Measuring Diet Chapter 3

Chapter 3: Measuring Diet

• This chapter outlines various methods for measuring dietary intake, including reasons, techniques, considerations for specific groups, issues and estimating portion sizes.

Reasons for Measuring Diet

• Assessing and monitoring food and nutrient intake: This includes evaluating diet adequacy, identifying malnutrition, and monitoring trends.
  • Adequacy of diet intake, malnutrition are both considered.
  • Trends in food/nutrient intake, food additives & contaminants are also assessed.
• Formulating and evaluating government health and agricultural policy: This encompasses planning food production, creating food guidelines, and implementing legislation.
  • Planning food production is a key aspect of this.
  • Establishing specific food guides, and legislation is important.
  • Regulations including labeling guidelines and fortification are examples of this.
• Conducting epidemiologic research: Understanding diet-disease relationships is essential for this area.
  • This includes exploring diet-disease relationships.
  • Identifying populations with diet-disease risks is a related area.
• Commercial purposes: Food manufacturers utilize this research for various business operations.
  • Examples of these are food manufacturers looking at this area.

Techniques in Measuring Diet

• The "BIG THREE": These are common methods.
  • 24-hour recall
    • Trained interviewer asks about intake.
    • Helps with portion size estimates.
    • Prompts to assist recall.
    • Checks for omissions/errors.
    • Techniques for 24-hour recall include what was consumed starting immediately upon waking up today or midnight to midnight the prior day.
    • Strengths include: Inexpensive, Quick (< 20 minutes), Detailed information, short-term memory, low burden, doesn't alter diet but can have limitations such as underreporting of certain foods, and overreporting of certain foods.
• Food record (or food diary): Involves recording what's consumed.
• Food frequency questionnaires: This assesses frequency of consumption.
• Less common techniques:
  • Diet history
  • Duplicate food collections
  • Food accounts
  • Food balance sheets
  • Telephone interviews
  • Technological innovations

Considerations for Certain Groups

• Daily intake, usual or average intake

• Meal-based versus list-based

• 24-Hour Recall, 3: Limitations may include withholding information, under/over reporting certain things, missing/phantom foods and intra-individual variability.

• 24-Hour Recall, 4: Multiple-Pass Method: Reviewing intake multiple times and Computer-assisted 5-step method used in NHANES (AMPM).

• Multiple days for recalls are often necessary, and rare food groups may not be captured using this method. Several factors affect the need for multiple recalls including various seasons, the individual characteristics, and nutritional requirements.

Issues in Dietary Measurement

-  Accuracy and reliability of dietary measures
- Various biases that can impact data collection
- Overall quality of collected data.

Estimating Portion Size

• Importance of accurate portion calculations for nutritional assessments.
• Methods for determining appropriate serving sizes.