==== Front PLoS One PLoS One plos PLOS ONE 1932-6203 Public Library of Science San Francisco, CA USA 10.1371/journal.pone.0288123 PONE-D-21-23343 Research Article Biology and Life Sciences Nutrition Diet Food Medicine and Health Sciences Nutrition Diet Food Biology and Life Sciences Physiology Physiological Processes Excretion Biology and Life Sciences Nutrition Diet Medicine and Health Sciences Nutrition Diet Biology and Life Sciences Anatomy Body Fluids Urine Medicine and Health Sciences Anatomy Body Fluids Urine Biology and Life Sciences Physiology Body Fluids Urine Biology and Life Sciences Biochemistry Biomarkers Biology and Life Sciences Nutrition Nutrients Medicine and Health Sciences Nutrition Nutrients Biology and Life Sciences Nutrition Medicine and Health Sciences Nutrition Biology and Life Sciences Anatomy Anthropometry Medicine and Health Sciences Anatomy Anthropometry Food frequency questionnaire for foods high in sodium: Validation with the triads method Food frequency questionnaire validation https://orcid.org/0000-0002-4817-3221 Souza Diana S. Conceptualization Data curation Formal analysis Investigation Writing – original draft * Santos Bianca I. Data curation Writing – original draft Costa Brenda M. Data curation Writing – original draft Santos Dalila M. Data curation Writing – original draft https://orcid.org/0000-0002-0868-8546 Aragão Laryssa G. S. Data curation Writing – original draft Pires Liliane V. Conceptualization Formal analysis Methodology Project administration Supervision Writing – review & editing Vieira Diva A. S. Conceptualization Methodology Supervision Writing – review & editing Freire Analícia R. S. Conceptualization Methodology Project administration Supervision Writing – review & editing Barbosa Kiriaque B. F. Conceptualization Funding acquisition Project administration Supervision Writing – review & editing Department of Nutrition, Federal University of Sergipe, São Cristóvão, Brazil Righini Nicoletta Editor Universidad de Guadalajara, MEXICO Competing Interests: The authors have declared that no competing interests exist. * E-mail: idiana-ss@hotmail.com 3 7 2023 2023 18 7 e028812331 7 2021 20 6 2023 © 2023 Souza et al 2023 Souza et al https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This study aimed to validate a food frequency questionnaire for foods high in sodium (FFQ-FHS) in a population aged ≥18 years and to test its reproducibility. This cross-sectional study included 50 individuals (≥18 years) of both sexes. In addition to the FFQ-FHS, four 24-h dietary recalls (24hRs) were conducted and a socioeconomic and lifestyle questionnaire was administered. Two 24-h urinary excretions were collected for sodium analysis, and anthropometry was performed. For validation, the triad method was applied using the validity coefficient (ρ). For reproducibility, the intraclass correlation coefficient (ICC), 95% confidence interval, kappa coefficient, and Bland–Altman plots were used to check for agreement. The Kolmogorov-Smirnov test was used to verify the data distribution. The validity coefficients for daily energy-adjusted sodium intake were high for the 24hR (ρRAI = 0.85) and weak for the FFQ-FHS (FFQAI = 0.26) and biomarker (ρBAI = 0.20). The ICC values were 0.68 for unadjusted sodium and 0.54 for energy-adjusted sodium intake. The weighed Kappa scores were 0.49 (p<0.01) and 0.260 (p = 0.02) for unadjusted and adjusted sodium intake, respectively. Although the FFQ-FHS is reproducible, it is not valid for the assessment of sodium intake and cannot be the sole instrument used for this purpose. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil financing code 001 Fundação de Apoio à Pesquisa e a Inovação Tecnológica do Estado de Sergipe This study was partially financed by the following: 1. Scholarship awarded by the Fundação de Apoio à Pesquisa e a Inovação Tecnológica do Estado de Sergipe (Fapitec/SE/Brasil) [Research and Technological Innovation Support Foundation in the State of Sergipe] https://fapitec.se.gov.br/ 2. Financial resources granted by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES/Brasil) [Coordination for the Improvement of Higher Education Personnel], financing code 001, PROMOB, process no. 88881.157882/2017-01 https://www.gov.br/capes/pt-br The funders had no role in the study design, data collection and analysis, decision to publish, or manuscript preparation. No additional external funding was received for the study. Data AvailabilityAll relevant data are within the paper and its Supporting Information files. Data Availability All relevant data are within the paper and its Supporting Information files. ==== Body pmcIntroduction Several studies [1–3] have developed food frequency questionnaires (FFQ) to estimate the sodium intake in different populations; however, validation is necessary. For this purpose, the FFQ should be compared with other methods of food intake assessment, such as food record (FR) and/or 24-hour dietary recall (24hR), which, although they are also prone to measurement errors, are considered reference methods. Biomarkers (Bs) are commonly used in validation studies because they have distinct and independent approaches from other methods that assess dietary intake. However, B have limitations in reflecting the intake of a particular nutrient over a short period. In addition, metabolic reactions, absorption, and excretion affect the B levels [4–7]. When nutrient intake is assessed using two dietary assessment tools and biological markers, the triad method is recommended because it estimates the validity coefficient between the unknown actual intake (AI) and the intake estimated using the FFQ, 24hR or FR, and B, allowing a triangular comparison between the different methods [4, 5, 8, 9]. The triad method is effective in comparing intake estimations using the instrument to be validated, the FFQ, the reference method (24hR or FR), and B. The proposed method assumes the existence of independent random errors in the three instruments and considers that each error is linearly related to the AI [5]. A systematic review investigated whether FFQs are reliable and valid for measuring the habitual sodium intake and concluded that the available instruments were inadequate because of the low agreement between intake measured by FFQ and 24-hour urinary excretion [10]. In Brazil, independent of the geographical region, the sodium intake of the population is high [11, 12] and corresponds to approximately twice the intake recommended by the World Health Organization (WHO) (2 g/day) [13]. Data from the 2008 to 2009 Household Budget Survey show that the contribution of processed and ultra-processed foods to the average sodium intake increased from that observed in the first edition of the survey (2002–2003) [11]. Despite this, studies seeking the validation of a tool to investigate sodium intake in the Brazilian population, especially in the northeast region, remain scarce. Thus, this study aimed to use the triad method to validate the food frequency questionnaire for foods high in sodium (FFQ-FHS) for Brazilian adults and determine its reproducibility. Materials and methods Study design and participants This was a cross-sectional study using a convenience sample. This study enrolled 50 adult Brazilian men and women. This sample size was considered the minimum sample size suggested for validation studies, as recommended by Cade et al. [14] and McLean et al. [10]. The study was approved by the Research Ethics Committee of the Federal University of Sergipe (process no. 1.875.674, CAAE no. 62502216.0.0000.5546). Participants were recruited through social media and traditional methods (posters and e-mails) in 2018. Fifty male and female individuals aged between 18 and 60 years and belonged to the academic community of a Federal Public University (undergraduate students and staff personnel) were selected. We excluded pregnant and lactating women, vegetarians, individuals clinically diagnosed with non communicable chronic diseases or following special diets, individuals with identifiable cognitive deficits, and nutrition professionals were not included. All four assistants were nutrition graduate students who received training and supervision from the nutritionists. The researcher and assistants conducted body measurements and interviews using a socioeconomic questionnaire. Data collection and interviews were carried out at the university nutrition school clinic. The researcher and assistants conducted four 24hRs and two FFQ-FHS surveys, in addition to the collection of two urine samples over a period of 6 months. Anthropometric measures were used to determine the nutritional status. The socioeconomic and demographic data were also collected. Fig 1 shows a schematic diagram of the study process. 10.1371/journal.pone.0288123.g001 Fig 1 Data collection process. Description of data collection process. SQ:sociodemographic questionnaire; 24hR:24-h dietary recall; FFQ-FHS:food frequency questionnaire for foods high in sodium; AA: anthropometric assessment. The participants signed a free and informed consent form, allowing voluntary participation, followed by the application of the socioeconomic questionnaire, 24hR and FFQ-FHS, and anthropometric assessment. In the first and fourth interviews, the FFQ-FHS was completed after the 24hR via face-to-face interviews with the support of a food portion photographic book. Food frequency questionnaire for foods high in sodium The FFQ-FHS is a 55-item semiquantitative tool developed by Santos et al. [15] to assess the habitual sodium intake during the preceding 6-month period. Participants in this validation study completed two sets of FFQ-FHS, at the beginning and end of the semester, to assess for reproducibility. The FFQ-FHS contain a list of foods that contain ≥400mg of sodium per 100g or ml, as defined by the National Health Surveillance [16] for high-sodium food. The list of items corresponds to the foods consumed by the local population, selected after applying the 24hR [15]. The foods and typical meals that make up the dietary pattern of the reference population or those that indicated a consumption rate of ≥5% in the northeast region [17] were also included in the FFQ-FHS. The standard portion size of each food or meal was defined according to the Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística, IBGE) database of reference measurements and portion sizes of foods and dishes consumed in Brazil [18]. The food items in the FFQ-FHS are divided into seven groups (processed meats, canned and preserved foods, dairy products, bakery and pasta, salts and condiments, miscellaneous, and regional foods), four portion options (½ portion, 1 portion, 2 portions, and more portions–the interviewee should specify the amount consumed), and eight intake frequency categories (rarely/never, once a month, 2–3 times a month, once a week, 2–4 times a week, once daily, twice daily, and ≥3 times a day). 24-h dietary recall Each volunteer answered three 24hR questions, with minimum and maximum intervals of 15 and 45 days, respectively, depending on the participants’ availability, including one day during the weekend. After 3 months, the fourth 24hR was carried out at the end of the period. The researcher and assistants were trained to conduct the four 24hRs using the multiple pass method, developed by the United States Department of Agriculture [19]. To facilitate the completion of all forms, a photographic manual of food quantification with preset portion sizes was used [20]. Added salt In addition to the sodium estimate obtained during the 24hR, the amount of sodium in the added salt was considered. The participants were asked if they had the habit of adding salt to the dish and salad. If yes, they were asked whether commercial sachets or table salt was used. Considering that each sachet contained 1 g of salt, the units used were counted to estimate the total sodium intake. For those who confirmed the use of table salt, the estimated consumption was 1 g of added salt. This estimate was adopted because the amount of salt added to the table could not be quantified. Sodium excretion biomarker A 24-h urine specimen was collected following the recommendation of McLean et al. [10] to determine the daily excretion of Na (spectrophotometry) and creatinine (Jaffé method). Between the third and the fourth 24hR, two 24-hr urine specimens were collected for urinary sodium analysis. The participants received instructions [21] on how to collect and deliver the biological materials. The participants received 2-L containers for 24-h urine collection. The participant had to discard the first urine of the day and collect all urine from that moment on, including nocturnal and bath urine, until the next day at the same time as that during which the first urine was discarded. The collected urine was stored in a container and kept in a refrigerator during and after collection. The delivered material was identified and sent to the Clinical Laboratory of the Department of Nutrition of the UFS. Considering the need for a minimum volume of urine to identify the excretion of metabolites, we used urine specimens with less than 400mL [22], or with a creatinine value <0.2 mmol/kg/day [23]. The results were expressed in mg/kg/day. Sociodemographic data A structured questionnaire was used to collect the sociodemographic information (sex, age, household per capita income, and educational level). The household per capita income was calculated by summing the monetary income reported and dividing by the number of all family members (minimum wage corresponding to USD $ 248.69). Anthropometry The assistants performed anthropometric measurements on the first day of the interviews. Standard and per protocol measurement techniques were used in this study. A digital platform scale (LIDER®, São Paulo, Brazil) was used to determine the body weight with a capacity of 200kg and a precision of 100g. Stature was measured using a portable 2-m stadiometer with a precision of 1 millimeter (Alturaexata®, Minas Gerais, Brazil). Waist circumference was measured in centimeters using inelastic anthropometric tape. Nutritional status was classified according to the body mass index based on the cut-off values proposed by the WHO [24]. Food composition analysis The food nutrient composition was analyzed using NutWin® software (version 1.5.2.51). All items listed in the applied 24hR and FFQ-FHS were standardized and typed individually in duplicate. The IBGE [25] nutrient composition table and product labels (mean values of the three brands) were used. Statistical analysis The Kolmogorov-Smirnov test was used to determine normality of data distribution. Descriptive statistics was conducted for calculation of the measures of central tendency and dispersion or absolute or relative frequencies. Spearman’s correlation coefficients were used to determine agreement between the FFQ-FHS, 24hR, and B. The FFQ-FHS validity was analyzed using the triad method, comparing the results of the FFQ-FHS survey, 24hR, and B assessment with the estimated AI. The validity coefficient was determined, which can vary from 0 to 1 and must not be negative. The correlations were considered low (r<0.3) or high (r>0.7) [5]. To check for agreement between FFQ-FHS, 24hR, and B, the weighted Kappa value was calculated using the daily energy-adjusted sodium intake categorized into tertiles. For reproducibility, the correlation between the two FFQ-FHS surveys was assessed using the intraclass correlation coefficient (ICC) and a confidence interval of 95% (95% CI). The weighted kappa value was used to check the agreement of sodium classifications categorized into tertiles. Bland–Altman [26] plots graphically demonstrate the level of agreement between the FFQ, 24hR, and B, and the reproducibility of the FFQ-FHS. The centerline indicates the bias. It is desirable that this line be positioned close to zero, which means that there is a small difference between the means of both instruments. The upper and lower limits represent the 95% CI [27]. Good agreement is also shown by a greater number of points concentrated around the centerline. In the plots, the disagreement is expressed by a great dispersion of points around the centerline; additionally, a proportional bias exists because the differences diminish as the means increase [26, 27]. The 24hR data were attenuated to correct for intra-individual variability using the Multiple Source Method [28]. The method estimates the individual usual intake based on the results of repeated measurements over a long period. The program estimates the probability of nutrient intake from the data provided and then estimates the usual intake of nutrients. The values obtained were multiplied with each other to obtain an estimate of the individual usual daily intake after removing the intra-individual variability. The significance level was set at p<0.05. Results The sample included 60% of men, 84% of individuals with secondary education, and 62% of individuals whose household per capita income was lower than one minimum wage. The participants’ average age was 22.5 years. With regard to nutritional status, 60% of the patients had normal weight. The prevalence of overweight and obesity was 30% (Table 1). 10.1371/journal.pone.0288123.t001 Table 1 Socioeconomic and demographic characteristics and nutritional status of the academic community. Aracaju, SE, 2018 (n = 50). Characteristic X¯±SD or n(%) or Age (years) 22.5±3.5 Sex Male 30 (60) Female 20 (40) Educational level Secondary education 42 (84) Higher education 8 (16) Per capita income ≤1 MW 31 (62) 2–3 MW 15 (30) 4–6 MW 3 (6) ≥9 MW 1 (2) Body mass index (kg/m2) Thin 5 (10) Normal 30 (60) Overweight 10 (20) Obese 5 (10) Data are shown as mean ± standard deviation [(±DP)] or absolute and relative frequency (n [%]). Household per capita income was calculated by summing the monetary income reported and dividing it by the number of all family members (minimum wage corresponding to USD $ 248.69). A total of 47 and 36 specimens from the first and second urine collections were adequate according to the urine volume [22] and creatinine value [23]. The mean sodium intake and urinary excretion values are presented in Table 2. The estimated values were higher after administering the first set of FFQ-FHS compared with that after the second set. In both cases, the sodium intake was above the recommended level. The level of urinary sodium excretion exceeded the average dietary intake estimated by both the 24hR and FFQ-FHS survey. The mean sodium estimated in the four 24hRs was also higher than that in the two FFQ-FHS surveys. 10.1371/journal.pone.0288123.t002 Table 2 Estimated values of unadjusted sodium intake and energy-adjusted sodium intake by the 24hR, FFQ-FHS survey, and biomarker assessment in individuals of the academic community. Aracaju, SE, 2018 (n = 50). Instrument Sodium (mg) X±SD 24hR 3421.8±909.4* 3422.8±500.3† FFQ 1 3749.2±2097.4* 3356.5±333.3† FFQ 2 3100.8±1422.4* 2838.6±270.9† Urinary excretion (1st collection, n = 47) 4844±1650.1 (2nd collection n = 36) 4812.6±1778.7 24hR = 24-h dietary recall, FFQ = food frequency questionnaire, X = mean, SD = standard deviation *Sodium unadjusted intake †Sodium adjusted for daily energy intake The Spearman’s correlations and validity coefficients are shown in Table 3. A statistical significance was only observed in the unadjusted sodium correlation between the FFQ and 24hR (r = 0.386). The validity coefficient was high for the 24hR (r>0.7). The validity coefficient for unadjusted sodium considering the average urinary excretion could not be verified because of the negative rRB. The analysis of the correlation coefficients indicates that the particular properties of sodium make it difficult to estimate the consumption. 10.1371/journal.pone.0288123.t003 Table 3 Spearman’s correlation and validity coefficients for unadjusted and energy-adjusted daily sodium intake in adults in the academic community. Aracaju, SE, 2018 (n = 50). Correlation coefficient Validity coefficient Unadjusted (p) Energy Adjusted (p)* Energy Adjusted * rFFQR 0.386 (<0.01) 0.129 (0.387) ρFFQAI 0.26 rRB † −0.026 (0.882) 0.172 (0.316) ρRAI † 0.85 rFFQB † 0.014 (0.936) 0.052 (0.763) ρBAI † 0.20 rFFQR, correlation between the food frequency questionnaire survey and the 24-h dietary recall rRB, correlation between the 24-h dietary recall and biomarker assessment rFFQB, correlation between the food frequency questionnaire survey and biomarker assessment ρFFQAI, validity coefficient of the food frequency questionnaire survey ρRAI, validity coefficient of the 24-h dietary recall ρBAI, biomarker validity coefficient ρFFQAI=√([rFFQRxrFFQB])/rRB ρRAI=√([rFFQRxrRB])/rFFQB ρBAI=√([rRBxrFFQB])/rFFQR *Daily energy-adjusted sodium intake †n,36 using the average urinary sodium excretion Classification by tertiles of energy-adjusted sodium intake using the three methods indicated a disagreement. The best agreement was observed between 24hR and B assessment (p = 0.271) (Table 4). A tertile analysis was performed to classify the individuals’ sodium consumption. The percentages indicated in the same tertile reveal the agreement of classification of the methods, whereas the opposite and adjacent tertiles indicate the degree of disagreement. 10.1371/journal.pone.0288123.t004 Table 4 Weighed kappa agreement ranked by tertiles of energy-adjusted daily sodium intake in adults in the academic community. Aracaju, SE, 2018 (n = 50). Method Same tertile (%) Adjacent tertile (%) Opposite tertile (%) Weighed Kappa p FFQx24hR 32 44 24 −0.041 0.772 FFQxB§ 27.8 47.2 25 −0.82 0.624 24hRxB§ 52.8 27.8 19.4 0.183 0.271 FFQ:food frequency questionnaire; 24hR: 24-h dietary recall; B: biomarker §n,36 Rank of average urinary sodium excretion Bland–Altman plots (Fig 2) were constructed to assess the agreement between the FFQ, 24hR, and B, and the reproducibility of the FFQ-FHS. A disagreement was observed between the instruments evaluated. The reproducibility graphs indicated a moderate agreement between the first FFQ-FHS survey and second FFQ-FHS survey as most of the points were placed around the centerline. 10.1371/journal.pone.0288123.g002 Fig 2 Bland–Altman plots to assess for agreement of daily energy-adjusted sodium between the FFQ survey, 24hR, and biomarker assessment in individuals from the academic community. Aracaju, SE, 2018 (n = 50). a) Food frequency questionnaire and 24-h dietary recall; b) 24-h dietary recall and average urinary excretion (n = 36); c) food frequency questionnaire and average urinary excretion (n = 36); d) agreement of the daily energy-adjusted sodium intake between the FFQ-FHS 1 and 2 *Absolute differences between values from the ordinate axes and mean intake of the abscissa axes. SD = standard deviation, AVG = average. The correlation and reproducibility coefficients of FFQ-FHS were moderate. The classification by tertiles of sodium intake and energy-adjusted sodium as estimated by the FFQ-FHS survey showed the exact agreement rates between 50% and 66% (Table 5). 10.1371/journal.pone.0288123.t005 Table 5 Reproducibility of the FFQ-FHS for unadjusted sodium intake and daily energy-adjusted sodium intake and classification by tertiles of sodium intake by individuals from the academic community. Aracaju, SE, 2018 (n = 50). Nutrient ICC 95% CI Same tertile (%) Adjacent tertile (%) Opposite tertile (%) Weighed Kappa p Unadjusted sodium 0.686 0.446–0.826 66 24 10 0.524 <0.01 Energy adjusted sodium 0.541 0.191–0.739 50 36 14 0.316 0.026 ICC = intraclass correlation coefficient, 95% CI = 95% confidence interval Discussion The correlations and validity coefficients found in this study were ranked as low to moderate. The correlation of unadjusted sodium between the FFQ survey and 24hR was weak, but was significant (r = 0.386; p<0.01), which eventually lost significance after adjustment for energy intake. The minimum correlation was 0.4 for the relative validity of an FFQ [29]. FFQ validation studies using FR or 24hR as a reference method also found non-significant associations and, sometimes, negative associations. Sodium correlations varied from 0.07 to 0.43 [1, 30–32]. The validity coefficients for daily energy-adjusted intake were considered high for the 24hR (ρRAI = 0.85) and weak for the FFQ-FHS survey (ρFFQAI = 0.26) and B assessment (ρBAI = 0.20). The findings of this study were similar to those of Pereira et al. [1], in which the B assessment showed the weakest validity coefficient (ρBAI = 0.21), while the 24hR showed the highest validity coefficient (ρRAI = 0.56). The validity coefficients based on unadjusted sodium levels were not verifiable owing to the negative correlation. Negative correlations have been reported in previous studies [9, 33]. In addition to the calculation of correlation and validity coefficients, the use of different analyses to estimate the validity of an instrument is important. Although the triad method was chosen for this study, other statistical tests were conducted to ensure the greater reliability of results, such as the weighted Kappa agreement and Bland–Altman [26] plots. Furthermore, the recommendations for carrying out an FFQ validation study to assess the sodium intake were followed according to McLean et al.’s study [10]. According to Kaaks [4], the FFQ survey and 24hR exhibit similar errors, which overestimate the correlation and, consequently, the validity coefficient. On the contrary, the correlation between the FFQ survey and B assessment was weak owing to the intra-individual influence; the B reflects the short-term intake, restricted to a short period of time, while the FFQ assesses the long-term intake. Strong correlations (r>0.7) produce high validity coefficients, whereas weak correlations (r<0.3) generate undesirable validity coefficients [4]. The quantification of sodium intake remains a challenging task. In addition to its great variability, sodium metabolic balance is sensitive to changes inherent to each individual [34]. Even for individuals who constantly consume salt (6, 9, and 12 g/day), urinary sodium excretion will not remain constant. The variation in excretion is a reflection of the biological rhythm; that is, salt intake does not necessarily reflect the corresponding excretion [34]. A single 24-h urine specimen is probably inadequate for validating the FFQ [10]. A single 24-h urine specimen, not with standing whether properly collected, cannot determine a 3-g difference in daily salt intake [34]. To assess for sodium intake, the 24-h urine collection should be repeated 2–7 times [10]. In the literature, urinary excretion tests to assess sodium intake varied from those using a single sample [1, 35] to six collected specimens [36]. Regardless of the number of repetitions of urinary excretion to assess for sodium intake, the correlations remained weak. The need for more urinary excretion repetitions can justify the difficulty in validating the instrument. Other studies corroborate that the correlations between urinary excretion and 24hR/FR are stronger than those between FFQ survey and urinary excretion [23, 36]. Day et al. [36] used six 24-h urine specimens to measure the sodium, potassium, and nitrogen intakes. The FFQ survey and 7-day FR underestimated the sodium intake, and the correlation between urinary excretion and the FFQ survey (r = 0.13) was lower than that with the FR(r = 0.36). Some studies reported that the correlations between dietary intake assessment methods are stronger than those between methods using Bs (urinary sodium excretion) because the different dietary intake assessment tools have correlating and systematic errors, which are different and independent from the errors inherent to a B analysis [4, 35, 36]. Tangney et al. [32] also reported the underestimation of sodium consumption. The food items in the assessment tool did not identify the main sources of sodium. A dietary assessment tool can never be expected to capture 100% of the sodium intake, but it is expected to provide a reliable estimate [32]. The selection of foods that comprise the FFQ for habitual sodium intake must include foods and/or dishes usually consumed by the population, considering their contribution to sodium intake, as well as processed and ultra-processed foods, because it is believed that the higher sodium intake is attributed to the consumption of these food items [11]. According to Cooper et al. [37], one of the limitations in the development of the Sodium AnaLysis Tool (SALT) was the absence of ethnic dishes, which are typical preparations of the study population. This may have interfered with the responses of individuals who consumed food items other than those listed in the instrument. Inclusion of these food items remains a challenge as the use of an extensive list can make the interview tiring and diminish the quality of the interviewee’s response, while the use of a short list makes it difficult to identify the variability of individual diets [38]. Dietary sodium has intrinsic peculiarities. The assessment of dietary sodium intake using an FFQ is limited by the fact that the list of food items with high sodium content is primarily composed of processed and ultra-processed foods, in which the in natura or minimally processed foods that comprise the main meals, lunch and dinner, of a Brazilians’ diet are not represented. In addition to the sodium present in foods, it is necessary to consider the amount of salt as a culinary ingredient and the added salt at the table. With regard to the study limitations, the 24hR was performed prior to the FFQ-FHS survey, which was in disagreement with the recommendations of some authors [14]. According to Willet [29], the time and effort undertaken by the research participants to complete the records and dietary recalls, either by direct weighing or by recording what was consumed, may influence the completion of subsequent FFQ. However, if the FFQ is administered prior to the reference method (24hR/FR), these records can be influenced by the FFQ responses and do not reflect the reality [29]. In addition, McLean et al. [10] recommended that in order to assess the sodium intake, the 24-h urinary excretion test should be used as a reference tool; thus, the order of administration of FFQ and 24hR would not be important in this case. In this study, both instruments were administered during in-person interviews, and not self-reported, using a photographic manual as an aid for completion of the 24hR and a specific album of photos showing the portion size of the FFQ-FHS items. As a positive aspect, the average dietary sodium intake was obtained by conducting a 24hR four times, which exceeds number of 24hRs performed in diverse validation studies (three repetitions of the 24hR or FR) [1, 9, 23]. The 24-h urinary excretion test was then repeated. Nonetheless, owing to the population profile, there was considerable sample loss, and a large portion of the urine specimens were collected on the weekend. This might have led to the misrepresentation of sodium that is usually consumed during the week. Because it is difficult to collect, the participants may not have collected all urine samples voided in 24 h, although they received oral and written instructions. Currently, the existing FFQs are not valid for dietary sodium assessment because they show poor agreement. Thus, 24-h urine remains the gold standard for estimating the intake of this nutrient [10]. Perhaps the validation of an FFQ as the only tool for estimating sodium intake is not the best method. The singularities of this nutrient, with a high influence of intra-individual variability, made it difficult or even impossible to assess the actual intake [34]. The FFQ-FHS was demonstrated to be reproducible over a period of 6 months, with unadjusted correlation coefficients (0.686) and energy-adjusted ones (0.541) considered acceptable. Cooper et al. [37] also found a significant correlation between these two SALT applications (p = 0.001). According to Cade et al. [14], the reproducibility of a short FFQ can be determined by considering the unadjusted data. Usually, the correlations of instruments re-administered within longer intervals, 6 months to 1 year apart, are lower than those of instruments re-administered within a shorter interval. Hence, the FFQ-FHS should be used as a complement to other methods of assessing sodium intake. The combined use of the FFQ and 24hR enables a better detailing of the eating habits and may be especially useful for identifying the foods that are not consumed for many days and, therefore, might have been totally forgotten during the 24hR [29]. In conclusion, despite the administration of four 24hRs and the repeated 24-h urinary sodium excretion, the instrument was not considered valid for the assessment of sodium intake and cannot be used alone for this purpose; however, it may be convenient as a complement to the reference method. The FFQ-FHS was reproducible over a 6-month period. Supporting information S1 File (ZIP) Click here for additional data file. We thank all the participants who agreed to participate in this study. We also thank TMSV, GBC, RKFS, ACOB, Hypertension Nutrition Care Group (Grupo de Atendimento Nutricional em Hipertensão, GANuH), and Nutrition Laboratory (Laboratório de Nutrição, LABNUT) for assistance in collecting data and analyzing biological samples. 10.1371/journal.pone.0288123.r001 Decision Letter 0 Vall-llosera Camps Miquel Staff Editor © 2023 Miquel Vall-llosera Camps 2023 Miquel Vall-llosera Camps https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Submission Version0 25 May 2022 PONE-D-21-23343FOOD FREQUENCY QUESTIONNAIRE FOR FOODS HIGH IN SODIUM: VALIDATION WITH THE TRIADS METHODPLOS ONE Dear Dr. Souza, Thank you for submitting your manuscript to PLOS ONE. 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You should list all authors and all affiliations as per our author instructions and clearly indicate the corresponding author. 11. Please amend either the abstract on the online submission form (via Edit Submission) or the abstract in the manuscript so that they are identical. 12.Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information.  [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes ********** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes ********** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: No ********** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: No ********** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The article addresses an important field of nutritional research. Evaluating the relative validity of a dietary assessment method is of great importance when studying the potential impact of diet exposures on health outcomes. The authors constructed an FFQ for foods high in sodium and proposed a validation protocol over a 6-month period of dietary data collection complemented by four 24-hour recalls and two 24-hour urinary excretion for sodium analysis. The FFQ was reproductible but not valid. Despite the good statistical procedures adopted, the writing is not always fluid and sometimes repetitive. The description of the study protocol is not clear. In addition, it is not always clear what each test adds to the overall evaluation of level of validity, which could be made clearer in the method section. Another concern I have is related to the 'per se' construction of FFQ that was done previously with another sample; so, in the middle of the methodology, the authors describe basically another study (not mentioned before) and confuse the reader. Important decisions on how FFQ was built are not provided in the text. Very important: The English needs considerable attention. Introduction: 1. I suggest deleting the first two paragraphs and getting straight to the point. In the last paragraph, authors could justify why this study was done and, especially to investigate sodium in that region of Brazil. (why a specific FFQ is needed to that region) Methods 2. I believe that the authors could benefit from checking the manuscript construction of previous FFQ validation studies. As mentioned above, the writing is not fluid and sometimes repetitive. First, provide an overall description of the (i) previous protocol to design the FFQ; (ii) the 6-month protocol to the FFQ validation: FFQ, rec24h, urine collection (in a 6-month period, when each instrument was applied/data was collected, providing the interval period among them). 3. In the sentence: “Each volunteer answered three 24hR, with a minimum and maximum interval of 15 and 45 days, respectively, and one of 24hR covered one weekend day.” How was the 15-45-day interval decided? Does it depend on the availability of the participant? 4. Do FFQ and Rec24h were paper-based methods? Were both a face-to-face interview? 5. Very important: do not describe “researchers” when referring to those people that collected the data in the field work; in this case, I would recommend to describe they as “research assistants” or “assistants”. It is better to restrict the term 'researchers' to those responsible for the study protocol and who wrote the manuscript. 6. How many research assistants and nutritionists conducted the field work? Was the team composed of undergrad and grad students? Those who applied the dietary instruments had any background in nutrition & dietetics? 7. Examples of information that seems repetitive in the text: (a) All the subjects who agreed to participate in the study received information on the study and signed the Free and Informed Consent Form. (b) The participants signed the Free and Informed Consent Form, allowing their voluntary participation, (a) All researchers had been trained and supervised by nutritionists. (b) Nutritionists trained and supervised the anthropometric measurements to ensure higher precision and accuracy of the data. 8. Rewrite the sentence: To assess daily sodium intake, to the 24hR estimate was added the amount of sodium from added salt. 9. Briefly describe the data collected from the socioeconomic questionnaire applied. Age, sex, occupation, etc. 10. Provide more details on the multiple pass method applied in the current protocol. 11. Validation paragraph: It does not add additional information. In the way described, this paragraph can be deleted. 12. How was the information of the dietary intake of rec24h and FFQ entered in NutWin? Food intake data entered one-by-one? who and how many people entered these data? There was any quality control in the data entered? how portion sizes were defined? The same questions is applied to FFQ. 13. Describe more about the MSM. What this method proposes and how? Results: 14. It calls my attention that the sample studied had higher education but low income. Who were they? Undergrad students or staff personnel? It is important to describe it in method section. 15. Table 1. Replace 'gender' by 'sex'. sex = biologic nature of being female or male. gender = social role construction of being male or female. If you are analyzing urinary excretion, it is more relevant that you provide the information on biology. Also, replace 'nutrition status' by 'body mass index (kg / m2)'. 16. Replace “CI95%” by 95% CI 17. I think authors can think about a better presentation on tables. ********** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. 10.1371/journal.pone.0288123.r002 Author response to Decision Letter 0 Submission Version1 30 Aug 2022 Response to Reviewers Journal Requirements: 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf Response: The suggested changes have been made. 2. We suggest you thoroughly copyedit your manuscript for language usage, spelling, and grammar. If you do not know anyone who can help you do this, you may wish to consider employing a professional scientific editing service. Response: The manuscript has been edited by Editage to ensure language and grammatical accuracy. 3. Please include additional information regarding the survey or questionnaire used in the study and ensure that you have provided sufficient details that others could replicate the analyses. For instance, if you developed a questionnaire as part of this study and it is not under a copyright more restrictive than CC-BY, please include a copy, in both the original language and English, as Supporting Information. Response: As requested, a copy in the original language and English of the constructed FFQ has been attached. 4. Please provide additional details regarding participant consent. In the Methods section, please ensure that you have specified (1) whether consent was informed and (2) what type you obtained (for instance, written or verbal). If your study included minors, state whether you obtained consent from parents or guardians. If the need for consent was waived by the ethics committee, please include this information. Response: The suggested changes have been made. 5. We note that the grant information you provided in the ‘Funding Information’ and ‘Financial Disclosure’ sections do not match. When you resubmit, please ensure that you provide the correct grant numbers for the awards you received for your study in the ‘Funding Information’ section. Response: This study was partially financed by the following: 1. Scholarship awarded by the Fundação de Apoio à Pesquisa e a Inovação Tecnológica do Estado de Sergipe (Fapitec/SE/Brasil) [Research and Technological Innovation Support Foundation in the State of Sergipe] https://fapitec.se.gov.br/ 2. Financial resources granted by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES/Brasil) [Coordination for the Improvement of Higher Education Personnel], financing code 001, PROMOB, process no. 88881.157882/2017-01 https://www.gov.br/capes/pt-br The funders had no role in the study design, data collection and analysis, decision to publish, or manuscript preparation. No additional external funding was received for the study. 6. Please provide an amended statement that declares *all* the funding or sources of support (whether external or internal to your organization) received during this study, as detailed online in our guide for authors at http://journals.plos.org/plosone/s/submit-now. Please also include the statement “There was no additional external funding received for this study.” in your updated Funding Statement. Please include your amended Funding Statement within your cover letter. We will change the online submission form on your behalf. Response: The suggested changes have been made. 7. We note that you have provided funding information that is not currently declared in your Funding Statement. However, funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form. Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement. Currently, your Funding Statement reads as follows: "This study was partially financed by the Fundação de Apoio à Pesquisa e a Inovação Tecnológica do Estado de Sergipe (Fapitec/SE/Brasil) [Research and Technological Innovation Support Foundation in the State of Sergipe] and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES/Brasil) [Coordination for the Improvement of Higher Education Personnel], financing code 001, PROMOB, process no. 88881.157882/2017-01. https://www.gov.br/capes/pt-br https://fapitec.se.gov.br/ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript." Please include your amended statements within your cover letter; we will change the online submission form on your behalf. Response: The suggested changes have been made. Acknowledgements We thank all the participants who agreed to participate in this study. We also thank TMSV, GBC, RKFS, ACOB, Hypertension Nutrition Care Group (Grupo de Atendimento Nutricional em Hipertensão, GANuH), and Nutrition Laboratory (Laboratório de Nutrição, LABNUT) for assistance in collecting data and analyzing biological samples. 8. In your Data Availability statement, you have not specified where the minimal data set underlying the results described in your manuscript can be found. PLOS defines a study's minimal data set as the underlying data used to reach the conclusions drawn in the manuscript and any additional data required to replicate the reported study findings in their entirety. All PLOS journals require that the minimal data set be made fully available. For more information about our data policy, please see http://journals.plos.org/plosone/s/data-availability. Upon re-submitting your revised manuscript, please upload your study’s minimal underlying data set as either Supporting Information files or to a stable, public repository and include the relevant URLs, DOIs, or accession numbers within your revised cover letter. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories. Any potentially identifying patient information must be fully anonymized. Important: If there are ethical or legal restrictions to sharing your data publicly, please explain these restrictions in detail. Please see our guidelines for more information on what we consider unacceptable restrictions to publicly sharing data: http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions. Note that it is not acceptable for the authors to be the sole named individuals responsible for ensuring data access. We will update your Data Availability statement to reflect the information you provide in your cover letter. Response: The database containing the collected data will be attached. 9. We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide. Response: The suggested changes have been made. 10. Please ensure that you include a title page within your main document. You should list all authors and all affiliations as per our author instructions and clearly indicate the corresponding author. Response: The suggested changes have been made. 11. Please amend either the abstract on the online submission form (via Edit Submission) or the abstract in the manuscript so that they are identical. Response: The suggested changes have been made. 12.Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. Response: The suggested changes have been made. Reviewers' comments: Reviewer #1: The article addresses an important field of nutritional research. Evaluating the relative validity of a dietary assessment method is of great importance when studying the potential impact of diet exposures on health outcomes. The authors constructed an FFQ for foods high in sodium and proposed a validation protocol over a 6-month period of dietary data collection complemented by four 24-hour recalls and two 24-hour urinary excretion for sodium analysis. The FFQ was reproductible but not valid. Despite the good statistical procedures adopted, the writing is not always fluid and sometimes repetitive. The description of the study protocol is not clear. In addition, it is not always clear what each test adds to the overall evaluation of level of validity, which could be made clearer in the method section. Another concern I have is related to the 'per se' construction of FFQ that was done previously with another sample; so, in the middle of the methodology, the authors describe basically another study (not mentioned before) and confuse the reader. Important decisions on how FFQ was built are not provided in the text. Very important: The English needs considerable attention. Response: For validation, the triad method was used by triangulation between the FFQ-FHS, 24hR, and biomarker. For reproducibility, the intraclass coefficient of correlation (ICC) and Kappa coefficient were used; Bland–Altman plots were constructed to graphically demonstrate the level of agreement between the FFQ-FHS, 24hR, and biomarker. More information about the constructed FFQ-FHS has been added to the methodology. Introduction: 1. I suggest deleting the first two paragraphs and getting straight to the point. In the last paragraph, authors could justify why this study was done and, especially to investigate sodium in that region of Brazil. (why a specific FFQ is needed to that region) Response: The suggested changes have been made. The two paragraphs have been deleted, and the justification has been inserted in the last paragraph. In Brazil, independent of the geographical region, the sodium intake of the population is high [11,12] and corresponds to approximately twice the intake recommended by the World Health Organization (WHO) (2 g/day) [13]. Data from the 2008 to 2009 Household Budget Survey show that the contribution of processed and ultra-processed foods to the average sodium intake increased from that observed in the first edition of the survey (2002–2003) [11]. Despite this, studies seeking the validation of a tool to investigate sodium intake in the Brazilian population, especially in the northeast region, remain scarce. Methods 2. I believe that the authors could benefit from checking the manuscript construction of previous FFQ validation studies. As mentioned above, the writing is not fluid and sometimes repetitive. First, provide an overall description of the (i) previous protocol to design the FFQ; (ii) the 6-month protocol to the FFQ validation: FFQ, rec24h, urine collection (in a 6-month period, when each instrument was applied/data was collected, providing the interval period among them). Response: The suggested changes have been made. 3. In the sentence: “Each volunteer answered three 24hR, with a minimum and maximum interval of 15 and 45 days, respectively, and one of 24hR covered one weekend day.” How was the 15-45-day interval decided? Does it depend on the availability of the participant? Response: Each volunteer answered three 24hR questions, with a minimum and maximum interval of 15 and 45 days, respectively, considering the participants' availability, including one day during the weekend. 4. Do FFQ and Rec24h were paper-based methods? Were both a face-to-face interview? Response: Yes, all interviews regarding the application of the R24h and FFQ instruments were conducted face-to-face. 5. Very important: do not describe “researchers” when referring to those people that collected the data in the field work; in this case, I would recommend to describe they as “research assistants” or “assistants”. It is better to restrict the term 'researchers' to those responsible for the study protocol and who wrote the manuscript. Response: The suggested changes have been made. 6. How many research assistants and nutritionists conducted the field work? Was the team composed of undergrad and grad students? Those who applied the dietary instruments had any background in nutrition & dietetics? Response: All four assistants were nutrition graduate students who received training and supervision from the nutritionists. 7. Examples of information that seems repetitive in the text: (a) All the subjects who agreed to participate in the study received information on the study and signed the Free and Informed Consent Form. (b) The participants signed the Free and Informed Consent Form, allowing their voluntary participation, (a) All researchers had been trained and supervised by nutritionists. (b) Nutritionists trained and supervised the anthropometric measurements to ensure higher precision and accuracy of the data. Response: The suggested changes have been made. 8. Rewrite the sentence: To assess daily sodium intake, to the 24hR estimate was added the amount of sodium from added salt. Response: The suggested changes have been made. 9. Briefly describe the data collected from the socioeconomic questionnaire applied. Age, sex, occupation, etc. Response: A structured questionnaire was used to collect sociodemographic information (sex, age, household per capita income, and educational level). 10. Provide more details on the multiple pass method applied in the current protocol. Response: The MPM is an approach technique for applying 24hR, aimed at increasing the accuracy of information. The MPM was proposed in five steps. 1 Quick list 2 Forgotten foods list 3 Time and occasion 4 Detail and review 5 Final review 11. Validation paragraph: It does not add additional information. In the way described, this paragraph can be deleted. Response: The suggested changes have been made. 12. How was the information of the dietary intake of rec24h and FFQ entered in NutWin? Food intake data entered one-by-one? who and how many people entered these data? There was any quality control in the data entered? how portion sizes were defined? The same questions is applied to FFQ. Response: To facilitate the completion of all forms, a photographic manual of food quantification with a preset portion size was used. The standard portion size of each food or meal was defined according to the Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística, IBGE) database of reference measurements and portion sizes of foods and dishes consumed in Brazil. The food nutrient composition was analyzed using NutWin® software (version 1.5.2.51). All items listed in the applied 24hR and FFQ-FHS were standardized and typed individually in duplicate. 13. Describe more about the MSM. What this method proposes and how? Response: More information about the MSM has been included in the statistical analysis section. Results 14. It calls my attention that the sample studied had higher education but low income. Who were they? Undergrad students or staff personnel? It is important to describe it in method section. Response: The suggested changes have been made. 15. Table 1. Replace 'gender' by 'sex'. sex = biologic nature of being female or male. gender = social role construction of being male or female. If you are analyzing urinary excretion, it is more relevant that you provide the information on biology. Also, replace 'nutrition status' by 'body mass index (kg / m2)'. Response: The suggested changes have been made. 16. Replace “CI95%” by 95% CI Response: The suggested changes have been made. 17. I think authors can think about a better presentation on tables. Response: The suggested changes have been made. ________________________________________ Attachment Submitted filename: Response to Reviewers.docx Click here for additional data file. 10.1371/journal.pone.0288123.r003 Decision Letter 1 Rinaldi Ana Elisa Madalena Academic Editor © 2023 Ana Elisa Madalena Rinaldi 2023 Ana Elisa Madalena Rinaldi https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Submission Version1 28 Oct 2022 PONE-D-21-23343R1Food frequency questionnaire for foods high in sodium: validation with the triads methodPLOS ONE Dear Dr. Souza, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. The reviewers highlighed the great quality of the new version of the manuscript. However, one of them highlighted some methodological information are required and are not described in the manuscript. All comments adressed to authors are describe below. Please submit your revised manuscript by Dec 12 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript:A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols. We look forward to receiving your revised manuscript. Kind regards, Ana Elisa Madalena Rinaldi, Ph.D. Academic Editor PLOS ONE Journal Requirements: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: All comments have been addressed Reviewer #2: All comments have been addressed ********** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes ********** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ********** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: No Reviewer #2: Yes ********** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: No Reviewer #2: Yes ********** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The current version of the manuscript had a great improvement from previous one. However, there are still some gaps to be described in the Methods section, considering that this is a methodological study, and it may be used as a reference for future studies in Brazil. Methods: Sodium biomarkers: 1. Please describe the instructions provided for participants of how to collect 24-h urine samples. Also, provide a reference for it. 2. The reference methods applied to verify the completeness of urine samples are not clear. First, is there a reference of less than 400 ml/day for completeness? Second, the study of Charlton KE et al 2008 (21) used multiple parameters, as volume of urine less than 500 ml/day and creatinine 0.2–0.3 mmol kg/day. These parameters and references are very important considering that urine provided the biomarker. If author be more rigid to accept a sample as valid (e.g., equal or more 500 ml/day + creatine output >0.2 mmol kg/day), how many samples would be valid in both methods? Did you test whether concordance with dietary method had improved? 3. Sociodemographic data. Please indicate the currency conversion of Brazilian currency to USD$ at the time of the study. 4. Anthropometric measurements: indicate the equipment (registered brand) of each anthropometric tool (electronic scale, stadiometer, and tape) 5. Food composition analysis of FFQ: Has NutWin a specific interface for FFQ calculation? Or were all food items converted to daily portion size in order to be entered in this software? Please, describe in methods. 6. Statistics: Which method was applied to calculate energy adjustment? 7. Line 200: Correct typing mistake “With Rregard to nutritional 200 status…” 8. Table 1: present variables summarized as mean first, then after the categorical ones; Use only 1 decimal to summarize age 9. Results: Line 209-211: Adequacy in urine sample collection: First, there is no need to repeat the parameter in parenthesis already described in methods; second, indicate how many were adequate according to volume and how many according to creatinine value. Also, as described above, test whether being more rigid in urine assessments could improve the final results with dietary methods. Reviewer #2: Thank you for addressing all the comments from the reviewers. The suggestions were incorporated to the manuscript. ********** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: Yes: Juliana dos Santos Vaz Reviewer #2: No ********** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. 10.1371/journal.pone.0288123.r004 Author response to Decision Letter 1 Submission Version2 24 Feb 2023 Response to Reviewers Methods: Sodium biomarkers: 1. Please describe the instructions provided for participants of how to collect 24-h urine samples. Also, provide a reference for it. Response: A 24-hour urine collection was adopted as an instrument to assess creatinine clearance and estimate Na+ electrolyte intake. Participants were instructed regarding urine collection and received a 2 L plastic bottle. Furthermore, the participants received a questionnaire containing written information about the correct urine collection procedure to be completed and delivered on the scheduled day. The following collection instructions were standardized: - At the beginning of the collection, the participant discarded all urine stored in the bladder in the toilet. From then on, the participant stored all urine, including night and bath urine, in the bottle until the next day. - The collected urine wasstored in a refrigerator, both during and after collection. Reference: Sociedade Brasileira de Patologia Clínica/Medicina Laboratorial(SBPC/ML). Recomendações da Sociedade Brasileira de Patologia Clínica/Medicina Laboratorial (SBPC/ML): coleta e preparo da amostra biológica. Barueri, SP: Manole: Minha Editora. 2014: 487p. 2. The reference methods applied to verify the completeness of urine samples are not clear. First, is there a reference of less than 400 ml/day for completeness? Second, the study of Charlton KE et al 2008 (21) used multiple parameters, as volume of urine less than 500 ml/day and creatinine 0.2–0.3 mmol kg/day. These parameters and references are very important considering that urine provided the biomarker. If author be more rigid to accept a sample as valid (e.g., equal or more 500 ml/day + creatine output >0.2 mmol kg/day), how many samples would be valid in both methods? Did you test whether concordance with dietary method had improved? Response: For the metabolites to be excreted, a minimum urine volume of 400mL is required, according to Nemeret al. (2010). For this research, urine samples lessthan 400mL and/or those whose collection period exceeded the determined 24 h were excluded. Creatinine excretion was also analyzed as an indicator of adequate urine collection. Urine samples with creatinine levels<0.2 mmol/kg/day were excluded. The results were converted to mg/kg/day (CHARLTON, et al., 2008). When performing urinary creatinine analysis, only one participant met the exclusion criterion of creatinine <0.2 mmol/kg/day, obtaining a result of 0.171 mmol/kg/day in the second urine sample collected. 3. Sociodemographic data. Please indicate the currency conversion of Brazilian currency to USD$ at the time of the study. Response: The suggested changes have been made. 4. Anthropometric measurements: indicate the equipment (registered brand) of each anthropometric tool (electronic scale, stadiometer, and tape) Response: Digital platform scale, with 100g precision (LIDER®, São Paulo, Brazil) Portable Stadiometer, with 0.1 cm resolution (Alturaexata®, Minas Gerais, Brazil) 5. Food composition analysis of FFQ: Has NutWin a specific interface for FFQ calculation? Or were all food items converted to daily portion size in order to be entered in this software? Please, describe in methods. Response: For the analysis of the nutritional composition of the food frequency questionnaire (FFQ), all items were converted into individual consumption portions and subsequently tabulated using the software. 6. Statistics: Which method was applied to calculate energy adjustment? Response: Sodium intake was adjusted using the residual method to control for confounding factors and remove external oscillations, according to Willetet al. (1997). Simple linear regression analysis was performed, considering energy as an independent variable and sodium as a dependent variable. 7. Line 200: Correct typing mistake “With Rregard to nutritional 200 status…” Response: The suggested changes have been made. 8. Table 1: present variables summarized as mean first, then after the categorical ones; Use only 1 decimal to summarize age Response: The suggested changes have been made. 9. Results: Line 209-211: Adequacy in urine sample collection: First, there is no need to repeat the parameter in parenthesis already described in methods; second, indicate how many were adequate according to volume and how many according to creatinine value. Also, as described above, test whether being more rigid in urine assessments could improve the final results with dietary methods. Response: Considering a urinary volume of ≥ 500mL, 43 and 36 urine samples from the first collection and second collections, respectivelywere considered adequate. By joining two exclusion criteria (e.g., equal or more 500 mL/day + creatine output >0.2 mmol kg/day), 43 urine samples from the first collection and 32 samples from the second collection were considered adequate. New statistical tests were performed on the 32 urine samples. The table below presents the results. Table 1. Spearman’s correlation and validity coefficients for unadjusted and energy-adjusted daily sodium intake in adults in the academic community. Aracaju, SE, 2018 (n=50) Correlation coefficient Validity coefficient Unadjusted (p) Adjusted (p)* Adjusted* rFFQR 0.386 (<0.01) 0.129 (0.387) ρFFQAI 0.26 rRB† −0.026 (0.882) 0.172 (0.316) ρRAI† 0.85 rFFQB† 0.014 (0.936) 0.052 (0.763) ρBAI† 0.20 rFFQR, correlation between the food frequency questionnaire survey and the 24-h dietary recall rRB, correlation between the 24-h dietary recall and biomarker assessment rFFQB, correlation between the food frequency questionnaire survey and biomarker assessment ρFFQAI, validity coefficient of the food frequency questionnaire survey ρRAI, validity coefficient of the 24-h dietary recall ρBAI, biomarker validity coefficient ρFFQAI=√([rFFQR x rFFQB])/rRB ρRAI=√([rFFQR x rRB])/rFFQB ρBAI=√([rRB x rFFQB])/rFFQR *Daily energy-adjusted sodium intake †n,36 using the average urinary sodium excretion Table 2. Spearman’s correlation and validity coefficients for unadjusted and energy-adjusted daily sodium intake in adults in the academic community. Aracaju, SE, 2018 (n=32) Correlation coefficient Validity coefficient Unadjusted (p) Adjusted (p)* Adjusted* rFFQR 0.242 (0.182) 0.244 (0.178) ρFFQAI 0.23 rRB† 0.139 (0.449) 0.232 (0.201) ρRAI 1.06 rFFQB† 0.225 (0.215) 0.050 (0.786) ρBAI 0.22 The repetition of statistical tests demonstrates that even after considering new inclusion parameters for adequate urine samples (e.g., equal or more 500 ml/day + creatine output >0.2 mmol kg/day), the correlations and validity coefficients remained insufficient for the FFQAI validation. Attachment Submitted filename: 2. Response_to_Reviewers.docx Click here for additional data file. 10.1371/journal.pone.0288123.r005 Decision Letter 2 Righini Nicoletta Academic Editor © 2023 Nicoletta Righini 2023 Nicoletta Righini https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Submission Version2 19 Apr 2023 PONE-D-21-23343R2Questionário de frequência alimentar para alimentos ricos em sódio: validação com o método das tríadesPLOS ONE Dear Dr. Souza, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.  All the previous queries have been addressed, there are only a few minor details that need to be taken care of. Once these are done, I consider that the ms can be accepted. Please submit your revised manuscript by Jun 03 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript:A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols. We look forward to receiving your revised manuscript. Kind regards, Nicoletta Righini, PhD Academic Editor PLOS ONE Journal Requirements: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: All comments have been addressed ********** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes ********** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes ********** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes ********** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes ********** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The authors addressed all comments raised in a previous round of review. The current version of the manuscript now reports all methodological aspects required in a validation study. I just request some minor corrections in the text, and 1-2 other adjustments in tables and text. Please add spacing in the following passages: Line 42: “However, Bshave limitations…” = B have Line 43: “…Blevels…” = B levels Line 47: “… 24hR or FR, and Bs,…” = B (all other instruments described in this sentence are in singular version) Line 58: “… to2009…” Line 62: “… remainscarce” Line 75: “… 2018.Fifty…” Line 85: “… period of 6months..” = 6 months Line 89: Fig1 Data collectionprocess Line 94: “…24hR and FFQ-FHS survey,” = there is no need the term “survey” Line 96: “… was completed after the 24hRviaface-to-face…” Line 123: “After 3months…” = 3 months Line 124: “…24hRsusing…” Line 140: “[10]to determine” Line 164: “…precision of 1millimeter” = 1 millimeter Line 325: “… notwithstanding…” Line 370: “… duringin-person interviews,…” Line 386: “… over a period of 6months” = 6 months Line 77: Please, reedit the sentence: “We excluded pregnant and lactating women…" Other minor corrections: Please review in all Tables and Bland and Altman figure the following: Clear state in the tables when the “adjusted” means “energy adjusted”, otherwise it means traditional statistical adjustments for covariates. Line 296: “… which eventually lost significance after adjustment.” Does it mean energy adjustment? Please specify in the text. ********** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: Yes: Juliana Vaz ********** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. 10.1371/journal.pone.0288123.r006 Author response to Decision Letter 2 Submission Version3 19 Jun 2023 I just request some minor corrections in the text, and 1-2 other adjustments in tables and text. Please add spacing in the following passages: Line 42: “However, Bshave limitations…” = B have Line 43: “…Blevels…” = B levels Line 47: “… 24hR or FR, and Bs,…” = B (all other instruments described in this sentence are in singular version) Line 58: “… to2009…” Line 62: “… remainscarce” Line 75: “… 2018.Fifty…” Line 85: “… period of 6months..” = 6 months Line 89: Fig1 Data collectionprocess Line 94: “…24hR and FFQ-FHS survey,” = there is no need the term “survey” Line 96: “… was completed after the 24hRviaface-to-face…” Line 123: “After 3months…” = 3 months Line 124: “…24hRsusing…” Line 140: “[10]to determine” Line 164: “…precision of 1millimeter” = 1 millimeter Line 325: “… notwithstanding…” Line 370: “… duringin-person interviews,…” Line 386: “… over a period of 6months” = 6 months Line 77: Please, reedit the sentence: “We excluded pregnant and lactating women…" Response: The requested corrections have been made. Other minor corrections: Please review in all Tables and Bland and Altman figure the following: Clear state in the tables when the “adjusted” means “energy adjusted”, otherwise it means traditional statistical adjustments for covariates. Response: The suggested changes have been made. Line 296: “… which eventually lost significance after adjustment.” Does it mean energy adjustment? Please specify in the text. Response: Yes, does it mean energy adjusment. The suggested changes have been made. Attachment Submitted filename: Response to Reviewers.doc Click here for additional data file. 10.1371/journal.pone.0288123.r007 Decision Letter 3 Righini Nicoletta Academic Editor © 2023 Nicoletta Righini 2023 Nicoletta Righini https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Submission Version3 20 Jun 2023 Questionário de frequência alimentar para alimentos ricos em sódio: validação com o método das tríades PONE-D-21-23343R3 Dear Dr. Souza, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Nicoletta Righini, PhD Academic Editor PLOS ONE Additional Editor Comments (optional): All the comments were addressed by the authors and the minor corrections were performed. Reviewers' comments: 10.1371/journal.pone.0288123.r008 Acceptance letter Righini Nicoletta Academic Editor © 2023 Nicoletta Righini 2023 Nicoletta Righini https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 23 Jun 2023 PONE-D-21-23343R3 Food frequency questionnaire for foods high in sodium: validation with the triads method Dear Dr. Souza: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Nicoletta Righini Academic Editor PLOS ONE ==== Refs References 1 Pereira TSS , Cade NV , Mill JG , Sichieri R , Molina MD . Use of the method of triads in the validation of sodium and potassium intake in the Brazilian longitudinal study of adult health (ELSA-Brasil). PLOS ONE. 2016;11 : e0169085. doi: 10.1371/journal.pone.0169085 28030625 2 Miranda Alatriste PV , Ramírez EC , Guillén Hernández M , Rivera Mancía S , Cartas Rosado R , Espinosa-Cuevas Á , et al . Development of a screening tool for a high sodium intake in an adult Mexican population. Nutr hosp. 2018;35 : 1163–1173. doi: 10.20960/nh.1789 30307301 3 Gallani MC , Proulx-Belhumeur A , Almeras N , Després JP , Doré M , Giguère JF . Development and validation of a salt food frequency questionnaire (FFQ-Na) and a Discretionary Salt Questionnaire (DSQ) for the evaluation of salt intake among French-Canadian population. Nutrients. 2020;13 : 105. doi: 10.3390/nu13010105 33396829 4 Kaaks RJ . Biochemical markers as additional measurements in studies of the accuracy of dietary questionnaire measurements: conceptual issues. Am J Clin Nutr. 1997;65 (suppl ): 1232S–1239S. doi: 10.1093/ajcn/65.4.1232S 9094927 5 Ocké MC , Kaaks RJ . Biochemical markers as additional measurements in dietary validity studies: application of the method of triads with examples from the European Prospective Investigation into Cancer and Nutrition. Am J Clin Nutr. 1997;65 (4)(suppl ): 1240S–1245S. doi: 10.1093/ajcn/65.4.1240S 9094928 6 Kaaks R , Ferrari P , Ciampi A , Plummer M , Riboli E . Uses and limitations of statistical accounting for random error correlations, in the validation of dietary questionnaire assessments. Public Health Nutr. 2002;5 : 969–976. doi: 10.1079/phn2002380 12638598 7 Cardoso MA . Desenvolvimento, validação e aplicações de Questionários de freqüência alimentar em estudos epidemiológicos. In: Kac G , Sichieri R , Gigante DP , editors. Epidemiologia nutricional. Rio de Janeiro: Editora Fiocruz/Atheneu; 2007. 8 Da Silva DCG , Segheto W , de Lima MFC , Pessoa MC , Pelúzio MCG , Marchioni DML , et al . 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