Saturated fatty acids: 4:0, butanoic, butyric;6:0, hexanoic, caproic; 8:0, octanoic, caprylic; 10:0, decanoic, capric; 12:0, dodecanoic, lauric; 13:0, tridecanoic, ; 14:0, tetradecanoic, myristic; 15:0, pentadecanoic, ; 16:0, hexadecanoic, palmitic; 17:0, heptadecanoic, margaric; 18:0, octadecanoic, stearic; 20:0, eicosanoic, arachidic; 22:0, docosanoic, behenic; 24:0, tetracosanoic, lignoceric. Monounsaturated fatty acids: 14:1, tetradecenoic, myristoleic; 15:1, pentadecenoic, ; 16:1 undifferentiated, hexadecenoic, palmitoleic; 16:1 c, , ; 16:1 t, , ; 17:1, heptadecenoic, ; 18:1 undifferentiated, octadecenoic, oleic; 18:1 c, , ; 18:1 t, , ; 20:1, eicosenoic, gadoleic; 22:1 undifferentiated, docosenoic, erucic; 22:1 c, , ; 24:1 c, cis-tetracosenoic, nervonic. Polyunsaturated fatty acids: 18:2 undifferentiated, octadecadienoic, linoleic; 18:2 n-6 c,c, , ; 18:2 i, , ; 18:2 t not further defined, , ; 18:3, octadecatrienoic, linolenic; 18:3 n-3 c,c,c, , alpha-linolenic; 18:3 n-6 c,c,c, , gamma-linolenic; 18:4 undifferentiated, octadecatetraenoic, parinaric; 20:2 n-6 c,c, eicosadienoic, ; 20:3 undifferentiated, eicosatrienoic, ; 20:4 undifferentiated, eicosatetraenoic, arachidonic; 20:5 n-3, eicosapentaenoic (EPA), timnodonic; 22:5 n-3, docosapentaenoic (DPA), clupanodonic; 22:6 n-3, docosahexaenoic (DHA). Fatty Acids * Omega-3 and Omega-6 Fatty Acid information is not a part of USDA SR17. CyberSoft derived these values by summing the Fatty Acid components of each of these two fatty acid complexes. Only food items which provided data for all the associated Fatty Acids were calculated. Lipid Components Fatty acids are expressed as the actual quantity of fatty acid in g per 100 g of food and do not represent fatty acids as triglycerides. Historically, most fatty acid data were obtained as the percentage of fatty acid methyl esters and determined by GLC 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 per 100 g edible portion of food. Data received as fatty acid esters and triglycerides are converted to fatty acids using Sheppard conversion factors. Sheppard conversion factors are based on the 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 conversion factors and then multiplied by total lipid (Nutrient No. 204) to give g fatty acid per 100 g edible portion of food. Occasionally, total lipid 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, and 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 nnumber 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 that cannot be easily 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 SR17 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 other 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 No. 618). Other fatty acid totals provided are (1) the sum of saturated, monounsaturated, and polyunsaturated fatty acids and (2) the 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; therefore, the sum of their values may exceed the sum of the individual fatty acids. 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 individually 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 of total lipid were converted to g fatty acids per 100 g of food, values of less than 0.0005 were rounded to 0. The Lipid Components Table 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. The most typical isomer for 18:1 is oleic. Thus, the specific isomer by that name, 18:1 c, is designated in table 2 as oleic. Cholesterol. Cholesterol values were generated primarily by GLC 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 zero. Plant sterols. Data on plant sterols (campesterol, stigmasterol, and ß-sitosterol) were obtained by colorimetric or gas-chromatographic procedures and summed to calculate total phytosterols. Related topics include Proximates, Minerals, Vitamins, and Amino Acids.