| Objective:To validate and evaluate the accuracy and feasibility of estimating sodium intake by four approaches of dietary survey,Kawasaki,INTERSALT and Tanaka methods;to understand sodium intake level among University students in Hebei Medical University and analyze the sources of dietary sodium,and to provide basis for establishing measures to curb high intake of salt.Methods:Healthy volunteers from Hebei Medical University(equal number of males and females)were enrolled in this study.Dietary sodium contents were calculated according to the "Chinese food composition table" and nutrition labeling.Concurrently,24-hour urine samples as well as timed urine samples were randomly collected.Potassium,sodium and creatinine levels in the urine samples were detected.Sodium contents in the randomly collected urine samples were estimated by Kawasaki,INTERSALT,and Tanaka methods.The consistencies between estimated sodium intake and real measured values of24-hour urine sodium excretion were compared by Bland-Altman plots in each of the methods.Taking the variability of sodium excretion in different seasons into account,this study was conducted separately in summer(end of June 2017)and fall(end of November 2017)to study the accuracy and feasibility of estimating sodium intake in urine.Results:1.Results of sodium intake by gold standard274 subjects were included in this study.The 24 h urinary sodium analysis result indicated an average daily sodium intake of 3043.0 ± 1223.3mg(synthetic salt 7.8±3.1g)in the summer,and daily sodium intake of3563.7±1370.0mg(synthetic salt 9.1±3.5g)in the fall.Compared with autumn,the average daily reduction in sodium was about 520.7 mg(synthetic salt 1.3 g).2.Consistency and correlation analysis between methods and gold standardsFrom the population level,the estimated deviation of the INTERSALT method for urine samples taken in the morning was the smallest in summer.The average deviation(estimated value-measured value)was-39.7 mg/day.The average total deviation of the dietary survey method was the smallest,with an average deviation of 42.7 mg/day.The deviation of Tanaka method for estimation of morning urine samples was the smallest in autumn.The average deviation(estimated value-measured value)was-149.8 mg/day.The Kawasaki method had the smallest average deviation of 163.7 mg/day.At the individual level,the correlation between 24-hour urinary sodium excretion and sodium intake measured through dietary survey methods was low,with a correlation coefficient of only 0.123.Correlation coefficients between Kawasaki,INTERSALT,Tanaka methods and 24-hour urinary sodium excretion,respectively was in the range of 0.52-0.64.The correlation coefficient of Kawasaki method was the highest in summer(0.612)while that of Tanaka method was highest in the autumn(0.635).Conclusions:1.Due to temperature variations,dietary sodium intake estimation from randomly collected urine samples and that of 24-hour urine collection method in summer show great deviation.Dietary sodium estimation using urine collection method is inappropriate in summer.2.Estimation of sodium intakes among college students using Dietary survey method as well as the three methods-Kawasaki,INTERSALT and Tanaka have varying degrees of bias and volatility.However,this study only involved analysis of part of the population and needs further research for verification.At the same time,it is necessary to develop a suitable method formeasuring sodium status in order to assess the salt intake amount in Chinese population.3.Salt intake control awareness and nutrition education should be strengthened among undergraduates. |
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