Methodological issues in estimating sodium intake in the Korea National Health and Nutrition Examination Survey

For policy goal setting, efficacy evaluations, and the development of related programs for reducing sodium intake, it is essential to accurately identify the amount of sodium intake in South Korea and constantly monitor its trends. The present study aimed to identify the status of sodium intake in South Korea and to review the methods and their validity for estimating sodium intake in each country; through this, we aim to determine more accurate methods for determining sodium intake and to monitor the trend in sodium intake for Korean citizens in the future. Using 24-hour dietary recall data from the 2012 Korea National Health and Nutrition Examination Survey (KNHANES) to estimate daily sodium intake, the average daily sodium intake among Koreans was 4,546 mg (men, 5,212 mg; women, 3,868 mg). In addition to the nutrition survey that uses the 24-hour dietary recall method, sodium intake can also be calculated from the amount of sodium excreted in 24-hour urine, 8-hour overnight urine, and spot urine samples. Although KNHANES uses the 24-hour dietary recall method to estimate the sodium intake, the 24-hour dietary recall method has the disadvantage of not being able to accurately determine the amount of sodium intake owing to its unique characteristics of the research method and in the processing of data. Although measuring the amount of sodium excreted in 24-hour urine is known to be the most accurate method, because collecting 24-hour urine from the general population is difficult, using spot urine samples to estimate sodium intake has been suggested to be useful for examining the trend of sodium intake in the general population. Therefore, we planned to conduct a study for estimating of 24-hour sodium excretion from spot urine and 8-hour overnight urine samples and testing the validity among subsamples in the KNHANES. Based on this result, we will adopt the most appropriate urine collection method for estimating population sodium intake in South Korea.