Potassium inhibits free radical formation

Urinary Na/K ratio is a predictor of developing chronic kidney disease in the general population

Chronic kidney disease (CKD) is a major risk factor for cardiovascular diseases as well as end-stage kidney disease. Increased dietary sodium (Na) or decreased dietary potassium (K) deteriorates kidney function; however, findings regarding the association of dietary Na/K ratio with kidney function are limited and conflicting. Therefore, the present study investigated the impact of urinary Na/K ratio on the development of CKD, defined as estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2, in the Japanese general population. In total, 14,549 subjects without CKD who participated in our medical checkup were enrolled. The urinary Na/K ratio was measured using a sample of overnight urine. The subjects were followed up until the endpoint (onset of CKD). During the median follow-up period of 61.4 months, CKD developed in 2096 participants (25.9 per 1000 person-years). The risk of developing CKD increased across the quartiles of baseline urinary Na/K ratio in the Kaplan-Meier analysis (log-rank, P < 0.001). In multivariate Cox proportional hazard regression analysis, urinary Na/K ratio was a significant predictor of new-onset CKD after adjustment for important factors including eGFR at baseline (hazard ratio, 2.013; 95% confidence interval, 1.658-2.445; p < 0.001). Moreover, baseline urinary Na/K ratio was found to be independently correlated with yearly decline in eGFR. Similar results were obtained in subgroups of participants with and without hypertension. Thus, urinary Na/K ratio is significantly associated with the development of CKD in the general population.

Potassium status and the risk of type 2 diabetes, cardiovascular diseases, and mortality: a meta-analysis of prospective observational studies

Epidemiological evidence on the association between potassium and cardiometabolic outcomes remains controversial. This study aimed to examine associations of dietary intake and blood and urinary levels of potassium with risk of type 2 diabetes, cardiovascular disease (CVD), and mortality. Relevant prospective studies were retrieved through a comprehensive search of four electronic databases up to July 1, 2023. Random-effects models were used to pool the study-specific relative risks (RRs) and 95% confidence intervals (CIs). Fifty-six studies were included in this meta-analysis. A higher intake of potassium was significantly associated with a 16% lower risk of CVD (RR: 0.84, 95% CI: 0.78-0.90). Similar inverse associations were also observed between potassium intake and mortality. Each 1.0 g/d increment in potassium intake was associated with a decreased risk of CVD (RR: 0.85, 95% CI: 0.80-0.91) and all-cause mortality (RR: 0.93, 95% CI: 0.88-0.99). For blood and urinary potassium levels, higher level of blood potassium increased the risk of all-cause mortality by 23% (RR: 1.23, 95% CI: 1.11-1.36). The association of blood potassium levels with mortality was nonlinear (Pnon-linearit<0.001). However, urinary potassium levels were inversely associated with the risk of all-cause mortality (RR: 0.84, 95% CI: 0.76-0.93). Our findings support the benefits of moderate potassium consumption for primary prevention of chronic diseases and premature death.

Aldosterone: Renal Action and Physiological Effects

Aldosterone exerts profound effects on renal and cardiovascular physiology. In the kidney, aldosterone acts to preserve electrolyte and acid-base balance in response to changes in dietary sodium (Na+ ) or potassium (K+ ) intake. These physiological actions, principally through activation of mineralocorticoid receptors (MRs), have important effects particularly in patients with renal and cardiovascular disease as demonstrated by multiple clinical trials. Multiple factors, be they genetic, humoral, dietary, or otherwise, can play a role in influencing the rate of aldosterone synthesis and secretion from the adrenal cortex. Normally, aldosterone secretion and action respond to dietary Na+ intake. In the kidney, the distal nephron and collecting duct are the main targets of aldosterone and MR action, which stimulates Na+ absorption in part via the epithelial Na+ channel (ENaC), the principal channel responsible for the fine-tuning of Na+ balance. Our understanding of the regulatory factors that allow aldosterone, via multiple signaling pathways, to function properly clearly implicates this hormone as central to many pathophysiological effects that become dysfunctional in disease states. Numerous pathologies that affect blood pressure (BP), electrolyte balance, and overall cardiovascular health are due to abnormal secretion of aldosterone, mutations in MR, ENaC, or effectors and modulators of their action. Study of the mechanisms of these pathologies has allowed researchers and clinicians to create novel dietary and pharmacological targets to improve human health. This article covers the regulation of aldosterone synthesis and secretion, receptors, effector molecules, and signaling pathways that modulate its action in the kidney. We also consider the role of aldosterone in disease and the benefit of mineralocorticoid antagonists. © 2023 American Physiological Society. Compr Physiol 13:4409-4491, 2023.

Effect of Potassium Supplementation on Endothelial Function: A Systematic Review and Meta-Analysis of Intervention Studies

(1) Background: Endothelial dysfunction is an early predictor of cardiovascular diseases. Although a large body of evidence shows an inverse association between potassium intake and cardiovascular risk, the studies on endothelial function provided contrasting results. Thus, we carried out a systematic review and a meta-analysis of the available intervention studies of the potassium supplementation on endothelial function. (2) Methods: A systematic search of the online databases available (up to December 2022) was conducted including the intervention trials that reported flow-mediated dilation (FMD) changes-a non-invasive method of assessing endothelial function-after two different potassium intake regimens. For each study, the mean difference (MD) and 95% confidence intervals were pooled using a random effect model. (3) Results: Five studies met the pre-defined inclusion criteria and provided eight cohorts with 332 participants. In the pooled analysis, potassium supplementation was associated with a significant increase in FMD (MD: 0.74%), with a higher effect for a urinary potassium excretion higher than 90 mmol/day. There was a moderate heterogeneity among studies (I² = 59%), explained by the different amount of potassium supplementation. (4) Conclusions: The results of our meta-analysis indicate that dietary potassium supplement improves endothelial function. This effect is directly associated with the amount of potassium supplement. The findings support the campaigns in favour of an increase in dietary potassium intake to reduce cardiovascular risk.

Introductory Chapter: Potassium in Human Health

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Effects of enriched-potassium diet on cardiorespiratory outcomes in experimental non-ischemic chronic heart failure

Background

Chronic heart failure (CHF) is a global health problem. Increased sympathetic outflow, cardiac arrhythmogenesis and irregular breathing patterns have all been associated with poor outcomes in CHF. Several studies showed that activation of the renin-angiotensin system (RAS) play a key role in CHF pathophysiology. Interestingly, potassium (K⁺) supplemented diets showed promising results in normalizing RAS axis and autonomic dysfunction in vascular diseases, lowering cardiovascular risk. Whether subtle increases in dietary K⁺ consumption may exert similar effects in CHF has not been previously tested. Accordingly, we aimed to evaluate the effects of dietary K⁺ supplementation on cardiorespiratory alterations in rats with CHF.

Methods

Adult male Sprague–Dawley rats underwent volume overload to induce non-ischemic CHF. Animals were randomly allocated to normal chow diet (CHF group) or supplemented K⁺ diet (CHF+K⁺ group) for 6 weeks. Cardiac arrhythmogenesis, sympathetic outflow, baroreflex sensitivity, breathing disorders, chemoreflex function, respiratory–cardiovascular coupling and cardiac function were evaluated.

Results

Compared to normal chow diet, K⁺ supplemented diet in CHF significantly reduced arrhythmia incidence (67.8 ± 15.1 vs. 31.0 ± 3.7 events/hour, CHF vs. CHF+K⁺), decreased cardiac sympathetic tone (ΔHR to propranolol: − 97.4 ± 9.4 vs. − 60.8 ± 8.3 bpm, CHF vs. CHF+K⁺), restored baroreflex function and attenuated irregular breathing patterns. Additionally, supplementation of the diet with K⁺ restores normal central respiratory chemoreflex drive and abrogates pathological cardio-respiratory coupling in CHF rats being the outcome an improved cardiac function.

Conclusion

Our findings support that dietary K⁺ supplementation in non-ischemic CHF alleviate cardiorespiratory dysfunction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-021-00365-z.

Serum Potassium Levels of 4.5 to Less Than 5.0 mmol/L Are Associated with Better Vascular Function

Aim: An experimental study showed that potassium inhibits the formation of reactive oxygen species by vascular cells. The purpose of this study was to investigate the association between serum potassium levels and vascular function.

Methods: We measured flow-mediated vasodilation (FMD) as an index of endothelial function in 3045 subjects (1964 men; mean age, 62.3±13.8 years) and nitroglycerine-induced vasodilation (NID) as an index of vascular smooth muscle function in 1578 subjects (1001 men; mean age, 61.8±16.3 years).

Results: In the 3045 subjects, there was a significant positive correlation between FMD and serum potassium levels (r=0.09,P＜0.001). Multivariate analysis revealed that serum potassium levels were significantly associated with FMD (β=0.109,P＜0.001). When subjects were divided into two groups based on treatment with drugs that could alter serum potassium levels, the association between serum potassium levels and FMD was significant both in subjects with (β=0.096,P＜0.001) and subjects without (β=0.123,P＜0.001) treatment with drugs that could alter serum potassium levels. In the 1578 subjects, there was a significant positive correlation between NID and serum potassium levels (r=0.11,P＜0.001). Multivariate analysis revealed that serum potassium levels were significantly associated with NID (β=0.098,P＜0.001). The association between serum potassium levels and NID was significant both in subjects with (β=0.121,P=0.001) and subjects without (β=0.083,P=0.03) treatment with drugs that could alter serum potassium levels.

Conclusions: Serum potassium levels of 4.5-＜5.0 mmol/L are associated with better vascular function regardless of the presence or absence of treatment with drugs that could alter serum potassium levels.

Lower Serum Potassium Levels at Admission are Associated with the Risk of Recurrent Stroke in Patients with Acute Ischemic Stroke or Transient Ischemic Attack

INTRODUCTION

Serum potassium abnormality is a risk factor of incident stroke, but whether it is associated with recurrent stroke in patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA) remains unknown. This study aimed to investigate the association of serum potassium with the risk of recurrent stroke in patients with AIS or TIA.

METHODS

We included 12,425 patients from the China National Stroke Registry III. Patients were classified into 3 groups according to tertiles of potassium. The outcomes were recurrence of stroke and combined vascular events at 1 year. Cox proportional hazards regression was adopted to explore the associations by calculating hazard ratios (HRs) and their 95% confidence intervals (CIs).

RESULTS

Among 12,425 enrolled patients, the median (interquartile range) of potassium was 3.92 (3.68-4.19) mmol/L. Compared with the highest tertile, after adjusted for confounding factors, the lowest tertile potassium was associated with increased risk of recurrent stroke at 1 year. The adjusted HR with 95% CI was 1.21 (1.04-1.41). There was an independent, linear association between serum potassium and stroke recurrence. Per 1 mmol/L decrease of potassium was associated with 19% higher risk of recurrent stroke (HR, 1.19; 95% CI, 1.04-1.37). Similar trends were found in ischemic stroke and combined vascular events.

CONCLUSIONS

Lower serum potassium level was independently associated with elevated risk of recurrent stroke in patients with AIS or TIA. The finding suggested that monitoring serum potassium may help physicians to identify patients at high risk of recurrent stroke and to stratify risk for optimal management.

Randomized Trial on the Effects of Dietary Potassium on Blood Pressure and Serum Potassium Levels in Adults with Chronic Kidney Disease

In the general population, an increased potassium (K) intake lowers blood pressure (BP). The effects of K have not been well-studied in individuals with chronic kidney disease (CKD). This randomized feeding trial with a 2-period crossover design compared the effects of diets containing 100 and 40 mmol K/day on BP in 29 adults with stage 3 CKD and treated or untreated systolic BP (SBP) 120–159 mmHg and diastolic BP (DBP) <100 mmHg. The primary outcome was 24 h ambulatory systolic BP. The higher-versus lower-K diet had no significant effect on 24 h SBP (−2.12 mm Hg; p = 0.16) and DBP (−0.70 mm Hg; p = 0.44). Corresponding differences in clinic BP were −4.21 mm Hg for SBP (p = 0.054) and −0.08 mm Hg for DBP (p = 0.94). On the higher-K diet, mean serum K increased by 0.21 mmol/L (p = 0.003) compared to the lower-K diet; two participants had confirmed hyperkalemia (serum K ≥ 5.5 mmol/L). In conclusion, a higher dietary intake of K did not lower 24 h SBP, while clinic SBP reduction was of borderline statistical significance. Additional trials are warranted to understand the health effects of increased K intake in individuals with CKD.

Gut Dysbiosis and Western Diet in the Pathogenesis of Essential Arterial Hypertension: A Narrative Review

Metabolic syndrome is a cluster of the most dangerous cardiovascular (CV) risk factors including visceral obesity, insulin resistance, hyperglycemia, alterations in lipid metabolism and arterial hypertension (AH). In particular, AH plays a key role in the complications associated with metabolic syndrome. High salt intake is a well-known risk factor for AH and CV diseases. Vasoconstriction, impaired vasodilation, extracellular volume expansion, inflammation, and an increased sympathetic nervous system (SNS) activity are the mechanisms involved in the pathogenesis of AH, induced by Western diet. Gut dysbiosis in AH is associated with reduction of short chain fatty acid-producing bacteria: acetate, butyrate and propionate, which activate different pathways, causing vasoconstriction, impaired vasodilation, salt and water retention and a consequent high blood pressure. Moreover, increased trimethylamine N-oxide and lipopolysaccharides trigger chronic inflammation, which contributes to endothelial dysfunction and target organs damage. Additionally, a high salt-intake diet impacts negatively on gut microbiota composition. A bidirectional neuronal pathway determines the “brain–gut” axis, which, in turn, influences blood pressure levels. Then, we discuss the possible adjuvant novel treatments related to gut microbiota modulation for AH control.

Admission serum potassium levels and prognosis of vasospastic angina

Hypokalemia is a common electrolyte disturbance and is related to poor prognosis in patients with cardiovascular disease. However, the role of hypokalemia in patients with vasospastic angina (VSA) has not yet been studied. The present study enrolled 1454 patients diagnosed with VSA according to ergonovine provocation test results and available admission serum potassium data. The primary outcome was a composite of cardiac death, acute coronary syndrome, and new-onset life-threatening arrhythmia. Based on a hypokalemia definition as serum potassium concentration ≤ 3.5 mEq/L, the hypokalaemia group included 70 patients (4.8%). The median potassium levels were 3.4 mEq/L [interquartile range (IQR) 3.3-3.5] in the hypokalemia group and 4.1 mEq/L (IQR 3.9-4.3) in the no-hypokalemia group. The median follow-up duration was 764 days. Primary outcomes occurred in seven patients (10.0%) in the hypokalemia group and 51 patients (3.7%) in the no-hypokalemia group. The Kaplan-Meier analysis showed a higher cumulative incidence of primary outcomes in the hypokalemia group compared to that in the no-hypokalemia group (log-rank P = 0.014). Multivariate Cox regression analysis also showed that hypokalemia was an independent predictor of primary outcomes. In conclusion, hypokalemia at admission was associated with adverse clinical outcomes in VSA.

Mechanisms of Dietary Sodium-Induced Impairments in Endothelial Function and Potential Countermeasures

Despite decades of efforts to reduce sodium intake, excess dietary sodium remains commonplace, and contributes to increased cardiovascular morbidity and mortality independent of its effects on blood pressure. An increasing amount of research suggests that high-sodium diets lead to reduced nitric oxide-mediated endothelial function, even in the absence of a change in blood pressure. As endothelial dysfunction is an early step in the progression of cardiovascular diseases, the endothelium presents a target for interventions aimed at reducing the impact of excess dietary sodium. In this review, we briefly define endothelial function and present the literature demonstrating that excess dietary sodium results in impaired endothelial function. We then discuss the mechanisms through which sodium impairs the endothelium, including increased reactive oxygen species, decreased intrinsic antioxidant defenses, endothelial cell stiffening, and damage to the endothelial glycocalyx. Finally, we present selected research findings suggesting that aerobic exercise or increased intake of dietary potassium may counteract the deleterious vascular effects of a high-sodium diet.

Postulating the major environmental condition resulting in the expression of essential hypertension and its associated cardiovascular diseases: Dietary imprudence in daily selection of foods in respect of their potassium and sodium content resulting in oxidative stress-induced dysfunction of the vascular endothelium, vascular smooth muscle, and perivascular tissues

We hypothesize that the major environmental determinant of the expression of essential hypertension in America and other Westernized countries is dietary imprudence in respect of the consumption of daily combinations of foods containing suboptimal amounts of potassium and blood pressure-lowering phytochemicals, and supraphysiological amounts of sodium. We offer as premise that Americans on average consume suboptimal amounts of potassium and blood pressure-lowering phytochemicals, and physiologically excessive amounts of sodium, and that such dietary imprudence leads to essential hypertension through oxidative stress-induced vascular endothelial and smooth muscle dysfunction. Such dysfunctions restrict nitric oxide bioavailability, impairing endothelial cell-mediated relaxation of the underlying vascular smooth muscle, initiating and maintaining inappropriately increased peripheral and renal vascular resistance. The biochemical steps from oxidative stress to vascular endothelial dysfunction and its pernicious cardiovascular consequences are well established and generally accepted. The unique aspect of our hypothesis resides in the contention that Americans' habitual consumption of foods resulting in suboptimal dietary intake of potassium and supraphysiological intake of sodium result in oxidative stress, the degree of which, we suggest, will correlate with the degree of deviation of potassium and sodium intake from optimal. Because suboptimal intakes of potassium reflect suboptimal intakes of fruits and vegetables, associated contributors to oxidative stress include suboptimal intakes of magnesium, nitrate, polyphenols, carotenoids, and other phytochemical antioxidants for which fruits and vegetables contain abundant amounts. Currently Americans consume potassium-to-sodium in molar ratios of less than or close to 1.0 and the Institute of Medicine (IOM) recommends a molar ratio of 1.2. Ancestral diets to which we are physiologically adapted range from molar ratios of 5.0 to 10.0 or higher. Accordingly, we suggest that the average American is usually afflicted with oxidative stress-induced vascular endothelial dysfunction, and therefore the standards for normal blood pressure and pre-hypertension often reflect a degree of clinically significant hypertension. In this article, we provide support for those contentions, and indicate the findings that the hypothesis predicts.

Dietary sodium, sodium-to-potassium ratio, and risk of stroke: A systematic review and nonlinear dose-response meta-analysis

BACKGROUND & AIMS

The association of high sodium intake with risk of stroke has been accepted. But considering the proposed J/U-shaped association between sodium intake and risk of all-cause mortality, the shape of the dose-response relationship has not been determined yet. This study aimed to test the dose-response association of dietary sodium and sodium-to-potassium ratio with risk of stroke in adults aged 18 years or older.

METHODS

We performed a systematic search using PubMed and Scopus, from database inception up to October 2017. Prospective and retrospective observational studies reporting risk estimates of stroke for three or more quantitative categories of dietary sodium or sodium-to-potassium ratio were included. Studies that reported results as continuous were also included. Two independent authors extracted the information and assessed the quality of included studies. Pooled relative risk (RR) was calculated using a random-effects model. Publication bias was tested. Sensitivity and subgroup analyses were done.

RESULTS

Of initial 20,412 studies identified, 14 prospective cohort studies, one case-cohort study, and one case-control study (total n = 261,732) with 10,150 cases of stroke were included. The Pooled RRs of stroke were 1.06 (95%CI: 1.02, 1.10; I² = 60%, n = 14 studies) for a 1 gr/d increment in dietary sodium intake, and 1.22 (95%CI: 1.04, 1.41; I² = 60%, n = 5 studies) for a one-unit increment in dietary sodium-to-potassium ratio (mmol/mmol). The risk of stroke increased linearly with increasing dietary sodium intake, and also along with the increase in dietary sodium-to-potassium ratio. No evidence of a J/U-shaped association was found in the analyses of total stroke, stroke incidence, and stroke mortality. High sodium intake was associated with a somewhat worse prognosis among Asian countries as compared to westerns.

CONCLUSION

Higher sodium intake and higher dietary sodium-to-potassium ratio were associated with a higher risk of stroke. Reducing dietary sodium-to-potassium ratio can be considered as a supplementary approach in parallel with the decrease in sodium intake in order to decrease stroke risk. The interpretation of the results is limited by observational nature of studies examined.

Diet and primary prevention of stroke: Systematic review and dietary recommendations by the ad hoc Working Group of the Italian Society of Human Nutrition

BACKGROUND AND AIMS

To systematically review the latest evidence on established and emerging nutrition-related risk factors for incidence of and mortality from total, ischemic and haemorrhagic strokes. The present review was conducted in the framework of the work carried out through 2015 and 2016 for the preparation of the Italian Guidelines for the Prevention and Treatment of Stroke, 8th Edition, by ISO-SPREAD (Italian Stroke Organization and the Stroke Prevention and Educational Awareness Diffusion).

METHODS AND RESULTS

Systematic review of articles focused on primary prevention of stroke published between January 2013 to May 2016 through an extensive search of the literature using MEDLINE/PUBMED, EMBASE and the Cochrane Library. Articles were ranked according to the SIGN methodology while the GRADE system was used to establish the strength of recommendations. As a result of our literature search, we examined 87 meta-analyses overall (mainly of prospective studies), a few isolated more recent prospective studies not included in the meta-analyses, and a smaller number of available randomized controlled trials and case-control studies. Based on the analysis of the above articles, 36 Syntheses of the available evidence and 36 Recommendations were eventually prepared. The present document was developed by organizing the available evidence into three individual areas (nutrients, food groups and dietary patterns) to provide a systematic and user-friendly overview of the available evidence on the relationship between nutrition and primary prevention of stroke. Yet analysis of foods and food patterns allowed translating the information about nutrients in a tool more amenable to use in daily life also in the light of the argument that people eat foods rather than nutrients.

CONCLUSIONS

The present literature review and dietary recommendations provide healthcare professionals and all interested readers with a useful overview for the reduction of the risk of total, ischemic and haemorrhagic stroke through dietary modifications.

Involvement of NLRP3 inflammasome in the impacts of sodium and potassium on insulin resistance in normotensive Asians

Salt, promoting oxidative stress, contributes to insulin resistance, whereas K, inhibiting oxidative stress, improves insulin sensitivity. Oxidative stress activation of NLRP3 inflammasome is a central player in the induction of insulin resistance. Therefore, we hypothesised that NLRP3 inflammasome may mediate the effects of salt and K on insulin resistance. In all, fifty normotensive subjects were recruited from a rural community of Northern China. The protocol included a low-salt diet for 7 d, then a high-salt diet for 7 d and a high-salt diet with K supplementation for another 7 d. In addition, THP-1 cells were cultured in different levels of Na with and without K. The results showed that salt loading elevated fasting blood glucose, insulin and C-peptide levels, as well as insulin resistance, whereas K supplementation reversed them. Meanwhile, additional K reversed the active effects of high salt on NLRP3 inflammasome in both the subjects and THP-1 cells, and the change of insulin resistance index notably related with the alteration of plasma IL-1β, the index of NLRP3 inflammasome activation, during intervention in the subjects. Additional K ameliorated oxidative stress induced by high salt in both the subjects and cultured THP-1 cells, and the change of oxidative stress related with the alteration of plasma IL-1β during intervention in the subjects. In vitro, antioxidant N-acetyl-l-cysteine significantly prevented the active effects of high Na or oxidant Rosup on NLRP3 inflammasome, so did K. Our study indicates that oxidative stress modulation of NLRP3 inflammasome may be involved in the impacts of Na and K on insulin resistance.

Diuretics: A possible keystone in upholding cognitive health

INTRODUCTION

Dementia encompasses diseases of progressive memory loss and neurological alterations, including Alzheimer disease. Hypertension is one risk factor proposed for development of Alzheimer disease. The objective is to evaluate the current literature for use of diuretics in the prevention of dementia.

METHODS

Literature was not considered if published before January 1, 2000, or after May 31, 2015. PubMed was used to locate sources. Four search terms were used to find data: Alzheimer disease, antihypertensive agents, diuretics, and dementia.

RESULTS

Four studies of efficacy of diuretic usage in the prevention against dementia met criteria. Potassium-sparing diuretics displayed risk reduction of Alzheimer disease and maintenance of cognitive function. Risk reduction was demonstrated when used alone (adjusted hazard ratio [aHR] 0.09, 95% confidence interval [CI] 0.01-0.41) as compared to use of other antihypertensives without potassium-sparing diuretics (aHR 0.76, 95% CI 0.49-1.15). Other antihypertensive drug classes did show some benefit, however. Diuretic and angiotensin receptor blocker users had a lower Alzheimer disease risk versus those with no antihypertensive use (hazard ratio 0.40, 95% CI 0.26-0.61) and (hazard ratio 0.37, 95% CI 0.19-0.72), respectively. Additionally, thiazide diuretics were also shown to reduce Alzheimer risk. Thiazide and potassium-sparing combination significantly reduced risk versus non-antihypertensive users (aHR 0.63, 95% CI 0.42-0.94).

DISCUSSION

Available research demonstrates an inverse association between diuretic use and the incident rate of dementia. Specifically, this has been found with thiazide and potassium-sparing diuretics when used alone or in combination. This review suggests that patients receiving diuretics for hypertension may receive an added neuroprotective effect.

Effect of Hypokalemia on Functional Outcome at 3 Months Post-Stroke Among First-Ever Acute Ischemic Stroke Patients

Background

Hypokalemia has been confirmed to be a predictor of adverse cardiovascular and renal outcomes. There is a paucity of studies focusing on the potential connection between the serum K⁺ level and the outcome after acute ischemic stroke (AIS). This study investigated whether hypokalemia in the acute stroke stage contributes to worse functional outcome in AIS patients.

Material/Methods

This retrospective cohort study included consecutive patients with first-ever AIS admitted between June 2015 and March 2016. Patients were divided into 2 groups: hypokalemia (K⁺ <3.5 mmol/L) and normokalemia (3.5 mmol/L ≤K⁺ ≤5.5 mmol/L). Primary outcome measure was poor outcome at 3 months (modified Rankin scale >2). Univariate and multivariate logistic regression analyses were used to assess the association between hypokalemia and poor outcome. Receiver operating curve (ROC) analysis was performed to determine the optimal cutoff point of serum K⁺ level for predicting poor outcome.

Results

The percent of patients with poor outcome at 3 months was higher in the hypokalemic group (62.9%) than in the normokalemic group (45.5%). Hypokalemic patients tended to have lower fasting glucose at admission, lower Glasgow coma scale score, and longer time from symptom onset to treatment compared with normokalemic patients. Hypokalemia was associated with poor outcome at 3 months after adjusting for potential confounders (odds ratio=2.42, 95% confidence interval=1.21–4.86, P=0.013). ROC analysis showed that the optimal threshold for serum K⁺ level was 3.7 mmol/L.

Conclusions

Hypokalemia at the initial admission is associated with poor prognosis at 3 months in first-ever AIS patients.

Treatment options and considerations for hypertensive patients to prevent dementia

INTRODUCTION

Dementia is a worldwide health concern, which leads to loss of autonomy. To date no curative treatment is available so focus on modifiable risk factors is of particular interest. Hypertension, particularly midlife high blood pressure, has been associated with an increased risk for cognitive decline and dementia including vascular dementia (VAD) and Alzheimer disease (AD). In this context, antihypertensive treatments might have a preventive effect. The objective of this review was to examine the relationship between antihypertensive therapy and cognitive decline or dementia. Areas covered: A literature search was conducted using PUBMED and the COCHRANE LIBRARY for publications from 1990 onwards mentioning cognitive decline, AD, Vad, mixed dementia, vascular cognitive impairment, hypertension and antihypertensive therapy. Thirty-nine relevant publications including 20 longitudinal studies, 10 randomized-controlled trials and 9 meta-analyses were taken into account. Expert opinion: Most observational studies have suggested a potential preventive effect of antihypertensive therapies on cognitive decline and dementia, particularly calcium channel blockers and renin-angiotensin system blockers. Randomized clinical trials and meta-analyses provided more conflicting results potentially due to methodological issues. In conclusion, antihypertensive therapies may reduce cognitive decline and incidence of dementia. Further randomized clinical trials conducted in populations at higher risk of cognitive decline, with longer periods of follow-up and cognition as the primary outcome are still needed.

Plasma potassium, diuretic use and risk of developing chronic kidney disease in a predominantly White population

Objective

Both hypokalemia and hyperkalemia are associated with disease progression in patients with chronic kidney disease (CKD). It is unclear whether similar associations are present in the general population. Our aim was to examine the association of plasma potassium with risk of developing CKD and the role of diuretics in this association in a population-based cohort.

Research design and methods

We studied 5,130 subjects free of CKD at baseline of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study, a prospective, population-based cohort of Dutch men and women aged 28–75 years. Hypokalemia was defined as plasma potassium <3.5 mmol/L, and hyperkalemia as plasma potassium ≥5.0 mmol/L. Risk of CKD was defined as de novo development of eGFR <60 ml/min/1.73m² and/or albuminuria >30 mg/24h.

Results

Mean baseline plasma potassium was 4.4±0.3 mmol/L. The prevalences of hypokalemia and hyperkalemia were 0.5% and 3.8%, respectively; 3.0% of the subjects used diuretics. During a median follow-up of 10.3 years (interquartile range: 6.3–11.4 years), 753 subjects developed CKD. The potassium-CKD association was modified by diuretic use (P_interaction = 0.02). Both hypokalemia without (HR, 7.74, 95% CI, 3.43–17.48) or with diuretic use (HR, 4.32, 95% CI, 1.77–10.51) were associated with an increased CKD risk as compared to plasma potassium 4.0–4.4 mmol/L without diuretic use. Plasma potassium concentrations ≥3.5 mmol/L were associated with an increased CKD risk among subjects using diuretics (P_trend = 0.01) but not among subjects not using diuretics (P_trend = 0.74).

Conclusion

In this population-based cohort, hypokalemia was associated with an increased CKD risk, regardless of diuretic use. In the absence of hypokalemia, plasma potassium was not associated with an increased CKD risk, except among subjects using diuretics.

Postischemic Inflammation in Acute Stroke

Cerebral ischemia is caused by arterial occlusion due to a thrombus or an embolus. Such occlusion induces multiple and concomitant pathophysiological processes that involve bioenergetic failure, acidosis, loss of cell homeostasis, excitotoxicity, and disruption of the blood-brain barrier. All of these mechanisms contribute to neuronal death, mainly via apoptosis or necrosis. The immune system is involved in this process in the early phases after brain injury, which contributes to potential enlargement of the infarct size and involves the penumbra area. Whereas inflammation and the immune system both exert deleterious effects, they also contribute to brain protection by stimulating a preconditioning status and to the concomitant repair of the injured parenchyma. This review describes the main phases of the inflammatory process occurring after arterial cerebral occlusion, with an emphasis on the role of single mediators.

NADPH oxidases as electrochemical generators to produce ion fluxes and turgor in fungi, plants and humans

The NOXs are a family of flavocytochromes whose basic structure has been largely conserved from algae to man. This is a very simple system. NADPH is generally available, in plants it is a direct product of photosynthesis, and oxygen is a largely ubiquitous electron acceptor, and the electron-transporting core of an FAD and two haems is the minimal required to pass electrons across the plasma membrane. These NOXs have been shown to be essential for diverse functions throughout the biological world and, lacking a clear mechanism of action, their effects have generally been attributed to free radical reactions. Investigation into the function of neutrophil leucocytes has demonstrated that electron transport through the prototype NOX2 is accompanied by the generation of a charge across the membrane that provides the driving force propelling protons and other ions across the plasma membrane. The contention is that the primary function of the NOXs is to supply the driving force to transport ions, the nature of which will depend upon the composition and characteristics of the local ion channels, to undertake a host of diverse functions. These include the generation of turgor in fungi and plants for the growth of filaments and invasion by appressoria in the former, and extension of pollen tubes and root hairs, and stomatal closure, in the latter. In neutrophils, they elevate the pH in the phagocytic vacuole coupled to other ion fluxes. In endothelial cells of blood vessels, they could alter luminal volume to regulate blood pressure and tissue perfusion.

The role of dietary potassium in hypertension and diabetes

Potassium is an essential mineral which plays major roles for the resting membrane potential and the intracellular osmolarity. In addition, for several years, it has been known that potassium also affects endothelial and vascular smooth muscle functions and it has been repeatedly shown that an increase in potassium intake shifts blood pressure to a more preferable level. Meanwhile, the blood pressure lowering effects of potassium were presented in several intervention trials and summarized in a handful of meta-analyses. Furthermore, accumulating epidemiological evidence from, especially, the last decade relates low dietary potassium intake or serum potassium levels to an increased risk for insulin resistance or diabetes. However, intervention trials are required to confirm this association. So, in addition to reduction of sodium intake, increasing dietary potassium intake may positively affect blood pressure and possibly also glucose metabolism in many populations. This concise review not only summarizes the studies linking potassium to blood pressure and diabetes but also discusses potential mechanisms involved, like vascular smooth muscle relaxation and endothelium-dependent vasodilation or stimulation of insulin secretion in pancreatic β-cells, respectively.

Intakes of magnesium, potassium, and calcium and the risk of stroke among men

BACKGROUND

Intakes of magnesium, potassium, and calcium have been inversely associated with the incidence of hypertension, a known risk factor for stroke. However, only a few studies have examined intakes of these cations in relation to risk of stroke.

AIM

The aim of this study was to investigate whether high intake of magnesium, potassium, and calcium is associated with reduced stroke risk among men.

METHODS

We prospectively examined the associations between intakes of magnesium, potassium, and calcium from diet and supplements, and the risk of incident stroke among 42 669 men in the Health Professionals Follow-up Study, aged 40 to 75 years and free of diagnosed cardiovascular disease and cancer at baseline in 1986. We calculated the hazard ratio of total, ischemic, and haemorrhagic strokes by quintiles of each cation intake, and of a combined dietary score of all three cations, using multivariate Cox proportional hazard models.

RESULTS

During 24 years of follow-up, 1547 total stroke events were documented. In multivariate analyses, the relative risks and 95% confidence intervals of total stroke for men in the highest vs. lowest quintile were 0·87 (95% confidence interval, 0·74-1·02; P, trend = 0·04) for dietary magnesium, 0·89 (95% confidence interval, 0·76-1·05; P, trend = 0·10) for dietary potassium, and 0·89 (95% confidence interval, 0·75-1·04; P, trend = 0·25) for dietary calcium intake. The relative risk of total stroke for men in the highest vs. lowest quintile was 0·74 (95% confidence interval, 0·59-0·93; P, trend = 0·003) for supplemental magnesium, 0·66 (95% confidence interval, 0·50-0·86; P, trend = 0·002) for supplemental potassium, and 1·01 (95% confidence interval, 0·84-1·20; P, trend = 0·83) for supplemental calcium intake. For total intake (dietary and supplemental), the relative risk of total stroke for men in the highest vs. lowest quintile was 0·83 (95% confidence interval, 0·70-0·99; P, trend = 0·04) for magnesium, 0·88 (95% confidence interval, 0·75-4; P, trend = 6) for potassium, and 3 (95% confidence interval, 79-09; P, trend = 84) for calcium. Men in the highest quintile for a combined dietary score of all three cations had a multivariate relative risk of 0·79 (95% confidence interval, 0·67-0·92; P, trend = 0·008) for total stroke, compared with those in the lowest.

CONCLUSIONS

A diet rich in magnesium, potassium, and calcium may contribute to reduced risk of stroke among men. Because of significant collinearity, the independent contribution of each cation is difficult to define.

Association between intakes of magnesium, potassium, and calcium and risk of stroke: 2 cohorts of US women and updated meta-analyses

BACKGROUND

Prospective data on the relation of magnesium, potassium, and calcium intakes with stroke risk are inconsistent, and to our knowledge, the effect of a combined mineral diet score has not been examined.

OBJECTIVE

We examined associations between intakes of magnesium, potassium, and calcium and risk of incident stroke in 86,149 women in the Nurses' Health Study (NHS) I and 94,715 women in the NHS II.

DESIGN

In this prospective cohort study, we calculated HRs of stroke by quintiles of intake for each mineral and for a combined diet score of all 3 minerals by using multivariate Cox proportional hazard models. In addition, we updated meta-analyses on dietary intakes of these minerals and risk of stroke.

RESULTS

During follow-up (30 y in the NHS I; 22 y in the NHS II) a total of 3780 incident stroke cases were documented. Pooled multivariate RRs of total stroke for women in the highest compared with the lowest quintiles were 0.87 (95% CI: 0.78, 0.97) for total magnesium, 0.89 (95% CI: 0.80, 0.99) for total potassium, and 0.97 (95% CI: 0.87, 1.09) for total calcium intake. Pooled RRs for women in the highest compared with the lowest quintiles of a combined mineral diet score were 0.72 (95% CI: 0.65, 0.81) for total stroke, 0.78 (95% CI: 0.66, 0.92) for ischemic stroke, and 0.80 (95% CI: 0.61, 1.04) for hemorrhagic stroke. In the updated meta-analyses of all prospective studies to date, the combined RR of total stroke was 0.87 (95% CI: 0.83, 0.92) for a 100-mg/d increase in magnesium intake, 0.91 (95% CI: 0.88, 0.94) for a 1000-mg/d increase in potassium intake, and 0.98 (95% CI: 0.94, 1.02) for a 300-mg/d increase in calcium intake.

CONCLUSIONS

A combined mineral diet score was inversely associated with risk of stroke. High intakes of magnesium and potassium but not calcium were also significantly associated with reduced risk of stroke in women.

NADPH Oxidase Activity in Cerebral Arterioles Is a Key Mediator of Cerebral Small Vessel Disease-Implications for Prevention

Cerebral small vessel disease (SVD), a common feature of brain aging, is characterized by lacunar infarcts, microbleeds, leukoaraiosis, and a leaky blood-brain barrier. Functionally, it is associated with cognitive decline, dementia, depression, gait abnormalities, and increased risk for stroke. Cerebral arterioles in this syndrome tend to hypertrophy and lose their capacity for adaptive vasodilation. Rodent studies strongly suggest that activation of Nox2-dependent NADPH oxidase activity is a crucial driver of these structural and functional derangements of cerebral arterioles, in part owing to impairment of endothelial nitric oxide synthase (eNOS) activity. This oxidative stress may also contribute to the breakdown of the blood-brain barrier seen in SVD. Hypertension, aging, metabolic syndrome, smoking, hyperglycemia, and elevated homocysteine may promote activation of NADPH oxidase in cerebral arterioles. Inhibition of NADPH oxidase with phycocyanobilin from spirulina, as well as high-dose statin therapy, may have potential for prevention and control of SVD, and high-potassium diets merit study in this regard. Measures which support effective eNOS activity in other ways-exercise training, supplemental citrulline, certain dietary flavonoids (as in cocoa and green tea), and capsaicin, may also improve the function of cerebral arterioles. Asian epidemiology suggests that increased protein intakes may decrease risk for SVD; conceivably, arginine and/or cysteine-which boosts tissue glutathione synthesis, and can be administered as N-acetylcysteine-mediate this benefit. Ameliorating the risk factors for SVD-including hypertension, metabolic syndrome, hyperglycemia, smoking, and elevated homocysteine-also may help to prevent and control this syndrome, although few clinical trials have addressed this issue to date.

Antihypertensive drugs, prevention of cognitive decline and dementia: a systematic review of observational studies, randomized controlled trials and meta-analyses, with discussion of potential mechanisms

BACKGROUND

Chronic hypertension, particularly midlife high blood pressure, has been associated with an increased risk for cognitive decline and dementia. In this context, antihypertensive drugs might have a preventive effect, but the association remains poorly understood.

OBJECTIVES

The aim of this systematic review was to examine all published findings that investigated this relationship and discuss the mechanisms underlying the potential benefits of antihypertensive medication use.

METHODS

A literature search was conducted using MEDLINE, Embase, and the Cochrane Library for publications from 1990 onwards mentioning hypertension, antihypertensive drugs, cognitive decline, and dementia.

RESULTS

A total of 38 relevant publications, corresponding to 18 longitudinal studies, 11 randomized controlled trials, and nine meta-analyses were identified from the 10,251 articles retrieved in the literature search. In total, 1,346,176 subjects were included in these studies; the average age was 74 years. In the seven longitudinal studies assessing the effect of antihypertensive medication on cognitive impairment or cognitive decline, antihypertensive drugs appeared to be beneficial. Of the 11 longitudinal studies that assessed the effect of antihypertensive medication on incidence of dementia, only three did not find a significant protective effect. Antihypertensive medication could decrease the risk of not only vascular dementia but also Alzheimer's disease. Four randomized controlled trials showed a potentially preventive effect of antihypertensive drugs on the incidence of dementia or cognitive decline: SYST-EUR (Systolic Hypertension in Europe Study) I and II, with a 55% reduction in dementia risk (3.3 vs. 7.4 cases per 1,000 patient years; p<0.001); HOPE (Heart Outcomes Prevention Evaluation), with a 41% reduction in cognitive decline associated with stroke (95% confidence interval [CI] 6-63); and PROGRESS (Perindopril Protection against Recurrent Stroke Study), with a 19% reduction in cognitive decline (95% CI 4-32; p=0.01). Meta-analyses have sometimes produced conflicting results, but this may be due to methodological considerations. The lack of homogeneity across study designs, patient populations, exposition, outcomes, and duration of follow-up are the most important methodological limitations that might explain the discrepancies between some of these studies.

CONCLUSION

Antihypertensive drugs, particularly calcium channel blockers and renin-angiotensin system blockers, may be beneficial in preventing cognitive decline and dementia. However, further randomized controlled trials with longer periods of follow-up and cognition as the primary outcome are needed to confirm these findings.

Hypokalemia in acute medical patients: risk factors and prognosis

OBJECTIVE

Hypokalemia is one of the most common electrolyte disorders in hospitalized patients. It is associated with a high mortality rate among patients with cardiovascular disease. Whether hypokalemia confers a similar risk in an unselected hospitalized population is not well established.

METHODS

We conducted a prospective cohort study involving all first-time admissions (n = 11,988) to the Acute Medical Department at Odense University Hospital linking potassium level at admission with registry data on patient characteristics, laboratory data, redeemed prescriptions, and time of death for the period from August 2009 to August 2011. We estimated hazard ratios for all-cause mortality within 0 to 7 days and 8 to 30 days after admission, comparing patients with hypokalemia at admission (plasma [K(+)] level <3.4 mmol/L) with patients with eukalemia at admission ([K(+)] level of 3.4-3.8 mmol/L).

RESULTS

Hypokalemia occurred in 16.8% of first-time admissions (n = 2011). It was associated with an adjusted hazard ratio [HR] of 1.34 (95% confidence interval [CI], 0.98-1.85) for 7-day mortality and 1.56 (95% CI, 1.18-3.06) for 8- to 30-day mortality. Among patients with more severe hypokalemia (plasma [K(+)] <2.9 mmol/L), the adjusted HR was 2.17 (95% CI, 1.34-3.49) for 7-day mortality and 1.90 (95% CI, 1.18-3.06) for 8- to 30-day mortality. Prognostic factors for both 7-day and 8- to 30-day mortality among hypokalemic patients were increasing age and Charlson Comorbidity Index, whereas there was no prognostic effect of current diuretic or beta-agonist use.

CONCLUSIONS

In a mixed population of hospitalized medical patients, hypokalemia is common, and plasma [K(+)] <2.9 mmol/L is associated with increased 7-day and 8- to 30-day mortality.

Low serum potassium concentration is a predictor of chronic kidney disease

AIMS

The aim of this study was to examine whether low serum potassium concentration could be a predictor of chronic kidney disease (CKD) in a community-based cohort.

MATERIALS AND METHODS

We enrolled 1001 subjects, median period of 5.7 years, and evaluated the risk factors for CKD, defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m(2), and assessed whether low serum potassium concentration could predict CKD.

RESULTS

Compared with the subjects without development of CKD, age, body mass index, fasting plasma glucose, uric acid (UA), creatinine and serum sodium concentration were higher, and serum potassium concentration was lower in subjects with development of CKD. Univariate Cox regression analyses demonstrated that age, body mass index, fasting plasma glucose, UA, creatinine, serum sodium concentration and serum potassium concentration were associated with progression of CKD. Multiple Cox regression analysis revealed that age, gender, creatinine and serum potassium concentration were independent predictors of CKD after adjustment for covariates. When serum potassium concentration was below 4.0 mmol/l at baseline, hazard ratio (95% confidence interval) of developing CKD was 2.65 (2.04-3.44; p < 0.0001).

CONCLUSIONS

Serum potassium concentration could be a clinically relevant risk factor for the progression of CKD, defined as eGFR < 60 ml/min/1.73 m(2) , in healthy subjects.

Cardiovascular risk factors promote brain hypoperfusion leading to cognitive decline and dementia

Heart disease is the major leading cause of death and disability in the world. Mainly affecting the elderly population, heart disease and its main outcome, cardiovascular disease, have become an important risk factor in the development of cognitive decline and Alzheimer's disease (AD). This paper examines the evidence linking chronic brain hypoperfusion induced by a variety of cardiovascular deficits in the development of cognitive impairment preceding AD. The evidence indicates a strong association between AD and cardiovascular risk factors, including ApoE(4), atrial fibrillation, thrombotic events, hypertension, hypotension, heart failure, high serum markers of inflammation, coronary artery disease, low cardiac index, and valvular pathology. In elderly people whose cerebral perfusion is already diminished by their advanced age, additional reduction of cerebral blood flow stemming from abnormalities in the heart-brain vascular loop ostensibly increases the probability of developing AD. Evidence also suggests that a neuronal energy crisis brought on by relentless brain hypoperfusion may be responsible for protein synthesis abnormalities that later result in the classic neurodegenerative lesions involving the formation of amyloid-beta plaques and neurofibrillary tangles. Insight into how cardiovascular risk factors can induce progressive cognitive impairment offers an enhanced understanding of the multifactorial pathophysiology characterizing AD and ways at preventing or managing the cardiovascular precursors of this dementia.

Diuretic use is associated with better learning and memory in older adults in the Ginkgo Evaluation of Memory Study

BACKGROUND

To investigate the association between diuretics, angiotensin-converting enzyme inhibitors (ACE-I), angiotensin II receptor blockers (AT2RB), and cognitive function.

METHODS

This post hoc analysis of the randomized controlled Ginkgo Evaluation of Memory Study trial focuses on 3069 nondemented community-dwelling participants aged >75 years. At baseline visit, detailed information about medication use was collected and five cognitive domains were assessed. Multivariate linear regression analyses were used to assess cross-sectional associations between medication use and cognitive function.

RESULTS

In all, 36% of participants reported history of hypertension and 53% reported antihypertensive medication use, with 17% reporting diuretic, 11% ACE-I, and 2% AT2RB use. Potassium-sparing diuretic use (N = 192) was associated with better verbal learning and memory measured by California Verbal Learning Test as compared with no antihypertensive medication users (β = 0.068, P = .01; β = 0.094, P < .001) and other antihypertensive medication users (β = 0.080, P = .03; β = 0.153, P < .001). Use of ACE-I or AT2RB was not associated with better cognitive function.

CONCLUSION

Results warrant further investigation into possible protective effects of potassium-sparing diuretics and the role of potassium in mitigating cognitive decline.

Marinobufagenin and cyclic strain may activate endothelial NADPH oxidase, contributing to the adverse impact of salty diets on vascular and cerebral health

Limited but provocative ecologic epidemiology suggests that dietary salt may play a central role in the genesis of not only of stroke, but also dementia, including Alzheimer's disease. Impairment of nitric oxide bioactivity in the cerebral microvasculature is a likely mediator of this effect. Salted diets evoke increased adrenal secretion of the natriuretic steroid marinobufagenin (MBG), which promotes natriuresis via inhibition of renal tubular Na+/K+-ATPase; this effect is notably robust in salt-sensitive rodent strains in which other compensatory natriuretic mechanisms are subnormally efficient. MBG-mediated inhibition of sodium pumps in vascular smooth muscle likely plays a role in the hypertension induced by salty diets in these rodents. However, salt sensitivity in humans is associated with increased vascular mortality and ventricular hypertrophy independent of blood pressure; this suggests that MBG may be pathogenic via mechanisms unrelated to blood pressure control. Indeed, recent evidence indicates that MBG, via interaction with alpha1 isoforms of the sodium pump, can activate various intracellular signaling pathways at physiological concentrations too low to notably inhibit pump activity. An overview of current evidence suggests the hypothesis that MBG - as well as the cyclic strain induced by hypertension per se - may induce endothelial oxidative stress by activating NADPH oxidase. If so, this could rationalize the increase in vascular and systemic oxidative stress observed in salt-sensitive rodents fed salty diets, or in rodents infused with MBG; moreover, if this effect is a particularly prominent determinant of oxidative stress in cerebrovascular endothelium, it might help to explain the virtual absence of stroke and dementia in low-salt societies. As a corollary of this hypothesis, it can be predicted that spirulina-derived phycobilins, which appear to mimic the physiological role of bilirubin as an inhibitor of NAPDH oxidase complexes, may have potential for ameliorating the adverse health impacts of MBG and of salty diets. Potassium-rich diets are also likely to be protective in this regard, as they should suppress MBG production via their natriuretic impact, while their stimulatory effect on sodium pump activity may exert a hyperpolarizing effect on plasma membranes that suppresses NADPH oxidase activity.

Association of dietary sodium and potassium intakes with albuminuria in normal-weight, overweight, and obese participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

BACKGROUND

Among obese adults, sodium intake has been associated with cardiovascular disease. Few data are available on sodium intake and albuminuria, a marker of kidney damage and risk factor for cardiovascular disease.

OBJECTIVE

We examined the relation between dietary sodium and potassium intakes and the ratio of sodium to potassium (Na/K) with albuminuria by BMI in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study (n = 30,239 adults aged ≥45 y).

DESIGN

A modified Block 98 food-frequency questionnaire was used for dietary assessment in 21,636 participants, and nutritional variables were categorized by sex-specific quintiles. Normal weight, overweight, and obese were defined as BMI (in kg/m(2)) categories of 18.5-24.9, 25-29.9, and ≥30, respectively. Albuminuria was defined as a ratio (mg/g) of urinary albumin to creatinine of ≥30.

RESULTS

The prevalences of albuminuria were 11.5%, 11.6%, and 16.0% in normal-weight, overweight, and obese participants, respectively. The multivariable-adjusted ORs for albuminuria in a comparison of the highest with the lowest quintile of Na/K intake (≥1.12 to <0.70 for men and ≥1.07 to <0.62 for women) were 0.89 (95% CI: 0.65, 1.22), 1.08 (95% CI: 0.85, 1.36), and 1.28 (95% CI: 1.02, 1.61) in normal-weight, overweight, and obese participants, respectively. The highest quintile of dietary sodium was associated with an increased OR for albuminuria in obese participants (OR: 1.44; 95% CI: 1.00, 2.07) but not in normal-weight or overweight participants. Dietary potassium was not associated with albuminuria.

CONCLUSION

In obese adults, higher dietary Na/K and sodium intakes were associated with albuminuria.

Dietary Potassium Intake and Risk of Stroke

Background and Purpose—

Potassium intake has been inconsistently associated with risk of stroke. Our aim was to conduct a meta-analysis of prospective studies to assess the relation between potassium intake and stroke risk.

Methods—

Pertinent studies were identified by a search of PubMed from January 1966 through March 2011 and by reviewing the reference lists of retrieved articles. We included prospective studies that reported relative risks with 95% CIs of stroke for ≥3 categories of potassium intake or for potassium intake analyzed as a continuous variable. Study-specific results were pooled using a random-effects model.

Results—

Ten independent prospective studies, with a total of 8695 stroke cases and 268 276 participants, were included in the meta-analysis. We observed a statistically significant inverse association between potassium intake and risk of stroke. For every 1000-mg/day increase in potassium intake, the risk of stroke decreased by 11% (pooled relative risk, 0.89; 95% CI, 0.83 to 0.97). In the 5 studies that reported results for stroke subtypes, the pooled relative risks were 0.89 (95% CI, 0.81 to 0.97) for ischemic stroke, 0.95 (95% CI, 0.83 to 1.09) for intracerebral hemorrhage, and 1.08 (95% CI, 0.92 to 1.27) for subarachnoid hemorrhage.

Conclusions—

Dietary potassium intake is inversely associated with risk of stroke, in particular ischemic stroke.

Hypertension, periodontal disease, and potassium intake in nonsmoking, nondrinker african women on no medication

The purpose of this cross-sectional study was to investigate the association of periodontitis and/or tooth loss with hypertension by excluding the common confounders. Eighty-one Tanzanian women who were aged 46-58 years, nonsmokers, nonalcoholic drinkers, and on no medication underwent clinical examination. Multiple-regression analysis showed that the severity of periodontitis was significantly correlated with increased systolic blood pressure and diastolic blood pressure. Simple-regression analysis indicated that the severity of periodontitis was inversely correlated with 24-hour urinary excretion of potassium (r = -0.579, P = 0.0004) and also inversely with the frequency of intakes of green vegetables (r = -0.232, P = 0.031) and fruits (r = -0.217, P = 0.0043). Low-potassium intake in the diet mostly accompanied by low dietary fiber intake increases BP as well as periodontal inflammation. Potassium intake may be an important factor linking periodontitis and hypertension in middle-aged nonsmoking and nonalcoholic women on no medication, although chronic inflammation such as periodontitis may cause hypertension through a more direct mechanism.

Medium osmolarity and pericellular matrix development improves chondrocyte survival when photoencapsulated in poly(ethylene glycol) hydrogels at low densities

The ability to encapsulate cells over a range of cell densities is important toward mimicking cell densities of native tissues and rationally designing strategies where cell source and/or cell numbers are clinically limited. Our preliminary findings demonstrate that survival of freshly isolated adult bovine chondrocytes dramatically decreases when photoencapsulated in poly(ethylene glycol) hydrogels at low densities (4 million cells/mL). During enzymatic digestion of cartilage, chondrocytes undergo a harsh change in their microenvironment. We hypothesize that the absence of exogenous antioxidants, the hyposmotic environment, and the loss of a protective pericellular matrix (PCM) increase chondrocytes' susceptibility to free radical damage during photoencapsulation. Incorporation of antioxidants and serum into the encapsulation medium improved cell survival twofold compared to phosphate-buffered saline. Increasing medium osmolarity from 330 to 400 mOsm (physiological) improved cell survival by 40% and resulted in approximately 2-fold increase in adenosine triphosphate (ATP) production 24 h postencapsulation. However, cell survival was only temporary. Allowing cells to reproduce some PCM before photoencapsulation in 400 mOsm medium resulted in superior cell survival during and postencapsulation for up to 15 days. In summary, the combination of antioxidants, physiological osmolarity, and the development of some PCM result in an improved robustness against free radical damage during photoencapsulation.

The hyperpolarizing impact of glycine on endothelial cells may be anti-atherogenic

Studies to date indicate that endothelial cells express glycine-activated chloride channels, which promote hyperpolarization of the endothelial plasma membrane. If such channels are expressed by endothelial cells lining conduit arteries, glycine is likely to have anti-atherogenic activity. This reflects the fact that endothelial hyperpolarization promotes calcium influx, activating the endothelial isoform of nitric oxide synthase, while also down-regulating the activity of the membrane-bound NADPH oxidase, chief endothelial source of superoxide. Since macrophages express glycine-activated chloride channels that suppress production of oxidants and cytokines, glycine may also oppose atherogenesis by influencing intimal macrophage function. In rats, supplemental glycine exerts anti-inflammatory and anti-angiogenic effects attributed to chloride channel activation. Administration of large daily doses of glycine would appear to be practical and safe, and has already been shown to inhibit protein glycation in human diabetics.

Bean consumption is associated with greater nutrient intake, reduced systolic blood pressure, lower body weight, and a smaller waist circumference in adults: results from the National Health and Nutrition Examination Survey 1999-2002

BACKGROUND

Epidemiological studies have shown positive findings associated with legume consumption and measures of cardiovascular disease and obesity. However, few observational trials have examined beans as a separate food variable when determining associations with health parameters.

OBJECTIVE

To determine the association of consuming beans on nutrient intakes and physiological parameters using the National Health and Examination Survey (NHANES) 1999-2002.

METHODS

Using data from NHANES 1999-2002, a secondary analysis was completed with a reliable 24-hour dietary recall where three groups of bean consumers were identified (N = 1,475). We determined mean nutrient intakes and physiological values between bean consumers and non-consumers. Least square means, standard errors and ANOVA were calculated using appropriate sample weights following adjustment for age, gender, ethnicity and energy.

RESULTS

Relative to non-consumers, bean consumers had higher intakes of dietary fiber, potassium, magnesium, iron, and copper (p's < 0.05). Those consuming beans had a lower body weight (p = 0.008) and a smaller waist size (p = 0.043) relative to non-consumers. Additionally, consumers of beans had a 23% reduced risk of increased waist size (p = 0.018) and a 22% reduced risk of being obese (p = 0.026). Also, baked bean consumption was associated with a lower systolic blood pressure.

CONCLUSIONS

Bean consumers had better overall nutrient intake levels, better body weights and waist circumferences, and lower systolic blood pressure in comparison to non-consumers. These data support the benefits of bean consumption on improving nutrient intake and health parameters.

A propensity-matched study of low serum potassium and mortality in older adults with chronic heart failure

OBJECTIVE

Most HF patients are older adults, yet the associations of low serum potassium and outcomes in these patients are unknown. We studied the effect of low serum potassium in a propensity-matched population of elderly HF patients.

METHODS

Of the 7788 patients in the Digitalis Investigation Group trial, 4036 were >or=65 years. Of these, 3598 had data on baseline serum potassium and 324 with potassium >or=5 mEq/L were excluded. Remaining patients were categorized into low (<4 mEq/L; n=590) and normal (4-4.9 mEq/L; n=2684) potassium groups. Propensity scores for low-potassium, calculated for each patient, were used to match 561 low-potassium and 1670 normal-potassium patients. Association of low potassium and outcomes were assessed using matched Cox regression analyses.

RESULTS

Patients had a mean (+/-SD) age of 72 (+/-6) years, 29% were women and 12% were non-whites. Of the 561 low-potassium patients, 500 had low-normal (3.5-3.9 mEq/L) potassium. All-cause mortality occurred in 37% (rate, 1338/10,000 person-years) normal-potassium and 43% (rate, 1594/10,000 person-years) low-potassium patients (hazard ratio {HR} for low-potassium, 1.22; 95% confidence interval {CI}, 1.04-1.44; p=0.014). Low-normal (3.5-3.9 mEq/L) potassium levels had a similar association with mortality (HR, 1.19, 95% CI, 1.00-1.41, p=0.049). Low (HR, 1.10; 95% CI, 0.96-1.25; p=0.175) or low-normal (HR=1.09, 95% CI=0.95-1.25, p=0.229) serum potassium levels were not associated with all-cause hospitalization.

CONCLUSIONS

In a propensity-matched population of elderly ambulatory chronic HF patients, well-balanced in all measured baseline covariates, low and low-normal serum potassium were associated with increased mortality but had no association with hospitalization.

Metabolic side effects and cardiovascular events of diuretics: should a diuretic remain the first choice therapy in hypertension treatment? The case of yes

Essential hypertension is a major cause of cardiovascular morbidity and mortality in the Western world. Numerous clinical trials have demonstrated that the treatment of hypertension results in a substantial reduction of hypertension-related morbidity and mortality. The efficacy and safety of diuretics has been shown in many clinical trials. Like most other antihypertensive agents, the side effects of diuretics are mostly benign and mild. The metabolic side effects of diuretics, however, have been a bone of contention for a long time. In this paper, we describe the most important and frequent metabolic side effects of diuretics, and emphasize particularly the non-life-threatening effect of diuretics on ventricular arrhythmias due to their hypokalemic effect, the detection of the new onset diabetes (perhaps caused by the administration of diuretics itself), and their significant beneficial effect on cardiovascular and cerebrovascular morbidity and mortality. At the end of the article, we highlighted the differences regarding the prescription of diuretics between the recently published American and European Guidelines of hypertension.

Dietary potassium supplementation improves vascular structure and ameliorates the damage caused by cerebral ischemia in normotensive rats

Background

Dietary potassium supplementation in hypertensive rats is cardioprotective. This protection includes a blood pressure independent reduction in the amount of damage caused by cerebral ischemia. Therefore, we hypothesized that dietary potassium supplementation would improve the outcome of ischemic stroke by improving cerebral vessel structure in normotensive rats.

Methods

Wistar Kyoto (WKY) rats were fed a high (HK) or low potassium (LK) diet for six weeks from six weeks of age. At the end of treatment, cerebral ischemia was induced by middle cerebral artery (MCA) occlusion and the resultant infarct was quantified and expressed as a percentage of the hemisphere infarcted (%HI). MCA structure was assessed in an additional group of rats using a pressurized arteriograph.

Results

The cerebral infarct was significantly smaller in rats fed the HK diet, compared to rats fed the LK diet (21 ± 5.4 vs 33.5 ± 4.8 %HI HK vs LK p < 0.05). Vessel structure was improved in WKY rats fed the HK diet as indicated by an increase in the MCA lumen (298 ± 6.3 vs 276 ± 3.9 μm HK vs LK p < 0.05) and outer diameters (322 ± 7.6 vs 305 ± 4.8 μm HK vs LK p < 0.05). Wall thickness and area were unchanged, suggesting an outward euthrophic remodelling process. The HK diet had no effect on body weight or telemetry blood pressure.

Conclusion

These studies are the first to show a beneficial effect of dietary potassium in rats with normal blood pressure.

Scavenging of peroxynitrite-derived radicals by flavonoids may support endothelial NO synthase activity, contributing to the vascular protection associated with high fruit and vegetable intakes

Ample intakes of fruit and vegetables have been linked epidemiologically with reduced risk for coronary disease, stroke, hypertension, obesity, many types of cancer, chronic pulmonary disease, osteoporosis, and various ocular disorders. The favorable impact of diets rich in fruit and vegetables on coronary risk has been confirmed in meta-analyses, and is thought to be largely attributable to the folk acid and potassium supplied by these foods. Although high intakes of vitamin C appear to confer some cardiovascular protection, the amounts supplied by typical diets may be too low to be of much benefit in this regard. High flavonoid intakes emerge as protective in some epidemiological studies, albeit the dose-response pattern observed is often L-shaped - seemingly more consistent with low intakes being harmful, than with high intakes being protective. Nonetheless, flavonoids have shown anti-atherogenic activity in rodent models, and both clinical and rodent supplementation studies with foods and food extracts rich in flavonoids demonstrate improvements in endothelium-dependent vasodilation traceable to increased endothelial nitric oxide synthesis. However, flavonoids do not appear to increase the expression of endothelial NO synthase, nor do they modify endothelial superoxide production. A likely explanation is that, even in nanomolar concentrations achievable in vivo, flavonoids can act as efficient scavengers of peroxynitrite-derived radicals, thereby protecting the cofactor tetrahydrobiopterin, crucial for NO synthase activity. Studies with cultured endothelial cells should be useful for evaluating this possibility. It would also be appropriate to assess the effects of flavonoids on prostacylin synthetase activity, on endothelial catabolism of asymmetric dimethylarginine, and on signaling mechanisms that activate NO synthase. Since peroxynitrite can induce mutagenic damage to DNA, it is conceivable that scavenging of peroxynitrite-derived radicals contributes to the reduction in mutagenesis associated with high intakes of fruits and vegetables. Carotenoids also have the potential to prevent peroxynitrite-mediated damage, although, as contrasted with flavonoids, there is comparatively little evidence that these compounds are anti-atherogenic or beneficial for endothelial function; a recent meta-analysis of epidemiological studies suggests that high lutein intakes may modestly reduce coronary risk.

High magnesium or potassium hair accumulation is not associated with ischemic stroke risk reduction: A pilot study

OBJECTIVES

Various studies suggest that deficiency of magnesium and potassium may be associated with increased risk of ischemic stroke. However, single time-point serum measurements may not be suitable for assessing long-term tissue levels.

PATIENTS AND METHODS

We investigated Mg and K levels in hair of patients with acute ischemic stroke. The elements hair accumulation analysis might provide historical information on their concentrations over a longer period of time and probably reflects the corresponding nutritional condition. The concentrations of Mg and K in hair of 48 men with acute ischemic stroke and a control group were measured using spectroscopic methods.

RESULTS

The mean Mg and K concentrations in hair of patients were significantly higher than in the controls.

CONCLUSIONS

This analysis does not seem to confirm the results of the previous studies suggesting that Mg or K high levels (or their diet supplementation) might protect humans against ischemic stroke.