A reduced dietary questionnaire: development and validation.

A reduced questionnaire was developed by successively omitting segments of the full (98-item) Block questionnaire and calculating the correlations between nutrient estimates produced by the full and reduced versions. The reduced version contains 60 food items and requires 17 minutes to administer by an interviewer. It is intended to capture all nutrients in the diet, as is the full version. The reduced version was validated against three four-day records in a group of middle-aged women, and against two seven-day records collected 10-15 years ago in a group of older men. The absolute value of macronutrients estimated by the reduced questionnaire was lower than food-record estimates, but most micronutrients were not underestimated. For macronutrients correlations with food records were slightly lower with the reduced questionnaire, but for micronutrients there was only slight or no reduction in correlations as a result of using the reduced version. The brief version may be useful in studies that cannot allow the 30-35 minutes required for the full-length questionnaire.