Urinary potassium is a clinically useful test to detect a poor quality diet

Importance of the Vegetable and Fruit Intake for Health Based on the Relationship between Urinary Potassium Excretion and Cerebro-cardiovascular-renal Events or All-cause Mortality

Since it is widely accepted that there is a positive correlation between the salt intake and hypertension or cerebro-cardiovascular-renal events, salt intake restriction is currently widely recommended, especially in patients with hypertension. However, salt intake restriction does not always have beneficial effects. Indeed, an excessively low salt intake has been reported to be harmful to health. While a reasonable vegetable and fruit intake reportedly decreases blood pressure, whether or not vegetable and fruit intake truly leads to reductions in cerebro-cardiovascular-renal events or all-cause mortality remains unclear. We reviewed the importance of vegetable and fruit intake for health, focusing on the relationship between urinary potassium excretion, a marker of vegetable and fruit intake, and cerebro-cardiovascular-renal events or all-cause mortality. In conclusion, vegetable and fruit intake may be essential for reducing cerebro-cardiovascular-renal events and all-cause mortality.

Potassium intake: the Cinderella electrolyte

Dietary guidelines recommend intake targets for some essential minerals, based on observational and experimental evidence relating mineral intake levels to health outcomes. For prevention of cardiovascular disease, reducing sodium intake and increasing potassium intake are the principal tools. While reducing sodium intake has received greatest public health priority, emerging evidence suggests that increasing potassium intake may be a more important target for cardiovascular prevention. Increased potassium intake reduces blood pressure and mitigates the hypertensive effects of excess sodium intake, and the recent large Phase III SSaSS trial reported that increasing potassium intake (and reducing sodium intake) in populations with low potassium intake and high sodium intake, through salt substitution (25% KCl, 75%NaCl), reduces the risk of stroke in patients at increased cardiovascular risk. As key sources of potassium intake include fruit, vegetables, nuts, and legumes, higher potassium intake may be associated with healthy dietary patterns. The current review makes the case that increasing potassium intake might represent a more advantageous dietary strategy for prevention of cardiovascular disease. Future research should focus on addressing the independent effect of potassium supplementation in populations with low or moderate potassium intake, and determine effective strategies to increase potassium intake from diet.

Empowerment-based nutrition interventions on blood pressure: a randomized comparative effectiveness trial

Introduction

Empowerment lifestyle programs are needed to reduce the risk of hypertension. Our study compared the effectiveness of two empowerment-based approaches toward blood pressure (BP) reduction: salt reduction-specific program vs. healthy lifestyle general program.

Methods

Three hundred and eleven adults (median age of 44 years, IQR 34-54 years) were randomly assigned to a salt reduction (n = 147) or a healthy lifestyle program (n = 164). The outcome measures were urinary sodium (Na+) and potassium (K+) excretion, systolic (SBP) and diastolic (DBP) blood pressure, weight, and waist circumference.

Results

There were no significant differences in primary and secondary outcomes between the two program groups. When comparing each program to baseline, the program focused on salt reduction was effective in lowering BP following a 12-week intervention with a mean change of -2.5 mm Hg in SBP (95% CI, -4.1 to -0.8) and - 2.7 mm Hg in DBP (95% CI, -3.8 to -1.5) in the intention-to-treat (ITT) analysis. In the complete-case (CC) analysis, the mean change was -2.1 mm Hg in SBP (95% CI, -3.7 to -0.5) and - 2.3 mm Hg in DBP (95% CI, -3.4 to -1.1). This effect increases in subjects with high-normal BP or hypertension [SBP - 7.9 mm Hg (95% CI, -12.5 to -3.3); DBP - 7.3 mm Hg (95% CI, -10.2 to -4.4)]. The healthy lifestyle group also exhibited BP improvements after 12 weeks; however, the changes were less pronounced compared to the salt reduction group and were observed only for DBP [mean change of -1.5 mm Hg (95% CI, -2.6 to -0.4) in ITT analysis and - 1.4 mm Hg (95% CI, -2.4 to -0.3) in CC analysis, relative to baseline]. Overall, improvements in Na+/K+ ratio, weight, and Mediterranean diet adherence resulted in clinically significant SBP decreases. Importantly, BP reduction is attributed to improved dietary quality, rather than being solely linked to changes in the Na+/K+ ratio.

Conclusion

Salt-focused programs are effective public health tools mainly in managing individuals at high risk of hypertension. Nevertheless, in general, empowerment-based approaches are important strategies for lowering BP, by promoting health literacy that culminates in adherence to the Mediterranean diet and weight reduction.

RAASi Therapy Attenuates the Association between 24-h Urinary Potassium Excretion and Dietary Potassium Intake in CKD Patients

The aim of this study was to evaluate urinary potassium (K) excretion as a reliable marker of dietary K intake, in a cohort of CKD patients with or without Renin-Angiotensin-Aldosterone System (RAAS) inhibitor therapy. One hundred and thirty-eight consecutive out-patients (51 f and 87 m) aged 60 ± 13 years and affected by CKD stage 3-4, who were metabolically and nutritionally stable, entered the study between November 2021 and October 2022. No difference was observed between patients with (n = 85) or without (n = 53) RAAS inhibitor therapy, regarding dietary intakes, blood biochemistry, and 24-h urine excretion parameters. Considering all patients, urinary K showed a weak relationship with eGFR (r = 0.243, p < 0.01), and with dietary K intake (r = 0.184, p < 0.05). Serum K was not associated with dietary K intake, but an inverse relationship was observed with eGFR (r = -0.269, p < 0.01). When patients were examined depending on whether they were receiving RAAS inhibitor therapy, the weak inverse relationship between serum K and eGFR was maintained in both groups. Conversely, urinary K excretion remained positively associated with dietary K intake only in the no RAAS inhibitor group. In conclusion, 24-h urine K excretion may be used as a surrogate of K intake, but RAAS inhibitor therapy reduces the association between 24-h urine K excretion and dietary K intake in CKD patients.

One-step rapid colorimetric detection of K+ using silver nanoparticles modified by crown ether

Urinary potassium is an important parameter in clinical health diagnosis. Rapid and convenient detection of potassium ions (K⁺) in urine is essential for personal healthcare and health management. Here, crown ether (4-aminodibenzo-18-crown-6, ADC) modified silver nanoparticles (ADC-Ag NPs) were successfully prepared for one-step rapid colorimetric detection of urinary potassium. The detection mechanism is as follows: due to the matching sizes of the diameter of K⁺ and the cavity in crown ether 6, K⁺ is encapsulated between the cavities of two crown ethers, resulting in the clumping of ADC-Ag NPs and the color of the solution being altered. The colorimetric detection method has a fast response and is completed within 20 minutes. It also shows good selectivity and interference immunity. The lowest detectable concentration is 20 μM with the naked eye and 2.16 μM for UV-vis absorption spectroscopy. A good linear relationship (R² = 0.9931) between the absorption intensity ratio and K⁺ concentration (0-100 μM) indicates that this colorimetric probe can be used to detect K⁺. The method was also applied for quantitative analysis of K⁺ in real urine samples with recovery between 116 and 120%.

Lower urinary potassium excretion was associated with higher risk of cerebro-cardiovascular- and renal events in patients with hypertension under treatment with anti-hypertensive drugs

BACKGROUND

Hypertension is one of the risk factors for cerebro-cardiovascular and renal (CCR) diseases. High blood pressure is affected by the amount of salt (NaCl) and potassium (K) intake. There are many studies reporting the relationship between urinary sodium or potassium excretion and CCR events or all-cause mortality in general populations. Thus, it is necessary to investigate the relationship between urinary NaCl or K excretion and CCR events or all-cause mortality in hypertensive patients under control with anti-hypertensive drugs.

METHODS

A prospective, multi-center cohort study was performed in 3210 hypertensives under treatment with anti-hypertensive drugs for 5 years. The primary outcome was the CCR events, and the secondary outcome was all-cause mortality. A time-dependent Cox proportional hazards regression analysis was performed to assess the association between outcomes and urinary NaCl and K excretion, blood pressure, or heart rate.

RESULTS

During the follow-up period, 61 CCR events and 110 all-cause deaths occurred. There was no association between urinary NaCl excretion and CCR events or all-cause mortality. Lower urinary K excretion and higher Na/K ratio were associated with higher risk of CCR events or all-cause mortality. The CCR events were not associated with systolic, diastolic blood pressure, or heart rate.

CONCLUSION

Lower urinary K excretion was associated with higher risk of CCR events or all-cause mortality in hypertensive patients under treatment with anti-hypertensive drugs.

Microbiota responses to different prebiotics are conserved within individuals and associated with habitual fiber intake

BACKGROUND

Short-chain fatty acids (SCFAs) derived from gut bacteria are associated with protective roles in diseases ranging from obesity to colorectal cancers. Intake of microbially accessible dietary fibers (prebiotics) lead to varying effects on SCFA production in human studies, and gut microbial responses to nutritional interventions vary by individual. It is therefore possible that prebiotic therapies will require customizing to individuals.

RESULTS

Here, we explored prebiotic personalization by conducting a three-way crossover study of three prebiotic treatments in healthy adults. We found that within individuals, metabolic responses were correlated across the three prebiotics. Individual identity, rather than prebiotic choice, was also the major determinant of SCFA response. Across individuals, prebiotic response was inversely related to basal fecal SCFA concentration, which, in turn, was associated with habitual fiber intake. Experimental measures of gut microbial SCFA production for each participant also negatively correlated with fiber consumption, supporting a model in which individuals' gut microbiota are limited in their overall capacity to produce fecal SCFAs from fiber.

CONCLUSIONS

Our findings support developing personalized prebiotic regimens that focus on selecting individuals who stand to benefit, and that such individuals are likely to be deficient in fiber intake. Video Abstract.

Urinary potassium excretion and mortality risk in community-dwelling individuals with and without obesity

BACKGROUND

Potassium intake has been shown to be inversely associated with blood pressure and premature mortality. Previous studies have suggested that the association between potassium intake and blood pressure is modified by obesity, but whether obesity similarly influences the association between potassium intake and mortality is unclear.

OBJECTIVES

We investigated whether potassium intake, reflected by 24-h urinary excretion, is associated with all-cause mortality, and explored potential effect modification by obesity.

METHODS

We performed a prospective cohort study in community-dwelling individuals. The association between urinary potassium excretion and all-cause mortality was investigated by using multivariable Cox regression. We performed multiplicative interaction analysis and subgroup analyses according to BMI and waist circumference.

RESULTS

In 8533 individuals (50% male), the mean age was 50 ± 13 y, mean urinary potassium excretion was 71 ± 21 mmol/24 h, median BMI (in kg/m2) was 25.6 (IQR: 23.1, 28.4) and mean waist circumference was 89 ± 13 cm. During median follow-up of 18.4 (IQR: 13.5, 18.8) y, 1663 participants died. Low urinary potassium excretion (first compared with third sex-specific quintile) was associated with an increased mortality risk (fully adjusted HR: 1.38; 95% CI: 1.18, 1.61), P < 0.001, irrespective of body dimensions (HR range for all body dimensions: 1.36-1.70, all P < 0.05). High urinary potassium excretion (fifth compared with third quintile) was associated with increased mortality risk in participants with obesity (BMI ≥30; HR: 1.52; CI: 1.00, 2.30), but not in participants without obesity (BMI: <25; HR: 0.89; 95% CI: 0.62, 1.26; P-interaction = 0.001).

CONCLUSIONS

Low potassium intake was associated with increased mortality risk in community-dwelling individuals. In individuals with obesity, high potassium intake was also associated with increased mortality risk.

Nutritional therapy can reduce the burden of depression management in low income countries: A review

Depression is a serious mental and mood disorder with global health and economic burden. This burden may be overwhelming in low income countries, although there are insufficient data. Most antidepressant formulations are predicated on the monoamine, neuroendocrine and neuro-inflammation hypotheses, with little or no cognizance to other neurochemicals altered in depression. A nutritional strategy with or without conventional antidepressants is recommended, as nutrition plays vital roles in the onset, severity and duration of depression, with poor nutrition contributing to its pathogenesis. This review discusses nutritional potentials of utilizing omega-3 fatty acids, proteins, vitamins, minerals and herbs or their phytochemicals in the management of depression with the aim of reducing depression burden. Literature search of empirical data in books and journals in data bases including but not limited to PubMed, Scopus, Science Direct, Web of Science and Google Scholar that might contain discussions of sampling were sought, their full text obtained, and searched for relevant content to determine eligibility. Omega-3 fatty and amino acids had significant positive anti-depression outcomes, while vitamins and minerals although essential, enhanced omega-3 fatty and amino acids activities. Some herbs either as whole extracts or their phytochemicals/metabolites had significant positive anti-depression efficacy. Nutrition through the application of necessary food classes or herbs as well as their phytochemicals, may go a long way to effectively manage depression. This therefore will provide inexpensive, natural, and non-invasive therapeutic means with reduced adverse effects that can also be applied alongside clinical management. This nutritional strategy should be given more attention in research, assessment and treatment for those with depression and other mental illness in low income countries, especially in Africa.

Estimation of potassium intake: single versus repeated measurements and the associated cardiorenal risk

BACKGROUND

High potassium intake has been associated with lower blood pressure and a lower incidence of chronic kidney disease and cardiovascular events. In cohort studies, potassium intake is often estimated with a single 24-h urine collection. However, this may not represent actual long-term individual intake. We assessed whether a single baseline versus multiple follow-up measurements of 24-h urine potassium excretion results in different estimates of individual potassium intake and different associations between potassium intake and long-term outcome.

METHODS

We performed a retrospective cohort study in outpatient subjects with an estimated glomerular filtration rate >60 mL/min/1.73 m² who had sampled a 24-h urine collection at baseline and had ≥1 collection during a 17-year follow-up. Potassium intake was estimated with a single baseline 24-h urine collection but also during 1-year, 5-year, and 15-year follow-up. We used cox regression analysis to assess the association between cardiorenal outcome and estimated potassium intake.

RESULTS

Average population (n = 541) 24-h potassium excretion was similar at baseline and follow-up but significant individual changes in potassium intake between baseline and follow-up were observed. Forty-four percent of the subjects switched between tertiles of estimated potassium intake when follow-up measurements were used instead of baseline measurements. Hazard ratios for renal and cardiovascular outcomes were 6.9 and 1.7 times higher when follow-up estimates of potassium intake were replaced by baseline estimates.

CONCLUSIONS

Estimated potassium intake and its association with long-term outcome change significantly when multiple follow-ups 24-h urine collections are used for estimation of potassium intake instead of a single baseline measurement.

Urinary Sodium and Potassium, and Risk of Ischemic and Hemorrhagic Stroke (INTERSTROKE): A Case-Control Study

BACKGROUND

Although low sodium intake (<2 g/day) and high potassium intake (>3.5 g/day) are proposed as public health interventions to reduce stroke risk, there is uncertainty about the benefit and feasibility of this combined recommendation on prevention of stroke.

METHODS

We obtained random urine samples from 9,275 cases of acute first stroke and 9,726 matched controls from 27 countries and estimated the 24-hour sodium and potassium excretion, a surrogate for intake, using the Tanaka formula. Using multivariable conditional logistic regression, we determined the associations of estimated 24-hour urinary sodium and potassium excretion with stroke and its subtypes.

RESULTS

Compared with an estimated urinary sodium excretion of 2.8-3.5 g/day (reference), higher (>4.26 g/day) (odds ratio [OR] 1.81; 95% confidence interval [CI], 1.65-2.00) and lower (<2.8 g/day) sodium excretion (OR 1.39; 95% CI, 1.26-1.53) were significantly associated with increased risk of stroke. The stroke risk associated with the highest quartile of sodium intake (sodium excretion >4.26 g/day) was significantly greater (P < 0.001) for intracerebral hemorrhage (ICH) (OR 2.38; 95% CI, 1.93-2.92) than for ischemic stroke (OR 1.67; 95% CI, 1.50-1.87). Urinary potassium was inversely and linearly associated with risk of stroke, and stronger for ischemic stroke than ICH (P = 0.026). In an analysis of combined sodium and potassium excretion, the combination of high potassium intake (>1.58 g/day) and moderate sodium intake (2.8-3.5 g/day) was associated with the lowest risk of stroke.

CONCLUSIONS

The association of sodium intake and stroke is J-shaped, with high sodium intake a stronger risk factor for ICH than ischemic stroke. Our data suggest that moderate sodium intake-rather than low sodium intake-combined with high potassium intake may be associated with the lowest risk of stroke and expected to be a more feasible combined dietary target.

Association between 24-h urinary sodium and potassium excretion and blood pressure among Chinese adults aged 18-69 years

The direction and magnitude of the association between sodium and potassium excretion and blood pressure (BP) may differ depending on the characteristics of the study participant or the intake assessment method. Our objective was to assess the relationship between BP, hypertension and 24-h urinary sodium and potassium excretion among Chinese adults. A total of 1424 provincially representative Chinese residents aged 18 to 69 years participated in a cross-sectional survey in 2017 that included demographic data, physical measurements and 24-h urine collection. In this study, the average 24-h urinary sodium and potassium excretion and sodium-to-potassium ratio were 3811.4 mg/day, 1449.3 mg/day, and 4.9, respectively. After multivariable adjustment, each 1000 mg difference in 24-h urinary sodium excretion was significantly associated with systolic BP (0.64 mm Hg; 95% confidence interval [CI] 0.05-1.24) and diastolic BP (0.45 mm Hg; 95% CI 0.08-0.81), and each 1000 mg difference in 24-h urinary potassium excretion was inversely associated with systolic BP (- 3.07 mm Hg; 95% CI - 4.57 to - 1.57) and diastolic BP (- 0.94 mm Hg; 95% CI - 1.87 to - 0.02). The sodium-to-potassium ratio was significantly associated with systolic BP (0.78 mm Hg; 95% CI 0.42-1.13) and diastolic BP (0.31 mm Hg; 95% CI 0.10-0.53) per 1-unit increase. These associations were mainly driven by the hypertensive group. Those with a sodium intake above about 4900 mg/24 h or with a potassium intake below about 1000 mg/24 h had a higher risk of hypertension. At higher but not lower levels of 24-h urinary sodium excretion, potassium can better blunt the sodium-BP relationship. The adjusted odds ratios (ORs) of hypertension in the highest quartile compared with the lowest quartile of excretion were 0.54 (95% CI 0.35-0.84) for potassium and 1.71 (95% CI 1.16-2.51) for the sodium-to-potassium ratio, while the corresponding OR for sodium was not significant (OR, 1.28; 95% CI 0.83-1.98). Our results showed that the sodium intake was significantly associated with BP among hypertensive patients and the inverse association between potassium intake and BP was stronger and involved a larger fraction of the population, especially those with a potassium intake below 1000 mg/24 h should probably increase their potassium intake.

Association between urinary potassium excretion and blood pressure: A systematic review and meta-analysis of observational studies

Background

The evidence base regarding the association between urinary potassium and blood pressure (BP), or risk of hypertension, is inconsistent. Therefore, we sought to conduct a qualitative and quantitative literature review on the association between potassium excretion and BP.

Materials and Methods

Medline, Scopus, Web of Science, Science Direct, and Google Scholar were searched up to June 2020. All observational studies that reported BP and measured potassium excretion in overnight or 24-h urine samples were included. Correlation coefficients, mean urinary potassium excretion, and odds ratio (ORs) of hypertension were extracted from the included studies. There were no language or publication date restrictions.

Results

Overall, twelve observational studies, including 16,174 subjects, were identified for inclusion in the present meta-analysis, and 21 effect sizes were extracted. Pooled mean potassium excretion was 3.46 mmol/24 h higher in normotensive individuals compared with hypertensive subjects (95% confidence interval [CI]: 0.61, 6.31). High urinary potassium excretion was not associated with the risk of hypertension (OR: 0.95; 95% CI: 0.79, 1.13). The pooled correlation coefficient between BP and urinary potassium was not significant (ES: 0.01; 95% CI: -0.03, 0.05). However, a subgroup analysis by age indicated a significant positive correlation between urinary potassium and systolic BP in children (ES: 0.12; 95% CI: 0.04, 0.19).

Conclusion

24 h urinary potassium excretion was not correlated to BP and risk of hypertension. In contrast, mean urinary potassium excretion was higher in normotensive individuals compared with hypertensive counterparts. Future studies should focus on the association between different sources of dietary potassium and BP.

Lower Socioeconomic Status is Associated With Adverse Urinary Markers and Surgical Complexity in Kidney Stone Patients

OBJECTIVE

To determine if socioeconomic status (SES) correlates with severity of kidney stone disease and 24-hour urine parameters.

MATERIALS AND METHODS

An IRB approved prospectively maintained database for nephrolithiasis was retrospectively analyzed for both 24-hour urine results and surgical procedures performed from 2009 to 2019. Severely distressed communities (SDC) were categorized as those with a Distressed Communities Index (DCI), a composite measure of SES, score in the top quartile (lowest for SES). Univariate and multivariate analyses were performed to evaluate the strength of the association of DCI on: stone size at presentation, need for and type of surgical procedure, need for staged surgery and specific stone risk factors in 24-hour urine collections.

RESULTS

Surgical procedures were performed on 3939 patients (1978 women) who were not from SDC and 200 (97 women) from SDC. Patients from SDC were older (57.1 years vs 54.2 years; P = .009). Patients from SDC were more likely to undergo proportionally more invasive procedures (17.5% vs 11.6%; P = .011) and require staged surgery at a higher rate (13.0% vs 8.5%; P = .028). Men from SDC had larger stones (12.5 mm vs 9.7 mm; P = .001). Among 24-hour urine results from 2454 patients (1187 women), DCI was not correlated with sodium, calcium, magnesium, volume, oxalate, phosphate, and pH levels. Higher DCI (lower SES) correlated with lower urine citrate (P = .001) and lower urine potassium (P = .002).

CONCLUSION

SES correlates with larger stone burden at the time of urologic intervention, requires proportionally more invasive procedures and more staged procedures. Lower SES correlated with lower urine citrate and potassium.

Sodium and potassium excretion predict increased depression in urban adolescents

This study examined the prospective role of urinary sodium and potassium excretion in depressive symptoms among urban, low-income adolescents, and whether these relationships vary by gender. A total of 84 urban adolescents (mean age 13.36 years; 50% male; 95% African American) self-reported on their depressive symptoms at baseline and 1.5 years later. At baseline, the youth also completed a 12-h (overnight) urine collection at home which was used to measure sodium and potassium excretion. After adjusting for baseline depressive symptoms, age, BMI percentile, and pubertal development, greater sodium excretion and lower potassium excretion predicted more severe depressive symptoms at follow-up, with no significant gender differences. The results suggest that consumption of foods high in sodium and low in potassium contributes to the development of depressive symptoms in early adolescence, and that diet is a modifiable risk factor for adolescent depression. Interventions focusing on diet may improve mental health in urban adolescents.

Nutriome-metabolome relationships provide insights into dietary intake and metabolism

Dietary assessment traditionally relies on self-reported data which are often inaccurate and may result in erroneous diet-disease risk associations. We illustrate how urinary metabolic phenotyping can be used as alternative approach for obtaining information on dietary patterns. We used two multi-pass 24-hr dietary recalls, obtained on two occasions on average three weeks apart, paired with two 24-hr urine collections from 1,848 U.S. individuals; 67 nutrients influenced the urinary metabotype measured with ¹H-NMR spectroscopy characterized by 46 structurally identified metabolites. We investigated the stability of each metabolite over time and showed that the urinary metabolic profile is more stable within individuals than reported dietary patterns. The 46 metabolites accurately predicted healthy and unhealthy dietary patterns in a free-living U.S. cohort and replicated in an independent U.K. cohort. We mapped these metabolites into a host-microbial metabolic network to identify key pathways and functions. These data can be used in future studies to evaluate how this set of diet-derived, stable, measurable bioanalytical markers are associated with disease risk. This knowledge may give new insights into biological pathways that characterize the shift from a healthy to unhealthy metabolic phenotype and hence give entry points for prevention and intervention strategies.

Evaluating the confounding effects of medical therapies on potassium intake assessment in patients with heart failure

BACKGROUND AND AIMS

Potassium-wasting (loop diuretics [LD]) and potassium-sparing (spironolactone) medications used for heart failure (HF) may alter renal potassium handling and confound the use of twenty-four-hour (24-h) urine collections as a surrogate marker for potassium intake, an effect that has been observed with dietary sodium assessment. The objective was to determine the strength of association between 24-h urine collections and weighed food records in assessing potassium intake in HF patients stratified by LD usage and spironolactone usage.

METHODS AND RESULTS

Stable outpatients with HF simultaneously completed two 24-h urine collections and two weighed food records on consecutive days. Analyses compared patients stratified by LD and/or spironolactone use. Pearson's correlation and the Bland-Altman method of agreement assessed the relationship between the techniques. Overall, 109 patients (61 ± 11 yrs, 74% male) were included. The mean difference in dietary potassium estimated between 24-h urine collections and food records was -353 ± 1043 mg (p < 0.01) for all patients, with no differences between measures among subgroups. The association between the two methods was r = 0.551 (95% CI, 0.373 to 0.852, p < 0.001) for LD users; r = 0.287 (95% CI, 0.01 to 0.570, p = 0.050) for LD non-users; r = 0.321 (95% CI, 0.13 to 0.798, p = 0.043) for spironolactone users, and; r = 0.534 (95% CI, 0.331 to 0.747, p < 0.001) for spironolactone non-users. There were no significant mean biases identified as part of the Bland-Altman analysis.

CONCLUSION

Among HF patients, potassium-wasting and potassium-sparing medications do not influence the agreement between the two methods in the assessment of potassium intake.

Regulation of the Renal NaCl Cotransporter and Its Role in Potassium Homeostasis

Daily dietary potassium (K+) intake may be as large as the extracellular K+ pool. To avoid acute hyperkalemia, rapid removal of K+ from the extracellular space is essential. This is achieved by translocating K+ into cells and increasing urinary K+ excretion. Emerging data now indicate that the renal thiazide-sensitive NaCl cotransporter (NCC) is critically involved in this homeostatic kaliuretic response. This suggests that the early distal convoluted tubule (DCT) is a K+ sensor that can modify sodium (Na+) delivery to downstream segments to promote or limit K+ secretion. K+ sensing is mediated by the basolateral K+ channels Kir4.1/5.1, a capacity that the DCT likely shares with other nephron segments. Thus, next to K+-induced aldosterone secretion, K+ sensing by renal epithelial cells represents a second feedback mechanism to control K+ balance. NCC’s role in K+ homeostasis has both physiological and pathophysiological implications. During hypovolemia, NCC activation by the renin-angiotensin system stimulates Na+ reabsorption while preventing K+ secretion. Conversely, NCC inactivation by high dietary K+ intake maximizes kaliuresis and limits Na+ retention, despite high aldosterone levels. NCC activation by a low-K+ diet contributes to salt-sensitive hypertension. K+-induced natriuresis through NCC offers a novel explanation for the antihypertensive effects of a high-K+ diet. A possible role for K+ in chronic kidney disease is also emerging, as epidemiological data reveal associations between higher urinary K+ excretion and improved renal outcomes. This comprehensive review will embed these novel insights on NCC regulation into existing concepts of K+ homeostasis in health and disease.

Joint association of urinary sodium and potassium excretion with cardiovascular events and mortality: prospective cohort study

OBJECTIVE

To evaluate the joint association of sodium and potassium urinary excretion (as surrogate measures of intake) with cardiovascular events and mortality, in the context of current World Health Organization recommendations for daily intake (<2.0 g sodium, >3.5 g potassium) in adults.

DESIGN

International prospective cohort study.

SETTING

18 high, middle, and low income countries, sampled from urban and rural communities.

PARTICIPANTS

103 570 people who provided morning fasting urine samples.

MAIN OUTCOME MEASURES

Association of estimated 24 hour urinary sodium and potassium excretion (surrogates for intake) with all cause mortality and major cardiovascular events, using multivariable Cox regression. A six category variable for joint sodium and potassium was generated: sodium excretion (low (<3 g/day), moderate (3-5 g/day), and high (>5 g/day) sodium intakes) by potassium excretion (greater/equal or less than median 2.1 g/day).

RESULTS

Mean estimated sodium and potassium urinary excretion were 4.93 g/day and 2.12 g/day, respectively. After a median follow-up of 8.2 years, 7884 (6.1%) participants had died or experienced a major cardiovascular event. Increasing urinary sodium excretion was positively associated with increasing potassium excretion (unadjusted r=0.34), and only 0.002% had a concomitant urinary excretion of <2.0 g/day of sodium and >3.5 g/day of potassium. A J-shaped association was observed of sodium excretion and inverse association of potassium excretion with death and cardiovascular events. For joint sodium and potassium excretion categories, the lowest risk of death and cardiovascular events occurred in the group with moderate sodium excretion (3-5 g/day) and higher potassium excretion (21.9% of cohort). Compared with this reference group, the combinations of low potassium with low sodium excretion (hazard ratio 1.23, 1.11 to 1.37; 7.4% of cohort) and low potassium with high sodium excretion (1.21, 1.11 to 1.32; 13.8% of cohort) were associated with the highest risk, followed by low sodium excretion (1.19, 1.02 to 1.38; 3.3% of cohort) and high sodium excretion (1.10, 1.02 to 1.18; 29.6% of cohort) among those with potassium excretion greater than the median. Higher potassium excretion attenuated the increased cardiovascular risk associated with high sodium excretion (P for interaction=0.007).

CONCLUSIONS

These findings suggest that the simultaneous target of low sodium intake (<2 g/day) with high potassium intake (>3.5 g/day) is extremely uncommon. Combined moderate sodium intake (3-5 g/day) with high potassium intake is associated with the lowest risk of mortality and cardiovascular events.

Urinary sodium excretion, blood pressure, cardiovascular disease, and mortality: a community-level prospective epidemiological cohort study

BACKGROUND

WHO recommends that populations consume less than 2 g/day sodium as a preventive measure against cardiovascular disease, but this target has not been achieved in any country. This recommendation is primarily based on individual-level data from short-term trials of blood pressure (BP) without data relating low sodium intake to reduced cardiovascular events from randomised trials or observational studies. We investigated the associations between community-level mean sodium and potassium intake, cardiovascular disease, and mortality.

METHODS

The Prospective Urban Rural Epidemiology study is ongoing in 21 countries. Here we report an analysis done in 18 countries with data on clinical outcomes. Eligible participants were adults aged 35-70 years without cardiovascular disease, sampled from the general population. We used morning fasting urine to estimate 24 h sodium and potassium excretion as a surrogate for intake. We assessed community-level associations between sodium and potassium intake and BP in 369 communities (all >50 participants) and cardiovascular disease and mortality in 255 communities (all >100 participants), and used individual-level data to adjust for known confounders.

FINDINGS

95 767 participants in 369 communities were assessed for BP and 82 544 in 255 communities for cardiovascular outcomes with follow-up for a median of 8·1 years. 82 (80%) of 103 communities in China had a mean sodium intake greater than 5 g/day, whereas in other countries 224 (84%) of 266 communities had a mean intake of 3-5 g/day. Overall, mean systolic BP increased by 2·86 mm Hg per 1 g increase in mean sodium intake, but positive associations were only seen among the communities in the highest tertile of sodium intake (p<0·0001 for heterogeneity). The association between mean sodium intake and major cardiovascular events showed significant deviations from linearity (p=0·043) due to a significant inverse association in the lowest tertile of sodium intake (lowest tertile <4·43 g/day, mean intake 4·04 g/day, range 3·42-4·43; change -1·00 events per 1000 years, 95% CI -2·00 to -0·01, p=0·0497), no association in the middle tertile (middle tertile 4·43-5·08 g/day, mean intake 4·70 g/day, 4·44-5.05; change 0·24 events per 1000 years, -2·12 to 2·61, p=0·8391), and a positive but non-significant association in the highest tertile (highest tertile >5·08 g/day, mean intake 5·75 g/day, >5·08-7·49; change 0·37 events per 1000 years, -0·03 to 0·78, p=0·0712). A strong association was seen with stroke in China (mean sodium intake 5·58 g/day, 0·42 events per 1000 years, 95% CI 0·16 to 0·67, p=0·0020) compared with in other countries (4·49 g/day, -0·26 events, -0·46 to -0·06, p=0·0124; p<0·0001 for heterogeneity). All major cardiovascular outcomes decreased with increasing potassium intake in all countries.

INTERPRETATION

Sodium intake was associated with cardiovascular disease and strokes only in communities where mean intake was greater than 5 g/day. A strategy of sodium reduction in these communities and countries but not in others might be appropriate.

FUNDING

Population Health Research Institute, Canadian Institutes of Health Research, Canadian Institutes of Health Canada Strategy for Patient-Oriented Research, Ontario Ministry of Health and Long-Term Care, Heart and Stroke Foundation of Ontario, and European Research Council.

Determination of major and trace element variability in healthy human urine by ICP-QMS and specific gravity normalisation

Sixty five urine samples obtained during one or two non-consecutive days from 10 healthy individuals were analysed for major (Na, Mg, K, Ca) and trace (Co, Cu, Zn, As, Rb, Sr, Mo and Pb) element concentrations. Following microwave digestion, the analyses were carried out using ICP-QMS (inductively coupled plasma quadrupole mass spectrometry) incorporating a collision/reaction cell. Repeat analyses of quality control samples show that the procedure produces unbiased results and is well suited for routine urinalysis of the investigated elements. Concentrations were normalised using specific gravity (SG) and the resultant decrease in variability supports previous conclusions that SG-normalisation appropriately corrects for differences in urine dilution. The elemental concentrations of the individual urine samples show large differences in dispersion. Most variable are As, Co and Zn, with CVs (coefficients of variation) of >75%. The major elements as well as Rb, Sr and Mo display intermediate variability, whilst Cu and Pb have the least elemental dispersion with CV values of about 30%. A detailed assessment shows that the overall elemental variability is governed both by differences between individuals and variations for a single individual over time. Spot urine samples exhibit elemental concentrations that, on average, resemble the daily mean values to within about 30% for all elements except K and Rb. Diet-related changes in urinary element concentration are most prominent for Mg, K, Co, Rb and Pb. The concentrations of Co, As and Rb appear to vary systematically with gender but this may primarily reflect co-variance with specific diets.

Urinary element concentrations were quantified by ICP-QMS and variations over time, between individuals and with gender and diet were assessed.

Essential role of Kir5.1 channels in renal salt handling and blood pressure control

Supplementing diets with high potassium helps reduce hypertension in humans. Inwardly rectifying K+ channels Kir4.1 (Kcnj10) and Kir5.1 (Kcnj16) are highly expressed in the basolateral membrane of distal renal tubules and contribute to Na+ reabsorption and K+ secretion through the direct control of transepithelial voltage. To define the importance of Kir5.1 in blood pressure control under conditions of salt-induced hypertension, we generated a Kcnj16 knockout in Dahl salt-sensitive (SS) rats (SSKcnj16-/-). SSKcnj16-/- rats exhibited hypokalemia and reduced blood pressure, and when fed a high-salt diet (4% NaCl), experienced 100% mortality within a few days triggered by salt wasting and severe hypokalemia. Electrophysiological recordings of basolateral K+ channels in the collecting ducts isolated from SSKcnj16-/- rats revealed activity of only homomeric Kir4.1 channels. Kir4.1 expression was upregulated in SSKcnj16-/- rats, but the protein was predominantly localized in the cytosol in SSKcnj16-/- rats. Benzamil, but not hydrochlorothiazide or furosemide, rescued this phenotype from mortality on a high-salt diet. Supplementation of high-salt diet with increased potassium (2% KCl) prevented mortality in SSKcnj16-/- rats and prevented or mitigated hypertension in SSKcnj16-/- or control SS rats, respectively. Our results demonstrate that Kir5.1 channels are key regulators of renal salt handling in SS hypertension.

Association between 24h Urinary Sodium and Potassium Excretion and Estimated Glomerular Filtration Rate (eGFR) Decline or Death in Patients with Diabetes Mellitus and eGFR More than 30 ml/min/1.73m2

Background

Data regarding the association between 24h urinary sodium and potassium excretion with kidney outcomes in patients with diabetes mellitus is currently scarce.

Methods

We conducted a single-center, retrospective cohort study in which 1230 patients with diabetes who had undergone a 24h urinary sodium and potassium excretion test were analyzed. Patients with incomplete urine collection were excluded based on 24h urinary creatinine excretion. Outcomes were the composite of a 30% decline in eGFR or death. Multivariate cox regression analysis was used to investigate the association between urinary sodium and potassium excretion and outcomes.

Results

With a mean follow up period of 5.47 years, 130 patients reached the outcomes (30% decline in eGFR: 124, death: 6). Mean (SD) eGFR and 24h urinary sodium and potassium excretion at baseline were 78.6 (19.5) ml/min/1.73m², 4.50 (1.64) g/day, and 2.14 (0.77) g/day. Compared with sodium excretion < 3.0 g/day, no significant change in risk of outcomes was observed with increased increments of 1.0 g/day. Compared with potassium excretion of < 1.5 g/day, 2.0–2.5 g/day, and 2.5–3.0 g/day were significantly associated with a lower risk of outcomes (hazard ratio [HR], 0.49 and 0.44; 95% confidence interval [CI], 0.28 to 0.84 and 0.22 to 0.87).

Conclusions

24h urinary sodium excretion was not significantly associated with a risk of 30% decline in eGFR or death in patients with diabetes. However, an increased risk of 30% decline in eGFR or death was significantly associated with 24h urinary potassium excretion < 1.5 g/day than with 2.0–2.5 g/day and 2.5–3.0 g/day.

Urinary potassium excretion and risk of cardiovascular events

BACKGROUND

Observational studies on dietary potassium and risk of cardiovascular disease (CVD) have reported weak-to-modest inverse associations. Long-term prospective studies with multiple 24-h urinary samples for accurate estimation of habitual potassium intake, however, are scarce.

OBJECTIVE

We examined the association between urinary potassium excretion and risk of blood pressure-related cardiovascular outcomes.

DESIGN

We studied 7795 subjects free of cardiovascular events at baseline in the Prevention of Renal and Vascular End-stage Disease study, a prospective, observational cohort with oversampling of subjects with albuminuria at baseline. Main cardiovascular outcomes were CVD [including ischemic heart disease (IHD), stroke, and vascular interventions], IHD, stroke, and new-onset heart failure (HF). Potassium excretion was measured in two 24-h urine specimens at the start of the study (1997-1998) and midway through follow-up (2001-2003).

RESULTS

Baseline median urinary potassium excretion was 70 mmol/24 h (IQR: 56-84 mmol/24 h). During a median follow-up of 10.5 y (IQR: 9.9-10.8 y), a total of 641 CVD, 465 IHD, 172 stroke, and 265 HF events occurred. After adjustment for age and sex, inverse associations were observed between potassium excretion and risk [HR per each 26-mmol/24-h (1-g/d) increase; 95% CI] of CVD (0.87; 0.78, 0.97) and IHD (0.86; 0.75, 0.97), as well as nonsignificant inverse associations for risk of stroke (0.85; 0.68, 1.06) and HF (0.94; 0.80, 1.10). After further adjustment for body mass index, smoking, alcohol consumption, education, and urinary sodium and magnesium excretion, urinary potassium excretion was not statistically significantly associated with risk (multivariable-adjusted HR per 1-g/d increment; 95% CI) of CVD (0.96; 0.85, 1.09), IHD (0.90; 0.81, 1.04), stroke (1.09; 0.86, 1.39), or HF (0.99; 0.83, 1.18). No associations were observed between the sodium-to-potassium excretion ratio and risk of CVD, IHD, stroke, or HF.

CONCLUSION

In this cohort with oversampling of subjects with albuminuria at baseline, urinary potassium excretion was not independently associated with a lower risk of cardiovascular events.

Potassium urinary excretion and dietary intake: a cross-sectional analysis in 8-10 year-old children

BACKGROUND

Data from studies assessing the intake of potassium, and the concomitant sodium-to-potassium ratio are limited. The aim of this study was to evaluate potassium and sodium-to-potassium ratio intake in 8-10 year-old children.

METHODS

A cross-sectional survey was carried out from January to June 2014 and data from 163 children (81 boys) were included. Potassium intake was estimated by 24-h urine collection and coefficient of creatinine was used to validate completeness of urine collections. Urinary sodium and sodium-to-potassium ratio were also analysed. A 24-h dietary recall was used to provide information on dietary sources of potassium. Height and weight were measured according to international standards.

RESULTS

The mean urinary potassium excretion was 1701 ± 594 mg/day in boys, and 1682 ± 541 mg/day in girls (p = 0.835); 8.0% of children met the WHO recommendations for potassium intake. The mean sodium excretion was 2935 ± 1075 mg/day in boys and 2381 ± 1045 mg/day in girls (p <0.001) and urinary sodium-to-potassium ratio was 3.2 ± 1.4 in boys, and 2.5 ± 1.1 in girls (p = 0.002). The mean fruit and vegetable intake was 353.1 ± 232.5 g/day in boys, and 290.8 ± 213.1 g/day in girls (p = 0.101).

CONCLUSIONS

This study reported a low compliance of potassium intake recommendations in 8-10 year-old children. Health promotion interventions are needed in order to broaden public awareness of potassium inadequacy and to increase potassium intake.

Mediterranean diet interventions to prevent cognitive decline--opportunities and challenges

Cognitive decline has a profound impact on the health and quality of life of older people and their caregivers. Exploring mechanisms to delay cognitive decline has become an urgent economic priority, given the projected changes in population demographics. Systematic reviews and meta-analyses of observational studies suggest that adherence to a Mediterranean Diet (MD) is associated with reduced cognitive decline, but such an observation needs to be tested in randomised controlled trials. Intervention evidence is currently limited, and future studies need to be adequately powered, with careful attention given to choice of participants, outcomes being assessed, study duration and strategies to achieve compliance. Alongside these studies, consideration has to be given to how best promote and encourage dietary change in older people in general, and particularly in those experiencing the early stages of cognitive decline, as there may be specific factors that need to be considered when designing lifestyle behaviour change interventions in this group.

Fad diets and their effect on urinary stone formation

The influence of unhealthy dietary habits on urinary stone formation has been widely recognized in literature. Dietary advice is indeed the cornerstone prescription for prevention of nephrolithiasis as well. However, only a small amount of medical literature has addressed the influence of popular or fad diets, often self-prescribed for the management of obesity and overweight or for cultural beliefs, on the risk of kidney stones. Thereby in this paper we analyze the current knowledge on the effects of some popular diets on overall lithogenic risk. High-protein diets, like Dukan diet, raise some concerns, since animal proteins are able to increase urinary calcium and to decrease urinary citrate excretion, thus leading to a high overall lithogenic risk. Low-carbohydrate diets, like Atkins diet or zone diet, may have a protective role against kidney stone formation, but there are also evidences stating that this dietary approach may rise calciuria and decrease citraturia, since it is generally associated to a relatively high intake of animal proteins. Vegan diet can be harmful for urinary stone disease, especially for the risk of hyperuricemia and micronutrient deficiencies, even if only few studies have addressed this specific matter. On the other side, the benefits of a lacto-ovo-vegetarian diet on kidney stone prevention have been largely emphasized, provided that the intake of calcium and oxalate is balanced. Traditional Mediterranean diet should exert a protective effect on nephrolithiasis as well, even if specific studies have not been carried out yet. High phytate and antioxidant content of this diet have however demonstrated to be beneficial in preventing the formation of new or recurrent calculi. Anyway, at the current state of knowledge, the most effective dietary approach to prevent kidney stone disease is a mild animal protein restriction, a balanced intake of carbohydrates and fats and a high intake of fruit and vegetables. Other fundamental aspects, which are often neglected in fad diets, are a normal intake of milk and dairy products and salt restriction. All these nutritional aspects should be greatly taken into account when patients who are willing to undergo fad or commercial diets ask for dietary advice.

Urinary sodium and potassium excretion, mortality, and cardiovascular events

BACKGROUND

The optimal range of sodium intake for cardiovascular health is controversial.

METHODS

We obtained morning fasting urine samples from 101,945 persons in 17 countries and estimated 24-hour sodium and potassium excretion (used as a surrogate for intake). We examined the association between estimated urinary sodium and potassium excretion and the composite outcome of death and major cardiovascular events.

RESULTS

The mean estimated sodium and potassium excretion was 4.93 g per day and 2.12 g per day, respectively. With a mean follow-up of 3.7 years, the composite outcome occurred in 3317 participants (3.3%). As compared with an estimated sodium excretion of 4.00 to 5.99 g per day (reference range), a higher estimated sodium excretion (≥ 7.00 g per day) was associated with an increased risk of the composite outcome (odds ratio, 1.15; 95% confidence interval [CI], 1.02 to 1.30), as well as increased risks of death and major cardiovascular events considered separately. The association between a high estimated sodium excretion and the composite outcome was strongest among participants with hypertension (P=0.02 for interaction), with an increased risk at an estimated sodium excretion of 6.00 g or more per day. As compared with the reference range, an estimated sodium excretion that was below 3.00 g per day was also associated with an increased risk of the composite outcome (odds ratio, 1.27; 95% CI, 1.12 to 1.44). As compared with an estimated potassium excretion that was less than 1.50 g per day, higher potassium excretion was associated with a reduced risk of the composite outcome.

CONCLUSIONS

In this study in which sodium intake was estimated on the basis of measured urinary excretion, an estimated sodium intake between 3 g per day and 6 g per day was associated with a lower risk of death and cardiovascular events than was either a higher or lower estimated level of intake. As compared with an estimated potassium excretion that was less than 1.50 g per day, higher potassium excretion was associated with a lower risk of death and cardiovascular events. (Funded by the Population Health Research Institute and others.).

Association of urinary sodium and potassium excretion with blood pressure

BACKGROUND

Higher levels of sodium intake are reported to be associated with higher blood pressure. Whether this relationship varies according to levels of sodium or potassium intake and in different populations is unknown.

METHODS

We studied 102,216 adults from 18 countries. Estimates of 24-hour sodium and potassium excretion were made from a single fasting morning urine specimen and were used as surrogates for intake. We assessed the relationship between electrolyte excretion and blood pressure, as measured with an automated device.

RESULTS

Regression analyses showed increments of 2.11 mm Hg in systolic blood pressure and 0.78 mm Hg in diastolic blood pressure for each 1-g increment in estimated sodium excretion. The slope of this association was steeper with higher sodium intake (an increment of 2.58 mm Hg in systolic blood pressure per gram for sodium excretion >5 g per day, 1.74 mm Hg per gram for 3 to 5 g per day, and 0.74 mm Hg per gram for <3 g per day; P<0.001 for interaction). The slope of association was steeper for persons with hypertension (2.49 mm Hg per gram) than for those without hypertension (1.30 mm Hg per gram, P<0.001 for interaction) and was steeper with increased age (2.97 mm Hg per gram at >55 years of age, 2.43 mm Hg per gram at 45 to 55 years of age, and 1.96 mm Hg per gram at <45 years of age; P<0.001 for interaction). Potassium excretion was inversely associated with systolic blood pressure, with a steeper slope of association for persons with hypertension than for those without it (P<0.001) and a steeper slope with increased age (P<0.001).

CONCLUSIONS

In this study, the association of estimated intake of sodium and potassium, as determined from measurements of excretion of these cations, with blood pressure was nonlinear and was most pronounced in persons consuming high-sodium diets, persons with hypertension, and older persons. (Funded by the Heart and Stroke Foundation of Ontario and others.).

Relationship between 24 h urinary potassium and diet quality in the adult Spanish population

Objective

To study the relationship between diet quality and 24 h urinary K excretion.

Design

K was measured in 24 h urine samples, while diet was studied using a 24 h recall method over two consecutive days. Diet quality was determined using the Healthy Eating Index (HEI). The body weight, height and body composition of all participants were recorded, and the BMI of each calculated.

Setting

Representative members of the adult Spanish population from the FANPE Study (‘Fuentes Alimentarias de Nutrientes en Población Española’; Dietary Sources of Nutrients in the Spanish Population).

Subjects

The final sample size was 329 participants aged 18–60 years.

Results

Participants with a 24 h urinary K excretion ≥93 mmol/d (group AP = adequate potassium) had greater self-reported K intakes, consumed more fruit and vegetables, had a more varied diet and had better HEI scores than those with a 24 h urinary K excretion <93 mmol/d (group IP = inadequate potassium). A significant positive correlation was seen between 24 h urinary K and dietary variety and the number of servings of fruits, vegetables and dairy products consumed, and between each of these and the HEI after correcting for age, sex, BMI, coefficient of activity, energy intake and the under-reporting of energy intake. AP participants were less likely to have an inadequate diet (HEI score <50) than IP participants (OR =0·439; 95 % CI 0·201, 0·961;P=0·039).

Conclusions

Diet quality, measured by the HEI, is correlated with 24 h urinary K excretion in Spanish adults.

Association of urinary sodium-to-potassium ratio with obesity in a multiethnic cohort

BACKGROUND

Previous studies that reported an association of dietary Na(+) intake with metabolic syndrome were limited by the use of imprecise measures of obesity, Na(+) intake, or exclusion of multiethnic populations. The effect of dietary K(+) intake on obesity is less well described.

OBJECTIVE

We hypothesized that high dietary Na(+) and low K(+), based on the ratio of urinary Na(+) to K(+) (U[Na(+)]/[K(+)]) in a first-void morning urinary sample, is independently associated with total body fat.

DESIGN

In a prospective population-based cohort, 2782 participants in the community-dwelling, probability-sampled, multiethnic Dallas Heart Study were analyzed. The primary outcome established a priori was total-body percentage fat (TBPF) measured by dual-energy X-ray absorptiometry. The main predictor was U[Na(+)]/[K(+)]. Robust linear regression was used to explore an independent association between U[Na(+)]/[K(+)] and TBPF. The analyses were stratified by sex and race after their effect modifications were analyzed.

RESULTS

Of the cohort, 55.4% were female, 49.8% African American, 30.8% white, 17.2% Hispanic, and 2.2% other races. The mean (±SD) age was 44 ± 10 y, BMI (in kg/m(2)) was 30 ± 7, TBPF was 32 ± 10%, and U[Na(+)]/[K(+)] was 4.2 ± 2.6; 12% had diabetes. In the unadjusted and adjusted models, TBPF increased by 0.75 (95% CI: 0.25, 1.25) and 0.43 (0.15, 0.72), respectively (P = 0.003 for both), for every 3-unit increase in U[Na(+)]/[K(+)]. A statistically significant interaction was found between race and U[Na(+)] /[K(+)], so that the non-African American races had a higher TBPF than did the African Americans per unit increase in U[Na(+)]/[K(+)] (P-interaction < 0.0001 for both). No interaction was found between sex and U[Na(+)]/[K(+)].

CONCLUSIONS

The ratio of dietary Na(+) to K(+) intake may be independently associated with TBPF, and this association may be more pronounced in non-African Americans. Future studies should explore whether easily measured spot U[Na(+)]/[K(+)] can be used to monitor dietary patterns and guide strategies for obesity management.

Current evidence on dietary pattern and cognitive function

With global aging population, age-related cognitive decline becomes epidemic. Lifestyle-related factor is one of the key preventative measures. Dietary pattern analysis which considers dietary complexity has recently used to examine the linkage between nutrition and cognitive function. A priori approach defines dietary pattern based on existing knowledge. Results of several dietary pattern scores were summarized. The heterogeneity of assessment methods and outcome measurements lead to inconsistent results. Posteriori approach derives a dietary pattern independently of the existing nutrition-disease knowledge. It showed a dietary pattern abundant with plant-based food, oily fish, lower consumption of processed food, saturated fat, and simple sugar which appears to be beneficial to cognitive health. Despite inconclusive evidence from both approaches, diet and exercise, beneficial for other diseases, remains to be the two key modifiable factors for cognitive function. Large-scale prospective studies in multiethics population are required to provide stronger evidence in the future.

Fruits and vegetables: measuring intake and encouraging increased consumption

A high intake of fruit and vegetables (FV) is associated with reduced risk of chronic disease, although the evidence base is mostly observational. Blood biomarkers offer an objective indicator of FV intake, potentially improving estimates of intakes based on traditional methods. A valid biomarker of overall FV intake would be able to confirm population intakes, more precisely evaluate the association between intakes and health outcomes and confirm compliance in FV interventions. Several substances have been proposed as biomarkers of FV intake: vitamin C, the carotenoids and polyphenols. Certain biomarkers are strong predictors of single FV; however, the proposed single biomarkers of FV consumption are only modestly predictive of overall FV consumption. This is likely to be due to the complexity of the FV food group. While accurately measuring FV intake is important in nutrition research, another critical question is: how best can an increase in FV intake be achieved? Increased FV intake has been achieved in efficacy studies using intensive dietary advice. Alternative, less intensive methods for encouraging FV consumption need to be developed and tested for population level intervention. Systematic reviews suggest peer support to be an effective strategy to promote dietary change. This review will describe the evidence for a link between increased FV intake and good health, outline possible novel biomarkers of FV consumption, present the most recently available data on population intake of FV and examine the usefulness of different approaches to encourage increased consumption of FV.

Association between 24-hour urine sodium and potassium excretion and diet quality in six-year-old children: a cross sectional study

Background

Limited data is available on sodium (Na) and potassium (K) intake in young children estimated by 24 hour (24h) excretion in urine. The aim was to assess 24h urinary excretion of Na and K in six-year-old children and its relationship with diet quality.

Methods

The study population was a subsample of a national dietary survey, including six-year-old children living in the greater Reykjavik area (n=76). Three day weighed food records were used to estimate diet quality. Diet quality was defined as adherence to the Icelandic food based dietary guidelines. Na and K excretion was analyzed from 24h urine collections. PABA check was used to validate completeness of urine collections. The associations between Na and K excretion and diet quality were estimated by linear regression, adjusting for gender and energy intake.

Results

Valid urine collections and diet registrations were provided by 58 children. Na and K excretion was, mean (SD), 1.64 (0.54) g Na/24h (approx. 4.1 g salt/24h) and 1.22 (0.43) g K/24h. In covariate adjusted models Na excretion decreased by 0.16 g Na/24h (95% CI: 0.31, 0.06) per 1-unit increase in diet quality score (score range: 1–4) while K excretion was increased by 0.18 g K/24h (95% CI: 0.06, 0.29).

Conclusions

Na intake, estimated by 24h urinary excretion was on average higher than recommended. Increased diet quality was associated with lower Na excretion and higher K excretion in six-year-old children.

Effects of cooking using multi-ply cookware on absorption of potassium and vitamins: a randomized double-blind placebo control study

This 2-week interventional study involved a randomized allocation of subjects into three groups: Group A (daily ingestion of 350 g vegetables cooked without water using multi-ply [multilayer-structured] cookware), Group B (daily ingestion of 350g vegetables; ordinary cookware) and Group C (routine living). Before and after intervention, each subject underwent health examination with 24-h urine sampling. Blood vitamin C significantly increased after intervention from the baseline in Group A (P < 0.01) and Group B (P < 0.05). β-Carotene levels also increased significantly after intervention in Group A (P < 0.01) and Group B (P < 0.01). Oxidized low-density lipoprotein decreased significantly after intervention in Group A (P < 0.01). In Group A, 24-h urinary potassium excretion increased significantly (P < 0.01) and 24-h urinary sodium (Na)/K ratio improved significantly (P < 0.05) after intervention. In conclusion, a cooking method modification with multi-ply cookware improved absorption of nutrients from vegetables and enhanced effective utilization of the antioxidant potentials of vegetable nutrients.

Evaluation of the Children's Eating Habits Questionnaire used in the IDEFICS study by relating urinary calcium and potassium to milk consumption frequencies among European children

BACKGROUND

Measuring dietary intake in children is notoriously difficult. Therefore, it is crucial to evaluate the performance of dietary intake assessment methods in children. Given the important contribution of milk consumption to calcium (Ca) and potassium (K) intakes, urinary calcium (UCa) and potassium (UK) excretions in spot urine samples could be used for estimating correlations with milk consumption frequencies.

OBJECTIVE

The aim of this study was to evaluate the assessment of milk consumption frequencies derived from the Food Frequency Questionnaire section of the Children's Eating Habits Questionnaire (CEHQ-FFQ) used in the IDEFICS (Identification and prevention of dietary- and lifestyle induced health effects in children and infants) study by comparing with UCa and UK excretions in spot urine samples.

DESIGN

This study was conducted as a setting-based community-oriented intervention study and results from the first cross-sectional survey have been included in the analysis.

SUBJECTS

A total of 10,309 children aged 2-10 years from eight European countries are included in this analysis.

METHODS

UCa and UK excretions were measured in morning spot urine samples. Calcium and potassium urine concentrations were standardised for urinary creatinine (Cr) excretion. Ratios of UCa/Cr and UK/Cr were used for multivariate regression analyses after logarithmic transformation to obtain normal distributions of data. Milk consumption frequencies were obtained from the CEHQ-FFQ. Multivariate regression analyses were used to investigate the effect of milk consumption frequencies on UCa and UK concentrations, adjusting for age, gender, study centre, soft drink consumption and frequency of main meals consumed at home.

RESULTS

A significant positive correlation was found between milk consumption frequencies and ratios of UK/Cr and a weaker but still significant positive correlation with ratios of UCa/Cr, when using crude or partial Spearman's correlations. Multivariate regression analyses showed that milk consumption frequencies were predictive of UCa/Cr and UK/Cr ratios, when adjusted for age, gender, study centre, soft drink consumption and frequency of main meals consumed at home. Mean ratios of UK/Cr for increasing milk consumption frequency tertiles showed a progressive increase in UK/Cr. Children consuming at least two milk servings per day had significantly higher mean UCa/Cr and UK/Cr ratios than children who did not. Large differences in correlations between milk consumption frequencies and ratios of UCa/Cr and UK/Cr were found between the different study centres.

CONCLUSION

Higher milk consumption frequencies resulted in a progressive increase in UK/Cr and UCa/Cr ratios, reflecting the higher Ca and K intakes that coincide with increasing milk consumption, which constitutes a major K and Ca source in children's diet.

Impact of dietary counseling on urinary stone risk parameters in recurrent stone formers

OBJECTIVES

The aim of this study was to investigate the current impact of dietary counseling on the risk for urolithiasis.

METHODS

A retrospective cohort study of the patients treated in our stone clinics from July 2007 to February 2009 was carried out. Patients' urinary risk factors for stone disease were evaluated with pre- and postintervention 24-hour urine collections. All patients received dietary recommendations from a registered dietician at each visit.

RESULTS

One hundred thirty-seven subjects were identified and managed initially with only dietary interventions to address their urinary stone risk parameters. Average follow-up for this group was 15.19 ± 13.7 months. Subjects showed significant changes in urine volume (71.1%, 1.68 ± 0.68 to 2.59 ± 0.80 L/day, p < 0.0001), urine sodium (58.1%, 229.68 ± 72.51 to 144.65 ± 52.70 mmol/day, p < 0.0001), urine calcium (43.8%, 314.33 ± 95.75 to 216.81 ± 80.90 mg/day, p < 0.0001), urinary uric acid (50%, 0.821 ± 0.210 to 0.622 ± 0.128 g/day, p < 0.0001), urinary citrate (50.7%, 583.19 ± 330.86 to 797.36 ± 412.31, p < 0.0001), and urine oxalate (55.5%, 46.28 ± 10.31 to 32.56 ± 9.02 mg/day, p < 0.0001). The supersaturation for calcium oxalate also decreased significantly from baseline (9.34-5.03, p < 0.0001).

CONCLUSION

Urolithiasis is a multifactorial disease requiring a multidisciplinary approach. Our results support the use of dietary counseling by a registered dietician in the management of urolithiasis.

Taurine's health influence on Japanese high school girls

BACKGROUND

The prevalence of metabolic syndrome (MS) in children and adolescents has been increasing at an alarming rate. MS risks during childhood and adolescence adversely affect health conditions in later life. Thus, the characterization of their MS risks is a critical research field. The aims of this study are to survey the health status of Japanese adolescent females, a poorly characterized population, and to investigate the potential relationship between their MS risks and dietary factors like potassium (K) and taurine.

METHODS

Anthropometric characteristics of 243 healthy school girls aged 13 to 18 years were measured. Serum levels of triglycerides, total cholesterol and high-density lipoprotein (HDL), and plasma levels of glucose and insulin were analyzed in fasting blood samples. We assessed overweight, disturbed lipid prolife, higher blood pressure (hBP) and higher plasma glucose (hGlc) levels as indicators of MS risks. The relationships between MS risks and urinary K or taurine excretion were investigated by dividing into higher and lower groups at medians of their urinary excretions.

RESULTS

Half of junior high school (JHS) and one-quarter of senior high school (SHS) girls had at least one MS risk. The quite common risk was hGlc, the rates being 21% in JHS girls and 14% in SHS. The prevalence of being overweight and obesity were only small portions, the rate being 0% and 0% in JHS girls, and 10% and 1% in SHS, respectively. Substantial differences in the prevalence of hBP were observed between JHS (22%) and SHS (4%) girls. Furthermore, higher urinary K excretion group showed a significant decrease in triglyceride level (P = 0.03) and increase in HDL level (P = 0.003) compared with the lower. Also, the higher urinary taurine excretion group exhibited a significant reduction in triglyceride level (P = 0.04) compared with the lower.

CONCLUSIONS

These results indicate that control of plasma glucose level rather than body weight is a crucial task in Japanese pubertal girls, and that a dietary habit rich in K and taurine could improve their lipid profile. Nutritional education based on these findings would help to prevent the future development of MS in Japanese female adolescents.

Diet quality is associated with better cognitive test performance among aging men and women

Most studies of association between diet and cognition among the elderly focus on the role of single nutrients or foods and ignore the complexity of dietary patterns and total diet quality. We prospectively examined associations between an index of diet quality and cognitive function and decline among elderly men and women of the Cache County Study on Memory and Aging in Utah. In 1995, 3634 resident men and women > or =65 y of age completed a baseline survey that included a 142-item FFQ. Cognition was assessed using an adapted version of the Modified Mini-Mental State Examination (3MS) at baseline and 3 subsequent interviews spanning approximately 11 y. A recommended food score (RFS) and non-RFS were computed by summing the number of recommended foods (n = 57) and nonrecommended foods (n = 23) regularly consumed. Multivariable-mixed models were used to estimate associations between the RFS and non-RFS and average 3MS score over time. Those in the highest quartile of RFS scored 1.80 points higher on the baseline 3MS test than did those in the lowest quartile of RFS (P < 0.001). This effect was strengthened over 11 y of follow-up. Those with the highest RFS declined by 3.41 points over 11 y compared with the 5.2-point decline experienced by those with the lowest RFS (P = 0.0013). The non-RFS was not associated with cognitive scores. Consuming a diverse diet that includes a variety of recommended foods may help to attenuate age-related cognitive decline among the elderly.

Can nocturnal hypertension predict cardiovascular risk?

Nocturnal hypertension and non-dipping of blood pressure during sleep are distinct entities that often occur together and are regarded as important harbingers of poor cardiovascular prognosis. This review addresses several aspects related to these blood pressure abnormalities including definitions, diagnostic limitations, pathogenesis and associated patient profiles, prognostic significance, and therapeutic strategies. Taken together, persistent nocturnal hypertension and non-dipping blood pressure pattern, perhaps secondary to abnormal renal sodium handling and/or altered nocturnal sympathovagal balance, are strongly associated with deaths, cardiovascular events, and progressive loss of renal function, independent of daytime and 24-hour blood pressure. Several pharmacological and non-pharmacological approaches may restore nocturnal blood pressure and circadian blood pressure rhythm to normal; however, whether this translates to a clinically meaningful reduction in unfavorable cardiovascular and renal consequences remains to be seen.