Sodium in the Finnish diet: II trends in dietary sodium intake and comparison between intake and 24-h excretion of sodium

Vascular disease and ischemic stroke in patients with atrial fibrillation: Temporal trends and age-related differences

BACKGROUND AND AIMS

We examined temporal trends and age-related differences in the prevalence of vascular diseases and in their association with ischemic stroke (IS) risk in patients with atrial fibrillation (AF).

METHODS

The registry-based FinACAF study covered all patients with AF in Finland during 2007-2018. Incidence rate ratios (IRRs) of IS were computed with Poisson regression, and the interaction of vascular diseases with age and calendar year period was assessed.

RESULTS

We identified 229,565 patients (50.0 % female; mean age 72.7 years) with incident AF. The overall prevalence of any vascular disease was 28.6 %, and the prevalence increased from 2007 to 2018, primarily among patients over 75 years. Overall, 5909 (2.6 %) patients experienced IS within the first year after AF diagnosis. Crude IS rate decreased continuously during the study period in both patients with and without vascular diseases, with the rates remaining consistently higher in patients with vascular diseases. Vascular diseases were independently associated with higher IS incidence among patients under 65 years (adjusted IRR with 95 % confidence interval 1.35 (1.10-1.66)), while among older patients, only peripheral artery disease was associated with IS, and other vascular conditions had no association with IS. No interactions between the calendar year period and vascular diseases with IS rate were observed.

CONCLUSIONS

The association between vascular diseases and IS has remained stable over time and vascular diseases were independently associated with higher incidence of IS particularly in patients with AF under the age of 65.

Salt: a narrative review and local policy initiatives in Israel

High salt intake is a well-known risk factor for cardiovascular disease (CVD). Some recent prospective studies have challenged the salt-CVD link. We conducted a narrative review based on a systematic search and provided a national policy update. We reviewed 14 observational prospective studies in healthy adults, reporting the association between sodium intake and excretion or reduction and CVD incidence. Validated by cohort studies, recommended sodium consumption levels (< 1.5-2 gram per day) are still relevant for the prevention of CVD in adults. We discussed the findings and policy initiatives implemented in Israel. Such initiatives included voluntary and mandatory food labeling, and culturally tailored educational programs. The Ministry of Health in Israel initiated a salt reduction policy in recent years-aimed for the future of the industry as well as the population.

Sodium - a systematic review for Nordic Nutrition Recommendations 2023

Blood pressure (BP) rises along with increasing sodium intake from early childhood to late adulthood, and leads to hypertension among most men and women living in Nordic and Baltic countries. Elevated BP is the leading global risk factor for premature deaths and disability-adjusted life-years. A reduction in sodium intake is essential in the prevention of hypertension in individuals, in the lowering of BP levels, in the treatment of hypertensive individuals, and in decreasing risks associated with elevated BP. There is a progressive linear dose-response relationship between sodium intake and BP beginning from a sodium intake of less than 0.8 g/day. Sodium reduction decreases BP linearly by a dose-response manner down to a sodium intake level of less than 2 g/day. Randomised intervention studies with a duration of at least 4 weeks confirm the efficiency and safety of reducing blood sodium intake to a level of less than 2 g/day. Results from prospective cohort studies show that higher sodium intake is positively associated with an increased risk of stroke and cardiovascular events and mortality among the general adult population, and the associations are linear in studies using proper sodium assessment methods. Analyses assessing sodium intake using at least two 24-h urine samples have shown a linear positive relationship between sodium intake and the risk of a cardiovascular event or death. Based on an overall evaluation of the available data, a limitation of the sodium intake to 2.0 g/day is suggested for adults. The optimal sodium intake level would be probably about 1.5 g/day. Sodium intake recommended for children can be extrapolated from the recommended sodium intake for adults. According to national dietary surveys, the average sodium intakes in Nordic countries range in adult men from 3.6 to 4.4 g/day and in adult women from 2.6. to 3.2 g/day, and in Baltic countries in men from 2.6 to 5.1 g/day and in women from 1.8 to 3.6 g/day.

Estimating habitual iodine intake and prevalence of inadequacy from spot urine in cross-sectional studies: a modeling analysis to determine the required sample size

BACKGROUND

The habitual/usual iodine intake and the prevalence of iodine inadequacy may be estimated from spot urinary iodine concentrations in cross-sectional studies by collecting a repeat spot urine in a subgroup of the study population and accounting for within-person variability in iodine intake. However, guidance on the required overall sample size (N) and the replicate rate (n) is lacking.

OBJECTIVES

To determine the sample size (N) and replicate rate (n) needed to estimate the prevalence of iodine inadequacy in cross-sectional studies.

METHODS

We used data from local observational studies conducted in women 17-49 y old in Switzerland (N = 308), South Africa (N = 154), and Tanzania (N = 190). All participants collected 2 spot urine samples. We calculated the iodine intake using urinary iodine concentrations and accounted for urine volume using urinary creatinine concentration. For each study population, we estimated the habitual iodine intake distribution and determined the prevalence of iodine intake below the average requirement using the Statistical Program to Assess habitual Dietary Exposure (SPADE). We used the obtained model parameters in power analyzes and estimated the prevalence of iodine inadequacy for different sample sizes (N = 400, 600, and 900) and replicate rates (n = 50, 100, 200, 400, 600, and 900).

RESULTS

The estimated prevalence (95% CI) of inadequate iodine intake was 21% (15, 28%), 5.1% (1.3, 8.7%), and 8.2% (3.4, 13%) for Swiss, South African, and Tanzanian women, respectively. An N of 400 women, with a repeated measure (n) in 100 women, achieved a satisfactory precision of the prevalence estimate in all study populations. Increasing the replicate rate (n) improved the precision more effectively than increasing the N of the study.

CONCLUSIONS

The sample size for cross-sectional studies aiming to assess the prevalence of inadequate iodine intake depend on the expected prevalence, the overall variance in intake, and the study design. However, an N of 400 participants with a repeated measure of 25% may be used as guidance when planning observational studies applying simple random sampling. This trial was registered at clinicaltrials.gov as NCT03731312.

National and sub-national trends of salt intake in Iranians from 2000 to 2016: a systematic analysis

Background

One fifth of the global burden of cardiovascular diseases (CVDs) in 2017 was attributable to excessive salt intake. As a member of the World Health Organization (WHO), Iran has committed itself to a 30% reduction in salt intake by 2025. Evidence on the amount and trend of salt intake among the Iranian population at national and sub-national levels is scarce. This study aimed to estimate the Iranian population’s salt intake during 2000–2016 at the national and sub-national levels, by sex and age groups.

Methods

Data on national and sub-national mean salt intake was obtained through systematically searching the literature and contacting the research studies’ principal investigators. Data collected through various methods were harmonized using the cross-walk method. Bayesian hierarchical and spatio-temporal-age regression models and simulation analysis were used to estimate the mean salt intake and its uncertainty interval across sex, age, year, and province.

Results

National age-sex standardized mean salt intake decreased from 10·53 g/day (95% uncertainty interval [UI]: 10·2 to 10·9) in 2000 to 9·41 (9·2 to 10·6) in 2016 (percent change: − 9·8% [− 21·1–3·1]). The age-standardized mean salt intake in women had decreased from 9·8 g/day (95% UI: 9·0–10·6) in 2000 to 9·1 g/day (8·6–9·7) in 2016 (percent change: − 6·6% [− 19·0–7·9]). The same measure in men was 11·1 g/day in 2000 (95% UI: 10·3–11·8) and 9·7 g/day (9·1–10·2) in 2016 (percent change: − 12·7% [− 23·0 – -0·9]).

Age-sex standardized mean salt intake at the sub-national level in 2016 varied from 8·0 (95% UI: 7·0–9·0) to 10·5 (10·0–11·1). The difference between the provinces with the highest and the lowest levels of salt intake in 2016 was 31·3%.

Conclusion

Salt intake decreased in Iran from 2000 to 2016, while persistently exceeding the recommended values. This declining trend was more pronounced between 2010 and 2016, which might be attributed to Iran’s compliance to WHO’s Action Plan for reducing NCDs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13690-022-00871-w.

Dietary sodium estimation methods: accuracy and limitations of old and new methods in individuals at high cardiovascular risk

OBJECTIVE

Accurate and easy to use methods for dietary Na intake estimation in population level are lacking. We aimed at (i) estimating the mean Na intake in the group level using a variety of dietary methods (DM) and urinary methods (UM) and correlating them with 24-h urine collection (24UCol) and (ii) improving the accuracy of the existing DM.

DESIGN

The most common DM (three 24-h dietary recalls (24DR) and FFQ) and UM (24UCol and spot urine collection using common equations) were applied. To improve the existing: (i) 24DR, discretionary Na was quantified using salt-related questions or adding extra 15 % in total Na intake and (ii) FFQ, food items rich in Na and salt-related questions were added in the standard questionnaire (NaFFQ).

SETTING

National and Kapodistrian University of Athens, Greece.

PARTICIPANTS

Totally, 122 high cardiovascular risk subjects (56·0 ± 12·6 years; 55·7 % males).

RESULTS

Mean 24 h Na excretion (24UNa) was 2810 ± 1304 mg/d. Spot urine methods overestimated the 24UNa (bias range: -1781 to -492 mg) and were moderately correlated to 24UCol (r = 0·469-0·596, P ≤ 0·01). DM underestimated the 24UNa (bias range: 877 to 1212 mg) and were weakly correlated with 24UCol. The improved DM underestimated the 24UNa (bias range: 877 to 923 mg). The NaFFQ presented the smallest bias (-290 ± 1336 mg) and the strongest correlation with 24UCol (r = 0·497, P ≤ 0·01), but wide limits of agreement in Bland-Altman plots (-2909 mg; 2329 mg), like all the other methods did.

CONCLUSIONS

The existing methods exhibit poor accuracy. Further improvement of the newly developed NaFFQ could be promising for more accurate estimation of mean dietary Na intake in epidemiological studies. Additional validation studies are needed.

Validation and reproducibility of a semi-qualitative food frequency questionnaire for assessment of sodium intake in Iranian population

Background

Few semi-quantitative food frequency questionnaires (SFFQ)s has yet been developed to assess sodium intake in Middle East region. This study was performed to validate a SFFQ for assessment of sodium consumption and food groups΄ contribution to sodium intake.

Methods

This study was performed on 219 healthy participants including 113 adults aged ≥19 years and 106 children aged 6–18 years in Isfahan, Iran. They were administered two SFFQ at the beginning and after 1 year to evaluate the reproducibility. The validity of SFFQ for assessment of sodium intake was compared with 24-h urine sodium and twelve 24-h dietary recalls which were completed monthly during a year as two standard methods.

Results

Correlation coefficient between the contribution of food groups to sodium intake based on SFFQ and 24-h dietary recalls varied from 0.04 for legumes (P = 0.667) to 0.47 for added salt (P < 0.001). There was a significant correlation between the estimated total sodium intake based on SFFQ and both standard methods (P < 0.01). Intraclass correlation coefficient (95% CI) between first and second SFFQ had a diverse range from 0.10 (-0.05, 0.17) for fats and oils to 0.49 (0.28, 0.69) for bread. According to the Bland-Altman plots, we observed an acceptable level of agreement between the two methods for sodium intake.

Conclusions

The SFFQ was a relatively valid and reproducible method for estimating sodium intake. Combination of this SFFQ with a valid prediction of 24-h urinary sodium excretion can be useful in achieving more accurate results.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-021-00749-7.

Seasonal effects on urinary iodine concentrations in women of reproductive age: An observational study in Tanzania and South Africa

BACKGROUND

Iodine intake in populations is usually assessed by measuring urinary iodine concentrations (UICs) in spot samples. Hot climate conditions may reduce urine volume, thus leading to overestimations of UIC and thereby masking inadequate iodine intake.

OBJECTIVES

We investigated the effects of season on UICs in 2 populations exposed to high-temperature climates.

METHODS

In this observational study, we examined women (18-49 years) in Tanzania (ncold = 206; nhot = 179) and South Africa (ncold = 157; nhot = 126) during cold and hot seasons. From each woman in both seasons, we obtained two 24-hour urine collections and 2 spot urine samples, as well as salt, water, and cow's milk samples. We measured the urine volume, UIC, and urinary creatinine concentration (UCC). The 24-hour urinary iodine excretion (UIE) was calculated and used to estimate the iodine intake. We used linear mixed-effects models to test for differences between seasons.

RESULTS

In Tanzanian women, we observed no seasonal effect on the urine volume, 24-hour UIE, 24-hour UIC, spot UIC, spot UIC:UCC ratio, or salt iodine concentration. In South African women, the median 24-hour urine volume was 1.40 L (IQR, 0.96-2.05 L) in the winter and 15% lower in the summer (P < 0.001). The median 24-hour UIE was 184 µg/day (IQR, 109-267 µg/day) in the winter and 34% lower in the summer (P < 0.001), indicating a lower iodine intake. As a result, UICs did not significantly differ between seasons in 24-hour collections and spot samples, whereas the spot UIC:UCC ratio differed by 21% (P < 0.001) and reflected the lower iodine intake. In both study populations, the within- and between-person variabilities in urine volume, 24-hour UICs, and spot UICs were higher than the variability between seasons.

CONCLUSIONS

Spot UIC may slightly overestimate the iodine intake in hot temperatures due to concentrated urine, and methods to correct for urine volume may be considered. Local seasonal differences in iodine intakes may also occur in some populations. This trial was registered at http://www.clinicaltrials.gov as NCT03215680.

A Systematic Review of the Sources of Dietary Salt Around the World

Excess salt intake contributes to hypertension and increased cardiovascular disease risk. Efforts to implement effective salt-reduction strategies require accurate data on the sources of salt consumption. We therefore performed a systematic review to identify the sources of dietary salt around the world. We systematically searched peer-reviewed and gray literature databases for studies that quantified discretionary (salt added during cooking or at the table) and nondiscretionary sources of salt and those that provided information about the food groups contributing to dietary salt intake. Exploratory linear regression analysis was also conducted to assess whether the proportion of discretionary salt intake is related to the gross domestic product (GDP) per capita of a country. We identified 80 studies conducted in 34 countries between 1975 and 2018. The majority (n = 44, 55%) collected data on dietary salt sources within the past 10 y and were deemed to have a low or moderate risk of bias (n = 75, 94%). Thirty-two (40%) studies were judged to be nationally representative. Populations in Brazil, China, Costa Rica, Guatemala, India, Japan, Mozambique, and Romania received more than half of their daily salt intake from discretionary sources. A significant inverse correlation between discretionary salt intake and a country's per capita GDP was observed (P < 0.0001), such that for every $10,000 increase in per capita GDP, the amount of salt obtained from discretionary sources was lower by 8.7% (95% CI: 5.1%, 12%). Bread products, cereal and grains, meat products, and dairy products were the major contributors to dietary salt intake in most populations. There is marked variation in discretionary salt use around the world that is highly correlated with the level of economic development. Our findings have important implications for the type of salt-reduction strategy likely to be effective in a country.

Comparison of 24-hour urine and 24-hour diet recall for estimating dietary sodium intake in populations: A systematic review and meta-analysis

This systematic literature review and meta-analysis examined whether 24-hour diet recall is a valid way to measure mean population sodium intake compared with the gold standard 24-hour urinary assessment. The authors searched electronic databases MEDLINE, Embase, and Scopus using pre-defined terms. Studies were eligible for inclusion if they assessed adult humans in free-living settings, and if they included group means for 24-hour diet recall and 24-hour urinary collection of sodium intake in the same participants. Studies that included populations with an active disease state that might interfere with normal sodium metabolism were excluded. Results of 28 studies are included in the meta-analysis. Overall, 24-hour diet recall underestimated population mean sodium intake by an average of 607 mg per day compared to the 24-hour urine collection. The difference between measures from 24-hour urine and 24-hour diet recall was smaller in studies conducted in high-income countries, in studies where multiple-pass methods of 24-hour diet recall were reported and where urine was validated for completeness. Higher quality studies also reported smaller differences between measures than lower quality studies. Monitoring of population sodium intake with 24-hour urinary excretion remains the most accurate method of assessment. Twenty-four-hour diet recall tends to underestimate intake, although high-quality 24-hour diet recall improves accuracy, and may be used if 24-hour urine is not feasible.

Associations of urinary sodium levels with overweight and central obesity in a population with a sodium intake

Background

Previous studies have reported an association between dietary sodium intake and overweight/central obesity. However, dietary survey methods were prone to underestimate sodium intake. Therefore, this study investigated the associations of calculated 24-h urinary sodium excretion, an index of dietary sodium intake, with various obesity parameters including body mass index (BMI) and waist circumference (WC) in a population with a relatively high sodium intake.

Methods

A total of 16,250 adults (aged ≥19 years) and 1476 adolescents (aged 10-18 years), with available information on spot urine sodium levels and anthropometric measurements from the Korea National Health and Nutrition Examination Survey (KNHANES) were included in this study. We calculated 24-h urine sodium excretion levels from spot urine sodium levels using the Tanaka formula.

Results

In adults, those with high sodium excretion levels (≥ 3200 mg) showed increased odds of overweight and central obesity compared to those with low urinary sodium excretion level (< 2200 mg) (odds ratio [OR] = 2.17, 95% confidence interval [CI] = 1.90-2.49 for overweight; OR = 2.50, 95% CI = 2.13-2.94 for central obesity). These associations were also observed in adolescents (OR = 5.80, 95% CI = 3.17-10.60 for overweight; OR = 4.19, 95% CI = 1.78-9.89 for central obesity).

Conclusions

The present study suggests that reducing salt intake might be important for preventing overweight and central obesity, especially in adolescents. However, because the present study was conducted with cross-sectional study design, further longitudinal studies are warranted to confirm the causal relationship between urinary sodium excretion and overweight/central obesity.

Twenty-Four-Hour Diet recall and Diet records compared with 24-hour urinary excretion to predict an individual's sodium consumption: A Systematic Review

This systematic literature review aimed to investigate whether 24 hour diet recall and diet records are reliable and valid ways to measure usual dietary sodium intake compared with 24 hour urinary assessment. We searched electronic databases Medline, Embase, Cinahl, Lilacs, Google Scholar and the Cochrane Library using pre-defined terms Studies were eligible for inclusion if they assessed adult humans in free-living settings, and if they included dietary assessment and 24 hours urinary collection for assessment of sodium intake in the same participants. Studies that included populations with an active disease state that might interfere with normal sodium metabolism were excluded. Results of 20 studies using 24 hour diet recall recall (including 14 validation studies) and 10 studies using food records (including six validation studies) are included in this review. Correlations between estimates from dietary assessment and urinary excretion ranged from 0.16 to 0.72 for 24 hour diet recall, and 0.11 to 0.49 for food diaries. Bland-Altman analysis in two studies of 24 hour diet recall showed poor agreement with 24 hours urinary sodium excretion. These results show that 24 hour diet recall and diet records inaccurately measure dietary sodium intake in individuals compared with the gold standard 24 hours urinary excretion. Validation studies of dietary assessment methods should include multiple days of assessment and 24 hours urine collection, use relevant food composition databases and Bland-Altman methods of analysis.

Dietary sodium intake in urban and rural Malawi, and directions for future interventions

Background

High dietary sodium intake is a major risk factor for hypertension. Data on population sodium intake are scanty in sub-Saharan Africa, despite a high hypertension prevalence in most countries.

Objective

We aimed to determine daily sodium intake in urban and rural communities in Malawi.

Design

In an observational cross-sectional survey, data were collected on estimated household-level per capita sodium intake, based on how long participants reported that a defined quantity of plain salt lasts in a household. In a subset of 2078 participants, 24-h urinary sodium was estimated from a morning spot urine sample.

Results

Of 29,074 participants, 52.8% of rural and 50.1% of urban individuals lived in households with an estimated per capita plain salt consumption >5 g/d. Of participants with urinary sodium data, 90.8% of rural and 95.9% of urban participants had estimated 24-h urinary sodium >2 g/d; there was no correlation between household per capita salt intake and estimated 24-h urinary sodium excretion. Younger adults were more likely to have high urinary sodium and to eat food prepared outside the home than were those over the age of 60 y. Households with a member with previously diagnosed hypertension had reduced odds (OR: 0.59; 95% CI: 0.51, 0.68) of per capita household plain salt intake >5 g/d, compared with those where hypertension was undiagnosed.

Conclusions

Sodium consumption exceeds the recommended amounts for most of the population in rural and urban Malawi. Population-level interventions for sodium intake reduction with a wide focus are needed, targeting both sources outside the home as well as home cooking. This trial was registered at clinicaltrials.gov as NCT03422185.

Association between Dietary Mineral Intake and Chronic Kidney Disease: The Health Examinees (HEXA) Study

Few studies have explored the association between mineral intake and chronic kidney disease (CKD). A cross-sectional analysis investigated the association between mineral intake (calcium, phosphorus, sodium, potassium, iron, and zinc) and CKD using the Health Examinee (HEXA) cohort of the Korean Genome and Epidemiologic Study (KoGES). For 159,711 participants, mineral intake was assessed by a food frequency questionnaire. CKD was defined as an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73 m². Dietary intake of each mineral was divided into quartiles and the quartile including recommended dietary allowance (RDA) or adequate intake (AI) of each mineral was used as a reference. We assessed the association between the quartile of mineral intakes and CKD using polytomous logistic regression models. The lowest quartiles of phosphorus (≤663.68 mg/day, odds ratio [OR] = 1.64, 95% confidence interval [CI]: 1.25–2.15), potassium (≤1567.53 mg/day, OR = 1.87, 95% CI: 1.27–2.75), iron (≤6.93 mg/day, OR = 1.53, 95% CI: 1.17–2.01), and zinc (≤5.86 mg/day, OR = 1.52, 95% CI: 1.02–2.26) were associated with higher odds for advanced CKD compared with the references. The present study suggests that an inadequate intake of some minerals may be associated with CKD occurrence in the general population. Due to the reverse causation issue in this cross-sectional study design, further longitudinal prospective studies are needed in order to prove the results.

Effect of individualised dietary advice for weight loss supplemented with walnuts on blood pressure: the HealthTrack study

BACKGROUND/OBJECTIVES

In addition to weight-loss, healthy dietary patterns and lower sodium intakes can help reduce blood pressure (BP), but individualised dietary advice may be necessary to achieve these effects. This study aimed to examine the impact of individualised dietary advice on BP in the intensive phase of a weight-loss trial.

SUBJECTS/METHODS

Secondary analysis of baseline and 3-month data from the HealthTrack randomised controlled trial (n = 211). Participants were randomly assigned to one of three dietary advice groups: general advice (control), individualised advice (intervention group, I), or intervention group supplemented with 30 g walnuts/day (IW). Resting BP and 24-h urine sodium and potassium were measured. Dietary intake was evaluated through diet history interviews.

RESULTS

Unadjusted SBP reduced significantly in all groups (IW and I groups P < 0.001; control group P = 0.002) and DBP in IW and I groups (P < 0.001). Compared to controls, the reductions in BP were 3-4 mmHg greater in the I and IW groups, but this only reached significance for DBP in the I group (-3.3 mmHg; P = 0.041). After controlling for age, sex, medication, weight-loss, physical activity and smoking, only the IW group showed a significant association between SBP reduction and increased urinary potassium (β = -0.101, P = 0.044), decreased sodium:potassium ratio (β = 2.446, P = 0.037) and increased consumption of seed and nut products and dishes (β = -0.108, P = 0.034).

CONCLUSIONS

Dietary patterns with distinctive foods and lower sodium:potassium ratios may enhance the effects of weight-loss on BP. The patterns were best achieved with individualised dietary advice and food supplements.

Associations of Usual 24-Hour Sodium and Potassium Intakes with Blood Pressure and Risk of Hypertension among Adults in China's Shandong and Jiangsu Provinces

BACKGROUND/AIMS

High sodium intake and low intake of potassium can increase blood pressure (BP) and risk of developing hypertension. Few studies have examined the association between 24-h urinary sodium and potassium excretion and BP or risk of hypertension in China, and most used only a single 24-h urinary sample.

METHODS

We analyzed data on 2281 participants aged 18-69 years by using two 24-h urinary sodium and potassium excretions from the supplemental baseline survey of the Shandong-Ministry of Health Action on Salt Reduction and Hypertension (SMASH) project. We used measurement error models to estimate usual intakes, multivariable linear regression to assess their association with B P, and logistic regression to estimate the risk of hypertension.

RESULTS

The average usual intakes of sodium and potassium, and the mean sodium-potassium ratio, were 166.9 mmol/day, 25.3 mmol/day, and 6.8, respectively. All three measures were significantly associated with systolic BP (SBP) and diastolic BP (DBP), with an increase of 1.39 mmHg (95% confidence interval [CI] 0.44─2.34) in SBP and 0.94 mmHg (95% CI 0.34─1.55) in DBP for a 1-standard deviation (SD) (25.6mmol/day) increase in sodium intake, a decrease of 1.42 mmHg (95% CI -2.37─ -0.47) in SBP and 0.91 mmHg (95% CI -1.52─ -0.30) in DBP for a 1-SD (3.4 mmol/day) increase in potassium intake, and an increase of 0.97 mmHg (95% CI 0.36─1.58) in SBP and of 0.65 mmHg (95% CI 0.26─1.04) in DBP per unit increase in the sodium-to-potassium ratio. The adjusted odds ratios comparing the risk of hypertension among adults in the highest with those in the lowest quintile differ significantly for potassium (0.51; 95% CI 0.29─0.88) and sodium-to-potassium ratio (1.40; 95% CI 1.01─1.94).

CONCLUSIONS

Our results suggested that higher sodium and lower potassium intakes are associated with increased BP and risk of hypertension in the Shandong and Jiangsu adults.

Socioeconomic Determinants of Sodium Intake in Adult Populations of High-Income Countries: A Systematic Review and Meta-Analysis

BACKGROUND

A poorer quality diet among individuals with low socioeconomic status (SES) may partly explain the higher burden of noncommunicable disease among disadvantaged populations. Because there is a link between sodium intake and noncommunicable diseases, we systematically reviewed the current evidence on the social patterning of sodium intake.

OBJECTIVES

To conduct a systematic review and a meta-analysis of the evidence on the association between SES and sodium intake in healthy adult populations of high-income countries.

SEARCH METHODS

We followed the PRISMA-Equity guidelines in conducting a literature search that ended June 3, 2016, via MEDLINE, Embase, and SciELO. We imposed no publication date limits.

SELECTION CRITERIA

We considered only peer-reviewed articles meeting the following inclusion criteria: (1) reported a measure of sodium intake disaggregated by at least 1 measure of SES (education, income, occupation, or any other socioeconomic indicator); (2) were written in English, Spanish, Portuguese, French, or Italian; and (3) were conducted in a high-income country as defined by the World Bank (i.e., per capita national gross income was higher than $12 746). We also excluded articles that exclusively sampled low-SES individuals, pregnant women, children, adolescents, elderly participants, or diseased patients or that reported results from a trial or intervention.

DATA COLLECTION AND ANALYSIS

As summary measures, we extracted (1) the direction (positive, negative, or neutral) and the magnitude of the association between each SES indicator and sodium intake, and (2) the estimated sodium intake according to SES level. When possible and if previously unreported, we calculated the magnitude of the relative difference in sodium intake between high- and low-SES groups for each article, applying this formula: ([value for high-SES group - value for low-SES group]/[value for high-SES group]) × 100. We considered an association significant if reported as such, and we set an arbitrary 10% relative difference as clinically relevant and significant. We conducted a meta-analysis of the relative difference in sodium intake between high- and low-SES groups. We included articles in the meta-analysis if they reported urine-based sodium estimates and provided the total participant numbers in the low- and high-SES groups, the estimated sodium intake means for each group (in mg/day or convertible units), and the SDs (or transformable measures). We chose a random-effects model to account for both within-study and between-study variance.

MAIN RESULTS

Fifty-one articles covering 19 high-income countries met our inclusion criteria. Of these, 22 used urine-based methods to assess sodium intake, and 30 used dietary surveys. These articles assessed 171 associations between SES and sodium intake. Among urine-based estimates, 67% were negative (higher sodium intake in people of low SES), 3% positive, and 30% neutral. Among diet-based estimates, 41% were negative, 21% positive, and 38% neutral. The random-effects model indicated a 14% relative difference between low- and high-SES groups (95% confidence interval [CI] = -18, -9), corresponding to a global 503 milligrams per day (95% CI = 461, 545) of higher sodium intake among people of low SES.

CONCLUSIONS

People of low SES consume more sodium than do people of high SES, confirming the current evidence on socioeconomic disparities in diet, which may influence the disproportionate noncommunicable disease burden among disadvantaged socioeconomic groups. Public Health Implications. It is necessary to focus on disadvantaged populations to achieve an equitable reduction in sodium intake to a population mean of 2 grams per day as part of the World Health Organization's target to achieve a 25% relative reduction in noncommunicable disease mortality by 2025.

Validity and reliability of the dietary sodium restriction questionnaire in patients with hypertension

The study aimed to evaluate the reliability and the validity of the dietary sodium restriction questionnaire (DSRQ) in patients with hypertension receiving outpatient treatment at a tertiary care university hospital in Southern Brazil. This instrument is composed of three subscales: attitude, subjective norm and perceived behavioral control. A total of 104 patients were included. They were 63.3±8.9 years old and 75% were females. Cronbach's alpha coefficient for the subscales of attitude, subjective norm and perceived behavioral control were 0.75, 0.37 and 0.82, respectively. The PCA with the extraction of three factors explained a total of 53.5% of the variance. The data suggest that the 15-item DSRQ is reliable and has internal consistency of its construct to measure the barriers and the attitudes of hypertensive patients related to dietary sodium restriction and may be useful to improve blood pressure control.

Associations between Dietary Patterns and Blood Pressure in a Clinical Sample of Overweight Adults

BACKGROUND

Dietary pattern analysis provides important evidence revealing diet-disease relationships. It may be especially useful in areas less well researched, such as diet and hypertension in clinical populations.

OBJECTIVE

The aim of this study was to identify the association between dietary patterns and blood pressure (BP) in a sample of overweight adults volunteering for a clinical trial for weight loss.

DESIGN

This cross-sectional analysis used baseline data from the HealthTrack study, a 12-month randomized controlled trial. Dietary intake was evaluated with 4-day food records.

PARTICIPANTS/SETTING

Participants were 328 adults recruited from the Illawarra region of New South Wales, Australia, between May 2014 and April 2015.

MAIN OUTCOME MEASURES

Resting BP and 24-hour urine sodium and potassium were measured.

STATISTICAL ANALYSIS

Dietary patterns were derived by principal component analysis from 21 food groups. Multiple regression analysis was performed to assess the association between the extracted dietary patterns and BP.

RESULTS

The participants' mean age was 43.6±8.0 years, mean body mass index was 32.4±4.2, and mean systolic BP/diastolic BP was 124.9±14.5/73.3±9.9 mm Hg. Six major dietary patterns were identified: "nuts, seeds, fruit, and fish," "milk and meat," "breads, cereals, and snacks," "cereal-based products, fats, and oils," "alcohol, eggs, and legumes," and "savoury sauces, condiments, and meat." The "nuts, seeds, fruit, and fish" dietary pattern was significantly and inversely associated with systolic BP (F [7,320]=15.248; P<0.0005; adjusted R²=0.234 and diastolic BP (F [7,320]=17.351; P<0.0005; adjusted R²=0.259) and sodium-to-potassium ratio (F [7,320]=6.210; P<0.0005; adjusted R²=0.100).

CONCLUSIONS

A dietary pattern rich in nuts, seeds, fruit, and fish was inversely associated with blood pressure in this clinical sample. The findings suggest that current dietary guidelines are relevant to an overweight clinical population and support the value of dietary pattern analysis when exploring the diet-disease relationship.

Relationship between sodium and potassium intake and blood pressure in a sample of overweight adults

OBJECTIVE

The aim of this study was to examine the relationship between sodium and potassium intakes and blood pressure (BP) in a clinical sample.

METHODS

Secondary analysis of baseline data from 328 participants (mean age: 43.6 ± 8 y, mean body mass index [BMI]: 32.4 ± 4.2 kg/m², mean systolic BP [SBP]/diastolic BP [DBP]: 124.9 ± 14.5/73.3 ± 9.9 mm Hg) of the 12-mo HealthTrack randomized controlled weight loss trial was conducted. Resting BP and 24-h urine sodium and potassium were measured. Dietary intake was evaluated with 4-d food records and self-reported diet histories.

RESULTS

Urinary sodium was positively correlated (Spearman's rho) with SBP (r = 0.176; P = 0.001) and DBP (r = 0.150; P = 0.003). The ratio of sodium to potassium was positively correlated with SBP (r = 0.1; P = 0.035). Urinary sodium (F [4,323] = 20.381; P < 0.0005; adjusted R² = 0.231) and sodium-to-potassium ratio (F[4,323] = 25.008; P < 0.0005; adjusted R² = 0.227) significantly predicted SBP after controlling for age, sex, BMI, and hypertension medication use. Dietary sodium and potassium significantly predicted urinary sodium (B = 0.33, t = 4.032, P < 0.01) and potassium (B = 0.67, t = 8.537, P < 0.01) excretion, respectively, after adjustment for energy and BMI. Median dietary sodium intake was 3197 mg/d and median dietary potassium intake was 2886 mg/d. Cereal-based products and dishes were the major contributors (22%) to total sodium intake.

CONCLUSIONS

In the present study, a high dietary sodium intake and high sodium-to-potassium ratio predicted high SBP. This suggests a need to focus dietary advice on reduction of sources of sodium and increasing sources of potassium in weight loss interventions to improve BP control.

Dietary sodium and health: more than just blood pressure

Sodium is essential for cellular homeostasis and physiological function. Excess dietary sodium has been linked to elevations in blood pressure (BP). Salt sensitivity of BP varies widely, but certain subgroups tend to be more salt sensitive. The mechanisms underlying sodium-induced increases in BP are not completely understood but may involve alterations in renal function, fluid volume, fluid-regulatory hormones, the vasculature, cardiac function, and the autonomic nervous system. Recent pre-clinical and clinical data support that even in the absence of an increase in BP, excess dietary sodium can adversely affect target organs, including the blood vessels, heart, kidneys, and brain. In this review, the investigators review these issues and the epidemiological research relating dietary sodium to BP and cardiovascular health outcomes, addressing recent controversies. They also provide information and strategies for reducing dietary sodium.

Effects of a behavioral intervention that emphasizes spices and herbs on adherence to recommended sodium intake: results of the SPICE randomized clinical trial

BACKGROUND

For decades, dietary sodium intake in the United States has remained high, and few studies have examined strategies for maintaining recommended intakes.

OBJECTIVE

We examined the effects of a behavioral intervention, which emphasized spices and herbs, on the maintenance of sodium intake at the recommended intake of 1500 mg/d in individuals to whom the US Dietary Guidelines for Americans apply.

DESIGN

We conducted a 2-phase study that included adults ≥18 y of age for whom Dietary Guidelines for Americans recommends 1500 mg Na/d. The study was conducted in Baltimore, Maryland, from 2012 to 2014. In phase 1, 55 individuals consumed a low-sodium diet for 4 wk. Participants were provided all foods, snacks, and calorie-containing drinks. In phase 2, 40 participants from phase 1 were randomly assigned to either a behavioral intervention to reduce sodium intake (n = 20) or a self-directed control group (n = 20) for 20 wk. The primary study outcome was the change in mean 24-h urinary sodium excretion during phase 2. Linear regression analyses were used to determine intervention effects on urinary sodium excretion.

RESULTS

Participant characteristics were as follows: women: 65%; African American: 88%; hypertension: 63%; diabetes: 18%; mean age: 61 y; and mean body mass index (in kg/m(2)): 30. At the end of phase 2, mean 24-h sodium excretion was lower in the behavioral intervention than in the self-directed group (mean difference: -956.8 mg/d; 95% CI: -1538.7, -374.9 mg/d) after sodium intake at screening was controlled for (P = 0.002). These findings persisted in sensitivity analyses that excluded potentially incomplete urine collections [Mage's equation mean difference: -1090 mg/d (P = 0.001); Joosens' equation mean difference: -796 mg/d (P = 0.04)].

CONCLUSIONS

A multifactorial behavioral intervention emphasizing spices and herbs significantly reduced sodium intake. Because of the ubiquity of sodium in the US food supply, multilevel strategies addressing individual behaviors and the food supply are needed to improve adherence to recommendations. This trial was registered at clinicaltrials.gov as NCT01615159.

Validation of diet and urinary excretion derived estimates of sodium excretion against 24-h urine excretion in a worksite sample

BACKGROUND AND AIMS

To validate diet and urinary excretion derived estimates of sodium intake against those derived from 24-h urine collections in an Irish manufacturing workplace sample.

METHODS AND RESULTS

We have compared daily sodium (Na) excretion from PABA validated 24-h urine collections with estimated daily sodium excretion derived from the following methods: a standard Food Frequency Questionnaire (FFQ), a modified 24-h dietary recall method, arithmetic extrapolations from morning and evening spot urine samples, predicted sodium excretion from morning and evening spot urine samples using Tanaka's, Kawasaki's and the INTERSALT formula. All were assessed using mean differences (SD), Bland-Altman plots, correlation coefficients and ROC Area under the Curve (AUC) for a cut off of ≥100 mmol of Na/day. The Food Choice at Work study recruited 802 participants aged 18-64 years, 50 of whom formed the validation sample. The mean measured 24-h urinary sodium (gold standard) was 138 mmol/day (8.1 g salt). At the group level, mean differences were small for both dietary methods and for the arithmetic extrapolations from morning urine samples. The Tanaka, Kawasaki and INTERSALT methods provided biased estimates of 24-h urinary sodium. R(2) values for all methods ranged from 0.1 to 0.48 and AUC findings from 0.57 to 0.76.

CONCLUSION

Neither dietary nor spot urine sample methods provide adequate validity in the estimation of 24-h urinary sodium at the individual level. However, group mean errors from dietary methods are small and random and compare favourably with those from spot urine samples in this population.

Cadmium body burden of the Swiss population

Urinary cadmium (Cd) excretion was measured within a representative Swiss collective. With a median of 0.23 µg/24 h (n = 1409) and the 95th percentile at 0.81 µg/24 h, no increased health risk for the general non-exposed population was identified. The independent variables Age, BMI and Smoking habit had a significant effect on urinary Cd excretion. No association was found with the region of residence and sex. A subsample comparison between 24-h and spot urines of the same subjects (n = 90) did not reveal an evident concentration difference for both creatinine-adjusted sample types. Dependencies on age and gender were observed for creatinine, which consequently impacts on the creatinine normalisation of urine samples.

High sodium intake: review of recent issues on its association with cardiovascular events and measurement methods

There has been a long-known association between high dietary sodium intake and hypertension, as well as the increased risk of cardiovascular disease. Reduction of sodium intake is a major challenge for public health. Recently, there have been several controversial large population-based studies regarding the current recommendation for dietary sodium intake. Although these studies were performed in a large population, they aroused controversies because they had a flaw in the study design and methods. In addition, knowledge of the advantages and disadvantages of the methods is essential in order to obtain an accurate estimation of sodium intake. I have reviewed the current literatures on the association between sodium intake and cardiovascular events, as well as the methods for the estimation of sodium intake.

High sodium intake is associated with short leukocyte telomere length in overweight and obese adolescents

Background/Objectives

Telomere shortening plays an important role in cellular aging. However, the impact of high sodium intake, an important risk factor of age-related diseases, on telomere shortening remains unknown. Therefore, we examined the relationship between high dietary sodium intake and leukocyte telomere length, particularly in the context of obesity since obesity increases salt sensitivity.

Subjects/Methods

Leukocyte telomere length (LTL) was determined by a quantitative polymerase chain reaction method in 766 adolescents aged 14–18 years (50% female, 49% African Americans). Dietary sodium intake was assessed by seven independent 24-h dietary recalls. We divided the sample into low sodium (mean 2388 ± 522 mg/day) or high sodium groups (mean 4142 ± 882 mg/day) based on the median value (3280.9 mg/day).

Results

In the entire cohort, there was no significant association between sodium intake and LTL (r = −0.05, p = 0.24). However, there was a significant interaction between sodium intake and obesity status (p = 0.049). Further multiple linear regression analyses revealed that higher dietary sodium intake was associated with shorter LTL in the overweight/obese group (BMI ≥ 85^th percentile, β = −0.37, p = 0.04), but not in the normal weight group (β = 0.01, p= 0.93) after adjusting for multiple confounding factors. In the overweight/obese group, LTL was significantly shorter in the high sodium intake subjects vs. low sodium intake subjects (1.24 ± 0.22 vs. 1.32 ± 0.20, p = 0.02), but not the normal weight group (1.29 ± 0.24 vs. 1.30 ± 0.24, p = 0.69).

Conclusions

Higher dietary sodium intake is associated with shorter telomere length in overweight and obese adolescents.

Health gain by salt reduction in europe: a modelling study

Excessive salt intake is associated with hypertension and cardiovascular diseases. Salt intake exceeds the World Health Organization population nutrition goal of 5 grams per day in the European region. We assessed the health impact of salt reduction in nine European countries (Finland, France, Ireland, Italy, Netherlands, Poland, Spain, Sweden and United Kingdom). Through literature research we obtained current salt intake and systolic blood pressure levels of the nine countries. The population health modeling tool DYNAMO-HIA including country-specific disease data was used to predict the changes in prevalence of ischemic heart disease and stroke for each country estimating the effect of salt reduction through its effect on blood pressure levels. A 30% salt reduction would reduce the prevalence of stroke by 6.4% in Finland to 13.5% in Poland. Ischemic heart disease would be decreased by 4.1% in Finland to 8.9% in Poland. When salt intake is reduced to the WHO population nutrient goal, it would reduce the prevalence of stroke from 10.1% in Finland to 23.1% in Poland. Ischemic heart disease would decrease by 6.6% in Finland to 15.5% in Poland. The number of postponed deaths would be 102,100 (0.9%) in France, and 191,300 (2.3%) in Poland. A reduction of salt intake to 5 grams per day is expected to substantially reduce the burden of cardiovascular disease and mortality in several European countries.

Reduced-Sodium Lunches Are Well-Accepted by Uninformed Consumers Over a 3-Week Period and Result in Decreased Daily Dietary Sodium Intakes: A Randomized Controlled Trial

BACKGROUND

Processed foods are major contributors to excessive sodium intake in Western populations. We investigated the effect of food reformulation on daily dietary sodium intake.

OBJECTIVE

To determine whether uninformed consumers accept reduced-sodium lunches and to determine the effect of consuming reduced-sodium lunches on 24-hour urinary sodium excretion.

DESIGN

A single-blind randomized controlled pretest-posttest design with two parallel treatment groups was used.

PARTICIPANTS/SETTING

Participants chose foods in an experimental real-life canteen setting at the Restaurant of the Future in Wageningen, the Netherlands, from May 16 until July 1, 2011.

INTERVENTION

After a run-in period with regular foods for both groups, the intervention group (n=36) consumed foods with 29% to 61% sodium reduction (some were partially flavor compensated). The control group (n=38) continued consuming regular foods.

MAIN OUTCOME MEASURES

Outcomes for assessment of acceptance were the amount of foods consumed, energy and sodium intake, remembered food liking, and intensity of sensory aspects. Influence on daily dietary sodium intake was assessed by 24-hour urinary sodium excretion.

STATISTICAL ANALYSES PERFORMED

Between and within-subject comparisons were assessed by analysis of covariance.

RESULTS

Energy intake and amount consumed of each food category per lunch remained similar for both groups. Compared with the control group, the intervention group's sodium intake per lunch was significantly reduced by -1,093 mg (adjusted difference) (95% CI -1,285 to -901), equivalent to 43 mmol sodium. Remembered food liking, taste intensity, and saltiness were scored similarly for almost all of the reduced-sodium foods compared with the regular foods. After consuming reduced-sodium lunches, compared with the control group, intervention participants' 24-hour urinary sodium excretion was significantly lower by -40 mEq (adjusted difference) (95% CI -63 to -16) than after consuming regular lunches, and this reflects a decreased daily sodium intake of 1 g.

CONCLUSIONS

Comparing the two treatment groups, consumption of reduced-sodium foods over a 3-week period was well accepted by the uninformed participants in an experimental real-life canteen setting. The reduced-sodium foods did not trigger compensation behavior during the remainder of the day in the intervention group compared with the control group, as reflected by 24-hour urinary sodium excretion. Therefore, offering reduced-sodium foods without explicitly informing consumers of the sodium reduction can contribute to daily sodium intake reduction.

Difference between 24-h diet recall and urine excretion for assessing population sodium and potassium intake in adults aged 18-39 y

BACKGROUND

Limited data are available on the accuracy of 24-h dietary recalls used to monitor US sodium and potassium intakes.

OBJECTIVE

We examined the difference in usual sodium and potassium intakes estimated from 24-h dietary recalls and urine collections.

DESIGN

We used data from a cross-sectional study in 402 participants aged 18-39 y (∼50% African American) in the Washington, DC, metropolitan area in 2011. We estimated means and percentiles of usual intakes of daily dietary sodium (dNa) and potassium (dK) and 24-h urine excretion of sodium (uNa) and potassium (uK). We examined Spearman's correlations and differences between estimates from dietary and urine measures. Multiple linear regressions were used to evaluate the factors associated with the difference between dietary and urine measures.

RESULTS

Mean differences between diet and urine estimates were higher in men [dNa - uNa (95% CI) = 936.8 (787.1, 1086.5) mg/d and dK - uK = 571.3 (448.3, 694.3) mg/d] than in women [dNa - uNa (95% CI) = 108.3 (11.1, 205.4) mg/d and dK - uK = 163.4 (85.3, 241.5 mg/d)]. Percentile distributions of diet and urine estimates for sodium and potassium differed for men. Spearman's correlations between measures were 0.16 for men and 0.25 for women for sodium and 0.39 for men and 0.29 for women for potassium. Urinary creatinine, total caloric intake, and percentages of nutrient intake from mixed dishes were independently and consistently associated with the differences between diet and urine estimates of sodium and potassium intake. For men, body mass index was also associated. Race was associated with differences in estimates of potassium intake.

CONCLUSIONS

Low correlations and differences between dietary and urinary sodium or potassium may be due to measurement error in one or both estimates. Future analyses using these methods to assess sodium and potassium intake in relation to health outcomes may consider stratifying by factors associated with the differences in estimates from these methods. This trial was registered at clinicaltrials.gov as NCT01631240.

Sodium intake in a cross-sectional, representative sample of New York City adults

OBJECTIVES

We estimated sodium intake, which is associated with elevated blood pressure, a major risk factor for cardiovascular disease, and assessed its association with related variables among New York City adults.

METHODS

In 2010 we conducted a cross-sectional, population-based survey of 1656 adults, the Heart Follow-Up Study, that collected self-reported health information, measured blood pressure, and obtained sodium, potassium, and creatinine values from 24-hour urine collections.

RESULTS

Mean daily sodium intake was 3239 milligrams per day; 81% of participants exceeded their recommended limit. Sodium intake was higher in non-Hispanic Blacks (3477 mg/d) and Hispanics (3395 mg/d) than in non-Hispanic Whites (3066 mg/d; both P < .05). Higher sodium intake was associated with higher blood pressure in adjusted models, and this association varied by race/ethnicity.

CONCLUSIONS

Higher sodium intake among non-Hispanic Blacks and Hispanics than among Whites was not previously documented in population surveys relying on self-report. These results demonstrate the feasibility of 24-hour urine collection for the purposes of research, surveillance, and program evaluation.

Methodological issues in estimating sodium intake in the Korea National Health and Nutrition Examination Survey

For policy goal setting, efficacy evaluations, and the development of related programs for reducing sodium intake, it is essential to accurately identify the amount of sodium intake in South Korea and constantly monitor its trends. The present study aimed to identify the status of sodium intake in South Korea and to review the methods and their validity for estimating sodium intake in each country; through this, we aim to determine more accurate methods for determining sodium intake and to monitor the trend in sodium intake for Korean citizens in the future. Using 24-hour dietary recall data from the 2012 Korea National Health and Nutrition Examination Survey (KNHANES) to estimate daily sodium intake, the average daily sodium intake among Koreans was 4,546 mg (men, 5,212 mg; women, 3,868 mg). In addition to the nutrition survey that uses the 24-hour dietary recall method, sodium intake can also be calculated from the amount of sodium excreted in 24-hour urine, 8-hour overnight urine, and spot urine samples. Although KNHANES uses the 24-hour dietary recall method to estimate the sodium intake, the 24-hour dietary recall method has the disadvantage of not being able to accurately determine the amount of sodium intake owing to its unique characteristics of the research method and in the processing of data. Although measuring the amount of sodium excreted in 24-hour urine is known to be the most accurate method, because collecting 24-hour urine from the general population is difficult, using spot urine samples to estimate sodium intake has been suggested to be useful for examining the trend of sodium intake in the general population. Therefore, we planned to conduct a study for estimating of 24-hour sodium excretion from spot urine and 8-hour overnight urine samples and testing the validity among subsamples in the KNHANES. Based on this result, we will adopt the most appropriate urine collection method for estimating population sodium intake in South Korea.

Prevalence of iodine inadequacy in Switzerland assessed by the estimated average requirement cut-point method in relation to the impact of iodized salt

OBJECTIVE

To assess the iodine status of Swiss population groups and to evaluate the influence of iodized salt as a vector for iodine fortification.

DESIGN

The relationship between 24 h urinary iodine and Na excretions was assessed in the general population after correcting for confounders. Single-day intakes were estimated assuming that 92 % of dietary iodine was excreted in 24 h urine. Usual intake distributions were derived for male and female population groups after adjustment for within-subject variability. The estimated average requirement (EAR) cut-point method was applied as guidance to assess the inadequacy of the iodine supply.

SETTING

Public health strategies to reduce the dietary salt intake in the general population may affect its iodine supply.

SUBJECTS

The study population (1481 volunteers, aged ≥15 years) was randomly selected from three different linguistic regions of Switzerland.

RESULTS

The 24 h urine samples from 1420 participants were determined to be properly collected. Mean iodine intakes obtained for men (n 705) and women (n 715) were 179 (sd 68.1) µg/d and 138 (sd 57.8) µg/d, respectively. Urinary Na and Ca, and BMI were significantly and positively associated with higher iodine intake, as were men and non-smokers. Fifty-four per cent of the total iodine intake originated from iodized salt. The prevalence of inadequate iodine intake as estimated by the EAR cut-point method was 2 % for men and 14 % for women.

CONCLUSIONS

The estimated prevalence of inadequate iodine intake was within the optimal target range of 2-3 % for men, but not for women.

Implementation Intentions on the Effect of Salt Intake among Hypertensive Women: A Pilot Study

This experimental study was aimed at assessing the potential effect of a theory-driven intervention-implementation intentions-on reducing salt intake among hypertensive Brazilian women. Ninety-eight participants were randomly assigned to participate in an implementation intentions intervention aimed at promoting lower salt intake through decreased addition of salt and salty spices to meals (intervention group, n = 49; group, n = 49). Endpoints were assessed at baseline and at the 2-month follow-up. Primary endpoints were a self-reporting measure of salt intake given by salt addition to meals (discretionary salt + salty spices = total added salt) and the 24 h urinary-sodium excretion. Secondary endpoints included intention, self-efficacy, and habit related to adding salt to meals. Patients in the intervention group showed a significant reduction in salt intake as assessed by 24 h urinary-sodium excretion. A significant reduction in the measure of habit was observed for both groups. No differences were observed for intention and self-efficacy. The results of this pilot study suggest the efficacy of planning strategies to help hypertensive women reduce their salt intake.

Urinary sodium excretion and dietary sources of sodium intake in Chinese postmenopausal women with prehypertension

Background

Reducing salt intake in communities is one of the most effective and affordable public health strategies to prevent hypertension, stroke and renal disease. The present study aimed to determine the sodium intake in Hong Kong Chinese postmenopausal women and identify the major food sources contributing to sodium intake and urine excretion.

Methods

This was a cross-sectional study among 655 Chinese postmenopausal women with prehypertension who were screened for a randomized controlled trial. Data collection included 24 h urine collection for the measurement of sodium, potassium and creatinine, 3-day dietary records, anthropometric measures and questionnaire survey on demographic data and dietary habits.

Results

The average salt intake estimated from urinary excretion was 7.8±3.2 g/d with 82.1% women above WHO recommendation of 5 g/day. Food groups as soup (21.6%), rice and noodles (13.5%), baked cereals (12.3%), salted/preserved foods (10.8%), Chinese dim sum (10.2%) and sea foods (10.1%) were the major contributors of non-discretionary salt. Discretionary salt use in cooking made a modest contribution to overall intake. Vegetable and fruit intake, age, sodium intake from salted foods, sea foods and soup were the independent determinants of urinary sodium excretion.

Conclusions

Our data revealed a significant room for reduction of the sodium intake. Efforts to reduce sodium from diets in Hong Kong Chinese postmenopausal women should focus on both processed foods and discretionary salt during cooking. Sodium reduction in soup and increase in fruit intake would be potentially effective strategy for reducing sodium.

The Baltic Sea Diet Score: a tool for assessing healthy eating in Nordic countries

OBJECTIVE

The health-related effects of the Nordic diet remain mostly unidentified. We created a Baltic Sea Diet Score (BSDS) for epidemiological research to indicate adherence to a healthy Nordic diet. We examined associations between the score and nutrient intakes that are considered important in promoting public health. We also examined the performance of the BSDS under two different cut-off strategies.

DESIGN

The cross-sectional study included two phases of the National FINRISK 2007 Study. Diet was assessed using a validated FFQ. Food and nutrient intakes were calculated using in-house software. Nine components were selected for the score. Each component was scored according to both sex-specific consumption quartiles (BSDS-Q) and medians (BSDS-M), and summed to give the final score values.

SETTING

A large representative sample of the Finnish population.

SUBJECTS

Men (n 2217) and women (n 2493) aged 25 to 74 years.

RESULTS

In the age- and energy-adjusted model, adherence to the diet was associated with a higher intake of carbohydrates (E%), and lower intakes of SFA (E%) and alcohol (E%, where E% is percentage of total energy intake; P < 0·01). Furthermore, the intakes of fibre, Fe, vitamins A, C and D, and folate were higher among participants who adhered to the diet (P < 0·05). After further adjustments, the results remained significant (P < 0·05) and did not differ remarkably between BSDS-Q and BSDS-M.

CONCLUSIONS

The BSDS can be used as a measure of a healthy Nordic diet to assess diet-health relationships in public health surveys in Nordic countries.

Monitoring salt and iodine intakes in Dutch adults between 2006 and 2010 using 24 h urinary sodium and iodine excretions

OBJECTIVE

To monitor the effectiveness of salt-reduction initiatives in processed foods and changes in Dutch iodine policy on Na and iodine intakes in Dutch adults between 2006 and 2010.

DESIGN

Two cross-sectional studies among adults, conducted in 2006 and 2010, using identical protocols. Participants collected single 24 h urine samples and completed two short questionnaires on food consumption and urine collection procedures. Daily intakes of salt, iodine, K and Na:K were estimated, based on the analysis of Na, K and iodine excreted in urine.

SETTING

Doetinchem, the Netherlands.

SUBJECTS

Men and women aged 19 to 70 years were recruited through random sampling of the Doetinchem population and among participants of the Doetinchem Cohort Study (2006: n 317, mean age 48·9 years, 43 % men; 2010: n 342, mean age 46·2 years, 45 % men).

RESULTS

While median iodine intake was lower in 2010 (179 μg/d) compared with 2006 (257 μg/d; P < 0·0001), no difference in median salt intake was observed (8·7 g/d in 2006 v. 8·5 g/d in 2010, P = 0·70). In 2006, median K intake was 2·6 g/d v. 2·8 g/d in 2010 (P < 0·01). In this 4-year period, median Na:K improved from 2·4 in 2006 to 2·2 in 2010 (P < 0·001).

CONCLUSIONS

Despite initiatives to lower salt in processed foods, dietary salt intake in this population remains well above the recommended intake of 6 g/d. Iodine intake is still adequate, although a decline was observed between 2006 and 2010. This reduction is probably due to changes in iodine policy.

Dietary sodium, adiposity, and inflammation in healthy adolescents

OBJECTIVES

To determine the relationships of sodium intake with adiposity and inflammation in healthy adolescents.

METHODS

A cross-sectional study involved 766 healthy white and African American adolescents aged 14 to 18 years. Dietary sodium intake was estimated by 7-day 24-hour dietary recall. Percent body fat was measured by dual-energy x-ray absorptiometry. Subcutaneous abdominal adipose tissue and visceral adipose tissue were assessed using magnetic resonance imaging. Fasting blood samples were measured for leptin, adiponectin, C-reactive protein, tumor necrosis factor-α, and intercellular adhesion molecule-1.

RESULTS

The average sodium intake was 3280 mg/day. Ninety-seven percent of our adolescents exceeded the American Heart Association recommendation for sodium intake. Multiple linear regressions revealed that dietary sodium intake was independently associated with body weight (β = 0.23), BMI (β = 0.23), waist circumference (β = 0.23), percent body fat (β = 0.17), fat mass (β = 0.23), subcutaneous abdominal adipose tissue (β = 0.25), leptin (β = 0.20), and tumor necrosis factor-α (β = 0.61; all Ps < .05). No relation was found between dietary sodium intake and visceral adipose tissue, skinfold thickness, adiponectin, C-reactive protein, or intercellular adhesion molecule-1. All the significant associations persisted after correction for multiple testing (all false discovery rates < 0.05).

CONCLUSIONS

The mean sodium consumption of our adolescents is as high as that of adults and more than twice the daily intake recommended by the American Heart Association. High sodium intake is positively associated with adiposity and inflammation independent of total energy intake and sugar-sweetened soft drink consumption.

Development and validation of a dietary screening tool for high sodium consumption in Australian renal patients

OBJECTIVE

The study objective was to develop and evaluate the feasibility and validity of a self-administered Scored Sodium Questionnaire (SSQ) for use in the routine clinical care of Australian chronic kidney disease (CKD) patients.

DESIGN AND METHODS

The study took place in community-based outreach clinics using a multidisciplinary model of care. Assessment of sources of dietary sodium intake in the target population used comprehensive diet history interviews (Phase 1) to inform development of a 10-item food frequency questionnaire that was scored and validated using 24-hour urinary sodium and 2 alternative dietary intake methods (Phase 2). Subjects were adults with CKD Stages 3 to 5 (Phase 1 n = 30; Phase 2 n = 47).

INTERVENTION

On a single day, participants (n = 47) completed the SSQ, feasibility survey, 24-hour urine collection, and 24-hour food record. A diet history interview was also conducted to confirm sodium intake on the day of data collection reflected habitual intake.

MAIN OUTCOME MEASURE

Validity of the SSQ score was confirmed by correlation with 24-hour urine sodium. Validity of a cutpoint on the SSQ score to correctly identify high- versus low-sodium consumers was confirmed by receiver operating characteristic curve analysis: area under the curve, sensitivity, and specificity.

RESULTS

Total SSQ score correlated significantly with 24-hour urine sodium (r = 0.371; P = .031). Correlation between 24-hour food record and diet history sodium confirmed consumption on the data collection day reflected habitual intake (r = 0.701; P ≤ .001). A cutpoint of 65 or greater on the SSQ score was confirmed as valid to identify high-sodium consumers: area under the curve 0.713, sensitivity 61%, and specificity 82%.

CONCLUSION

The SSQ is feasible and valid to assess habitual sodium intake in the Australian CKD population and to identify high-sodium consumers for referral to individualized counseling on a low-sodium diet.

Association between usual sodium and potassium intake and blood pressure and hypertension among U.S. adults: NHANES 2005-2010

OBJECTIVES

Studies indicate high sodium and low potassium intake can increase blood pressure suggesting the ratio of sodium-to-potassium may be informative. Yet, limited studies examine the association of the sodium-to-potassium ratio with blood pressure and hypertension.

METHODS

We analyzed data on 10,563 participants aged ≥20 years in the 2005-2010 National Health and Nutrition Examination Survey who were neither taking anti-hypertensive medication nor on a low sodium diet. We used measurement error models to estimate usual intakes, multivariable linear regression to assess their associations with blood pressure, and logistic regression to assess their associations with hypertension.

RESULTS

The average usual intakes of sodium, potassium and sodium-to-potassium ratio were 3,569 mg/d, 2,745 mg/d, and 1.41, respectively. All three measures were significantly associated with systolic blood pressure, with an increase of 1.04 mmHg (95% CI, 0.27-1.82) and a decrease of 1.24 mmHg (95% CI, 0.31-2.70) per 1,000 mg/d increase in sodium or potassium intake, respectively, and an increase of 1.05 mmHg (95% CI, 0.12-1.98) per 0.5 unit increase in sodium-to-potassium ratio. The adjusted odds ratios for hypertension were 1.40 (95% CI, 1.07-1.83), 0.72 (95% CI, 0.53-0.97) and 1.30 (95% CI, 1.05-1.61), respectively, comparing the highest and lowest quartiles of usual intake of sodium, potassium or sodium-to-potassium ratio.

CONCLUSIONS

Our results provide population-based evidence that concurrent higher sodium and lower potassium consumption are associated with hypertension.

Twenty-two-year population trends in sodium and potassium consumption: the Minnesota Heart Survey

Background

Limiting dietary sodium consumption is a core lifestyle recommendation for the prevention of hypertension. There is increasing evidence that low potassium consumption also increases hypertension risk. We estimated sex‐specific 22‐year trends in sodium and potassium consumption.

Methods and Results

We used data from the Minnesota Heart Survey, which performs surveillance of risk factors for cardiovascular disease in the Minneapolis–St. Paul metropolitan area. The Minnesota Heart Survey is a random population‐based sample of free‐living adults aged 25 to 74. Surveys were conducted in 1985–1987 (n=2273), 1990–1992 (n=2487), 1995–1997 (n=1842), 2000–2002 (n=2759), and 2007–2009 (n=1502). Dietary intake of sodium and potassium was estimated from one 24‐hour dietary recall. Over 22 years, age‐adjusted sodium and potassium intake among men remained relatively stable in 1985–1987 and 2007–2009 (P_trend=0.41 and 0.29, respectively); sodium ranged from 3820 mg/day (1995–1997) to 3968 mg/day (2007–2009) and potassium from 3111 mg/day (2000–2002) to 3249 mg/day (1995–1997). Sodium and potassium intake increased among women, from 2531 mg/day in 1985–1987 to 2854 mg/day in 2007–2009 (P_trend=0.001) for sodium and from 2285 to 2533 mg/day (P_trend<0.0001) for potassium. We observed stable or increasing sodium and potassium intake within some strata of age, education, and body mass index.

Conclusions

Despite long‐standing public health recommendations to limit sodium intake to <2300 mg/day, high sodium intake levels have persisted over the past 22 years. Furthermore, although potassium consumption increased in some subgroups over the study period, mean consumption remained significantly lower than the recommended 4700 mg/day in all groups.