| Food Composition Data: A User's Perspective (1987) |
|Managing food composition data|
|Managing food composition data at the national level|
The management of food composition data at the national level is carried out with the US Department of Agriculture's National Nutrient Data Bank (NDB). A distinction should be made between this management and nutrient data-base management in the more usual sense, such as is carried out in support of the many computerized dietary analysis systems - often called nutrient data-base systems - now in operation. They differ in that the NDB summarizes individual analytical values into a nutrient data base of representative values for foods. These in turn can serve as the foundation for the dietary analysis systems. Essentially, the NDB is the provider of summarized data, and the managers of data systems built upon those summarized data are the NDB's primary users. It is the purpose of this paper to provide insight into the NDB's present mode of operation, describe modifications for improvement now under way, discuss efforts for improving the quality of data, and indicate new applications of the system that may benefit INFOODS.
The Nutrient Data Bank was conceived and established as a computerized means of storing and compiling data on the nutrient composition of foods and of providing average, or representative, nutrient values to data users. Because the computerized system serves as the mechanism for the revision of Agriculture Handbook No. 8, the expansion of data stored in the NDB parallels progress on the handbook revision. The current publication status is shown in table 1 . Food groups covered by AH-8, section nos. 18-22, are those most actively pursued in the data-entering stage at the present time.
The essential features of the NDB system have been described in detail elsewhere [5, 8]. For this discussion it may be helpful to describe briefly the NDB at each of its three levels. Data Base 1 (DB1) consists of the individual entries of nutrients in a food item, together with detailed descriptions of the food item and particulars concerning the measured value. At present, over 800,000 individual records are stored in the NDB, and additions continue to be made at the rate of about 6,000 to 9,000 per month.
Table 1. Status of Agriculture Handbook No. 8 revisions
|Sections published ||Sections in preparation|
|8-1 Dairy and egg products||8-13 Beef products|
|8-2 Spices and herbs||8-14 Beverages|
|8-3 Baby foods||8-15 Fish and shellfish|
|8-4 Fats and oils||8-16 Legumes|
|8-5 Poultry products||8-17 Lamb, veal, and game|
|8-6 Soups, sauces, and gravies||8-18 Bakery products|
|8-7 Sausages and luncheon meats||8-19 Sugars and sweets|
|8-8 Breakfast cereals||8-20 Cereal grains, flours, and pasta|
|8-9 Fruits and fruit juices||8-21 Fast foods|
|8-10 Pork and pork products||8-22 Mixed dishes|
|8-11 Vegetables and vegetable products||8-23 Miscellaneous foods|
|8-12 Nut and seed products|
Data Base 2 (DB2) consists of summarized values of nutrients in food items that have like descriptions. Individual values are averaged and standard deviations calculated for each grouping. Data at this stage of summary provide the opportunity to examine specific food descriptions, such as year of harvest or region of growth. The application of DB2 information to development of an international data base of cereal grain foods was described in a previous publication . At present, data in DB2 are generally too limited for meaningful statistical distinctions, but the potential for such use by INFOODS should be kept in mind as a means of providing more detailed access to data than is now possible.
Data Base 3 (DB3) contains data at the level familiarly known in Agriculture Handbook No. 8. The aim is to provide data that are representative of foods across the nation on a yearround basis. To this end, groupings within DB2 that are indistinguishable at point of purchase or consumption, or that have nearly identical nutrient profiles, may be combined to yield overall mean values. The total number of observations and standard error are also calculated. A provision of the NDB system allows the components to be weighted to produce averages that are more representative for the nation. DB3 is also used to create the computerized version, the USDA Nutrient Data Base for Standard Reference (available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161).
The Nutrient Data Bank is still in its formative period and has not yet reached the stage of continuous maintenance management. At this time, attention is still focused on completing the revision of Agriculture Handbook No. 8, and data management is thus devoted primarily to control of data input and output.