The term "multiple-pass method" refers to a sophisticated dietary assessment technique, not a procedure for withdrawing contaminated food from the market. This five-step process is used by trained interviewers or automated computer programs to help respondents remember and accurately report their dietary intake over a recent period, typically the previous 24 hours. It is a cornerstone of nutrition research and public health surveillance, used in large-scale studies such as the USDA's 'What We Eat in America' survey.
The Five-Step Multiple-Pass Process
The multiple-pass method is more effective than a simple, open-ended 24-hour recall because it is specifically designed to leverage human memory and overcome common recall biases. It divides the interview into distinct "passes," each building upon the last to trigger memories and collect detailed information. The steps of the USDA AMPM are as follows:
- The Quick List: The interview begins with an unstructured, uninterrupted query where the respondent lists all foods and beverages they can recall consuming in the last 24 hours. The interviewer prompts from morning to night, but the respondent can add items as they remember them.
- The Forgotten Foods Probe: The interviewer then uses specific memory cues and probes to ask about foods and beverages that are often forgotten. These can include condiments, snacks between meals, ingredients in mixed dishes, or drinks.
- Time and Occasion: In this pass, the interviewer reviews the quick list with the respondent, assigning a specific time and meal occasion (e.g., breakfast, afternoon snack, dinner) to each food item reported. This chronological review helps place foods in context.
- The Detail Cycle: This is the most extensive pass, where the interviewer systematically goes through each item on the list. For each food or beverage, detailed information is collected, including the preparation method, brand names, recipes, and most importantly, the portion size. Visual aids, such as food models or photographs, are often used to help with portion size estimation.
- The Final Probe: The final step is a last-chance review question that gives the respondent one more opportunity to recall any remaining items that might have been overlooked during the previous passes.
Why the Method Works: Cognitive Psychology in Action
The success of the multiple-pass method lies in its grounding in cognitive psychology. Instead of relying on a single, potentially flawed memory retrieval, it uses multiple cognitive pathways to ensure completeness. The quick list captures a general, top-of-mind recollection. The time and occasion pass reinforces chronological memory. The detail cycle forces a deeper dive into the specifics of each eating occasion. Finally, the various probes and cues act as external memory aids, targeting items and moments that are easily overlooked. This layered approach is far more robust than a single pass.
Applications in Health and Research
Beyond national surveys, this method is used in various health and research settings. For instance, it's used in clinical dietetics to get a precise one-day snapshot of a patient's diet for personalized counseling. Researchers also use it as a benchmark to validate other, less intensive dietary assessment methods like food frequency questionnaires. By comparing the results of a quick-and-easy FFQ against the more accurate multiple-pass recall, researchers can understand the potential for bias in their studies.
Comparison of Dietary Recall Methods
| Feature | Single 24-Hour Recall | Multiple-Pass 24-Hour Recall | Food Frequency Questionnaire (FFQ) |
|---|---|---|---|
| Accuracy | Prone to recall bias and underreporting. | Higher accuracy; uses memory cues to minimize errors. | Measures long-term, habitual intake; less precise for a single day. |
| Respondent Burden | Low and relatively fast. | Moderate; longer than a single pass but well-accepted. | Higher overall but spread out over time. |
| Data Detail | Lacks descriptive details and accurate portion sizes. | Highly detailed, including cooking methods, brands, and condiments. | Provides estimates of frequency, not specific details. |
| Cost | Low cost, especially when self-administered. | Can be more costly if using trained interviewers or advanced automated systems. | Typically low cost for administration and analysis. |
| Best For | Quick dietary snapshots or patient motivation. | Validating other methods, national health surveillance. | Estimating usual intake for a large population over a long period. |
Conclusion: The Gold Standard for Dietary Reporting
For many researchers and clinicians, the multiple-pass method represents the gold standard for collecting detailed and accurate dietary intake data over a short period. Its systematic, layered approach effectively addresses the inherent challenges of memory bias, yielding more reliable information than a simple, single-pass interview. While it requires more time and resources than less-intensive methods like food frequency questionnaires, its superior ability to capture comprehensive and specific details about what was consumed makes it invaluable for specific research purposes and validation studies. The development of automated systems like AMPM has further enhanced its consistency and ease of use, solidifying its place as a key tool in nutritional science and public health monitoring. For additional information on dietary assessment methodologies, visit the National Cancer Institute's Dietary Assessment Primer: dietassessmentprimer.cancer.gov/profiles/recall/.
