The use of telephone interview methodology to obtain 24-hour dietary recalls.

OBJECTIVE: To compare 24-hour dietary recalls collected over the telephone to in-person recalls collected in the 1994-1996 Continuing Survey of Food Intakes by Individuals (CSFII). DESIGN: Trained interviewers collected 24-hour dietary recalls over the telephone using the multiple-pass approach. These results were compared to in-person interviews from a pooled subsample of CSFII respondents. SUBJECTS/SETTING: List-assisted random-digit dialing was used to identify 700 women between the ages of 20 and 49 years. One eligible woman per household was selected to participate. STATISTICAL ANALYSES: Approximate t tests to examine differences in average nutrient and energy intakes were conducted on weighted data. RESULTS: The reported intakes of most nutrients in the current 24-hour dietary recalls collected over the telephone were significantly higher than those reported in the 1994 and 1995 CSFII, but there were no significant differences between the telephone survey and 1996 CSFII results. The 24-hour dietary recalls collected over the telephone yielded consistently greater mean nutrient intake per respondent compared with a comparable pooled subsample from the 1994, 1995, and 1996 CSFII. Generally, no significant differences were found in the food group data between the telephone survey and the CSFII survey. Mean dietary intakes reported by the comparable CSFII subsample increased from 1994 to 1996. APPLICATIONS: Collecting 24-hour dietary recalls over the telephone is a practical and valid data collection tool for use in national food consumption surveys.

Separating fact from artifact in changes in nutrient intake over time.

OBJECTIVE: To determine whether the differences between the procedures and nutrient databases used in the 1977-1978 Nationwide Food Consumption Survey (1977-78 NFCS) and those used in the 1987-88 NFCS could notably affect the estimated mean nutrient intakes. DESIGN: This was a split-sample field experiment. Seventy-two area segments were randomly selected; 10 housing units were selected in each segment and randomly assigned to one of two experimental groups. SETTING: The study took place in the Philadelphia, Pa, metropolitan area. SUBJECTS: The subjects were 697 women aged 20 to 49 years. TREATMENT: Group A was interviewed using 1987-88 NFCS 24-hour recall procedures and their nutrient intakes were calculated using the 1987-88 NFCS food codes, weight conversion factors, and nutrient database. Group B was interviewed using 1977-78 NFCS 24-hour recall procedures and nutrient intakes were calculated four ways using various combinations of 1987-88 and 1977-78 NFCS food codes, weight conversions, and nutrient database. MAIN OUTCOME MEASURE: Mean intakes of food energy and 14 nutrients were calculated. STATISTICAL ANALYSIS: We used two-sample, multivariate t tests; univariate t tests; univariate repeated measures analysis of variance; and univariate paired t tests. RESULTS: Changes in the nutrient database caused by improved analytic techniques and increased number of foods sampled were great enough to warrant revising the 1977-78 NFCS estimated intakes for iron, magnesium, and vitamins B-6 and B-12. Changes in intake of fat, vitamin A, and thiamin, however, were caused by real changes in foods so no revisions were necessary for these nutrients. Other nutrients were unaffected. CONCLUSION: When considering changes in nutrient intake over time, it is important to correct the earlier food composition estimates so that they accurately reflect the composition of foods at the time they were consumed. This requires preserving the real differences in the composition of foods while correcting for artifactual differences attributable to improvements in the quality of nutrient data.

Dietary intake methodology. II. USDA's Nutrient Data Base for Nationwide Dietary Intake Surveys.

The U.S. Department of Agriculture's (USDA) Nutrient Data Base for Nationwide Dietary Intake Surveys is specifically organized and maintained to analyze data from nationwide dietary surveys within the federal government's National Nutrition Monitoring System. These surveys include the Nationwide Food Consumption Survey and the Continuing Survey of Food Intakes by Individuals conducted by USDA, and the National Health and Nutrition Examination Survey conducted by the Department of Health and Human Services (DHHS). Each public release of the data base covers one or more specific surveys. The data base contains data for energy and 28 components for over 5000 food items. Data are based on the latest information from USDAs National Nutrient Data Bank, the computer-based system used to update USDAs standard reference on food composition, Agriculture Handbook No. 8. An automated system is also used to update the survey nutrient data base with new information released from the Nutrient Data Bank. This system includes three supplementary data sets (primary nutrient data set, recipe file, and table of nutrient retention factors) and a computer program for calculating nutrient content of mixed food items based on nutrient content of their ingredients. Updates are performed at the beginning of new surveys to incorporate the most up-to-date nutrient values.

Analysis of dietary data.

A reliable dietary analysis system is a requirement for accurate nutritional analysis of dietary data. Information provided in this paper can be used to assist with the development of new systems or with evaluation of existing systems. Development of a dietary analysis system for research usually beings with a food composition data set from USDA. Major sources of data to insert for missing values include USDA (provisional data released from the USDA Nutrient Data Bank prior to final data processing), food companies, and the scientific literature. Calculations can be used for estimating nutrient content of some foods. Other components of a dietary analysis system include the method for computerizing the dietary data and the software for making conversions and producing reports. Several resources exist to help researchers develop reliable systems.

Computerized nutrient data bases: II. Development of model for appraisal of nutrient data base system capabilities.

A review model has been developed that present a methodology for assessing the computational accuracy of a computerized dietary analysis system and provides a strategy for examining the status of nutrient data utilized in the computations. The model, which consists of a questionnaire, five computing tasks, and an interpretation guide, was tested by seven nutrient data base systems and was found to be a capable tool for assessing their capabilities and accuracy. The review model is intended to be a prototype that can be modified for special needs. Developers of nutrient data base systems are encouraged to utilize this systematic methodology to review their data bases and the performance of their computer programs.

Folacin in selected foods.

Representative values for folacin in 299 foods have been developed, based on an extensive literature review. A provisional table of these folacin values has been prepared for foods in 100-gm. portions and for specified weights, representing common household units. The data reflect newer methodology than that used for a prior USDA publication, namely, protection of folacin by ascorbic acid. L. casei is the preferred assay organism. The table includes values for both free and total folacin; however, the authors recommend that, in calculating routine hospital diets, total rather than free folacin be used; this would allow easy and direct comparison with the Recommended Dietary Allowances.