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Revista Brasileira de Epidemiologia

Print version ISSN 1415-790XOn-line version ISSN 1980-5497

Rev. bras. epidemiol. vol.22  supl.2 Rio de Janeiro  2019  Epub Oct 07, 2019

http://dx.doi.org/10.1590/1980-549720190009.supl.2 

ORIGINAL ARTICLE

Estimation of salt intake in the Brazilian population: results from the 2013 National Health Survey

José Geraldo MillI 
http://orcid.org/0000-0002-0987-368X

Deborah Carvalho MaltaII 
http://orcid.org/0000-0002-8214-5734

Ísis Eloah MachadoIII 
http://orcid.org/0000-0002-4678-2074

Arthur PateIV 

Cimar Azeredo PereiraV 

Patrícia Constante JaimeVI 
http://orcid.org/0000-0003-2291-8536

Célia Landman SzwarcwaldVII 
http://orcid.org/0000-0002-7798-2095

Luiz Gastão RosenfeldVIII  *

IDepartment of Physiological Sciences, Health Science Center, Universidade Federal do Espírito Santo - Vitória (ES), Brazil.

IIDepartment of Maternal-Child Nursing and Public Health, Nursing School, Universidade Federal de Minas Gerais - Belo Horizonte (MG), Brazil.

IIINursing Graduate Program, Universidade Federal de Minas Gerais - Belo Horizonte (MG), Brazil.

IVInstitute of Scientific and Technological Communication and Information in Health, Fundação Oswaldo Cruz - Rio de Janeiro (RJ), Brazil.

VDirectorate of Surveys, Brazilian Institute of Geography and Statistics - Rio de Janeiro (RJ), Brazil.

VIEpidemiological Research Center in Nutrition and Health, Department of Nutrition, School of Public Health, Universidade de São Paulo - São Paulo (SP), Brazil.

VIIInstitute of Scientifc and Technological Communication and Information in Health, Fundação Oswaldo Cruz - Rio de Janeiro (RJ), Brazil.

VIIIHematology Center of São Paulo - São Paulo (SP), Brazil.


ABSTRACT:

Objective:

To estimate the salt intake in the Brazilian population according to their urinary sodium excretion.

Methods:

The National Health Survey (2013) aimed to gather data on the health of adults (≥ 18 years) through a random selection of households. In each household, one adult was selected to have their biological data collected (anthropometry, blood pressure, and blood and urine tests). The urine sample was sent to a central laboratory to determine sodium (ion-selective electrode) and creatinine (Jaffé method) concentrations. Sodium excretion was estimated with the Tanaka equation.

Results:

Urinary sodium and creatinine concentrations were measured in 8,083individuals (58% women). The mean salt intake was estimated at 9.34 g/day (95% confidence interval - 95%CI 9.27 - 9.41) and was higher in males (9.63 g/day; 95%CI 9.52 - 9.74) than in females (9.08 g/day; 95%CI 8.99 - 9.17). Wefound no significant differences regarding age group, ethnicity, or schooling. Salt intake was higher in the Southeast and South regions and lower in the Northeast and North. Only 2.4% (95%CI 2.0 - 2.8) of the sample consumed less than 5 g/day, and 58.2% (95%CI 56.7 - 59.6) of participants had an estimated intake of 8 to 12 g/day.

Conclusion:

The mean salt intake in the Brazilian population is approximately twice the recommended by the World Health Organization (5g/day).Given the association of high salt intake with hypertension and decreased renal function, these data indicate the need to adopt comprehensive public policies to reduce the consumption in the Brazilian population.

Keywords: Urine; Sodium; Diet; Arterial pressure; Brazil

RESUMO:

Objetivo:

Estimar o consumo de sal na população brasileira pela excreção urinária de sódio.

Métodos:

A Pesquisa Nacional de Saúde (2013) teve como objetivo obter dados de saúde de adultos (≥ 18 anos) por meio de seleção aleatória de domicílios. Em cada domicílio foi selecionado um adulto para coleta de dados biológicos (antropometria, pressão arterial, sangue e urina). A urina foi enviada para um laboratório central, para medida da concentração de sódio (eletrodo sensível) e creatinina (método de Jaffé). A estimativa da excreção de sódio foi feita com a equação de Tanaka.

Resultados:

A dosagem urinária de sódio e de creatinina foi obtida em 8.083 indivíduos (58% mulheres). O consumo médio de sal foi estimado em 9,34 g/dia (intervalo de confiança de 95% - IC95% 9,27 - 9,41), sendo maior em homens (9,63 g/dia; IC95% 9,52 - 9,74) do que em mulheres (9,08 g/dia; IC95% 8,99 - 9,17). Não foram observadas diferenças importantes em relação à faixa etária, cor da pele nem escolaridade. O maior consumo foi detectado nas regiões Sudeste e Sul e o menor no Nordeste e Norte. Apenas 2,4% (IC95% 2,0 - 2,8) da amostra apresentou consumo inferior a 5 g/dia, e 58,2% (IC95% 56,7 - 59,6) dos participantes tiveram consumo estimado de 8 a 12 g/dia.

Conclusão:

O consumo médio de sal da população brasileira é, aproximadamente, o dobro da recomendação da Organização Mundial da Saúde (5g/dia). Tendo em vista a associação da alta ingestão de sal com hipertensão arterial e decréscimo da função renal, os dados apontam para a necessidade de adoção de políticas públicas abrangentes para redução desse consumo na população brasileira.

Palavras-chave: Urina; Sódio; Dieta; Pressão arterial; Brasil

INTRODUCTION

Chronic non-communicable diseases (NCDs) are responsible for approximately 70% of global mortality and, among them, deaths from cardiovascular diseases (CVDs) are the most common1. Arterial hypertension (AH) is the most important risk factor for cardiovascular morbidity and mortality 2,3,4,5. The prevalence of AH is quite high, affecting 28% of Brazilian adults6, and its onset depends on genetic predisposition and lifestyle-related factors7. Thus,low levels of education and income, sedentary lifestyle, weight gain, and insulin resistance are factors associated with the increase in blood pressure with age and, consequently, higher blood pressure levels in adults 2,8,9. Children have lower blood pressure levels than adults. Body growth is associated with the progressive increase in blood pressure, which should stabilize in adulthood. In some individuals, however, blood pressure continues increasing and eventually they develop hypertension. Data from the Intersalt study suggest that sodium intake is a key factor for the rise in blood pressure during adulthood5,9,10.

Table salt has been used for millennia as a food preservative. Over time, the primitive diet, high in potassium and low in sodium, was progressively replaced by the current one, which presents an inversion of this relationship. Sodium is an important dietary component for the maintenance of blood volume and blood pressure11. However, a diet high in sodium and low in potassium increases blood pressure levels and facilitates the onset of AH. Therefore, low sodium and high potassium intake are recommended to prevent the development of AH in genetically susceptible individuals; however, the current dietary pattern of the population is very far from reaching the suggested daily intake of sodium and potassium (2 and 3 g, respectively)12. Estimates indicate that up to 10% of deaths from CVDs can be attributed to sodium intake exceeding 2 g/day 12,13,14.

The mechanism that allows high sodium intake to increase blood pressure is still little known, but the greater consumption of this nutrient leads to water retention to maintain osmotic balance, with extracellular volume expansion11. In the long term, sodium also accumulates inside the smooth muscle cells of arterioles, causing increased peripheral vascular resistance and persistence of high blood pressure levels11. In addition to AH, excessive salt intake also predisposes to other comorbidities, including chronic kidney disease, ventricular hypertrophy, cerebrovascular accident, and even obesity 15,16,17,18.

The World Health Organization (WHO) recommends daily consumption of up to 2g of sodium, equivalent to 5 g of table salt12. The Global Burden of Diseases Nutrition and Chronic Diseases Expert Group (NutriCoDE) estimated the mean sodium intake in the global population. They collected data from 66 countries and, using a hierarchical Bayesian model, calculated a mean sodium intake of 3.95 g/day, with a variation of 2.18 to 5.51 g/day19. Based on these data, we can estimate that more than 95% of the world’s population consumes excess salt20.

More robust studies on salt intake in Brazil are still scarce, and most estimates were based on questionnaires, which can lead to inaccurate measurements due to the low perceived salt intake by the population21. In Vitória, Espírito Santo, using the 12-hour urine collection, salt intake was estimated at 12.6 g/day, with a standard deviation of 5.6 g/day22.Data from the National Household Budget Survey (HBS, 2008-2009) revealed a mean sodium intake of 4.7 g/day, equivalent to 12 g/day of salt23. Also in Vitória, salt intake was estimated at 11.4 g/day with the 24-hour urine collection24. Thus, regardless of the method, region, and period, all data indicate that salt intake is more than twice the recommended by WHO.

The Strategic Action Plan for Tackling Chronic NCDs in Brazil (2011-2022) defined reducing salt intake as one of its goals25. In 2013, WHO set a target to reduce by 30% the mean salt intake26. The Ministry of Health included questions about salt intake in the 2013 National Health Survey (NHS) and also planned a casual urine collection to estimate the consumption of this nutrient so as to monitor this variable in Brazil27. The objective of this study was to estimate the salt intake in the Brazilian adult population according to their urinary sodium concentration.

METHODS

We used data from the 2013 NHS collected by the Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística - IBGE) in partnership with the Ministry of Health. NHS is a household survey with a representative sample of the Brazilian population that covers all states in the country. It aims at characterizing the health status and lifestyle of the adult population28.

NHS has a complex three-stage sampling process: census tracts, households, and individuals. Census tracts, or set of tracts, comprise the primary sampling units; households are the secondary units; and residents aged 18 years or older represent the tertiary sampling units. In each census tract, 10 to 14 households were selected, and in each household, an adult ≥18years was chosen by drawing 28,29.

The questionnaire administered in the household was divided into three parts to collect different types of information. The first involved questions about the household; the second, about socioeconomic characteristics and use of health services by all residents of the household; the third was a self-report of the health status and lifestyle of the individual randomly selected29. This individual also had his or her weight, height, waist circumference, and blood pressure measured30. A subsample of these individuals also had their blood and urine collected.

A total of 6,069 census tracts and 81,254 households were selected, of which 69,994 were eligible for the study, composing the sample of interviewees. Interviews were conducted in 64,348 households, with 60,202 complete individual interviews. After the household interviews, the information of the participants selected for the subsample was transferred to the laboratory for later collection of biological material. Thegoal was to include 15 thousand individuals from cities with better infrastructure for the collection, using probability proportional to the inverse of the distance between the city where the primary sampling unit was located and the nearest city with at least 80thousand inhabitants. However, only 8,952 individuals had their material collected for analysis (blood and urine) due to operational issues. The main reasons for these losses were: the laboratory agent did not locate the household, the individual refused to have his or her material collected, unawareness of the project, and unavailability to receive the researcher.

Out of the 8,952 urine samples, 8,083 were analyzed, with the losses (10.0%) resulting from incomplete tests or insufficient material. Due to sample losses, we adopted a post-stratification method, which included variables such as gender, age, ethnicity, and region, aiming at reducing non-representativeness bias. Another publication30 described the details about the sampling process, data collection, and weighting.

The selected resident had his or her urine sample collected at home with no time constraints and no prior food restriction. The urine sample could be the first in the morning or any other, as long as the participant went at least 2 hours without urinating. The project provided the materials for collection. The participant was instructed to wash his or her hands, clean the genital area with water and soap, discard the first stream, collect the urine in a wide mouth container, and then pour the urine collected into a narrow capped tube. A5mL aliquot of the sample was transferred to a sterile vial, put in a thermal bag, and stored in a refrigerator until it was sent to the central laboratory, located in São Paulo. Theurinary sodium concentration was determined by the ion-selective electrode method, and creatinine (Cr) levels, by the Jaffé method 31,32.

The 24-h urinary sodium excretion was estimated by the equation of Tanaka et al.33, which was validated for the Brazilian population in a substudy in Vitória34. To use this equation, initially, the Cr excretion predicted for 24 h (CrPr24h) is estimated based on age, weight, and height, as in Equation 1:

CrPr24h = {(14.89 × weight, kg) + [(16.14 × height, cm) x (2.04 × age, years)] - 2,244.5} (1)

After determining the CrPr24h, Equation 2 calculates the urinary sodium excretion in 24 hours (NaUr, mEq):

NaUr (mEq) = [Na casual urine, mEq/L/(Cr casual urine, mg/dL × 10)] × CrPr24h (2)

Lastly, an exponential equation (Equation 3) estimates the sodium excretion in 24 h (mEq):

Na24h (mEq) = 21.98 x NaUr0.398 (3)

Salt intake was calculated considering all sodium excreted in the urine, ingested as NaCl (Equation 4):

Estimated salt intake (g/day) = Na24 h (mEq) × 58.5 (4)

The estimated salt intake was described according to gender (male and female), age group (18 to 29; 30 to 44; 45 to 59; and 60 or older), schooling (illiterate up to incomplete elementary school; complete elementary school up to incomplete high school; and complete high school and higher), ethnicity (white, black, multiracial, and other), and region of Brazil (North, Northeast, Midwest, Southeast, and South). We analyzed the data with the software Stata (Stata Corp. 2015 Statistical Software Release 14, College Station, TX, USA), using the set of commands for surveys with a complex sample. Continuous data were expressed as mean and standard deviation and 95% confidence interval (CI).

The National Research Ethics Committee (Comissão Nacional de Ética em Pesquisa - CONEP) of the National Health Council, Ministry of Health, approved the 2013 NHS (Report No.328,159 of June 26, 2013).

RESULTS

Table 1 presents the estimated salt intake according to sociodemographic characteristics. The mean salt intake was 9.34 g/day (95%CI 9.27 - 9.41) and was higher in males (9.63 g/day;95%CI 9.52 - 9.74; N=3,391) than in females (9.08 g/day; 95%CI 8.99 - 9.17; N=4,692). The age group 30 to 44 years had the highest consumption (9.56 g/day; 95%CI 9.44 - 9.68), while the group ≥ 60 years had the lowest (9.01 g/day; 95%CI 8.86 - 9.17). Ethnicity and schooling did not show a significant difference in salt intake. As to the regions of Brazil, we found lower intake in the North Region (8.78 g/day; 95%CI 8.68- 8.88) and higher in the Southeast (9.50 g/day; 95%CI 9.36 - 9.64) and South (9.40 g/day; 95%CI 9.25 - 9.55).

Table 1. Mean daily salt intake (g/day) among the Brazilian adult population according to sociodemographic variables. 2013 National Health Survey (NHS), Brazil.  

Total (n=8,083) Mean SE Lower CI Upper CI
9.34 0.04 9.27 9.41
Gender
Male 9.63 0.06 9.52 9.74
Female 9.08 0.05 8.99 9.17
Age group (years)
18 to 29 9.36 0.08 9.20 9.53
30 to 44 9.56 0.06 9.44 9.68
45 to 59 9.28 0.06 9.16 9.41
60 or older 9.01 0.08 8.86 9.17
Schooling (years)*
Range A 9.34 0.05 9.23 9.44
Range B 9.52 0.10 9.32 9.72
Range C 9.28 0.05 9.18 9.39
Ethnicity
White 9.35 0.05 9.24 9.46
Black 9.36 0.14 9.08 9.64
Multiracial 9.33 0.05 9.23 9.43
Other 9.28 0.34 8.62 9.94
Region
North 8.78 0.05 8.68 8.88
Northeast 9.19 0.05 9.10 9.28
Southeast 9.50 0.07 9.36 9.64
South 9.40 0.08 9.25 9.55
Midwest 9.33 0.08 9.17 9.50

SE: standard error; CI: confidence interval; N: number of individuals; *range A: illiterate up to incomplete elementary school; range B: complete elementary school up to incomplete high school; range C: complete high school or higher.

Table 2 shows the ranges of salt intake according to sociodemographic characteristics. Only 2.39% of the sample consumed < 5 g/day, that is, within the range recommended by WHO. The consumption within this range was greater among women, older individuals, and in Northern Brazil. Considering the moderately high intake (5 to 8 g/day), only 30% of individuals reached its upper limit. Most participants consumed 8 to 12 g/day. Very high intake (≥ 12 g/day) was more frequent in men (15.7%; 95%CI 14.0 - 17.6) than in women (10.8%; 95%CI 9.6 - 12.1). In the group with higher schooling, a smaller proportion of individuals consumed ≥ 12 g/day (11.35%; 95%CI 9.90 - 12.98). With respect to regions, the percentage of individuals with very high intake was lower in the North and Midwest regions. Figure 1 demonstrates how the intake quartiles are distributed among the regions. The lowest quartile (less intake) was more representative in the North region, while the highest (more intake) was prevalent in the Southeast (31.9% of individuals).

Table 2. Ranges of estimated salt intake according to sociodemographic characteristics. 2013 National Health Survey (NHS), Brazil*.  

  • < 5 g/day

  • (n=241)

  • 5 to < 8 g/day

  • (n=2,279)

  • 8 to < 12 g/day

  • (n=4,702)

  • ≥ 12 g/day

  • (n=861)

p
% 95%CI % 95%CI % 95%CI % 95%CI
Total 2.4 2.0 - 2.8 26.3 25.0 - 27.6 58.2 56.7 - 59.6 13.1 12.1 - 14.2
Gender
Male 1.9 1.4 - 2.5 22.2 20.4 - 24.1 60.2 57.9 - 62.4 15.7 14.0 - 17.6 <0.001
Female 2.8 2.3 - 3.5 30.0 28.3 - 31.8 56.4 54.5 - 58.3 10.8 9.6 - 12.1
Age (years)
18 to 29 1.7 1.0 - 2.8 26.3 23.4 - 29.3 59.6 56.2 - 62.9 12.4 10.2 - 15.0 <0.001
30 to 44 1.9 1.3 - 2.7 23.5 21.5 - 25.8 59.4 56.9 - 62.0 15.2 13.2 - 17.3
45 to 59 2.6 1.9 - 3.5 26.3 24.0 - 28.8 58.8 56.1 - 61.4 12.3 10.5 - 14.4
60 or older 4.0 3.1 - 5.3 31.1 28.4 - 33.9 53.1 50.1 - 56.1 11.8 9.9 - 14
Schooling (years)**
Range A 3.0 2.4 - 3.7 26.9 25.1 - 28.7 55.8 53.6 - 57.9 14.4 12.8 - 16.2 <0.001
Range B 2.4 1.5 - 3.8 23.9 20.9 - 27.3 58.6 54.8 - 62.3 15.1 12.3 - 18.3
Range C 1.9 1.4 - 2.6 26.6 24.6 - 28.8 60.1 57.8 - 62.4 11.4 9.9 - 13.0
Ethnicity
White 1.8 1.3 - 2.5 25.9 23.9 - 28 59.5 57.2 - 61.8 12.8 11.3 - 14.5 <0.001
Black 3.0 1.8 - 5.0 29.9 25.6 - 34.6 51.3 46.3 - 56.3 15.8 12.1 - 20.5
Multiracial 2.9 2.3 - 3.6 25.9 24.2 - 27.7 58.3 56.2 - 60.2 13.0 11.5 - 14.5
Other 3.2 1.4 - 7.1 28.3 16.9 - 43.3 57.2 43.1 - 70.2 11.4 5.0 - 23.8
Region
North 4.0 3.2 - 4.9 32.9 30.8 - 35.1 55.4 53.1 - 57.6 7.7 6.6 - 9.1 <0.001
Northeast 2.7 2.1 - 3.4 27.3 25.6 - 29.1 59.1 57.2 - 61.0 11.0 9.8 - 12.3
Southeast 2.1 1.5 - 3.1 25.6 23.2 - 28.1 56.6 53.7 - 59.3 15.8 13.8 - 18.0
South 1.8 1.2 - 2.8 24.5 21.7 - 27.5 60.7 57.4 - 64.0 12.9 10.8 - 15.4
Midwest 2.6 1.7 - 3.9 24.3 21.4 - 27.5 62.5 59.0 - 65.9 10.6 8.6 - 13.1

*Data in g/day; n: number of individuals; 95%CI: 95% confidence interval; **same ranges described in Table 1.

Q1, Q2, Q3, Q4: quartiles.

Figure 1. Distribution of salt intake quartiles among the Brazilian great regions. 2013 National Health Survey (NHS), Brazil. 

According to Table 2, 71.3% of the total population presented high salt intake (≥ 8 g/day), being more frequent in men (74.2%; 95%CI 73.9 - 77.8) than in women (67.2%; 95%CI 66.9 - 67.5). Regarding age group, the consumption decreased in individuals aged 60 years and older in both genders, especially among women (p<0.001). Schooling and ethnicity showed no differences. As to regions, high intake predominated (p<0.001) in the South (79.9%), Midwest (77.7%), and Southeast (77.5%), and was lower in the North (66.1%). High salt intake in females presented no differences among regions.

DISCUSSION

This was the first nationwide study that estimated salt intake in the Brazilian population according to urine analysis. Data indicate that nearly three-quarters of the population consumes a high amount of salt (> 8 g/day), being higher among men and younger people. Consumption had little variation among regions, with lower values in the North and higher in the South and Southeast.

Although 24-h urinary sodium excretion is the gold standard to estimate salt intake35, this procedure is complex and difficult to adopt in epidemiological studies, as it presents important operational issues, requiring the individual to stay in a reserved place, suitable to collect and store urine. In this scenario, population studies with 24-h collection can be weakened by an increased refusal rate and collection errors 13,14.

Several studies have sought alternatives to simplify the collection, reduce costs, and minimize errors 35,36,37. A pilot study performed in Vitória to validate equations that estimate 24-h urinary sodium excretion measured the sodium/creatinine ratio in casual urine34. In this investigation, the 24-h collection was combined with casual collection on the same day and in the same individuals. Salt intake was determined in the 24-h urine, and, based on data collected from the casual urine, two equations were tested to estimate salt intake 33,38. The sodium/creatinine ratio was measured in the casual urine collected at any time of the day. The Tanaka formula was able to predict the consumption with accuracy of 1 g/day in individuals who ingested 9 to 12 g/day, that is, in the intake range of the population mean34. The study, in addition to validating the Tanaka equation, also defined the methodology used in the 2013 NHS across the country. This methodology facilitated the procedures for sample collection, reduced costs, and enabled its application in nationwide studies. We emphasize that requiring casual urine, and not 24-h collection, allowed a greater adherence and promptness in data gathering. Thus, Brazil has innovated and revealed a path for other countries, demonstrating that simpler techniques can also be adopted to aid in the monitoring of sodium intake 26,27.

The study confirmed previous estimates that indicated that salt intake in Brazil was high compared not only with the WHO recommendation (5 g/day) but also with other countries 5,9,13,15. Given the association of high salt intake with AH10 and CVDs14, the data presented reinforce the need to implement preventive actions aimed at reducing its consumption and the events related to chronic NCDs 39,40,41.

Reducing sodium intake leads to a drop in mean blood pressure levels and, consequently, in the prevalence of AH 13,15,40 and incidence of cardiovascular events. Evidence from a meta-analysis of prospective studies showed that high sodium intake was associated with an increased mortality rate for coronary artery disease (relative risk - RR = 1.32; 95%CI 1.13 - 2.10) and cerebrovascular accident (RR = 1.63; 95%CI 1.27-2.10)13. Furthermore, dietary sodium was also related to non-fatal cardiovascular events, chronic kidney disease, and gastric cancer. On the other hand, reducing salt intake by 2.3 g/day was associated with a 3.8mmHg (95%CI 3.08 - 4.55) drop in systolic blood pressure. Decreasing salt intake to values lower than 5 g/day showed no positive or adverse effects regarding renal function and levels of catecholamines and lipids in the blood 13,15.

Data from the 2013 NHS also revealed that the perceived high salt intake is low21, as only 14.2% (95%CI 13.6 - 14.7) of adults declared their consumption as high, the inverse of what the urine levels evidenced. This perception was slightly higher in men (16.1%), individuals aged 18 to 29 years (17.3%), residents of urban areas (14.8%), and in the South Region (18.2%)21. We can speculate that this finding results not only from these individuals effectively consuming more salt but also because they are better informed about how this practice can be detrimental to their health and more aware of their lifestyle habits.

The high sodium intake detected in this study had already been identified in the 2002-2003 HBS42. The second edition of HBS (2008-2009) analyzed the reported food consumption in non-consecutive days in a sample of 21,003 individuals aged 20 to 59 years and revealed that excessive salt intake was more frequent in men than in women (89.3% vs. 70%)23. The Surveillance of Risk and Protective Factors for Chronic Diseases by Telephone Survey (Vigilância de Fatores de Risco e Proteção para Doenças Crônicas por Inquérito Telefônico - VIGITEL) showed that men have less healthy dietary indicators than women43. Studies that used questionnaires for data collection21 had already reported a greater prevalence of high salt intake among younger individuals. Molina et al. identified higher salt intake - estimated based on 12-h urinary excretion - in individuals of lower socioeconomic status22, data consistent with those from VIGITEL, which found worse indicators of dietary quality in subjects with lower education43.

According to HBS, the main source of sodium is the salt added to food preparations42. The reduction in the annual per capita household acquisition of salt (fine or coarse) - from 2.98 to 2.47 kg42 - between 2002-2003 and 2008-2009 does not indicate decrease in sodium intake, as the consumption of processed and ultra-processed foods increased in these periods, and these products usually have higher sodium content44. Moreover,the participation of out-of-home eating in total food consumption also increased during this time interval 23,45.

This study indicates that high salt intake is widespread in the Brazilian population, covering all age groups and levels of schooling. Therefore, programs that promote a reduction in salt intake should be developed to reach all these subcategories, and not only specific groups, such as patients with hypertension or kidney diseases. We underline that the 2011-2022 Strategic Action Plan for Tackling Chronic NCDs established initiatives to improve access to healthy foods in all life stages25. The “Dietary Guidelines for the Brazilian Population,” released in 2014, provided information and recommendations about food choice, preparation, and intake, valuing the consumption of fresh foods of regional origin, and warning for the risks of consuming ultra-processed products, given their high sodium, fat, and sugar content46.

Establishing voluntary agreements (consent decree) with segments of the productive sector involved in the industrial food chain was also an effective initiative, which has produced satisfactory results in other countries, such as England and Portugal. Theassessment of these agreements showed a reduction in the sodium content of most processed foods evaluated45.

Health, educational, and nutrition policies aimed at children and adolescents are also crucial in this area, given the growth in obesity and, consequently, blood pressure in this segment of the population. The Health at School Program (Programa Saúde na Escola - PSE) has encouraged actions that prevent obesity in childhood and adolescence by improving the dietary quality of foods provided in schools, stipulating a minimum offer of 30% of fresh foods 46,47.

In addition to educational actions, regulation and control measures for foods are also necessary, such as a national review of the standard nutrition labeling of packaged foods, so the consumers can understand and identify critical levels of components, like sodium, in processed foods; for instance, a recent experience in Chile included warnings in nutrition labels and placed them in the frontal part of the product47.

CONCLUSION

Lowering salt intake is one of the interventions with better cost-effectiveness to reduce the chronic NCD burden, especially CVDs, mainly by decreasing the mean blood pressure levels in the population. Considering that hypertension is, directly and indirectly, responsible for approximately nine million deaths each year worldwide, reducing salt intake can potentially save millions of lives.

The Global Action Plan for the Prevention and Control of NCDs from WHO has defined targets to decrease salt intake, showing the importance of monitoring its consumption in population surveys. Thus, the data collected by NHS will serve as a baseline for the continued surveillance of this variable in the population.

The present study indicates that salt intake is high across the country and in all subgroups of the population, requiring coordinated actions to tackle this issue, such as improving access to healthy foods, promoting health education actions, and regulating and monitoring the agreements entered into with the food industry.

ACKNOWLEDGMENTS

We thank doctor Jarbas Barbosa da Silva (Pan American Health Organization, Washington, D.C.) and doctor Gonzalo Vecina (School of Public Health of Universidade de São Paulo).

REFERENCES

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Financial support: Health Surveillance Secretariat, Ministry of Health.

Received: December 21, 2018; Revised: March 12, 2019; Accepted: March 19, 2019

Corresponding author: José Geraldo Mill. Departamento de Ciências Fisiológicas, Universidade Federal do Espírito Santo. Avenida Marechal Campos, 1.468, Maruípe, CEP: 29040-090, Vitória, ES, Brasil. E-mail: josegmill@gmail.com

*

in memoriam.

Conflict of interests: nothing to declare

Authors’ contribution: José Geraldo Mill: data analysis, writing, critical review, and submission of the final version of the article. Deborah Carvalho Malta: data analysis, writing, and critical review of the final version of the article. Ísis Eloah Machado: data analysis, writing, and critical review of the final version of the article. Arthur Pate: data analysis, writing, and critical review of the final version of the article. Cimar Azeredo Pereira: data analysis, writing, and critical review of the final version of the article. Patrícia Constante Jaime: data analysis, writing, and critical review of the final version of the article. Célia Landman Szwarcwald: data analysis, writing, and critical review of the final version of the article. Luiz Gastão Rosenfeld: coordination of field collection, conception, and planning of the NHS laboratory study, definition of laboratory parameters, study planning, and review.

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