Abstract 19598: Estimation of Population Sodium Intake in Different Countries: Comparison of 24-h Dietary Recall With 24-h Urine Collection

Abstract

Introduction: Twenty-four-hour (24-h) urine excretion is the “gold standard” for estimation of sodium intake. Sodium intake assessed by 24-h dietary recall has been reported to correlate with urinary sodium excretion, and is considered reliable for assessing population sodium intake. However, the validity of 24-h dietary recall across countries has rarely been studied. The present study aims to compare the 24-h dietary recall with 24-h urine collection for the estimation of population sodium intake in different countries. Methods: Data from the International study of Macro- and Micro-nutrients and Blood Pressure (INTERMAP) were used in the analyses, including 4680 men and women ages 40-59 years from 17 population samples in China, Japan, UK and USA. Four 24-h dietary recalls and two timed 24-h urine samples were collected for each participant; the averages of the dietary and urinary sodium measurements were used. The correlation and difference between the two methods were then explored and compared across countries. Results: After adjustment for population sample and gender, a significant correlation was found in all four countries between dietary and urinary sodium measurements (r=0.33, 0.45, 0.36 and 0.46 for China, Japan, UK and USA respectively, P<0.01 for all). The mean difference of sodium measurements between dietary recalls and urine collection was small for Japan (3.9 mmol), UK (2.9 mmol), and USA (-3.5 mmol), whereas it was large for China (-54.0 mmol). Further, population average sodium intake was over- or under-reported by about 2% for Japan, UK and USA participants with use of urinary sodium excretion as the reference, while the sodium intake was under-reported by 24% for Chinese. Conclusions: The correlation of sodium intake estimated by the two methods is similar (0.33-0.46) for the four countries, and the 24-h dietary recall data demonstrate great accuracy in assessing sodium intake at the population level for Japan, UK and USA. For Chinese populations, however, the 24-h urine collection is preferable to the 24-h dietary recall since dietary recalls yielded considerable underestimation of sodium intake.