality of the data. This code is derived using the expert system first described by Mangels et al (1993), which has been expanded and enhanced for the new Nutrient Databank System. This field has not been populated for this release.
• Reference ID - a code identifying the source of analytical data.

For more details on the Nutrient Data File, see the discussion under Explanation of File Formats 

Nutrient values represent the total amount of the nutrient present in the edible portion of the food, including any nutrients added in processing. The values do not necessarily represent the nutrient amounts available to the body. Table 1 gives an idea of the comprehensiveness of the database by listing for each nutrient the number of items that contain data.

Table 1. Number of foods in database (n=6,039) containing selected nutrients

V_c = (V_r*RF)/Y_c

where

V_c = nutrient content of cooked food,
V_r = nutrient content of raw food,
RF = retention factor, and
Y_c = yield of cooked food.

%TR = (N_c × G_c) / (N_r × G_r) × 100

where

N_c = nutrient content per g of cooked food,
G_c = g of cooked food,
N_r = nutrient content per g of raw food, and
G_r = g of food before cooking.

In general, levels of fortified nutrients are the values calculated by the manufacturer or Nutrient Data Laboratory food specialists, based on the Nutrition Labeling and Education Act label declaration of %Daily Value (DV) (CFR, Title 21, Pts. 100-169). Such values represent the minimum nutrient level one can expect in the product. If analytical values were available to estimate levels of added nutrients, a number is present in the sample count field for these nutrients.

Proximates. Proximate components include water (moisture), protein, total lipid (fat), total carbohydrate, and ash. The values for protein were calculated from the level of total nitrogen (N) in the food, using the conversion factors recommended by Jones (1941). The specific factor applied to each food item is provided in the N_Factor field in the Food Description File. The general factor of 6.25 is used to calculate protein in items that do not have a specific factor. There is no factor for items prepared using the recipe program of the Nutrient Data Bank System or for items where protein is calculated by the manufacturer.

Protein values for chocolate, cocoa products, coffee, mushrooms, and yeast were adjusted for nonprotein nitrogenous material. The adjusted protein conversion factors used to calculate protein for these items are as follows:

When these items were ingredients, only their protein nitrogen content was used to determine their contribution to the protein and amino acid content of the food. Protein calculated from total nitrogen, which may contain nonprotein nitrogen, was used in determining carbohydrate by difference. This unadjusted protein value is not given in the Nutrient Data File for SR14; rather, it is given as a footnote in prior printed sections of Agriculture Handbook No. 8.

For soybeans, nitrogen values were multiplied by a factor of 5.71 (Jones 1941) to calculate protein. The soybean industry, however, uses 6.25 to calculate protein. The protein content of soy flours, soy meals, soy protein concentrates, and soy protein isolates is expressed both ways. The item calculated using the 6.25 factor is identified as "crude protein basis."

Total lipid content of most foods was determined by gravimetric methods, including extraction methods such as those which employ ether or a mixed solvent system of chloroform and methanol, or by acid hydrolysis.

Carbohydrate, when present, was 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 dietary fiber content was determined by the following enzymatic-gravimetric methods: 985.29 and 991.43 of the Association of Official Analytical Chemists (AOAC, 1995). Total sugars were determined using AOAC methods (1995), either high-performance liquid chromatography (HPLC) or gas-liquid chromatography (GLC), and are the sum of individual monosaccharides (i.e., galactose, glucose, and fructose) and disaccharides (i.e., sucrose, lactose, and maltose). Data for total sugars are available primarily for formulated foods, but we anticipate that values for other foods will likely be added in future releases. Starch was analyzed by AOAC method 966.11 (1996).

Food energy is expressed in kilocalories (kcal) and kilojoules (kJ). One kcal equals 4.184 kJ. The data are for physiological energy, which is the energy value remaining after losses from digestion and metabolism are deducted from gross energy. Calorie values, with the exception of formulated foods, are based on the Atwater system for determining energy values. Derivation of the Atwater calorie factors is outlined in Agriculture Handbook No. 74 (Merrill and Watt 1973). For formulated foods, calorie values (source codes 8 or 9; for more information on source codes, see page 21) generally reflect industry practices (as permitted by the Nutrition Labeling and Education Act) of calculating calories from 4-4-9 kcal/g of protein, carbohydrate, and fat, respectively, or from 4-4-9 kcal/g of protein, carbohydrate minus insoluble fiber, and fat. The latter method is frequently used for high-fiber foods.

Calorie factors for protein, fat, and carbohydrates are included in the Food Description File. For foods containing alcohol, a factor of 6.93 was used to calculate calories per gram of alcohol. No calorie factors are presented for items prepared using the recipe program of the Nutrient Data Bank System. Instead, total calories for these items equal the sums of the calories contributed by each ingredient after adjustment for changes in yield, as appropriate. For formulated foods, if the calories calculated by the manufacturer are reported, no calorie factors are presented.

Calorie factors for fructose and sorbitol, not available in the Atwater system, were derived from the work of Livesay and Marinos (1988). Calorie factors for coffee and tea were estimated from seeds and vegetables, respectively.

Minerals. Minerals included in the database are: calcium, iron, magnesium, phosphorus, potassium, sodium, zinc, copper, manganese, and selenium. Levels of minerals for most foods were determined by methods of the Association of Official Analytical Chemists (1995). Phosphorus was determined colorimetrically. Sodium and potassium were usually determined by flame photometry. Calcium, iron, magnesium, zinc, copper, and manganese were determined by atomic absorption and inductively coupled plasma emission spectrophotometry (ICP).

Much of the analytical data for selenium in foods were published earlier (USDA 1992) and were determined by the modified selenium hydride and fluorometric methods. The selenium content of plants, in particular cereal grains, is strongly influenced by the quantity of biologically available selenium in the soil in which they grow, that is, by their geographical origin (Kubota and Allaway 1972). The selenium content of fruits and vegetables is normally very low. While the soil affects the selenium content of fruits and vegetables, it does not significantly increase the amount of selenium in them. The values given are national averages and should be used with caution when considering levels of selenium in locally grown foods.

Vitamins. Vitamins included in the database are: ascorbic acid (vitamin C), thiamin, riboflavin, niacin, pantothenic acid, vitamin B₆, folate, vitamin B₁₂, vitamin A, vitamin E, and vitamin D.

Ascorbic acid. In the current database system, all data for ascorbic acid are listed under nutrient number 401 (total ascorbic acid), although reduced ascorbic acid content is reported for many food groups, especially those which are major nutritional contributors of ascorbic acid such as fruits and vegetables. Total ascorbic acid was reported for food groups 1 (Dairy and Eggs), 2 (Spices and Herbs), 4 ( Fats and Oils), 12 (Nut and Seeds), and 17 (Lamb, Veal, and Game). Food group 10 (Pork and Pork Products) contains a mixture of total and reduced forms, which are reported under nutrient number 401. Reduced ascorbic acid was determined by the dichloroindophenol method, and total ascorbic acid by the fluorometric method.

Thiamin, Riboflavin and Niacin. Thiamin was determined chemically by the thiochrome procedure or by microbiological methods. Fluorometric or microbiological methods were used to measure riboflavin. The values for niacin are for preformed niacin only and do not include the niacin contributed by tryptophan, a niacin precursor. The term "niacin equivalent" applies to the potential niacin value, that is, to the sum of the preformed niacin and the amount that could be derived from tryptophan. In estimating the amounts of niacin available from foods, the mean value of 60 mg tryptophan is considered equivalent to 1 mg niacin (National Academy of Sciences 1989).

Pantothenic acid, Vitamins B₆ and B₁₂. Pantothenic acid was determined microbiologically. Vitamins B₆ and B₁₂ were determined by microbiological or chromatographic methods. Vitamin B₁₂ is found in foods of animal origin or those containing some ingredient of animal origin; for example, cake that contains eggs or milk. For foods that contain only plant products, the value for vitamin B₁₂ is assumed to be 0. Some reports contain values for vitamin B₁₂ in certain fermented foods (beer, soy sauce, and miso). It is believed that this B₁₂ is synthesized not by the microorganisms responsible for the fermentation of the food but, rather, by other contaminating microorganisms. Therefore, one should not consider these foods to be a consistent source of vitamin B₁₂ (Liem et al. 1977).

Folate. In this release, in addition to a total folate value that has been reported in the past, we are reporting values for folic acid, food folate, and total folate reported as g of DFE.

This changes responds to new Dietary Reference Intakes (DRIs) for folate issued by the national Academy of Sciences, Institute of Medicine, (NAS-IOM, 1998). Recommended Dietary Allowances for folate are expressed in dietary folate equivalents (DFE). DFE take into account the greater bioavailability of synthetic folic acid compared to naturally occurring food folate.

To calculate DFE it is necessary to have separate values for naturally occurring food folate and added synthetic folic acid.

µg DFE = µg food folate + (1.7 X µg folic acid)

In 1998 (SR release 12), the folate values in the database were updated to reflect regulations requiring the addition of folic acid to enriched cereal grain products subject to standards of identity (CFR, Title 21, Pts. 136, 137). These products include flour, cornmeal and grits, farina, rice, macaroni, noodles, bread, rolls, and buns. Folic acid may continue to be added (with some restrictions on amounts) to breakfast cereals, infant formulas, medical foods, food for special dietary use, and meal replacement products. For the most part, values for this database were calculated based on enrichment levels specified in the regulations, since analytical values were not yet available. For those foods where the enrichment level is given as a range, the midpoint was used to set the value. Food items containing any of these enriched products as ingredients, such as baked products made with enriched flour, were also updated.

In enriched and fortified foods, total folate includes both food folate and added folic acid. The total folate values found in SR11-1 preceded the implementation of the new enrichment standards and represent the amount of folate naturally occurring in foods. For this release we calculated folic acid by subtracting the food folate value in SR11-1 from the total folate content we estimated in fortified foods for SR12.

For unenriched foods, the total folate value is food folate. Therefore the value for total folate with number of data points and standard error, if present, was also used for food folate. The folic acid value was assumed to be zero.

Enriched ready-to-eat (RTE) cereals have generally included folic acid fortification for over 25 years. Therefore, food folate values were not readily available for these products. Food folate was estimated by means of the databank formulation program for a variety of high consumption cereals. Mean folate values were calculated for categories of RTE cereals based on grain content. Added folic acid was then calculated by subtracting estimated food folate from the total folate content reported in SR13.

Most analytical values shown for folate were determined by the use of conjugase and Lactobacillus casei. Beecher and Matthews (1990) reported that the methodology used in determining folate values needed improvement, particularly, in the areas of extraction procedures and applications to specific foods. Research on determining the folate content of high-protein and high-carbohydrate foods indicates that additional improvements in methodology are needed (Martin et al. 1990). Limited amounts of data generated by USDA were obtained by the tri-enzyme extraction using additional enzymes, amylase and protease, to release bound forms of folate. Microbiological methods measure total folate; for enriched foods, folic acid and food folate are not distinguished from each other.

Vitamin A. The data for vitamin A include chemically determined preformed vitamin A and provitamin-A carotenoids as determined by methods of the Association of Official Analytical Chemists. Total vitamin A activity is expressed in international units (IUs) and retinol equivalents (REs). One IU is equivalent to 0.3 mcg retinol, 0.6 mcg beta carotene, or 1.2 mcg other provitamin-A carotenoids. One RE is equivalent to 1 mcg retinol, 6 mcg beta carotene, or 12 mcg other provitamin-A carotenoids. One RE is equal to 3.33 IU retinol or 10 IU beta carotene (National Academy of Sciences 1989).

In 2001 the Institute of Medicine, National Academy of Sciences issued new DRIs for vitamin A (NAS-IOM, 2001). Along with the new DRI's they recommended changing the factors used for calculating vitamin A activity from the individual carotenoids and developed a new unit for expressing vitamin A activity-Retinol Activity Equivalent (RAE). Vitamin A will be calculated in RAE in the future. Data on individual carotenoids are presented in a separate table (USDA-NCC, 1998) available on the NDL Web site. Plans are underway to add individual carotenoids to this database in future releases.

Vitamin E. Vitamin E was determined by GLC or HPLC. Total vitamin E activity is reported as mg alpha-tocopherol equivalents and was calculated from the amounts and relative activities of the various tocopherols and tocotrienols. In this release, data are also presented on the individual tocopherols when available. In the future we will be adding more data for alpha-tocopherol and dropping alpha-tocopherol equivalents to be in line with the new DRIs for vitamin E (NAS-IOM, 2000).

Lipid Components. Fatty acids are expressed as the actual quantity of fatty acid in g/100 food and do not represent fatty acids as triglycerides. Historically, most fatty acid data reported in USDA Nutrient Databases were obtained as the percentage of fatty acid methyl esters and were determined by gas-liquid chromatographic analyses. These data were converted to g fatty acid per 100 g total lipid using lipid conversion factors and then to g fatty acid per 100 g edible portion of food using the total lipid content. Details of the derivation of lipid conversion factors were published by Weihrauch et al. 1977. In the redesigned NDBS, fatty acid data may be imported in a variety of units and converted within the system. No conversions are required if data are received as g fatty acid/100 g edible portion of food. Data received as fatty acid esters and triglycerides are converted to fatty acids using Sheppard factors. Sheppard conversion factors are based on the differential molecular weights of the specific fatty acid and its corresponding esters (butyl or methyl) and triglyceride (Sheppard 1992). When fatty acid data are received as percentages of fatty acid methyl esters, methyl esters are converted to fatty acids using Sheppard factors and then multiplied by total lipid (nutrient 204) to give g fatty acid per 100 g edible portion of food. Occasionally total fat (nutrient 204) values are available from a variety of data sources, but individual fatty acids are available from fewer references. In those cases, it may be necessary to normalize the individual fatty acids to the mean fat value of the food item. In the case of normalized fatty acids, the sum of the individual fatty acids will equal the mean fat value multiplied by the Weihrauch lipid conversion factor for that food item. No statistics of variability are reported for normalized fatty acids.

The basic format for describing individual fatty acids is that the number before the colon indicates the number of carbon atoms in the fatty acid chain; the number after the colon indicates the number of double bonds. For unsaturated fatty acids, additional nutrient numbers have been added to accommodate the reporting of many specific positional and geometric isomers. Of the specific isomers, there are two basic classifications considered: omega double bond position and cis/trans configuration of double bonds.

Omega-3 and omega-6 isomers are denoted in shorthand nomenclature as n-3 and n-6. The n- number indicates the position of the first double bond from the methyl end of the carbon chain. The letter c or t indicates whether the bond is cis or trans. For polyunsaturated fatty acids, cis and trans configurations at successive double bonds may be indicated. For example, linoleic acid is an 18 carbon omega-6 fatty acid with 2 double bonds, both in cis configuration. When data are isomer specific, linoleic acid is described as 18:2 n-6 c,c. Other isomers of 18:2 for which new nutrient numbers have been assigned include 18:2 c,t; 18:2 t,c; and 18:2 t,t; 18:2 t not further defined; and 18:2 i. 18:2 i is not a single isomer, but includes isomers other than 18:2 n-6 c,c with peaks which cannot easily be differentiated in the particular food item. Systematic and common names for fatty acids are given in Table 2.

Fatty acid totals: Only a small portion of the fatty acid data received for release in SR14 contains specific positional and geometric isomers. Therefore, it has been necessary to maintain the usual nutrient numbers corresponding to fatty acids with no further differentiation than carbon length and number of double bonds. To aid users of our data, specific isomers are always summed to provide a total value for the undifferentiated fatty acid. Thus, mean values for the specific isomers of 18:2 would be summed to provide a mean for 18:2 undifferentiated (nutrient number 618). Other fatty acid totals provided in SR are: 1) the sum of saturated, monounsaturated and polyunsaturated fatty acids and 2) sum of trans-monoenoic, the sum of trans-polyenoic, and the sum of all trans fatty acids.

Values for total saturated, monounsaturated, and polyunsaturated fatty acids may include individual fatty acids not reported in SR; therefore, the sum of their values may exceed the sum of the individual fatty acids listed. In rare cases, the sum of the individual fatty acids may exceed the sum of the values given for the total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA). These differences are generally caused by rounding and may be relatively small.

For formulated brand name foods, industry data were often available for fatty acid classes (SFA, MUFA, and PUFA) but were lacking for individual fatty acids. In these cases, individual fatty acids were calculated from the fatty acids of the individual listed ingredients and normalized to the total fat level. A best-fit approximation was made to fatty acid classes but, unavoidably, calculated sums of individual fatty acid totals did not always match industry data for fatty acid classes. Zero values for individual fatty acids should be understood to mean that trace amounts may be present. When g fatty acids per 100 g total lipid were converted to g fatty acids per 100 g food, values of less than 0.0005 were rounded to 0.

Table 2 is provided for the convenience of users in attaching common names or systematic names to fatty acids in our database. Although individual fatty acids are more specific than in past releases, it is not possible to include every possible geometric and positional isomer. Where specific isomers exist for a fatty acid, the common name of the most typical isomer is listed for the undifferentiated fatty acid and an asterisk (*) designates the specific isomer by that name. Thus, the most typical isomer for 18:1 is oleic. The specific isomer by that name is 18:1 c, is designated in Table 2 as oleic *.

Table 2. Systematic and common names for fatty acids

For some fatty acids listed in the above table, there are no data in this release.

Cholesterol. Cholesterol values were generated primarily by gas-liquid chromatographic procedures. It is assumed that cholesterol is present only in foods of animal origin and foods containing at least one ingredient of animal origin (for example, cake that contains eggs). For mixtures containing ingredients derived from animal products, the cholesterol value may have been calculated from the value for those ingredients. For foods that contain only plant products, the value for cholesterol is assumed to be 0.

Plant sterols. Data on plant sterols (campesterol, stigmasterol, -sitosterol) were obtained by colorimetric or gas-chromatographic procedures and summed to calculate total phytosterols.

Amino Acids. Amino acid data for a class or species of food are aggregated to yield a set of values which serve as the pattern for calculating the amino acid profile of other similar foods in that class or species. The amino acid values for the pattern are expressed on a per-gram-of-nitrogen basis. Data to develop amino acid patterns for simple foods were obtained primarily by ion-exchange chromatography. The amino acid patterns and the total nitrogen content were used to calculate the levels of individual amino acids per 100 g of food, using the following formula:

AA_f = (AA_n*V_p ) / N_f

where

AA_f = amino acid content per 100 g food,
AA_n = amino acid content per g nitrogen,
V_p = protein content of food, and
N_f = nitrogen factor.

In the past, the number of data points appeared only on the food item for which the amino acid pattern was developed, not on other foods that used the same pattern. It referred to the number of observations used in developing the amino acid pattern for that food. For foods processed in the new NDBS, the number of observations used in developing an amino acid pattern will only be released with the release of the pattern. The amino acid profiles calculated from these patterns will show the number of data points to be zero.

If amino acid values are presented for an item with more than one protein-containing ingredient, the values may have been calculated on a per-gram-of-nitrogen basis from the amino acid patterns of the various protein-containing ingredients. Then the amino acid contents for an item on the 100-g basis were calculated as the sum of the amino acids in each protein-containing ingredient multiplied by total nitrogen in the item.

Weights and Measures

Information is provided on household measures for food items (for example, 1 cup, 1 tablespoon, 1 fruit, 1 leg). Weights are given for edible material without refuse. The Gram Weight File contains the gram weights and measure descriptions for each food item. This file can be used to calculate nutrient values for food portions from the values provided per 100 g food. The formula used to calculate the nutrient content per household measure is:

N = (V*W)/100

where

N = nutrient value per household measure,
V = nutrient value per 100 g (Nutr_Val in the Nutrient Data File), and
W = g weight of portion (Gm_wt in Weight File).

Footnotes

Footnotes are provided for a few items where information about food description, weights and measures, or nutrient values could not be accommodated in existing fields. Many of the footnotes published in Agriculture Handbook 8 are no longer needed because the information was moved to other fields and tables. For example, details about the measure description, once contained in footnotes, are now part of the measure description in the Gram Weight file. Values for additional nutrients once included in footnotes were given nutrient numbers, when appropriate, and included in the Nutrient Data File. The database also incorporates data that cover enrichment or fortification or cases where nutrient content is affected by plant part or color (yellow and white corn, for example).

References

This is a new file added with this release. It contains the sources of data for the nutrient values and links to an identification number on each nutrient record. Since much of the data in this release was carried forward from SR13, nutrient specific source documentation was not electronically available. However, as new data for these foods are generated and as additional documentation is entered into the new NDBS, data source information will increase in future releases.

Explanation of File Formats

The data are presented in two different organizational formats. One is a relational format of four principal and five support files comprising the database (figure 1). The relational format is complete and contains all food, nutrient, and related data. The other is a flat file, which is an abbreviated file, with fewer nutrients and related information.

Relational Files

The four principal and five support files of the relational database can be linked together in a variety of combinations to produce queries and generate reports. The formats of these files are identified in tables 3-11. Information on the various relationships that can be made among these files is also given. Fields that always contain data and fields that can be left blank or null are identified in the "blank" column; Y indicates a field that is always filled, N indicates a field that may be left blank (null) (see tables 3-11). An asterisk (*) indicates that the field is indexed. Although the files are not indexed, the file descriptions show where indices were used to sort and manage records within the Nutrient Data Bank System. When importing these files into a database management system, if files are to be indexed, it is important to use the indices listed here, particularly with the Nutrient Data File, which uses two.

ASCII.

Food Description File (file name = FOOD_DES). The Food Description File (Table 3) contains a long and a short description and food group for 6,039 food items, and when applicable, common names, manufacturer name, scientific name, percentage of refuse, and factors used for calculating protein and calories.

• Links to the Food Group Description File by the FdGp_Cd field.
• Links to the Nutrient Data File by the NDB_No field.
• Links to the Gram Weight File by the NDB_No field.
• Links to the Footnote File by the NDB_No field.

 Food Group Description File  (file name = FD_GROUP) (Table 4)

• Links to the Food Description File by FdGp_Cd.

Table 4. Food Group Description File Format

Nutrient Data File  (file name = NUT_DATA). The Nutrient Data File (Table 5) contains the nutrient values and information about the values, including expanded statistical information.

• Links to the Food Description File by NDB No.
• Links to the Gram Weight File by NDB_No.
• Links to the Footnote File by NDB No.
• Links to the Nutrient Definition File and Footnote File by Nutr_No.
• Links to the Source Codes File by Src_Cd.
• Links to the Derviation Code File by Deriv_Cd

Table 5. Nutrient Data File Format

Definitions of each Statistical Comment included in the Nutrient Data table follow:

• The displayed summary statistics were computed from data containing some less than values. Less than, trace and not detected values were calculated.
• The displayed degrees of freedom were computed using Satterthwaite's approximation (Korz, Samuel and Johnson, Norman L. (1988). Encyclopedia of Statistical Sciences, Vol. 8, page 261-262, John Wiley and Son, New York, NY)
• The procedure used to estimate the reliability of the generic mean requires that the data associated with each study be a simple random sample from all the products associated with the given data source (e.g. manufacturer, variety, cultivar, species).
• For this nutrient, one or more data sources had only one study (observation). Therefore the standard errors, degrees of freedom and error bounds were computed from the between unit standard deviation of one or more weighted groups having only one study (observation with the between study (observation) standard deviation.
 

Nutrient Definition File (file name = NUTR_DEF). The Nutrient Definition File (Table 6) is the support file to the Nutrient Data File. It provides the 3-digit nutrient code, unit of measure, INFOODS tagname, and description.

• Links to the Nutrient Data File by Nutr_No.

Table 6. Nutrient Definition File Format

* Klensin et al, 1989

Source Code File (file name = SRC_CD) (table 7)

• Links to the Nutrient Data File by Src_Cd.

Table 7. Source Code File Format

The Source Code File contains codes indicating the type of data (analytical, calculated, assumed zero, and so on) in the Nutrient Data File. To improve the usability of the database, Nutrient Data Lab staff imputed nutrient values for many proximate components, total dietary fiber, and vitamin and mineral values.

A description of each source code follows:

Data Derivation Code Description File: (File Name=DERIV_CD) (table 8)

• Links to the Nutrient Data File by Deriv_Cd

Table 8. Data Derivation Code File Format

• Links to Food Description File by NDB_No.
• Links to Nutrient Data File by NDB No.

Table 9. Gram Weight File Format

• Links to the Food Description File by NDB_No.
• Links to the Nutrient Data File by NDB No and Nutr. No.

Table 10. Footnote File Format

Flat Files

Abbreviated File (file name = ABBREV). The abbreviated file is available in ASCII formats. The ASCII file (table 12) is in free format. Fields are separated by a caret (^). Text fields are surrounded by a tilde (~). Data refer to 100 g of the edible portion of the food item. Decimal points are included in the fields. Missing values are denoted by the null value of two consecutive carets (^^). The file is sorted in ascending order by the NDB number.

This file is a flat file and is provided for those users who do not need a relational database. It contains the information in one record per food item and is suitable for importing into a spreadsheet. It contains less descriptive information and fewer nutrients and weights than the larger relational files. If additional information is needed, this file can be linked to the other files by the NDB_No.