Indicator foods for vitamin A assessment

Area of Science:

• Nutritional Epidemiology
• Dietary Assessment Methodology
• Public Health Nutrition

Background:

• Epidemiological studies on vitamin A and cancer are limited by interview time and non-standardized food lists.
• Difficulty in comparing results across studies due to varying food groups assessed.
• Need for a reliable method to assess total vitamin A intake in population studies.

Purpose of the Study:

• To identify a standardized list of indicator foods for assessing total vitamin A intake.
• To improve the comparability of results in epidemiological studies on vitamin A and cancer.
• To develop a more accurate dietary assessment tool for vitamin A.

Main Methods:

• Analysis of 24-hour dietary recalls from 13,201 adults in the First National Health and Nutrition Examination Survey (NHANES I).
• Ranking food items by their contribution to overall vitamin A intake using an index reflecting consumption frequency, portion size, and vitamin A concentration.
• Comparison of food rankings across various subpopulations (sex/race, season, age, region).

Main Results:

• The top 50 foods were sufficient to classify 80%-90% of individuals into low, moderate, or high vitamin A consumer categories.
• Key vitamin A sources included retinol (dairy, liver) and carotenoids (fruits, vegetables), plus mixed dishes.
• Food contribution varied by sex/race, season, age, and region; income had minimal impact.

Conclusions:

• A standardized list of indicator foods can accurately assess vitamin A intake in diverse populations.
• Future dietary questionnaires should incorporate these identified indicator foods for improved vitamin A assessment.
• This methodology enhances the reliability of epidemiological research linking vitamin A to cancer risk.