Excessive salt intake is a well-documented risk factor for numerous non-communicable diseases (NCDs), especially hypertension, cardiovascular diseases, and stroke [1, 2]. Globally, public health efforts are increasingly emphasizing reducing sodium consumption as part of broader strategies to lower the prevalence of NCDs [3, 4]. Elevated salt intake is directly linked to higher blood pressure, and in many countries, including Vietnam, average salt consumption far exceeds the recommended limits set by the World Health Organization (WHO), which advocates for less than 5 g of salt per day [5]. Numerous studies have demonstrated that reducing salt intake is a highly cost-effective, and in some cases, cost-saving strategy for lowering blood pressure and reducing the risk of cardiovascular diseases (CVDs) [3, 6, 7]. As a result, salt reduction has been identified as a priority intervention for preventing NCDs [8].

Vietnamese diets are often high in sodium due to salt, fish sauce, soy sauce, and other sodium-based condiments deeply rooted in cultural practices and traditional food preservation methods [9]. Recognizing the adverse health impacts of excessive salt consumption, Vietnam has implemented national policies to reduce sodium intake [10]. However, despite these efforts, there remains limited information on how salt consumption has changed over time among the general population, especially among individuals with NCDs such as hypertension, diabetes, and overweight. This lack of data is concerning, as understanding salt consumption trends in the general population and high-risk groups is crucial for monitoring the effectiveness of public health interventions designed to reduce sodium intake. With accurate and up-to-date information, assessing the success of these initiatives becomes easier. More importantly, excessive sodium intake can exacerbate conditions such as hypertension and insulin resistance, which are critical factors in the development and progression of diabetes [11, 12]. For individuals with diabetes, high salt intake is particularly problematic, as it can lead to elevated blood pressure, further complicating their health management [11]. Similarly, individuals with high body mass index (BMI) are often at increased risk for both hypertension and diabetes, creating a complex interplay between these conditions and dietary sodium intake [13]. By investigating salt consumption patterns in relation to these metabolic factors, targeted interventions can be developed to address the unique needs of these populations.

This study aims to fill the knowledge gap by examining changes in salt intake between 2015 and 2021, utilizing data from two national representative surveys conducted in Vietnam. The country has conducted three rounds of STEPwise approach to NCD risk factor surveillance (STEP surveys) in 2010, 2015, and 2021. These surveys offer nationally representative data on the Vietnamese population, making them efficient for investigating changes in many NCD risk behaviors over time. However, only the STEPs surveys from 2015 to 2021 included participants aged 18–69 and conducted spot urine tests to measure urinary sodium levels, a direct indicator of salt intake. This study used these two surveys to address three objectives: first, to assess changes in salt intake measuring by urinary sodium levels in the general population; second, to analyze this change among individuals with high-risk metabolic factors for NCDs, including hypertension, diabetes, and elevated body mass index (BMI); and finally assess the practices to reduce salt consumption among Vietnamese populations aged 18–69 in the year 2021. Understanding the salt consumption patterns of individuals with these risk factors is crucial for developing effective prevention and management strategies that can improve health outcomes.

This study aimed to assess changes in salt intake among the Vietnamese population and to evaluate the effectiveness of salt reduction efforts. In 2021, the average 24-hour salt intake for Vietnamese individuals aged 18–69 was 8.07 g/day. While this is lower than the 2019 average for other Southeast Asian countries (9.8 g/day), it remains higher than other global regions such as the African Region or Eastern Mediterranean [18]. The findings also show a significant reduction in average salt intake in Vietnam, decreasing from 9.42 g/day in 2015 to 8.07 g/day in 2021. This suggests that public health efforts to reduce salt intake are making progress. The reduction in salt consumption was observed across different age groups, with the most notable decrease seen in individuals under 25 years old. These results are promising, given the well-established link between high salt intake and non-communicable diseases (NCDs), especially hypertension and cardiovascular diseases [1, 6, 11].

While salt consumption in Vietnam has decreased, further action is needed to meet health guidelines. In 2015, 99.89% of the population exceeded the WHO-recommended limit of 5 g of salt per day, dropping only slightly to 97.79% in 2021. Although the proportion consuming more than the global average of 10.78 g/day fell significantly from 24.88% to 8.31%, nearly the entire population still consumes excessive salt. The traditional Vietnamese diet includes salt as a staple, highlighting the need for stricter regulations on salt intake. While some countries have enforced mandatory limits on salt levels in food, Vietnam has predominantly relied on voluntary approaches [21]. However, previous studies suggest that voluntary programs are less effective in reducing salt consumption [4, 22]. Strengthening regulations could amplify the effectiveness of public health initiatives to reduce salt intake.

High-risk groups, such as individuals with hypertension, diabetes, and elevated BMI, consistently exhibit higher salt intake compared to others, even with noticeable reductions over time. In 2015, hypertensive individuals had a higher prevalence of excessive salt consumption (29.75%) compared to non-hypertensive individuals (23.74%), and while this gap narrowed by 2021, hypertensive individuals still consumed more salt (12.14% vs. 6.93%). Similarly, despite significant reductions, individuals with higher BMI (≥23 or ≥25) showed persistently higher salt intake than those with normal BMI. This trend emphasizes the vulnerability of overweight or obese populations to excessive salt intake, a key risk factor for cardiovascular diseases and other non-communicable diseases (NCDs). These findings highlight the need for more targeted interventions for high-risk groups, such as hypertensive and overweight individuals [6–8, 12]. Customized public health campaigns, stricter sodium content regulations in processed foods, and enhanced dietary education focused on these high-risk populations are crucial to further reducing salt intake and addressing the associated health risks [23].

The study also looked at salt reduction practices and found that the most common behaviors included limiting processed foods, avoiding eating out, and using less salt during cooking. These practices show a positive change in dietary habits among the population. However, less commonly adopted behaviors, such as checking food labels and buying low-sodium alternatives, indicate a need for more consumer awareness and knowledge about the sodium content in foods. Only 60.9% of the general population had heard, seen, or received advice about reducing salt intake. Surprisingly, this figure was not significantly higher among individuals with hypertension, diabetes, or overweight/obesity, who are at greater risk for complications related to high salt intake. This points to more targeted education and interventions for high-risk groups to encourage better adherence to salt reduction guidelines. Vietnam launched a National Plan for Dietary Salt Intake Reduction in 2018 and conducted a large-scale consumer awareness campaign. However, plans for sustaining and expanding these efforts remain uncertain due to limited resources [21]. Enhancing public knowledge through media and educational programs about the health risks associated with excessive salt intake and the benefits of adopting a low-salt diet may encourage more robust behavioral changes [24, 25].

This study benefits from a large, nationally representative sample (2,893 participants in 2015 and 3,682 in 2021), enhancing the generalizability of findings. The use of spot urine tests provides an objective and reliable measure of salt intake, minimizing biases associated with self-reported dietary data [15–17]. The repeated cross-sectional design (comparing 2015 and 2021) offers valuable insights into trends over time and the potential impact of public health efforts. Additionally, the study focuses on high-risk groups, including individuals with hypertension, diabetes, and overweight/obesity, adding depth to the analysis. The inclusion of salt reduction practices in 2021 further provides useful information on behavioral changes. The novelty of this study lies in its comprehensive analysis of salt intake trends within high-risk groups, providing more detailed insights into how these populations, who are more vulnerable to the health impacts of excessive salt, have responded to public health campaigns. While previous research has broadly examined national salt intake trends, this study stands out by specifically focusing on hypertensive, diabetic, and overweight/obese individuals, offering a deeper understanding of salt consumption patterns within these vulnerable populations. The study also employs the WHO-recommended STEPS framework [26], ensuring that the methodology aligns with international standards for measuring salt intake and enhancing the comparability of results. The inclusion of salt reduction practices further contributes to the novelty of this research, highlighting changes in behavioral practices and identifying gaps in consumer knowledge that could inform future public health strategies.

Despite these strengths, the study has several limitations. The cross-sectional nature of each survey round prevents tracking individual changes over time. Spot urine measurements, while practical and cost-effective, can be influenced by factors such as hydration status and physical activity, affecting individual accuracy [27]. The STEPS survey did not measure potassium alongside sodium, limiting the ability to assess the sodium-to-potassium balance, which is crucial for understanding cardiovascular health risks. A key limitation is the absence of 24-hour sodium excretion measurements for calibration in a representative subsample, which could lead to less precise sodium intake estimates, particularly among high-risk populations. This may impact the reliability of findings and hinder cross-country comparisons. Future studies should incorporate 24-hour urine collection in a representative subsample to improve the accuracy of sodium intake assessments. Although we did not have calibration, the STEPS survey is a standardized technical framework recommended by the World Health Organization (WHO) for monitoring salt intake over time [26]. This ensures methodological consistency and allows for meaningful comparisons within and across countries. Another limitation of this study is the absence of CVD outcome data in the STEPS survey, preventing a direct analysis of the relationship between high salt intake and CVD risks. However, we examined salt intake patterns among high-risk groups, including individuals with hypertension, diabetes, and overweight/obesity, to provide relevant insights. Finally, the cross-sectional design does not allow for causal inferences regarding the relationship between sodium reduction awareness, behavioral practices, and actual sodium intake. While a decline in population sodium intake was observed, it remains unclear whether this reduction resulted from individual efforts or broader policy initiatives. Future longitudinal or intervention studies are needed to better assess the effectiveness of specific sodium reduction strategies.

In conclusion, this study highlights a significant reduction in salt intake among the Vietnamese population from 2015 to 2021. However, the proportion of high-risk groups—those with hypertension, diabetes, and high BMI—who continue to consume excessive salt remains concerning. Ensuring these vulnerable groups are better informed and actively engaged in salt reduction efforts is crucial. Customized interventions focusing on education, community support, and policy reforms will be essential in reducing salt consumption and ultimately improving public health outcomes, especially for those at higher risk.