Inaccuracy of Self-reported Low Sodium Diet among Chinese: Findings from Baseline Survey for Shandong & Ministry of Health Action on Salt and Hypertension (SMASH) Project

This study was aimed to evaluate the agreement between the self-reported sodium intake level and 24-h urine sodium excretion level in Chinese. The 24-h urine collection was conducted among 2112 adults aged 18-69 years randomly selected in Shandong Province, China. The subjects were asked whether their sodium intake was low, moderate, or high. The weighted kappa statistics was calculated to assess the agreement between 24-h urine sodium excretion level and self-reported sodium intake level. One third of the subjects reported low sodium intake level. About 70% of the subjects had mean 24-h sodium excretion >9 g/d, but reported low or moderate sodium intake. The agreement between self-reported sodium intake level and 24-h urine sodium excretion level was low in both normotensive subjects and hypertensive subjects. These findings suggested that many subjects who reported low sodium intake had actual urine sodium excretion >9 g/d. Sodium intake is often underestimated in both hypertensive and normotensive participants in China.