Individual Salt Intake Research Articles

Association of dietary salt intake with diabetes mellitus in the Japanese general population

Abstract Background/Introduction Excess salt intake, one of the most important modifiable factors in our lifestyle, has been reported to be a risk of cardiovascular morbidity and mortality. Several mechanisms underlying the development of cardiovascular disease after excess salt intake are proposed, among which hypertension has been established. Diabetes mellitus (DM) is also a risk factor of cardiovascular disease and, thus, there may be some association between excess salt intake and DM. Purpose The present study was designed to investigate possible relationship between dietary salt intake and DM in the general population. Methods Dietary salt intake was estimated using a spot urine sample in 16018 subjects (male=9642, 52.0±12.3 year-old) who visited our hospital for a yearly physical checkup from July 2008 to March 2019 (baseline). A cross-sectional analysis for the relationship between salt intake and DM was performed at baseline. Then, subjects without DM (n=14715, male=8651, 51.3±12.3 year-old) were followed up until March 2020 (median 2107 days) with the endpoint being the development of DM. DM was defined as fasting plasma glucose (FPG) ≥126mg/dL, HbA1c≥6.5% or the use of antidiabetic medications. Results A cross-sectional analysis revealed that salt intake in subjects was 8.67±1.98 g/day. Salt intake was significantly higher in subjects with (n=1280) than without DM (9.55±2.17 vs. 8.61±1.94 g/day). Multivariate regression analysis adjusted for age, gender, body weight, systolic blood pressure, pulse rate, serum creatinine, uric acid, FPG, LDL-cholesterol, triglyceride, current smoking and frequent alcohol drink showed that salt intake was associated with the presence of DM (r=0.027, p<0.001). In the follow-up study, 861 subjects developed DM (10.1 per 1000 person-year), with the incidence being more frequent in males than in females (11.7 vs. 7.6 per 1,000 person-year). The incidence of DM was increased across the quartiles of salt intake at baseline (7.5, 7.6, 10.5 and 14.8 per 1000 person-year). In analysis where salt intake at baseline was taken as continuous variables, non-adjusted hazard ratio (HR) (95% confidence interval [CI]) of salt intake for the new onset of DM was 1.146 (1.109-1.184). Multivariate Cox-hazard analysis adjusted for possible risk factors showed that salt intake was a significant predictor for the future development of DM (HR: 1.037, 95%CI: 1.001-1.073), while additional adjustment for baseline body weight disappeared the statistical significance (HR: 0.994, 95%CI: 0.958-1.031). Conclusions Salt intake is associated with the development of DM and excess salt intake may predict future development of DM in the general population. Excess food intake which is usually accompanied by excess salt intake in individuals with increased body weight may be responsible for the development of DM. Maintenance of appropriate body weight as well as restriction of dietary salt may lead to the prevention from developing DM.

PS-BPP06-8: DIETARY SALT INTAKE PREDICTS FUTURE DEVELOPMENT OF METABOLIC SYNDROME IN THE GENERAL POPULATION

Objective: Dietary salt consumption is one of the most important modifiable factors in our lifestyle and restriction of dietary salt results in the reduction of blood pressure in previous studies. Excessive salt intake causes cardiovascular diseases independently of its effects on blood pressure. Since metabolic syndrome also increases a risk of cardiovascular disease, there may be some association between salt intake and metabolic syndrome. Therefore, we investigated a possible relationship between salt intake and future development of metabolic syndrome in the general population. Design and Methods: Consecutive 12,256 subjects without metabolic syndrome (male = 7,053, 52.1 ± 12.3 year-old) who visited our hospital for an annual physical check-up from April 2010 to March 2018 were enrolled. After baseline examination, subjects were followed up until March 2019 (median 1,582 days) with the endpoint being the development of metabolic syndrome. Metabolic syndrome was diagnosed according to the Japanese criteria (2005). Individual salt intake was estimated using a spot urine by a previously reported Tanaka method. Results: Salt intake was 8.7 ± 1.9 and 8.4 ± 1.8 g/day in male and female subjects, respectively, at baseline. During the follow-up period, 1,669 subjects developed metabolic syndrome (29.9 per 1,000 person-year) with the incidence being more frequent in male than female subjects (41.8 vs. 14.2 per 1,000 person-year). Non-adjusted hazard ratio (HR) (95% confidence interval [CI]) of salt intake for the development of metabolic syndrome was 1.192 (1.164–1.221). Kaplan-Meier analysis where subjects were divided into gender-specific quartiles according to the baseline salt intake revealed that the incidence of metabolic syndrome were increased across the quartiles (19.5, 24.2, 33.1, and 43.9 per 1,000 person-years; logrank p < 0.001). Multivariate Cox proportional hazard analysis adjusted for age, gender, body mass index, systolic blood pressure, heart rate, serum creatinine, uric acid, fasting plasma glucose, low-density lipoprotein cholesterol, triglyceride, hemoglobin and current smoking habit at baseline revealed that salt intake predicted the new onset of metabolic syndrome (HR:1.055, 95%CI:1.028–1.082). Conclusions: Excessive salt intake is significantly associated with the new development of metabolic syndrome in the general population. The results suggest that salt restriction prevents cardiovascular diseases through the prevention of not only hypertension but also metabolic syndrome.

VERIFY AND EVALUATE FOUR SPOT URINARY METHODS FOR ESTIMATING 24-HOUR URINARY SODIUM EXCRETION RATE IN TIBETAN POPULATION

Objective: To verify and evaluate four spot urinary methods for estimating 24-hour urinary sodium excretion rate in Tibetan population (Kawasaki method, Tanaka method, INTERSALT method and SH2 method). Design and method: 323 subjects were selected from the Ganzi Tibetan Autonomous Prefecture of Sichuan Province, China. The morning second urine samples and 24 hours urine samples were collected. The concentrations of creatinine, sodium and potassium in the morning second urine samples and 24 hours urine samples were measured. To compare the mean deviation, correlation, and consistency between the measured values and estimated 24-hour urinary sodium excretion by Kawasaki method, Tanaka method, INTERSALT method and SH2 method. Results: The average differences between the estimated values and measured values by Kawasaki method, Tanaka method, INTERSALT method and SH2 method were 124.86 mg/days, -937.58 mg/days, -1314.15 mg/days and -1747.436 mg/days, respectively. The correlation coefficient with the measured values was 0.434, 0.38, 0.273 and 0.348, respectively. The intraclass correlation coefficient was higher for Kawasaki method (0.473) than for Tanaka method (0.397), INTERSALT method (0.269) and SH2 method (0.348). The Bland Altman analysis showed 3.4%, 6.2%, 5.9% and 5.6% of the subjects’ estimated values exceeded the consistent boundary of ± 1.96 for Kawasaki method, Tanaka method, INTERSALT method and SH2 method. When four spot urinary sodium methods used for evaluating the individual salt intake, the misclassification rate was more than 45%. Compared with the other three methods, the misclassification probability of Kawasaki method was 48.2%, while the misclassification probability of Tanaka, INTERSALT and SH2 methods was 72.1%, 75.5% and 74.6%, respectively. However, when individual's salt intake was higher than 12.8 g/days, the probability of misclassification of Kawasaki method, Tanaka method, INTERSALT method and SH2 method was 20%, 90%, 97.5% and 97.5%, respectively. Conclusions: When the Kawasaki method is used to evaluate the salt intake of Tibetan population, the deviation, consistency and reproducibility were better than Tanaka method, INTERSALT method and SH2 method. It was especially suitable for the evaluation of 24-hour urinary sodium excretion rate of people with high salt intake. It can be used to investigate the salt intake of Tibetan population in a large-scale epidemiological study.

Dietary salt intake increases with age in Japanese adults

Excess salt intake is linked to cardiovascular disease as well as hypertension, but whether individual salt intake increases with age has not been studied. The present study was designed to test the hypothesis that individual salt intake increases with age in Japanese adults. In this retrospective observational follow-up study, men and women age ≥30 years who participated in a baseline health checkup (2008–2009) at our center and had a health checkup 10 years later (n = 2598) were enrolled and salt intake was estimated by spot urine analysis. Yearly changes in salt intake were also assessed in participants with complete annual data over the course of 10 years from baseline (n = 1543). The follow-up study demonstrated increased salt intake (8.8 ± 2.0 to 9.3 ± 2.1 g/d, P < .001) with increasing age (54.0 ± 9.7 to 64.0 ± 9.8 years). Salt intake increased year over year in participants who had a health checkup annually for the 10-year follow-up period (n = 1543; analysis of variance, P < .001). Cross-sectional analyses using propensity-matched model revealed similar regional levels of salt intake in the baseline period (8.9 ± 2.0 g/d, 55.8 ± 11.4 years, n = 5018) and at 10 years (8.8 ± 2.0 g/d, P = .21; 55.9 ± 13.0 years, P = .65, n = 5105). These results suggest that dietary salt intake increases with age in Japanese adults, which should be considered in devising population-based strategies to lower dietary salt intake.

Current status and recent changes in blood pressure and dietary salt consumption in Japanese individuals

ABSTRACT Purpose: Treatment of hypertension has recently shown remarkable advances. It is quite important to survey the current general status of blood pressure (BP) and recent changes to verify whether people are benefitting from these advances. The present study aimed to investigate the current status of, and recent changes in, BP, the prevalence and treatment rate of hypertension, the achievement rate of target BP, and salt intake in Japanese individuals. Methods: Recent changes in salt intake as well as BP, the prevalence and treatment rate of hypertension, and the rate of achievement of target BP were investigated in participants in our yearly physical checkup program from 2009 to 2018 (n = 79,789). Individual salt intake was assessed by estimating 24-hour urinary sodium excretion using a spot urine sample. Results: The prevalence of hypertension did not change, but the treatment rate of hypertension (from 64% to 75%) and the achievement rate of the target BP improved during the period (from 35% to 57%). BP decreased, prominently in hypertensive participants under antihypertensive treatment (from 133 ± 14/84 ± 9 to 128 ± 13/76 ± 10 mmHg). Salt intake did not decline noticeably during the 10 years of observation. Conclusions: The prevalence of hypertension did not change, but the treatment rate of hypertension and the achievement rate of the target BP improved during a recent 10-year period. These findings suggest that improved pharmacological management of hypertension resulted in a gradual reduction in BP levels, but lifestyle modification has not yet really taken root in the Japanese general population.

Excessive salt intake is a significant predictor for future development of metabolic syndrome in the general population

Abstract Background/Introduction Dietary salt consumption is one of the most important modifiable factors in our lifestyle and restriction of dietary salt results in the reduction of blood pressure in previous studies. Excessive salt intake causes cardiovascular diseases independently of its effects on blood pressure. Since metabolic syndrome also increases a risk of cardiovascular disease, there may be some association between salt intake and metabolic syndrome. Purpose The present study was designed to investigate a possible relationship between salt intake and future development of metabolic syndrome in the general population. Methods Consecutive 12,256 subjects without metabolic syndrome (male=7,053, 52.1±12.3 year-old) who visited our hospital for an annual physical check-up from April 2010 to March 2018 were enrolled. After baseline examination, subjects were followed up until March 2019 (median 1,582 days) with the endpoint being the development of metabolic syndrome. Metabolic syndrome was diagnosed according to the Japanese criteria (2005). Individual salt intake was estimated using a spot urine by a previously reported method. Results Salt intake was 11.9±3.0 g/day in male and 8.2±2.1 g/day in female subjects at baseline. During the follow-up period, 1,669 subjects developed metabolic syndrome (29.9 per 1,000 person-year) with the incidence being more frequent in male than female subjects (41.8 vs. 14.2 per 1,000 person-year). Non-adjusted hazard ratio (HR) (95% confidence interval [CI]) of salt intake for the development of metabolic syndrome was 1.157 (1.142–1.173). In analysis where subjects were divided into gender-specific quartiles according to the baseline salt intake, Kaplan-Meyer curve analysis revealed that the incidence of metabolic syndrome were increased across the quartiles (20.6, 25.0, 32.4, and 42.7 per 1,000 person-years; logrank p&amp;lt;0.001). Multivariate Cox proportional hazard analysis adjusted for age, gender, body mass index, systolic blood pressure, heart rate, serum creatinine, uric acid, fasting plasma glucose, low-density lipoprotein cholesterol, triglyceride, hemoglobin and current smoking habit at baseline revealed that salt intake predicted the new onset of metabolic syndrome (HR: 1.036, 95% CI: 1.019–1.054). Conclusions Excessive salt intake is significantly associated with the new development of metabolic syndrome in the general population. The results suggest that salt restriction prevents metabolic syndrome as well as hypertension leading to cardiovascular diseases. Funding Acknowledgement Type of funding source: None

Increased Salt Intake for Orthostatic Intolerance Syndromes: A Systematic Review and Meta-Analysis

BackgroundGuidelines recommend increased salt intake as a first-line recommendation in the management of symptomatic orthostatic hypotension and recurrent syncope. There have been no systematic reviews of this intervention. We sought to summarize the evidence for increased salt intake in patients with orthostatic intolerance syndromes. MethodsWe conducted a systematic review and meta-analysis of studies in PubMed, EMBASE, and CINAHL. Interventional studies that increased salt intake in individuals with orthostatic intolerance syndromes were included. Primary outcome measures included incidence of falls and injuries, and rates of syncope and presyncope. Secondary outcome measures included other orthostatic intolerance symptoms, blood pressure, and heart rate. ResultsA total of 14 studies were eligible, including participants with orthostatic hypotension, syncope, postural orthostatic tachycardia syndrome, and idiopathic orthostatic tachycardia (n = 391). Mean age was 35.6 (± 15) years. All studies were small and short-term (<60 mins-90 days). No study reported on the effect of increased salt intake on falls or injuries. Meta-analysis demonstrated that during head-up tilt, mean time to presyncope with salt intake increased by 1.57 minutes (95% confidence interval [CI], 1.26-1.88), mean systolic blood pressure increased by 12.27 mm Hg (95% CI, 10.86-13.68), and mean heart rate decreased by −3.97 beats per minute (95% CI, −4.08 to −3.86), compared with control. Increased salt increased supine blood pressure by 1.03 mm Hg (95% CI, 0.81 to 1.25). Increased salt intake resulted in an improvement or resolution of symptoms in 62.3% (95% CI, 51.6 to 72.6) of participants in short-term follow-up studies (mean follow-up of 44.3 days, 6 studies; n=91). Methodological quality of studies were low with high statistical heterogeneity in all meta-analyses. ConclusionsOur meta-analysis provides low-quality evidence of a short-term improvement in orthostatic intolerance with increased salt intake. There were no clinical trials demonstrating the efficacy and safety of increased salt intake on long-term clinical outcomes. Overall, there is a paucity of clinical trial evidence to support a cornerstone recommendation in the management of orthostatic intolerance syndromes.

Practical and personal education of dietary therapy in hypertensive patients.

The guidelines for the management of hypertension by the Japanese Society of Hypertension (JSH2019) defined blood pressure (BP) levels of 130-139/80-89 mmHg as "elevated blood pressure". The JSH2019 also revised the target level of BP control to a lower level. Thus, lifestyle modifications are quite important regardless of the use of antihypertensive drugs. Among the lifestyle modifications, salt reduction is most important, especially among East Asian people, who still consume a significant amount of salt. Since the awareness of salt reduction may not necessarily lead to actual salt reduction, the assessment of individual salt intake is essential when members of the medical staff provide practical guidance regarding salt reduction. The evaluation methods of salt intake are classified as the assessment of dietary contents and the measurement of urinary sodium (Na) excretion. Since highly reliable methods, such as the measurement of 24-h urinary Na excretion, are not convenient in practical clinical settings, the combination of the assessment of dietary contents using questionnaires and the estimation of salt intake using spot urine is recommended as a practical evaluation procedure. Repeated assessment of salt intake and practical guidance from dieticians are useful for long-term adherence to salt reduction. The Japanese Society of Hypertension Salt Reduction Committee began to certify flavorful foods as being low in salt content in 2013. More than 200 products have been certified as of April 2019. The utilization of these products is expected to aid in the salt reduction of hypertensive individuals as well as the Japanese general population.

Close association between circulating high-sensitivity cardiac troponin I and metabolic syndrome in the general population.

Individuals with metabolic syndrome reportedly have an increased risk of cardiovascular disease, although the association between asymptomatic myocardial damage and metabolic syndrome has not been sufficiently investigated. The present study investigated possible associations between circulating cardiac troponin and metabolic syndrome or related factors. Subjects undergoing their annual health checkups were enrolled in the study (n = 1242). Laboratory measurements included serum high-sensitivity cardiac troponin I (hs-cTnI) and plasma B-type natriuretic peptide (BNP). Individual salt intake was estimated by calculating 24-h urinary sodium excretion from spot urine. Subjects whose electrocardiograms revealed ST-T segment abnormalities or who had renal insufficiency or a history of cardiovascular events were excluded. Subjects with metabolic syndrome had higher hs-cTnI levels than those without, but their BNP levels were equivalent. hs-cTnI levels were significantly associated with the presence and components of metabolic syndrome. Logistic regression analysis with the endpoint of hs-cTnI levels higher than the median value identified metabolic syndrome as an independent determinant of increased hs-cTnI levels. Additionally, urinary salt excretion levels were increased in subjects with metabolic syndrome or any of its components. Logistic regression analysis with the endpoint of metabolic syndrome revealed that hs-cTnI levels were independently associated with the presence of metabolic syndrome. A close association between hs-cTnI levels and the presence of metabolic syndrome, at least partially mediated by increased salt intake, was confirmed to exist in the general population. The findings support the idea that patients with metabolic syndrome develop asymptomatic myocardial damage without obvious ischaemic findings, which leads to increased cardiovascular risk.

Evaluation of an education program based on the theory of planned behavior for salt intake in individuals at risk of hypertension.

This study was conducted to evaluate an education program based on the theory of planned behavior (TPB) for salt intake in individuals at risk of hypertension. This randomized controlled trial was conducted from February 2017 to December 2017 in Shahediyeh, Yazd Province, Iran. For this purpose, 140 people were selected and assigned to two groups of 70 each, namely, intervention and control. Data were gathered by a self-administered TPB based questionnaire, and also 24-h urinary sodium and potassium levels and systolic and diastolic blood pressure were measured. The intervention group received TPB based on a training package, while the control group received no intervention. Post-test was administered 2 months after completion of the intervention. Independent and paired t-tests, χ2 and analysis of covariance (ANCOVA) were used for data analysis. All mean scores on TPB constructs increased significantly except motivation to comply and power of control for intervention group. Average salt intake decreased in intervention group compared with the control group (-4.73 g/day �0.73 versus -0.24 g/day �0.94, P < 0.001), but systolic and diastolic blood pressure did not change significantly in intervention group compared with control group. TPB can be implemented along with other approaches in educational programs to reduce salt intake. Code: IRCT201701108803N3.

Assessing whether a spot urine specimen can predict 24-h urinary sodium excretion accurately: a validation study.

Aimed to evaluate the validity of five published equations that estimate 24-h urinary sodium excretion (24-h USE) by timed spot urine specimens. All of the spot urines within 24 h were collected from 99 healthy volunteers aged 21-57 years. The spot urinary sodium and 24-h USE were measured. The 24-h USE was estimated by INTERSALT equation and Tanaka equation with casual spot urine and four timed spot urines (i.e. overnight, second morning, post meridiem, and evening urine), by Kawasaki equation and SunSMU equation with second morning urine, and by SunPM equation with post meridiem urine, respectively. At last, the agreement between measured and estimated 24-h USE was evaluated. The average of the measured 24-h USE was 4558.25 ± 1908.75 mg/day. The proportion of participants with more than ±40% of relative difference between measured 24-h USE and estimated 24-h USE by five equations varied from 21.18 to 42.35%. The absolute differences of 24-h USE among approximately half of the participants were more than ±1170.00 mg/day estimated by Kawasaki equation, INTERSALT equation, and SunPM equation, respectively. In addition, misclassification rates of individual salt intake for five equations were more than 60%. It was found that overestimation occurred at low levels of sodium excretion whereas underestimation occurred at high levels of sodium excretion except Kawasaki equation. The 24-h USE estimated using Tanaka equation with four timed spot urine specimens varied substantially, although Tanaka equation with casual spot urine specimen provided the highest correlation coefficient and the least mean difference. There is still no evidence to support that 24-h USE could be estimated accurately using the current equations, especially for the equations developed by casual spot urine specimens.

Dietary Salt Intake is a Significant Determinant of Impaired Kidney Function in the General Population

Background/Aims: Kidney dysfunction is an important risk factor for cardiovascular disease and end-stage renal disease. This study investigated whether dietary salt intake predicts deterioration of kidney function in the general population. Methods: In all, 12 126 subjects with a normal estimated glomerular filtration rate (eGFR ≥60 mL/min per 1.73m2) attending an annual check-up were enrolled in the study and were followed-up for a median of 1754 days; the endpoint was the development of impaired kidney function (eGFR < 60 mL/min per 1.73m2). Individual salt intake was estimated using spot urine analysis. Results: At baseline, mean (± SD) salt intake and eGFR were 10.6 ± 3.4 g/day and 80.8 ± 12.9 mL/min per 1.73m2, respectively. During the follow-up period, 1384 subjects (25.2 per 1000 person-years) developed impaired kidney function. Multivariate Cox hazard regression analysis revealed salt intake as a significant predictor of the new onset of kidney impairment (hazard ratio 1.045; 95% confidence interval 1.025–1.065). Subjects were divided into two groups based on salt intake; the incidence of impaired kidney function was higher in the group with high than low salt intake (P < 0.001, log-rank test). Multivariate Cox hazard regression analysis indicated a 29% increased risk of developing impaired kidney function in the high-salt group. Multivariate linear regression analysis showed a significant correlation between salt intake and yearly decline in eGFR (β = 0.060, P < 0.001). Conclusion: Salt intake is associated with the development of impaired kidney function in the general population, independent of its effects on blood pressure. Salt restriction may help prevent the development of impaired kidney function.

Abstract P332: Dietary Salt Intake and Blood Pressure Control in Hypertensive Individuals Under Antihypertensive Treatment During 7 Years

Purpose: Excess salt intake is one of the most important causes of hypertension. Salt restriction is a key strategy in the management of hypertension and, thus, should be instructed for hypertensive patients under medical treatment. We investigated recent changes in dietary salt intake and blood pressure (BP) levels in hypertensive patients. Methods: Total of 12422 hypertensive subjects (male 71.0% [8814 of 12422], 64.6±9.2 year-old) under medical treatment who visited our hospital for a physical checkup from 2010 to 2016 were enrolled. They were divided into 3 groups according to the number of antihypertensive drugs prescribed (1, 2 and ≥3 drugs). Cross-sectional analyses were performed using data in each year and changes during the 7 years were investigated. Individual salt intake was estimated using a spot urine by a previously reported method. Results: BP levels and the accomplishment rate of the target BP (&lt;140/90mmHg) were improved in each group during the 7 years without significant difference among the groups (Overall 2010 to 2016; BP 132.7±13.6/80.0±8.9 to 128.8±13.7/76.3±9.6 mmHg and accomplishment ratio 65.6 [968 of 1475] to 76.4% [1433 of 1875]). However, individual salt intake was gradually increased in all groups (2010 to 2016 in 1, 2, and ≥3 drugs; 11.7±3.7 to 12.2±4.0, 11.9±3.7 to 12.7±3.9, and 12.2±3.9 to 12.9±4.1 g/day, respectively) and the accomplishment rate of salt restriction (&lt;6g/day) was significantly reduced in subjects with increased number of antihypertensive drugs (3.5 [225 of 6435], 2.8 [125 of 4564], and 2.3% [33 of 1423] in groups with 1, 2, and ≥3 drugs, respectively). The accomplishment rate of the target BP was significantly higher in patients who achieved salt restriction than in those who did not achieve salt restriction in all groups (Over all; 80.2 [307 of 383] vs. 73.3% [8829 of 12039]). Conclusions: The control of BP in individuals with antihypertensive medications was improved in the last 7 years. However, salt restriction has not been successfully achieved especially in hypertensive patients with multiple antihypertensive medications. Excess salt intake may induce resistance to antihypertensive treatment and, thus, increases the number of antihypertensive drugs for BP control.

Knowledge, attitudes and behaviours related to dietary salt among adults in the state of Victoria, Australia 2015

BackgroundInformation on consumer’s knowledge, attitudes and behaviours (KABs) related to salt can be used to inform awareness and education campaigns and serve as a baseline measure to monitor changes in KABs over time. The aim of this study was to determine KABs related to salt intake among Victorian adults.MethodsCross-sectional survey conducted in Victorian adults aged 18–65 years. Participants were recruited from shopping centres located in Melbourne and Geelong and via online methods (Facebook and Consumer Research Panel) to complete an online survey assessing KABs related to dietary salt. Descriptive statistics (mean (SD) or n (%)) were used to report survey findings.ResultsA total of 2398 participants provided a valid survey (mean age 43 years (SD 13), 57% female). The majority (80%) were born in Australia and 63% were the main household grocery shopper. The majority (89%) were aware of the health risks associated with a high salt intake. Eighty three percent believed that Australians eat too much salt. Three quarters (75%) correctly identified salt from processed foods as being the main source of salt in the diet. Less than a third (29%) of participants believed their own individual salt intake exceeded dietary recommendations and only 28% could correctly identify the maximum recommended daily intake for salt. Just under half (46%) of participants were concerned about the amount of salt in food. Almost two thirds (61%) of participants believed that there should be laws which limit the amount of salt added to manufactured foods and 58% agreed that it was difficult to find lower salt options when eating out.ConclusionsThe findings of this study serve as a baseline assessment of KABs related to salt intake in Victorian adults and can be used to assess changes in salt related KABs over time. Public concern about salt is low as many people remain unaware of their own salt intake. An increased awareness of the excessive amount of salt consumed and increased availability of lower salt foods are likely to reduce population salt intake.

PP.30.09] DOSE SALT INTAKE PREDICT THE NEW ONSET OF CHRONIC KIDNEY DISEASE?

Objective: Dietary salt, which is one of the most important modifiable factors in our life style, is associated not only with blood pressure but also with several cardiovascular diseases in a blood pressure–independent manner. We investigated if salt intake predicts new onset of chronic kidney disease (CKD) in the general population. Design and method: Consecutive 8,161 participants (male = 5,168, 55.8 ± 11.3 year-old) with normal estimated glomerular filtration rate (eGFR;> = 60 ml/min/1.73 m2) in our physical health check-up program were enrolled in this study. After baseline examination, participants were followed up (median 1,098 day) with the endpoint being the development of CKD (eGFR<60 ml/min/1.73 m2). Individual salt intake was estimated using spot urine by a previously reported method and GFR was estimated using the Japanese Society of Nephrology formula. Results: Salt intake was 8.9 ± 2.0 g/day in male and 8.6 ± 1.9 g/day in female subjects. eGFR was 80.1 ± 12.7 ml/min/1.73 m2 at baseline, and during the follow-up period, CKD developed in 706 subjects (29.9 per 1000 person-year), with the incidence being more frequent in male than female subjects (31.1 vs. 27.8 per 1000 person-year). Non-adjusted hazard ratio (HR) (95% confidence interval [CI]) of salt intake for the new CKD was 1.071 (1.034–1.109). Multivariate Cox-hazard analysis adjusted for body mass index, systolic blood pressure, heart rate, uric acid, fasting plasma glucose, low-density lipoprotein cholesterol, triglyceride, hemoglobin, smoking status and eGFR at baseline demonstrated that salt intake was a significant predictor of new onset CKD (HR = 1.077, 95%CI = 1.037–1.119). Univariate and adjusted multivariate liner regression analyses indicated the significant correlation between salt intake at baseline and yearly changes in eGFR (r = -0.081, p < 0.001 and r = -0.069, p < 0.001, respectively). Similar results were obtained in a sub-analysis performed in subjects with normal blood pressure (n = 5,863). Conclusions: Dietary salt intake is significantly associated with the development of CKD and decrease in eGFR in the general population, even in normotensive subjects. These results suggest that salt restriction is beneficial for the prevention of the impairment of kidney function and the development of CKD.

Significance of adjusting salt intake by body weight in the evaluation of dietary salt and blood pressure

The close association between dietary salt and hypertension is well established. However, previous studies generally assessed salt intake without adjustment for body weight. Herein, we investigated the significance of body weight–adjusted salt intake in the general population. The present cross-sectional study included 7629 participants from our yearly physical checkup program, and their salt intake was assessed using a spot urine test to estimate 24-hour urinary salt excretion. Total salt intake increased with increasing body weight. Body weight–adjusted salt intake was greater in participants with hypertension than in those without hypertension. Systolic blood pressure, estimated glomerular filtration rate, and urinary albumin were independently correlated with body weight–adjusted salt intake after adjustment for possible cardiovascular risk factors. Excessive body weight–adjusted salt intake could be related to an increase in blood pressure and hypertensive organ damage. Adjustment for body weight might therefore provide clinically important information when assessing individual salt intake.

Dietary Salt and Blood Pressure: Verdict is Clear, so why Any Debate?

Repeated reviews of the evidence to produce recommendations for dietary salt intake have been conducted by independent committees of national and international scientific and governmental organizations. These recommendations support reducing dietary salt to less than 6 gm/day and many to less than 5 gm/day. Nevertheless, there is controversy about recommendations to reduce dietary salt. This commentary discusses low quality research studies and commercial interests as sources of the controversy. Especially, research that assesses usual salt intake in individuals based on a single spontaneously voided (spot) urine sample is discussed as a weak research method prone to erroneous findings. Further, some investigators have altered scientific formula to make their data using spot urine samples appear more robust and made misleading and false statements about evidence relating to dietary salt. Counterintuitive findings based on studies that have used spot urine samples is frequently disregarded in expert committee review given the low quality evidence is incompatible with higher quality evidence which shows direct linear relationships between dietary salt, hypertension and cardiovascular disease in the general population.

Agreement between 24-hour salt ingestion and sodium excretion in a controlled environment.

Accurately collected 24-hour urine collections are presumed to be valid for estimating salt intake in individuals. We performed 2 independent ultralong-term salt balance studies lasting 105 (4 men) and 205 (6 men) days in 10 men simulating a flight to Mars. We controlled dietary intake of all constituents for months at salt intakes of 12, 9, and 6 g/d and collected all urine. The subjects' daily menus consisted of 27 279 individual servings, of which 83.0% were completely consumed, 16.5% completely rejected, and 0.5% incompletely consumed. Urinary recovery of dietary salt was 92% of recorded intake, indicating long-term steady-state sodium balance in both studies. Even at fixed salt intake, 24-hour urine collection for sodium excretion (UNaV) showed infradian rhythmicity. We defined a ±25 mmol deviation from the average difference between recorded sodium intake and UNaV as the prediction interval to accurately classify a 3-g difference in salt intake. Because of the biological variability in UNaV, only every other daily urine sample correctly classified a 3-g difference in salt intake (49%). By increasing the observations to 3 consecutive 24-hour collections and sodium intakes, classification accuracy improved to 75%. Collecting seven 24-hour urines and sodium intake samples improved classification accuracy to 92%. We conclude that single 24-hour urine collections at intakes ranging from 6 to 12 g salt per day were not suitable to detect a 3-g difference in individual salt intake. Repeated measurements of 24-hour UNaV improve precision. This knowledge could be relevant to patient care and the conduct of intervention trials.

Abstract 326: Salt Intake, Drinking Behavior, And The Body Corporate

Clinical practice and public health advice on salt consumption relies on the generally accepted notion that accurately collected 24-hour urine collections are valid estimates for salt and fluid intake. Reduced salt intake would also reduce thirst and ingestion of sugary drinks accordingly. To test these widely accepted ideas, we performed two independent ultra-long term salt balance studies lasting 105 and 205 days in 10 men simulating a flight to Mars. We fixed dietary intake of all constituents for months at salt intakes of 6, 9, and 12 grams per day and collected all urine. We controlled all environmental factors for rigorous quantitative comparison of urine volume and salt excretion with daily fluid and salt intake. In 1646 collected 24-hour urine samples, our ten subjects recovered 92% of salt they ingested. Due to infradian rhythmical renal salt excretion, only 781 out of 1646 daily urine samples correctly classified a 3 g difference in salt intake (47%). Reducing salt intake from 12 to 6 g reduced 24-hour cortisone excretion (78.3±19.6 vs. 67.2±19.3 μg/d; P&lt;0.001) and increased water intake by 299 ml/d due to reduced glucocorticoid-driven metabolic water production. Even accurately collected 24-hour urine collections at intakes ranging from 6-12 grams salt per day provide no reliable information on individual salt intake. Reducing salt intake leads to reduced glucocorticoid levels decreased metabolic water production and a counterintuitive increase in fluid intake. Traditional views on fluid and electrolyte homeostasis may lead to misinterpretations in clinical practice, public health research, and policy-decision making.

Reduced salt intake for heart failure

© 2014 The Cochrane Collaboration. This is the protocol for a review and there is no abstract. The objectives are as follows: To review RCTs examining the effects of reduced dietary salt intake in individuals with heart failure.