China is currently facing an escalating burden of hypertension, necessitating the implementation of lifestyle modifications and antihypertensive medications as the fundamental components of an effective hypertension management approach [18, 19]. Among the various lifestyle interventions aimed at alleviating the burden of noncommunicable diseases within society, the reduction of salt intake in the diet holds significant importance[3]. To achieve favorable outcomes, diverse state and community salt reduction strategies have been devised, such as the implementation of The National Essential Public Health Services Package, which was introduced by the Chinese government in 2009[20]. This package offers a range of services, including health records management, screening, and follow-up, thereby contributing to the overall objective of salt reduction. The predominant source of sodium intake in China is salt used in domestic food preparation, whereas in western countries, processed foods are the main contributor to dietary salt [21]. Consequently, there is a need for a public campaign aimed at reducing salt usage in cooking. Additionally, it is crucial to develop a suitable assessment methodology for measuring sodium intake and to provide a reference for the formulation of precise policies for the prevention of hypertension. This approach is essential for effectively controlling blood pressure in individuals with hypertension.
Multiple studies have demonstrated that the spot urine method is a suitable approach for estimating 24-hour urinary sodium excretion, enabling the investigation of the correlation between salt intake and hypertension and other diseases within the general population. Groenland E.H. et al [22] employed Kawasaki formulae to assess the relationship between estimated salt intake and blood pressure (BP). The findings revealed that, for each 1 g/day augmentation in sodium urinary excretion, the average systolic blood pressure (SBP) and diastolic blood pressure (DBP) increased by 1.28 mmHg (95% CI: 0.95–1.62) and 0.46 mmHg (95% CI: 0.28–0.65), respectively. In a study conducted by Goto A et al [23], the risk of developing stomach cancer was assessed by comparing it to the estimated salt consumption obtained from spot urine using the Tanaka technique. Similarly, X F Du et al[24] employed three spot urine methods to estimate 24-hour urine sodium excretion among residents in Zhejiang Province and compared it to actual values (167.10 (74.70) mmol/day). The Kawasaki method yielded an overestimation of 184.61 (57.10) mmol/day, whereas the INTERSALT and Tanaka methods resulted in underestimations of 134.62 (39.21) and 143.20 (35.66) mmol/day, respectively.
According to our research, the sodium excretion values estimated using the Kawasaki, INTERSALT, and Tanaka formula for a 24-hour period were 208.70 (65.65), 154.78 (33.91), and 162.61 (40.87) mmol/day, respectively. These values exceed the average sodium intake of Zhejiang Province residents [24]. Despite slight variations between the estimated sodium salt intake and the precise individual value, our study indicates that individuals with uncontrolled hypertension are part of the population with elevated sodium consumption. Significantly, the estimations of salt consumption were notably elevated among individuals classified as obese, in comparison to those who were categorized as normal-weight or overweight. Likewise, upon stratifying the responses based on hypertension status, it was observed that participants diagnosed with Grade 2 hypertension exhibited the highest sodium intake. Previous studies have also documented the augmented sodium consumption observed in individuals with a higher body mass index, as well as inadequate blood pressure regulation among hypertensive outpatients [17, 25].The potential mechanistic pathways through which insulin resistance and overweight may contribute to the development of isolated systolic hypertension involve an increase in salt sensitivity, leading to endothelial dysfunction, arterial rigidity, and elevated blood pressure [26]. Furthermore, these pathways may be influenced by suboptimal dietary habits, including a preference for high-fat foods and the use of sodium as a flavor enhancer. Prior studies have shown that the addition of salty condiments to meals can enhance their taste, but this practice may carry the risk of excessive caloric intake and subsequent weight gain[27].
In order to mitigate salt intake across the entire population of China, the implementation of a multi-faceted initiative, including the adoption of SAS, has been widely employed [28]. In the present study, the prevalence of SAS utilization was determined to be 30.21%, surpassing the 12.0% reported in a previous survey conducted in 2017 among 7512 individuals residing in China's Zhejiang Province (of whom 35.3% were identified as hypertensive)[14]. Furthermore, the findings indicate that the use of SAS and hypertension status were positively associated with reduced sodium intake, rather than a lower sodium-to-potassium ratio. This disparity could potentially be ascribed to the fact that the participants consisted of individuals with poorly controlled hypertension, who were more inclined to receive salt-restriction spoons from the China CDC. This initiative was implemented by the national, provincial, municipal, and county levels of the CDC, advocating the utilization of a ration salt spoon during cooking as a precautionary measure [7, 29]. Additionally, the presence of hypertension is a significant determinant in the alteration of blood pressure induced by sodium restriction. A comprehensive analysis of multiple studies revealed that hypertensive individuals experienced a substantially greater increase in systolic blood pressure compared to a mixed group of hypertensive and normotensive participants within the same study on dietary salt reduction [28]. These findings strongly indicate that, when implementing dietary sodium restriction interventions, priority should be given to hypertensive adults.
Additional findings of the study indicate a higher prevalence of correct knowledge, attitude, and behavior among SAS users, suggesting that possessing positive and accurate beliefs and attitudes serves as a fundamental basis for modifying health-related behaviors. Notably, a considerable proportion (79.18%) of the participants demonstrated awareness regarding the detrimental consequences of excessive salt consumption. However, this knowledge did not seem to translate into effective practices for reducing salt intake, as evidenced by the frequent consumption of salty condiments by a significant portion (67.90%) of the respondents (more than 3–5 days per week). Merely relying on educational initiatives and increasing awareness is unlikely to be adequate in addressing this matter. It is preferable to actively translate this awareness into tangible actions, such as reducing the amount of salt used during cooking through the utilization of SAS or opting for salt alternatives.
The study revealed a significantly high percentage of patients (73.33%) with uncontrolled blood pressure, similar to the findings of a survey conducted on 2198 patients in sub-Saharan countries (77.4%)[19]. Additionally, it was observed that individuals using multiple antihypertensive drugs had a significantly higher prevalence of uncontrolled hypertension (p < 0.001). Previous studies have indicated that the occurrence of medication errors, drug interactions, and the utilization of high-risk pharmaceuticals tend to increase with the number of medications being administered[30]. The combination of improper drug utilization and excessive salt intake has the potential to hinder hypertensive individuals in effectively managing their blood pressure, presenting a significant opportunity for intervention in China. Our research findings demonstrate that the implementation of salt-restriction spoons during the cooking process is linked to a decrease in the progression of hypertension, thereby endorsing the SAS-based approach for individuals whose primary source of sodium consumption is domestic culinary practices.
There are limitations to the study. First, it should be noted that this study is of a cross-sectional nature, which inherently limits the ability to establish causality. Second, the considerable variability in daily salt consumption among individuals introduces the potential for measurement error when converting spot urine sodium measurements to estimated 24-hour urinary excretion. To enhance the accuracy of estimating sodium excretion, it is recommended to collect spot or 24-hour urine samples repeatedly. However, it is important to acknowledge that in this particular population, the estimated 24-hour urinary excretion may not adequately reflect actual salt intake due to the significant participant burden associated with complete collection. Third, the findings from a survey utilizing questionnaires to assess smoking habits and physical activity failed to demonstrate any statistically significant correlation with blood pressure status. It was observed that knowledge, attitude, and behavior were somewhat linked to the utilization of salt-restriction spoons, although this association may be influenced by societal expectations.
This study possesses several notable strengths, primarily its extensive sample size consisting of community-based patients stratified based on their hypertension status. Previous research has demonstrated the efficacy of salt reduction in cooking for lowering blood pressure (BP), yet only a limited number of studies have taken into consideration the participants' hypertension status or their use of antihypertensive medication when summarizing the outcomes. Furthermore, our study was bolstered by the support of an organized multidisciplinary collaborative network, which facilitated the involvement of Chinese cardiologists and ultimately benefited patients with inadequately controlled hypertension.