Abstract

The aim of this study was to develop various types of a dish frequency questionnaire (DFQ) for estimating the habitual sodium intake and to evaluate the validity of a 125 item dish frequency questionnaire (DFQ 125) with the DFQ 70, DFQ 36 and DFQ 15. For the DFQ 125, one hundred and twenty five dish items were selected based on the information of sodium content of a one serving size, consumption frequency and dish items that contributed most to the variation of sodium intake. Frequency of consumption was determined through nine categories ranging from more than 3 times a day to almost never to indicate how often the specified amount of each food item was consumed during the past 6 months. The sodium intake estimated with DFQ 125 was 5775.0 +/- 3636.3mg, 12.6% higher than that estimated with a 24 hr urine analysis (5009.7 +/- 1541.9mg) and significant correlation was observed between them (r = 0.3315, p < 0.001). When sodium content in broth leftover was subtracted from the total intake, the actual sodium intakes was decreased to 5309.6 +/- 3076.6mg, which was 3.2% higher than that with a 24-hr urine analysis. Overall, 56% of subjects in the lowest quintile of sodium intake computed with DFQ 125 were also in the lowest of adjacent quintile while categorization into the opposite quintile were 4.9%. DFQ 70 was developed from DFQ 125 by omitting the food items not frequently consumed, selecting the dish items that showed higher sodium content per one portion size and higher consumption frequency. The sodium intake estimated with DFQ 70 (5026.6 +/- 3107.1mg) showed only 0.2% difference from that estimated with a 24-hr urine analysis, significant correlation with it (r = 0.3199, p < 0.001) and higher proportion of subjects to be classified into the same or adjacent quintile. The sodium intake estimated with DFQ 36 or DFQ 15 was also significancy correlated with that estimated with a 24-hr urine analysis (r = 0.3441, p < 0.001; r = 0.321, p < 0.001 respectively) and more. The proportion of subjects was classified into the same or adjacent quintile. However, the actual sodium intake estimated with DFQ 36 or DFQ 15 were 3534.0 +/- 1804.6mg and 2508.0 +/- 1261.5mg, respectively, 31.3% or 51.3% less than that estimated with a 24-hr urine analysis. It seems the DFQ 125 with subtraction of sodium content in broth leftover or DFQ 70 can be used quantitatively to estimate sodium intake of adults. DFQ 36 or DFQ 15 can be used as a screening tool or to assess the changes of sodium intake after nutrition education.

• Keywords: validity; dish frequency questionnaire; 24-hr urine analysis; DFQ 125; DFQ 70; DFQ 36; DFQ 15