A comparison of dietary methods in nutritional studies

Area of Science:

• Nutritional Science
• Dietary Assessment Methods
• Maternal and Infant Nutrition

Background:

• Accurate dietary assessment is crucial for evaluating nutrient adequacy in lactating women.
• Previous studies have highlighted variability in dietary intake measurement methods.

Purpose of the Study:

• To compare the accuracy of a 1-day record (1DR), 3-day record (3DR), and a food frequency form against a 7-day record (7DR) for assessing nutrient intake in lactating women.
• To evaluate the reliability of different dietary assessment tools for energy, protein, calcium, phosphorus, and iron.

Main Methods:

• Dietary intakes of 40 lactating women were assessed using a 7-day food record (7DR).
• Data from 1DR, 3DR, and a novel food frequency questionnaire were compared to 7DR using intraclass correlation coefficients and regression analysis.
• Nutrient intakes were classified as high, medium, or low relative to Recommended Daily Allowances, with agreement measured by Cohen's kappa.

Main Results:

• The 3-day record (3DR) showed good agreement with the 7DR for general diet quality but not for individual nutrient estimates.
• The 1-day record (1DR) and food frequency form demonstrated moderate and poor agreement, respectively, with the 7DR.
• Classification of nutrient intake levels (high, medium, low) showed no agreement between methods and the 7DR.
• Intraindividual variation in dietary intake exceeded interindividual variation.

Conclusions:

• The 7-day food record (7DR) remains the most reliable method for assessing individual nutrient intake in lactating women.
• Shorter dietary records (1DR, 3DR) and food frequency questionnaires are less suitable for precise individual nutrient assessment in this population.
• Dietary assessment in lactating women is subject to significant intraindividual variability, impacting the accuracy of shorter-term measures.