Validity and reliability of beverage intake questionnaire: evaluating hydration status.

OBJECTIVE The purpose of this investigation is to test the validity and reliability the assessment methods for the true beverage consumption of adults. METHODS This cross-sectional study was carried out 291 healthy volunteers. The beverage intake questionnaire (BIQ) was prepared in combination with a new one which is developed based on basic principles and the existing one developed for the beverages consumed the most with respect to frequency and amount by Turkish populations. During the initial visit the participants completed BIQ1 and then provided a urine sample to determine urinary specific gravity(USG). For validity, participants recorded the type and quantity of foods and beverages consumed on the same day and previous two days. Two weeks later, for reliability, participants completed the same beverage intake questionnaire (BIQ2). RESULTS Mean daily total fluid intake was estimated at 1,773 ± 49.4mL using the dietary intake record (DIR), 2,120 ± 49.5 mL with BIQ1 and 1,990 ± 46.3 mL for BIQ2. The largest contribution to total fluid intake was plain water. The response on the two assessment tools (DIR and BIQ1) all beverage intakes were significantly correlated (p < 0.01) except for alcoholic beverage intake. One could see a significant correlation between BIQ1 and BIQ2 in relation to total fluid intakes (r = 0.838,p < 0.01). The USG measurement was negatively correlated with three assessment tools (DIR, BIQ1 and BIQ2), the amount of plain water and the amount of total fluid intake. CONCLUSIONS The self-administered instrument described in this study may be useful for researchers interested in assessing habitual beverage consumption patterns or evaluating hydration status for adults.