Converting foods to nutrients
Before the computer age, the conversion of food con-sumption into nutrient intake had to be done manu-ally, which was a laborious and time-consuming task. Later, much of the work, especially for larger surveys, was done on mainframe computers, and has since passed on to microcomputers, because of their ready accessibility and ease of use. Data on food and nutri-ent intakes were often subsequently transferred to a mainframe computer, where they were combined with other survey data for further analysis. Today, there is little that cannot be done on a microcom-puter, including data manipulation such as sorting and calculations.
Before proceeding to calculate nutrient intake from data on food consumption, it is necessary to ensure that mistakes that have crept into the data set during acquiring, coding, merging, transcription, and storage are reduced to an acceptable level. Regardless of the method used for the collection of data on food con-sumption, consideration should be given to how the data will be entered into the computer. Suitable forms should be designed for the collection of data. These can be on paper or in a personal computer-based program that can save time and eliminate errors asso-ciated with the transcription of data from paper to the computer. The use of carefully prepared forms, with information to guide those collecting the data, can reduce the chance of error during the collection of data and, if a separate process, during entry into the computer. The collection and entry of data are subject to human and computer error; therefore, pro-cedures must be developed to ensure that the quality of data is as high as possible. Editing and error-checking routines should be incorporated in the data entry process and subsets of data entered into the computer should be compared with the original written records. Where mistakes are found, the extent of the error should be determined, because it could involve data for the previous (or next) subject or day, or those previously (or subsequently) entered by the operator involved. In addition to such checks, fre-quency distributions of all amounts of food and food codes should be carried out. The Food Surveys Research Group of the Agricultural Research Service of the USDA has developed an automated method for collecting and processing dietary intake data. The three computer systems, Automated Multiple Pass Method (AMPM), Post-Interview Processing System (PIPS) and Survey Net collect, process, code, review, and analyze data for nutrient intakes. The system has been used for the National Health and Nutrition Examination survey since 2002.
A crucial aspect of food composition research is the transmission of information from those working in food composition and analysis to those working in food monitoring, to scientists trying to improve the food supply, to workers in epidemiological, training and nutrition programs, and to regulators. Yet there is little discussion in the scientific literature of the issues relating directly to the compilation of food composition databases, which are the primary means of transmission of food composition data to most professionals in the field. If good food statistics are available in a country, as well as access to food intake and food composition databases, estimates of a higher quality can be made regarding the nutrient intake of the individual or population as a whole. However, few data on food composition exist for the 790 million people in developing countries who are chronically undernourished and where malnutrition in the form of deficiencies of iron, iodine, and vitamin A is rife.