Estimation of Sodium and Potassium Intake: Current Limitations and Future Perspectives

The potassium puzzle: exploring the intriguing connection to albuminuria

Background

Studies have revealed a relationship between dietary potassium intake and albuminuria, despite the fact that the human body needs a lot of potassium. Our study concentrated on the link between dietary potassium intake and albuminuria.

Methods

This study used subgroup analysis and weighted multivariate regression analysis. Data from the National Health and Nutrition Examination Survey (NHANES) were examined to determine the urinary albumin-to-creatinine ratio (ACR) and participant age (20 years or older). ACR >30 mg/g was the threshold for albuminuria.

Results

7,564 individuals in all were included in the study. The link between the two was significant in both our original model (OR = 0.99; 95% CI, 0.98-0.99, p < 0.0001) and the minimum adjusted model (OR = 0.99; 95% CI, 0.98-0.99, p < 0.0001). A fully adjusted model did not change the significance of the negative correlation between potassium consumption and albuminuria (OR = 0.99; 95% CI, 0.98-1.00, p = 0.0005), indicating that each unit increase in potassium intake was related with a 1% decrease in the chance of developing albuminuria. The negative correlation between potassium intake and albuminuria was not significantly influenced by sex, age, BMI, hypertension, diabetes, or smoking, according to interaction tests (p for interaction >0.05).

Conclusion

Reduced risk of albuminuria was linked to higher dietary potassium intake. The particular mechanism linking the two still has to be explained by several inventive and prospective studies.

Association between sodium and potassium excretion estimated from spot urine and socioeconomic status among primary school children and their mothers in Okinawa, Japan

Hypertension is the greatest and the most preventable risk factor for cardiovascular disease. Excessive sodium (Na) intake and insufficient potassium (K) intake have been identified as risk factors for hypertension. Socioeconomic status (SES) may be related to diet quality. In Japan, few studies have examined the relationship between urinary Na and K excretion and SES in adults, and there are no studies in children. In 2014, 1944 children (1382 households) in all public elementary schools in Yaese town, Okinawa, Japan were recruited to participate in a study. Casual urine specimens were collected to estimate 24-h urinary Na and K excretion and urinary Na/K ratio. Mother's educational background and household incomes were assessed and used as indicators of SES. A total of 236 pairs of children and their mothers were analyzed in this study. Urinary Na and K excretion were not significantly related to educational levels of mothers and household incomes in children. On the other hand, in mothers, lower household income group had higher 24-h estimated urinary Na excretion and urinary Na/K ratio than other groups. There was no significant difference between urinary excretion and educational levels in mothers. Household income disparities in urinary levels seen in mothers were not seen in children. There may be some factors that moderate the dietary inequalities in children.

Phosphorus Intake and Potential Dietary Influences Examined via 24-Hour Urinary Biomarker Measurements in German Children and Adolescents Over 3 Decades

BACKGROUND

Increases in phosphorus intake have been observed over the past years in adult populations. However, biomarker-based data are lacking on whether or not phosphorus intake also increased in children.

OBJECTIVE

The aim of this study was to examine 24-hour urinary phosphate excretion (PO4-Ex) and diet-related biomarkers potentially influencing phosphorus status in German children and adolescents from 1985 to 2015.

DESIGN

This longitudinal noninvasive biomarker-based cohort study examined 24-hour urine samples from children and adolescents of the Dortmund Nutritional and Anthropometric Longitudinally Designed Study, collected over 3 decades.

PARTICIPANTS/SETTING

Examined individuals (n = 1,057) were healthy participants of the Dortmund Nutritional and Anthropometric Longitudinally Designed Study, situated in Dortmund, Germany, who had been asked to collect one yearly 24-hour urine sample. Six thousand seven hundred thirty-seven samples collected from participants aged 3 to 17 years between 1985 (baseline) and 2015, were included.

MAIN OUTCOME MEASURES

phosphorus intake was examined biomarker-based by analyzed PO4-Ex in 24-hour urine samples. Whether acid-base status and intakes of protein, salt, and fruits and vegetables, may have relevantly contributed to PO4-Ex levels was assessed by determining 24-hour excretions of net acid, urea-nitrogen, and sodium as well as specific standardized excretions of potassium plus oxalate.

STATISTICAL ANALYSES PERFORMED

Trend analysis over 30 years and potentially influencing diet factors were examined using linear mixed-effect regression models (PROC-MIXED). Adjustments for sex, age, and body surface area were performed.

RESULTS

No change was identifiable for PO4-Ex over the 3 decades; neither in 3 to 8, 9 to 13, nor in 14 to 17 year olds. However, sodium excretion increased (P = .001). PROC-MIXED analysis on intraindividual changes in PO4-Ex revealed direct relationships with net acid excretion, urea-nitrogen, and sodium excretion and an inverse relationship with a biomarker of fruit and vegetable intake.

CONCLUSIONS

Despite a direct relationship between PO4-Ex and a biomarker of industrially processed food consumption; that is, sodium excretion, which showed an increasing time trend, phosphorus intake was found to remain stable over decades in children and adolescents.

Moderate stepwise restriction of potassium intake to reduce risk of hyperkalemia in chronic kidney disease: A literature review

A potassium-rich diet has several cardiovascular and renal health benefits; however, it is not recommended for patients with advanced chronic kidney disease or end-stage kidney disease because of the risk of life-threatening hyperkalemia. To assess the strength of evidence supporting potassium intake restriction in chronic kidney disease, the medical literature was searched looking for the current recommended approach and for evidence in support for such an approach. There is a lack of strong evidence supporting intense restriction of dietary potassium intake. There are several ways to reduce potassium intake without depriving the patient from fruits and vegetables, such as identifying hidden sources of potassium (processed food and preservatives) and soaking or boiling food to remove potassium. An individualized and gradual reduction of dietary potassium intake in people at risk of hyperkalemia is recommended. The current potassium dietary advice in chronic kidney disease needs to be reevaluated, individualized, and gradually introduced.

Does the Mediterranean Dietary Pattern Promote Lower Sodium Urinary Excretion in Children?

An adequate sodium intake is related to various health benefits. Parallelly, the Mediterranean diet (MD) is a dietary pattern known for its many positive impacts on health. Nonetheless, the association between adherence to the MD and sodium urinary excretion is scarce, even more in children. This study aimed to assess the association between MD adherence and the excretion of sodium, as a proxy of intake. This cross-sectional analysis comprised 295 children (46.8% females, aged 7-11 years, mean age: 8.53 ± 0.73 years) from 20 schools within Porto, Portugal. MD adherence was evaluated utilizing the alternate Mediterranean score (aMED). Higher scores denote a healthier dietary pattern (0-8). Sodium excretion was estimated by 24-h urine collection. The association between adherence to MD and Na excretion was estimated by logistic regression, adjusting for confounders. Children in the higher sodium excretion group had a higher intake of legumes, a higher body mass index and parents with lower education levels compared to children in the lower sodium excretion group. In logistic regression analysis, sodium urinary excretion was not associated with higher MD adherence, even after adjustment for confounders. High MD adherence could not be associated with lower sodium excretion in children.

Quality Evaluation of Shiitake Blanched and Centrifuged Broths as Functional Instant Drinks

In the process of making mushrooms into vacuum-fried crisps, the resulting blanched broth (BB) and centrifuged broth (CB) are often discarded, thereby increasing the amount of wastewater and treatment costs. This study measured the proximate compositions, bioactive components, taste components, and minerals of freeze-dried BB and CB and then used functional indigestible dextrin (Fibersol-2) as a carrier to make these two broths into instant drinks. The solids of the BB and CB contained protein (16.88-19.21%), fat (0.01-0.23%), ash (12.89-13.50%), carbohydrate (67.28-70.00%), sugars and polyols (40.55-45.68%), free amino acids (6.58-6.69%), 5'-nucleotides (0.98-1.47%), and bioactive components, especially polysaccharides (4.53-7.45%), ergothioneine (both 0.19%), and total phenols (0.15-0.36%). The equivalent umami concentration of BB was 2.77-fold higher than that of the CB. Both BB and CB showed compositions and essential minerals that are rich in taste. Using a nine-point hedonic test, it was found that the solid contents of BB and CB in the instant drink affected the consumer's preference. The flavor and overall preference of instant drinks with 2.5% BB or CB were the best amongst consumers. Overall, the BB and CB were rich in nutrients and bioactive and taste components and could be developed as a functional food in the form of a drink.

Salt Substitutes-An Important Tool to Increase Potassium and Reduce Sodium Intakes?

Potassium is an essential mineral and is the main cation in intracellular fluid [...].

Comparison between 24-hour diet recall and 24-hour urine collection for estimating sodium and potassium intakes and their ratio among Korean adults

BACKGROUND/OBJECTIVES

This study aimed to compare 24-h diet recall (DR) and 24-h urine collection (UC) for estimating sodium and potassium intakes and their ratio (Na/K), identifying factors associated with sodium and potassium intakes and Na/K, and identifying those who were likely to underestimate sodium and potassium intakes by DR.

SUBJECTS/METHODS

A total of 640 healthy adults aged 19-69 yrs completed a questionnaire survey, salty taste assessment, anthropometric measurement, two 24-h DRs, and two 24-h UCs.

RESULTS

The mean sodium and potassium intakes and Na/K were 3,755 mg/d, 2,737 mg/d, and 1.45 according to DR, and 4,145 mg/d, 2,812 mg/d, and 1.57 according to UC, with percentage differences of -9.4%, -2.7%, and -7.6% in the values between the two methods, respectively. Men, older adults, smokers, obese individuals, those who consumed all the liquid in the soup, and those who were found to be salty in the salty taste assessment consumed significantly more sodium; older adults, the heavy- activity group, and obese individuals consumed more potassium; and men, younger adults, smokers, and obese individuals had a significantly higher Na/K, according to UC. Compared with UC, DR was more likely to underestimate sodium intake in older adults, smokers, obese individuals, those who consumed all the liquid in the soup, and those who consumed eating-out/delivery food at least once a day, and potassium intake in older adults, the heavy-activity group, and obese individuals.

CONCLUSIONS

The mean sodium and potassium intakes and Na/K estimated by DR were comparable to those measured by UC. However, the association of sodium and potassium intakes with sociodemographic and health-related factors showed inconsistent results when estimated by DR and UC. Factors influencing the underestimation of sodium intake by DR compared to UC should be further investigated.

Association Between Dietary Potassium Intake Estimated From Multiple 24-Hour Urine Collections and Serum Potassium in Patients With CKD

Introduction

Limited and inconclusive evidence for the association of dietary potassium intake with serum potassium in chronic kidney disease (CKD) patients have been shown, though restricting dietary potassium has been recommended for CKD patients to prevent hyperkalemia. Multiple 24-hour urine collections are necessary to adequately assess potassium intake. We investigated associations of 24-hour urinary potassium excretion (UKV) with serum potassium in CKD outpatients based on multiple 24-hour urine collections.

Methods

This retrospective cohort study was based on outpatients with CKD stages G3 to G5, median age of 72.0 years; and median follow-up of 3.9 months and 8.9 months, respectively, for analyses using 3-time measurement (N = 290 and 870 observations) and 7-time measurements (N = 220 and 1540 observations). The outcome was serum potassium.

Results

Multivariable-adjusted mean difference in serum potassium (mEq/l) and odds ratio of hyperkalemia per 10 mEq/d increase in UKV were, respectively, 0.12 (95% confidence interval [CI]: 0.09-0.15) and 2.15 (1.70-2.73) in generalized estimating equations (GEEs) with 3-time measurements. The mean difference became more pronounced as CKD stages progressed: 0.08 (0.05-0.12), 0.12 (0.08-0.16), and 0.16 (0.12-0.20) for CKD G3, G4, and G5. Similar results were obtained from analyses using 7-time measurements and hierarchical Bayesian measurement error models treating measurement error of UKV adequately.

Conclusion

We suggest significant but weak associations (R²: 0.08, 0.14, and 0.18 for CKD G3, G4, and G5) between serum potassium and dietary potassium intake estimated by multiple 24-hour urine collections in CKD patients. Further studies are needed to validate nutritional and clinical aspects of the associations.

Nutri-Score: Its Benefits and Limitations in Children's Feeding

Reducing the burden of noncommunicable diseases (NCDs) is one of the top priorities of public health policies worldwide. One of the recognized means of achieving this objective is to improve the diet quality. The Nutri-Score (N-S) is a [five-color-A, B, C, D, E letters] front-of-pack labeling logo intended to help consumers quickly identify the healthier prepackaged foods within a food category. Available studies have shown that the N-S is an efficient tool to achieve this aim in terms of consumers' awareness, perception, understanding, and purchasing and that its use may help to reduce the prevalence of NCDs. The N-S is currently implemented on a voluntary basis in 7 European countries and a discussion is underway within the European Commission to achieve a harmonized mandatory label. However, no study on the putative impact of the N-S on children's dietary patterns and health is available. The N-S is not applicable to infants' and young children's formulas and to specific baby foods, the compositions of which are already laid down in European Union regulations. The N-S does not replace age-appropriate dietary guidelines. As children consume an increasing number of adult type and processed foods, the relevance of the N-S for children should be evaluated considering the children's high specific requirements, especially in younger children. This is especially necessary for fitting fat and iron requirements, whereas protein-rich foods should be better framed. Moreover, efforts should be made to inform on how to use the N-S and in education on healthy diets.

Dietary sodium, potassium intake, sodium-to-potassium ratio and risk of hypertension: a protocol for systematic review and dose-response meta-analysis of cohort studies

INTRODUCTION

Hypertension (HTN) is the leading cause of disease and death on a global scale. Diet's sodium and potassium levels may synergistically affect blood pressure. Currently, the sodium-to-potassium (Na/K) ratio is becoming a more reliable indicator. There has not been a systematic investigation of the dose-response relationship between dietary sodium, potassium, the Na/K ratio and the incidence of HTN based on the same study criteria. This study will conduct a thorough dose-response meta-analysis of cohort studies to estimate the effects of dietary sodium, potassium, and the Na/K ratio on the incidence of HTN to provide the most accurate reference for sodium and potassium intake.

METHODS AND ANALYSIS

We will identify all relevant prospective and retrospective cohort studies by searching PubMed, Embase and Web of Science (from inception until December 2022). Exposures are 24 hours urinary excretions, and the outcome is the incidence of HTN. Two researchers will perform the literature selection and data extraction separately. The Newcastle-Ottawa Scale will be used to evaluate the quality of the included studies. We will use both linear and non-linear regression models to investigate the dose-response relationship among different levels (≥3) of sodium, potassium, Na/K ratio intake and the incidence of HTN (OR/RR/HR). Subgroup and sensitivity analyses will be applied to assess the potential heterogeneity sources and examine the stability of the results. We will also evaluate heterogeneity across studies and publication bias. Stata V.15.0 and RevMan V.5.0 will be used for statistical analyses.

ETHICS AND DISSEMINATION

According to the Institutional Review Board/Independent Ethics Committee of the Guang'anmen Hospital of the China Academy of Chinese Medical Science, this systematic meta-analysis protocol does not require ethical approval or informed consent. This meta-analysis will be published in a scientific journal with peer reviews.

PROSPERO REGISTRATION NUMBER

CRD42022331203.

Salt-related practices and its association with 24-hour urinary sodium excretion in an Uruguayan population cohort

Objectives.

To evaluate the association between knowledge, attitudes, and behavior (KAB) towards sodium use and sodium intake measured by 24-hour urinary collection in an adult cohort from Uruguay (Genotype Phenotype and Environment of Hypertension Study, GEFA-HT-UY).

Methods.

In a cross-sectional study (n = 159), a single 24-hour urinary sample, participants' physical, biochemical and blood pressure measurements and questionnaire data were collected. The association between KAB and 24-hour urinary sodium excretion was assessed using general linear models.

Results.

Mean age of participants was 49.8±15.5 years, 67.9% were women, and mean 24-hour urinary sodium excretion was 3.6±1.7 g/day. Although 90.6% of participants exceeded the maximum recommended intake as indicated by urinary sodium excretion, more than half misperceived their actual intake, reporting consuming “the right amount.” Almost three-quarters of the participants reported being concerned about the amount of sodium in their diet, but only 52.8% reported taking action to control it. Lack of procedural knowledge was observed. There was no association between KAB and sodium use and intake assessed by 24-hour urinary sodium excretion.

Conclusions.

The lack of association between KAB towards the use of sodium and intake measured by 24-hour urinary excretion reflects the need to support people with opportunities and motivations to reduce sodium consumption. Structural actions to promote an adequate food environment, such as the effective implementation of the front-of-package nutrition labeling in Uruguay, are positive steps.

A Method for Estimating 24 h Urinary Sodium and Potassium Excretion by Spot Urine Specimen in Stroke Patients

Spot urine specimens have been used to estimate 24 h urinary sodium (Na) excretion (24UNaV) and potassium (K) excretion (24UKV). However, the validity is limited for 24UNaV and unknown for 24UKV in stroke patients, using the existing formulas. Herein, we developed and validated a new formula for 24UNaV and 24UKV by spot urine specimens in stroke patients. Spot and 24 h urine samples were collected from 970 stroke patients. The models of 24UNaV and 24UKV were developed using stepwise multivariate linear regression in 689 patients. The performance of different formulas was internally validated in 281 patients at the population and individual levels. The obtained new formulas were: (1) estimated 24UNaV (mmol/day): -0.191 × Age + 4.349 × BMI + 0.229 × Spot_Na + 1.744 × Spot_Na/Spot creatinine (Cr) + 41.492 (for male); -1.030 × Age + 2.011 × BMI + 0.143 × Spot_Na + 1.035 × Spot_Na/Spot_Cr + 147.159 (for female); and (2) estimated 24UKV (mmol/day): -0.052 × Age + 0.410 × BMI + 0.031 × Spot_K + 33.280 × Ln (spot_K/spot _Cr) - 5.789 × Ln (spot_Na/spot _Cr) - 1.035 (for male); -0.235 × Age + 0.530 × BMI + 0.040 × Spot_K + 30.990 × Ln (spot _K/spot _Cr) - 7.837 × Ln (spot_Na/spot_Cr) + 4.318 (for female). The new formula obtained the lowest mean bias (5.17 mmol/day for 24UNaV and 0.85 mmol/day for 24UKV) and highest proportion at the cutoff under the ±30% level for the estimation of 24UNaV (59.43%) and 24UKV (70.11%). The new formula provides a meaningful exploration to estimate 24UNaV and 24UKV in stroke patients by using spot urine specimens.

Accuracy of equations for predicting 24-h urinary potassium excretion from spot urine samples in Chinese children

Accurate assessments of potassium intake in children are important for the early prevention of CVD. Currently, there is no simple approach for accurate estimation of potassium intake in children. We aim to evaluate the accuracy of 24-h urinary potassium excretion (24UKV) estimation in children using three common equations: the Kawasaki, Tanaka and Mage formulas, in a hospital-based setting. A total of 151 participants aged 5-18 years were initially enrolled, and spot urine samples were collected in the whole 24-h duration to measure the concentrations of potassium and creatinine. We calculated the mean difference, absolute and relative difference and misclassification rate between measured 24UKV and the predicted ones using Kawasaki, Tanaka and Mage formulas in 129 participants. The mean measured 24UKV was 1193·3 mg/d in our study. Mean differences between estimated and measured 24UKV were 1215·6, -14·9 and 230·3 mg/d by the Kawasaki, Tanaka and Mage formulas, respectively. All estimated 24UKV were significantly different from the measured values in all the time point (all P < 0·05), except for the predicted values from Tanaka formula using morning, afternoon and evening spot urine. The proportions with relative differences over 40 % were 87·2%, 32·5% and 47·3 % for Kawasaki, Tanaka and Mage formulas, respectively. Misclassification rates were 91·5 % for Kawasaki, 44·4 % for Tanaka and 58·9 % for Mage formula at the individual level. Our findings showed that misclassification could occur on the individual level when using Kawasaki, Tanaka and Mage formulas to estimate 24UKV from spot urine in the child population.

Prediction Tool to Estimate Potassium Diet in Chronic Kidney Disease Patients Developed Using a Machine Learning Tool: The UniverSel Study

There is a need for a reliable and validated method to estimate dietary potassium intake in chronic kidney disease (CKD) patients to improve prevention of cardiovascular complications. This study aimed to develop a clinical tool to estimate potassium intake using 24-h urinary potassium excretion as a surrogate of dietary potassium intake in this high-risk population. Data of 375 adult CKD-patients routinely collecting their 24-h urine were included to develop a prediction tool to estimate potassium diet. The prediction tool was built from a random sample of 80% of patients and validated on the remaining 20%. The accuracy of the prediction tool to classify potassium diet in the three classes of potassium excretion was 74%. Surprisingly, the variables related to potassium consumption were more related to clinical characteristics and renal pathology than to the potassium content of the ingested food. Artificial intelligence allowed to develop an easy-to-use tool for estimating patients' diets in clinical practice. After external validation, this tool could be extended to all CKD-patients for a better clinical and therapeutic management for the prevention of cardiovascular complications.

Modifiable Lifestyle Behaviors and CKD Progression: A Narrative Review

Living a healthy lifestyle is one of the safest and most cost-effective ways to improve one's quality of life and prevent and/or manage chronic disease. As such, current CKD management guidelines recommend that patients adhere to a healthy diet, perform ≥150 minutes per week of physical activity, manage their body weight, abstain from tobacco use, and limit alcohol. However, there are limited studies that investigate the relationship between these lifestyle factors and the progression of CKD among people with established CKD. In this narrative review, we examine the reported frequencies of health lifestyle behavior engagement among individuals with non-dialysis-dependent CKD and the existing literature that examines the influences of diet, physical activity, weight management, alcohol consumption, and tobacco use on the progression of CKD, as measured by decline in GFR, incident ESKD, or elevated proteinuria or albuminuria in individuals with CKD. Many of the available studies are limited by length of follow-up and small sample sizes, and meta-analyses were limited because the studies were sparse and had heterogeneous classifications of behaviors and/or referent groups and of CKD progression. Further research should be done to determine optimal methods to assess behaviors to better understand the levels at which healthy lifestyle behaviors are needed to slow CKD progression, to investigate the effect of combining multiple lifestyle behaviors on important clinical outcomes in CKD, and to develop effective techniques for behavior change. Despite the lack of evidence of efficacy from large trials on the ability of lifestyle behaviors to slow CKD progression, maintaining a healthy lifestyle remains a cornerstone of CKD management given the undisputed benefits of healthy lifestyle behaviors on cardiovascular health, BP control, and survival.

A New Carbohydrate Food Quality Scoring System to Reflect Dietary Guidelines: An Expert Panel Report

Existing metrics of carbohydrate food quality have been based, for the most part, on favorable fiber- and free sugar-to-carbohydrate ratios. In these metrics, higher nutritional quality carbohydrate foods are defined as those with >10% fiber and <10% free sugar per 100 g carbohydrate. Although fiber- and sugar-based metrics may help to differentiate the nutritional quality of various types of grain products, they may not aptly capture the nutritional quality of other healthy carbohydrate foods, including beans, legumes, vegetables, and fruits. Carbohydrate food quality metrics need to be applicable across these diverse food groups. This report introduces a new carbohydrate food scoring system known as a Carbohydrate Food Quality Score (CFQS), which supplements the fiber and free sugar components of previous metrics with additional dietary components of public health concern (e.g., sodium, potassium, and whole grains) as identified by the Dietary Guidelines for Americans. Two CFQS models are developed and tested in this study: one that includes four dietary components (CFQS-4: fiber, free sugars, sodium, potassium) and one that considers five dietary components (CFQS-5: fiber, free sugars, sodium, potassium, and whole grains). These models are applied to 2596 carbohydrate foods in the Food and Nutrient Database for Dietary Studies (FNDDS) 2017−2018. Consistent with past studies, the new carbohydrate food scoring system places large percentages of beans, vegetables, and fruits among the top scoring carbohydrate foods. The whole grain component, which only applies to grain foods (N = 1561), identifies ready-to-eat cereals, oatmeal, other cooked cereals, and selected whole grain breads and crackers as higher-quality carbohydrate foods. The new carbohydrate food scoring system shows a high correlation with the Nutrient Rich Food (NRF9.3) index and the Nutri-Score. Metrics of carbohydrate food quality that incorporate whole grains, potassium, and sodium, in addition to sugar and fiber, are strategically aligned with multiple 2020−2025 dietary recommendations and may therefore help with the implementation of present and future dietary guidelines.

Monitoring population salt intake using casual urinary sodium: Tehran Lipid and Glucose Study

Background

We aimed to estimate salt intake among an Iranian population using spot urine-based equations and a dietary-based method.

Methods

Adult men and women (n = 2069) were recruited from the Tehran Lipid and Glucose Study (2014–2017). Urinary sodium (Na), potassium (K), and creatinine (Cr) concentrations were measured in the morning spot urine samples. The 24-h urinary Na excretion and predicted salt intake was estimated using five equations, i.e., Kawasaki, Tanaka, Intersalt, Toft, and Whitton. A validated food frequency questionnaire (FFQ) was used to obtain dietary intake of salt. The agreement of each urinary- and FFQ-based salt estimation with the overall mean of the methods, considered as the gold standard, was assessed using the Bland–Altman method.

Results

Mean age of the participants was 45.6 ± 14.8 y, and 45.4% were men. Mean (SD) estimated salt intake, derived from the overall mean of the methods, was 9.0 ± 2.2 g/d (10.2 ± 2.1 and 7.9 ± 1.7 g/d in men and women, respectively). Mean bias of the estimations from the overall mean ranged from − 0.2.42 to 2.75 g/d, with the Tanaka equation having the least bias (mean bias = 0.13 ± 1.10, 95% CI − 2.37, 2.30 g/d). Tanaka estimated a mean salt intake of 8.9 g/d (range 2.1 to 18.7 g/d); accordingly, only 5.1% of participants adhered to the recommendation (< 5 g/d salt intake), whereas 26.8% and 2.4% exceeded the recommendation by 2- and threefold.

Conclusion

The Tanaka equation could provide a more accurate mean-population estimated salt intake from casual urinary Na concentration in our population. About 95% of the Iranian population exceeded the current recommendations of salt intake.

Methods for the dietary assessment of adult kidney stone formers: a scoping review

BACKGROUND

Kidney stones are a frequent and potentially severe condition, affecting 5-10% of the European population. Causes are multifactorial, diet in particular plays a major role in the formation and management of kidney stones. The aim of this scoping review is to assess the methods used to study the diet of adult kidney stone formers.

METHODS

We conducted a systematic search in Medline Ovid SP, Embase, Cinahl, Cochrane (CENTRAL), Web of Sciences databases on June 10th, 2020. Self-report methods (such as food frequency questionnaires or 24-h dietary recalls), objective nutritional biomarkers and controlled diets were considered. We analyzed the selected publications based on the origin of participants, study design and dietary assessment methods used.

RESULTS

We screened 871 publications and included 162 of them. Most studies included participants from North America and Europe and were observational. Short and cost-effective tools such as food frequency questionnaires and other questionnaires were the most frequently used. Moreover, food diary was a frequently selected method to study the diet of kidney stone formers. New technologies (e.g. online questionnaires, phone applications, connected tools) were rarely used.

CONCLUSION

Accurate reporting of the methods used in nutritional studies is of key importance to interpret results and build evidence. Assessing long-term dietary intake is still a challenge for nutritional epidemiology. A combination of self-report methods with objective dietary biomarkers and new technologies probably represents the best way forward.

Impact of an Innovative Equipment to Monitor and Control Salt Usage during Cooking at Home on Salt Intake and Blood Pressure-Randomized Controlled Trial iMC SALT

(1) Background: Excessive salt consumption is associated with an increased risk of hypertension and cardiovascular disease, and it is essential to reduce it to the level recommended by the World Health Organization (<5 g/day). The main objective of this study is to verify the impact of an intervention, which used the Salt Control H equipment to reducing salt consumption; (2) Methods: The study was an 8-week randomized control trial with 114 workers from a public university. The intervention group (n = 57) used the equipment to monitor and control the use of salt during cooking (Salt Control H) at home for 8 weeks. The primary outcome was 24 h urinary sodium excretion as a proxy of salt intake. Secondary outcomes included changes in 24 h urinary potassium excretion, sodium to potassium ratio (Na:K), and blood pressure. (3) Results: There was a decrease in sodium intake after the intervention but with no statistical significance. When analyzing the results by sex and hypertension status, there was a reduction in sodium (-1009 (-1876 to -142), p = 0.025) and in Na:K ratio (-0.9 (-1.5 to -0.3), p = 0.007) in hypertensive men in the intervention group. (4) Conclusions: Interventions with dosage equipment can be valid approaches in individual salt reduction strategies, especially in hypertensive men.

High Adherence to Mediterranean Diet Is Not Associated with an Improved Sodium and Potassium Intake

Prevention and control of hypertension and cerebro-cardiovascular diseases are associated with adequate sodium and potassium intake and adherence to a Mediterranean dietary pattern. The aim of this study was to assess the association between adherence to a Mediterranean diet (MD) and the excretion of sodium and potassium as surrogate measures of intake. This is a cross-sectional analysis as part of a larger study (the iMC SALT randomized controlled trial) among workers of a public university. A food frequency questionnaire was used to assess the adherence to MD, using the alternative Mediterranean diet (aMED) score; sodium and potassium excretions were estimated by 24-h urine collections. Sociodemographic and other lifestyle characteristics were also obtained. The associations between the adherence to MD and Na and K excretion were calculated by logistic regression, adjusting for confounding variables. From the 109 selected participants, seven were excluded considering urine screening and completeness criteria, leaving a final sample of 102 subjects (48% male, average age 47 years). Mean sodium and potassium excretion were 3216 mg/day and 2646 mg/day, respectively. Sodium and potassium excretion were significantly higher in men, but no differences were found according to different levels of MD adherence. In logistic regression analysis, sodium, potassium, and sodium-to-potassium ratio urinary excretion tertiles were not associated with MD adherence (low/moderate versus high), even after adjustment for confounding variables. A high adherence to MD was thus not associated with a different level of sodium and potassium intake.

A multiple 24-hour urine collection study indicates that kidney function decline is related to urinary sodium and potassium excretion in patients with chronic kidney disease

Multiple 24-hour urine collections are necessary to adequately assess sodium and potassium intake. Here, we assessed kidney function decline for four years after baseline in relation to seven-time averaged 24-hour urinary sodium and potassium excretion (UNaV, UKV), their UNaV/UKV ratio, and their categorical combination in outpatients with chronic kidney disease (CKD). This retrospective cohort study was based on 240 outpatients with baseline CKD stages 3-5, baseline age 20 years or more (median age 72.0 years), and a median follow-up (with interquartile range) of 2.9 (1.4-4.0) years. Outcome was the percentage change in annual slope of estimated glomerular filtration rate (delta eGFR per year). In linear mixed models, percentage changes in delta eGFR per year were -3.26% (95% confidence interval -5.85 to -0.60), +5.20% (2.34 to 8.14), and -5.20% (-7.64 to -2.69), respectively, per one standard deviation increase in the seven-time averaged UNaV and UKV, and their UNaV/UKV ratio. Additionally, percentage changes per year in delta eGFR per year were -16.27% (-23.57 to -8.27) in the middle-to-high UNaV and low UKV group, compared with the low UNaV and middle-to high UKV group. Thus, our study reinforces the observation of opposite associations between GFR decline and urinary excretion rates of sodium (positive) and potassium (negative), respectively. Whether changes in dietary sodium and potassium intake slow GFR decline still requires further study.

Estimating 24-Hour Urinary Excretion of Sodium and Potassium Is More Reliable from 24-Hour Urine Than Spot Urine Sample in a Feeding Study of US Older Postmenopausal Women

BACKGROUND

Assessing estimated sodium (Na) and potassium (K) intakes derived from 24-h urinary excretions compared with a spot urine sample, if comparable, could reduce participant burden in epidemiologic and clinical studies.

OBJECTIVES

In a 2-week controlled-feeding study, Na and K excretions from a 24-h urine collection were compared with a first-void spot urine sample, applying established algorithms and enhanced models to estimate 24-h excretion. Actual and estimated 24-h excretions were evaluated relative to mean daily Na and K intakes in the feeding study.

METHODS

A total of 153 older postmenopausal women ages 75.4 ± 3.5 y participated in a 2-wk controlled-feeding study with a 4-d repeating menu cycle based on their usual intake (ClinicalTrials.gov Identifier: NCT00000611). Of the 150 participants who provided both a first-void spot urine sample and a 24-h urine collection on the penultimate study day, statistical methods included Pearson correlations for Na and K between intake, 24-h collections, and the 24-h estimated excretions using 4 established algorithms: enhanced biomarker models by regressing ln-transformed intakes on ln-transformed 24-h excretions or ln-transformed 24-h estimated excretions plus participant characteristics and sensitivity analyses for factors potentially influencing Na or K excretion (e.g., possible kidney disease estimated glomerular filtration rate <60 mL/min/1.73 m2 ).

RESULTS

Pearson correlation coefficients between Na and K intakes and actual 24-h excretions were 0.57 and 0.38-0.44 for estimated 24-h excretions, depending on electrolyte and algorithm used. Enhanced biomarker model cross-validated R 2 (CVR2) for 24-h excretions were 38.5% (Na), 40.2% (K), and 42.0% (Na/K). After excluding participants with possible kidney disease, the CVR2 values were 43.2% (Na), 40.2% (K), and 38.1% (Na/K).

CONCLUSIONS

Twenty-four-hour urine excretion measurement performs better than estimated 24-h excretion from a spot urine as a biomarker for Na and K intake among a sample of primarily White postmenopausal women.

The impact of baseline potassium intake on the dose-response relation between sodium reduction and blood pressure change: systematic review and meta-analysis of randomized trials

Sodium and potassium appear to interact with each other in their effects on blood pressure with potassium supplementation having a greater blood pressure lowering-effect when sodium intake is high. Whether the effect of sodium reduction on blood pressure varies according to potassium intake levels is unclear. We carried out a systematic review and meta-analysis to examine the impact of baseline potassium intake on blood pressure response to sodium reduction in randomized trials in adult populations, with sodium and potassium intake estimated from 24-h urine samples. We included 68 studies involving 5708 participants and conducted univariable and multivariable meta-regression. The median intake of baseline potassium was 67.7 mmol (Interquartile range: 54.6-76.4 mmol), and the mean reduction in sodium intake was 128 mmol (95% CI: 107-148). Multivariable meta-regression that included baseline 24-h urinary potassium excretion, age, ethnicity, baseline blood pressure, change in 24-h urinary sodium excretion, as well as the interaction between baseline 24-h urinary potassium excretion and change in 24-h urinary sodium excretion did not identify a significant association of baseline potassium intake levels with the blood pressure reduction achieved with a 50 mmol lowering of sodium intake (p > 0.05 for both systolic and diastolic blood pressure). A higher starting level of blood pressure was consistently associated with a greater blood pressure reduction from reduced sodium consumption. However, the nonsignificant findings may subject to the limitations of the data available. Additional studies with more varied potassium intake levels would allow a more confident exclusion of an interaction.

Nutrient Profiles of Dishes Consumed by the Adequate and High-Salt Groups in the 2014-2018 National Health and Nutrition Survey, Japan

Dish-based nutrient profile analyses are essential for setting goals to achieve a balanced diet. In 2014, the Japanese government proposed the “Healthy Meal” criteria, which requires a salt content of 3 g/650 kcal per meal. To examine the current intake status of a nationally representative sample, we conducted a series of secondary analyses of the 2014–2018 National Health and Nutrition Survey data. Participants (aged 18–74 years) were grouped as “high-salt” consumers if their salt intake was 3 g/650 kcal or higher and “adequate” consumers if they consumed less than 3 g/650 kcal. A total of 13,615 participants were identified as “adequate” consumers and 22,300 as “high-salt” consumers. The median salt intake in the “high-salt” group was 11.3 g/day, while that in the “adequate” group was 7.5 g/day. Almost all dishes consumed by the “adequate” group had significantly high energy and fat content but low salt content, compared with those consumed by the “high-salt” group. For example, the median energy, fat, and salt contents in the main dishes consumed by the “adequate” group were 173 kcal, 10.4 g, and 0.9 g/dish, respectively, while those in the main dishes consumed by the “high-salt” group were 159 kcal, 8.9 g, and 1.1 g/dish, respectively. Examples of balanced dishes that are low in both salt and fat content can be proposed to help improve the Japanese consumers’ dietary behavior.

Urinary sodium-to-potassium ratio: a simple and useful indicator of diet quality in population-based studies

Background

Current evidence regarding the prognostic relevance of urinary sodium-to-potassium ratio (Na-to-K ratio), as an indicator of diet quality is limited. This study was conducted to investigate whether urinary Na-to-K ratio could be related to habitual dietary patterns, in a general population.

Methods

This study was conducted in the framework of the Tehran Lipid and Glucose Study (2014–2017) on 1864 adult men and women. Urinary Na and K concentrations were measured in the morning spot urine samples. Dietary intakes of the participants were assessed using a validated 147-item Food Frequency Questionnaire (FFQ) and major dietary patterns were obtained using principal component analysis. Mediterranean dietary pattern and Dietary Approaches to Stop Hypertension (DASH) score, were also calculated. Multivariable-adjusted linear regression was used to indicate association of dietary patterns and urinary Na-to-K ratio.

Results

Mean (± SD) age of participants was 43.7 ± 13.9 years and 47% were men. Mean (± SD) urinary Na, K and the ratio was 139 ± 41.0 and 57.9 ± 18.6 mmol/L, 2.40 ± 0.07, respectively. Higher urinary Na-to-K ratio (> 2.37 vs. < 1.49) was related to lower intakes of vegetables (282 vs. 321 g/day), low-fat dairy (228 vs. 260 g/day) and fruits (440 vs. 370 g/day). Western dietary pattern was related to higher urinary Na-to-K ratio (β = 0.06; 95% CI 0.01, 0.16). Traditional dietary pattern, Mediterranean and DASH diet scores were inversely associated with urinary Na-to-K ratio (β = − 0.14; 95% CI − 0.24, − 0.11, β = − 0.07; 95% CI − 0.09, − 0.01, β = − 0.12; 95% CI − 0.05, − 0.02, respectively).

Conclusions

Spot urinary Na-to-K ratio may be used as a simple and inexpensive method to monitor diet quality in population-based epidemiological studies.