Twenty-four-Hour Urinary Potassium Excretion, But Not Sodium Excretion, Is Associated With All-Cause Mortality in a General Population

Assessment of 24 h Sodium and Potassium Urinary Excretion in Normotensive and Hypertensive Dominican Adults

Higher salt (sodium) intake has been associated with higher blood pressure (BP). The degree of association may be influenced by factors such as age, origin, and dietary components. This study aimed to evaluate the 24 h urinary sodium (Na) and potassium (K) excretion in normotensive and hypertensive Dominican adults and estimate their salt intake. 163 volunteers (18-80 years old) participated in a cross-sectional study. The 24 h Na and K urinary excretion were measured using an ion-selective electrode technique. Na and K urinary excretion (99.4 ± 46.5 and 35.0 ± 17.5 mmol/24 h) did not correlate with BP, except in the normotensive group, in which K correlated with SBP (0.249, p = 0.019). Na and K excretion were similar in normotensive and hypertensive subjects. When considering two age groups (18-45, 46-80 years), the Na-to-K molar ratio (3.1 ± 1.3) was higher in younger subjects (p = 0.040). Na-to-K ratio was associated with DBP in the total group (r = 0.153, p = 0.052), in the hypertensive group (r = 0.395, p < 0.001), and in the older group with SBP (0.350, p = 0.002) and DBP (0.373, p < 0.001). In the older group, Na-to-K ratio and DBP correlated after controlling for subjects with hypertension controlled by treatment (r = 0.236, p = 0.041). The Na-to-K ratio correlated, when salt intake was over 5 g/day (52.2%), with SBP (rho = 0.219, p = 0.044) and DBP (rho = 0.259, p = 0.017). Determinants of BP in the total sample were age (SBP, beta: 0.6 ± 0.1, p < 0.001; DBP, beta: 0.2 ± 0.1, p < 0.002), sex (SBP, beta: 11.2 ± 3.5, p = 0.001), body mass index (BMI) (SBP, beta: 1.0 ± 0.3, p < 0.001; DBP, beta: 0.4 ± 0.2, p = 0.01), and Na-to-K ratio (SBP, beta: 3.0 ± 1.1, p = 0.008; DBP, beta: -12.3 ± 4.0, p = 0.002). Sex and BMI were determinants in the younger group. Na-to-K molar ratio was determinant in the older group (SBP, beta: 6.7 ± 2.4, p = 0.005; DBP, beta: 3.8 ± 1.1, p < 0.001). The mean Na and salt intakes (2.3 and 5.8 g/day) were slightly higher and the K intake lower (1.4 g/day) than WHO recommendations.

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.

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.

Low potassium intake and its association with blood pressure among adults in Malaysia: findings from the MyCoSS (Malaysian Community Salt Survey)

BACKGROUND

High blood pressure or hypertension is well recognized as an important modifiable risk factor for cardiovascular diseases. Several studies had indicated potassium intake has a blood pressure lowering effect. This study aimed to estimate potassium intake via 24-h urinary potassium excretion and to determine the association between potassium intake and blood pressure among adults in Malaysia.

METHODS

Data for 424 respondents in this study were drawn from MyCoSS, a nationwide cross- sectional study conducted among Malaysians who were 18 years and above. Respondents were recruited using stratified cluster sampling, covering urban and rural areas in each state in Malaysia. Data collection was undertaken from October 2017 until March 2018. A single urine sample was collected over 24 h for quantification of potassium excreted. Information on socio-demography and medical history of the respondents were collected by interviewer-administered questionnaires. Anthropometric measurements were measured using validated equipment. BMI was estimated using measured body weight and height. Digital blood pressure monitor (Omron HBP-1300) was used to measure blood pressure. Descriptive statistics, analysis of variance (ANOVA), and multivariable linear regression were used to analyze the data in SPSS Version 21.

RESULTS

Mean 24-h urinary potassium excretion for the 424 respondents was 37 mmol (95% CI 36, 38). Gender and ethnicity showed statistically significant associations with 24-h urinary potassium excretion. However, potassium excretion was not significantly associated with blood pressure in this study.

CONCLUSION

Potassium intake is very low among the adults in Malaysia. Therefore, further education and promotional campaigns regarding daily consumption of potassium-rich diet and its benefits to health need to be tailored for the Malaysian adult population.

Differential impacts of 24 hour urinary sodium excretion on cardiovascular diseases or cancer mortality in a general population

BACKGROUND

Elevated blood pressure is a major risk factor for cardiovascular (CV) disease. But the effects of sodium intake or excretion on CV mortality are uncertain. The present study aimed to investigate the association between 24 h urinary sodium excretion, as a marker of dietary salt intake, and CV or cancer mortality in a healthy Japanese population using 24 hurine collection.

METHODS

The baseline study was conducted in 1980. A total of 1291 participants aged 21 to 85 years, underwent health check-ups, which included blood chemistry measurements and the collection of 24 h urine samples. Enrolled 1291 participants were followed up for 27.5 years, in whom the final follow-up rate was 95.8%. Cox proportional hazards regression models were used to assess the association between 24 h urinary sodium excretion and CV or cancer mortality.

RESULTS

The mean 24 h urinary sodium excretion was 5.80 ± 2.28 g/day. There were 631 deaths: 153 (27%) from cancer, 142 (26%) from CV disease. In the Cox proportional hazard regression model after adjustment for confounding factors, systolic and diastolic blood pressures, and uric acid were positively associated with CV mortality, and the 24 h urinary sodium and potassium excretions were inversely associated with CV mortality (p < 0.05). On the other hand, there were no association between 24 h urinary sodium excretions and cancer mortality. We divided the urinary sodium excretions levels into quartiles. After adjustment for confounding factors, the hazard ratio of CV mortality in the highest quartile of 24 h urinary sodium excretion versus the lowest was 0.46 (p < 0.05). The cumulative survival rate for CV death was significantly decreased in the lowest quartile compared with the other higher groups.

CONCLUSIONS

We found that impacts of 24 h sodium excretion on CV and cancer mortalities were much different in the general population.

Potassium Intake in India: Opportunity for Mitigating Risks of High-Sodium Diets

INTRODUCTION

Most Indians are vegetarian or eat very little meat, which could imply high potassium intake. Because a high-potassium diet could counterbalance the adverse health effects of high-sodium intake, this study aimed to describe potassium relative to sodium intake and investigate the relationship between blood pressure and potassium intake relative to sodium intake in rural and urban India.

METHODS

Investigators collected 24-hour urines from 1,445 participants in a subset of 2 population-based surveys in North India in 2012-2013. Standardized questionnaires were used to collect information on demography, behaviors (tobacco, alcohol consumption, physical activity, and diet [food frequency and 24-hour recall]), and medical history. After evaluating expected versus measured creatinine excretion, the authors calculated median urine potassium excretion and sodium/potassium ratio, according to sex and urban or rural residence, and estimated least square means for the urine measures by participant demographics and comorbidities, after accounting for caloric intake. Two-year blood pressure follow-up data were available in the urban study, and ANCOVA regression was used to determine the association with urine measures. All the statistical analyses of the data were done in January 2019.

RESULTS

Acceptable 24-hour urine collections were available in 1,397 participants (rural, n=730). Median urine potassium excretions were 1,492 (IQR=1,012-2,063) and 975 (615-1,497) mg/day; sodium/potassium ratios met the recommended target of <1 in 2.9% rural and 6.6% urban participants. Rural participants did not have higher potassium or lower (better) sodium/potassium ratios when diagnosed with hypertension or other cardiovascular conditions. Higher potassium excretion was associated with lower blood pressure during follow-up among the urban participants (mean systolic blood pressure, 129 vs 133 mm Hg in highest vs lowest potassium excretion tertiles; p=0.029).

CONCLUSIONS

Low potassium intake in India warrants dietary policies promoting intake of potassium-rich foods to improve heart health. This approach may be more acceptable than programs focused on sodium reduction alone.

Habitual coffee intake reduces all-cause mortality by decreasing heart rate

It is well known that subjects with metabolic syndrome show an elevated resting heart rate. We previously reported that elevated heart rate was significantly related to all-cause mortality, and that coffee consumption was inversely associated with metabolic syndrome. We hypothesized that higher coffee consumption may decrease all-cause mortality by reducing resting heart rate. We performed a longitudinal epidemiological study in Tanushimaru (a cohort of the Seven Countries Study). A total of 1920 residents aged over 40 years received health checkups in 1999. We measured components of metabolic syndrome, and eating and drinking patterns were evaluated by a food frequency questionnaire. We followed up the participants annually for 15 years. During the follow-up period, 343 of the participants died. Of these, 102 subjects died of cancer, 48 of cerebro-cardiovascular diseases, and 44 of infectious diseases. Multivariate analyses revealed that higher coffee consumption was inversely associated with resting heart rate. Kaplan-Meier curves found lower mortality rates in the higher coffee consumption groups. In the lower coffee consumption groups, elevated hazard ratios of all-cause death were observed in the increased heart rate quintiles, whereas heart rate was not associated with all-cause death in the higher coffee consumption groups. These significant associations remained after further adjustment for confounders. This prospective study suggests that higher coffee consumption may have a protective effect against all-cause death due to reducing resting heart rate.