Evalue Dieta: Capitulo 3

Chapter 3: Measuring Diet

• This chapter outlines various aspects of measuring dietary intake.
• The chapter's structure includes sections on reasons, techniques, considerations for specific groups, issues in dietary measurement, and estimating portion sizes.

Topic 1: Reasons for Measuring Diet

• Assessing and monitoring food and nutrient intake: Evaluating adequacy of intake, identifying malnutrition, tracking trends in food and nutrient consumption, and monitoring contaminants in food are vital aspects of this topic.
• Formulating and evaluating government health and agricultural policy: Dietary data is used in developing policies for food production, assistance programs, guidelines, and regulations (e.g., food labeling, fortification).
• Conducting epidemiological research: Investigating diet-related diseases and health outcomes and identifying populations at risk involves this process.
• Commercial purposes: Food manufacturers use dietary data to develop new products and understand consumer preferences.

Topic 2: Techniques in Measuring Diet

• "The Big Three": 24-hour recall, food records (diaries), and food frequency questionnaires are common methods.
• Less common techniques: Diet history, duplicate food collections, food accounts, food balance sheets, telephone interviews, and technological innovations.

24-Hour Recall

• Strengths: Inexpensive, quick, provides detailed information, captures short-term memory, manageable burden for respondents (less stress), and does not directly alter diet.

• Limitations: Potential for underreporting or overreporting of certain food types or details. "Flat-slope syndrome" can exist. Intra-individual variability may influence results. Can be used for single day or multiple sessions.

• Multiple-Pass Method: Multiple reviews of intake throughout the day; used to reduce underreporting and enhance recall accuracy.

• Computer-assisted multiple-pass method: A method used in NHANES (National Health and Nutrition Examination Survey). Involves multiple steps to reduce underreporting of foods. Training for interviewers are essential for success.

• USDA's Automated Multiple-pass Method: Uses standardized questions, categorizes food, and collects accurate intake information using structured approach and specific methods.

• Food Record (Diet Record, Food Diary): The study participants document their daily dietary intake over a specific timeframe (e.g., one to seven days).

Considerations and Limitations of Food Measurement Methods

• Dietary assessment instruments: Each instrument has strengths and limitations concerning recall bias, accuracy, quantitative detail, participant burden, and cost.
• Food frequency questionnaires: A self-reporting approach capturing the frequency of food intake over a period.

24-Hour Recall, Additional Information and Detail

• Technique 1: Intake from the moment the study participant woke up until the current moment.
• Technique 2: Intake from midnight to midnight the previous day.
• Interviewer support: Provides portion size estimates, prompts for memory aid, checks for omissions or errors in assessment.
• Additional limitations for all methods : High level of intra-individual variability. Variability within individual. The number of days to track intake (i.e. one or seven). Individual characteristics within a population (e.g. age, health status or any condition). Nutrients of interest; sample size. Degree of within/between variability.