Reduction of blood pressure with calcium and potassium supplementation in children with salt sensitivity: a 2-year double-blinded placebo-controlled trial

Salt sensitivity of blood pressure in childhood and adolescence

Although moderation of sodium intake is recommended population-wide, it remains uncertain who benefits from salt restriction. Salt sensitivity refers to changes in blood pressure in response to sodium intake and may occur with or without hypertension. Unfortunately, there is no practical way to assess salt sensitivity in daily practice. Assessment of salt sensitivity even in research studies is challenging with varying protocols utilized which may contribute to differing results. Building on studies in animals and adults, risk factors and conditions associated with salt sensitivity have been identified in the pediatric and young adult populations. This review presents the limited evidence linking obesity, low birth weight, diabetes, chronic kidney disease, and race/ethnicity with salt sensitivity in children, adolescents, and young adults. The impact of stress on sodium handling is also reviewed. The influence of age on the timing of introduction of dietary salt restriction and the long-term influence of salt sensitivity on risk for hypertension are considered. Lastly, interventions other than salt restriction that may improve salt sensitivity and may inform recommendations to families are reviewed.

Association between urinary sodium excretion and uric acid, and its interaction on the risk of prehypertension among Chinese young adults

High uric acid (UA) level and high salt intake are reportedly associated with cardiovascular disease. This study investigated the association between UA and urinary sodium excretion, as well as its interaction on the risk of prehypertension. A total of 1869 participants without hypertension were recruited from a previously established cohort in Shaanxi Province, China. The participants were classified as normotensive or prehypertensive on the basis of their blood pressure. Increasing quartiles of sodium excretion were associated with high urinary UA/creatinine levels in prehypertensive participants. Estimated sodium excretion positively correlated with urinary UA/creatinine excretions in the prehypertensive group. In addition, the multivariate-adjusted odds ratios for prehypertension compared with normotension were 1.68 (1.27–2.22) for sodium excretion and 1.71 (1.21–2.42) for serum UA. Increasing sodium excretion and serum UA were associated with higher risk of prehypertension. Compared with the lowest quartiles, the highest sodium excretion and serum UA quartiles entailed 3.48 times greater risk of prehypertension. Sodium excretion is associated with urinary UA excretion in prehypertensive participants. The present study shows that high levels of salt intake and serum UA simultaneously are associated with a higher risk of prehypertension.

Greater adherence to the dietary approaches to stop hypertension (DASH) dietary pattern is associated with lower blood pressure in healthy Iranian primary school children

PURPOSE

The dietary determinants of children blood pressure (BP) are poorly understood. We examined the association between adherence to the dietary approaches to stop hypertension (DASH) dietary pattern and BP in healthy Iranian primary school children.

METHODS

This cross-sectional study was conducted among a representative sample (n = 407) of healthy Shirazi students aged 6-12 years. Subjects' systolic and diastolic BP were measured by a validated oscillometric BP monitor. Usual dietary intakes over the past 12 months were assessed using a valid and reproducible 168-item semi-quantitative food frequency questionnaire via face-to-face interviews. A DASH score was calculated for each subject based on his/her energy-adjusted intakes of 8 major dietary components emphasized or minimized in the DASH dietary pattern. The higher the DASH score of a subject, the more his/her adherence to the DASH dietary pattern.

RESULTS

After controlling for several potential confounders in the analysis of covariance models, multivariable-adjusted means of systolic and mean BP of subjects in the highest tertile of DASH score were significantly lower than those in the lowest tertile (for systolic BP: mean difference -6.2 mmHg, P = 0.010; and for mean BP: mean difference -5.4 mmHg, P = 0.013). Furthermore, a similar but statistically insignificant difference was found in terms of multivariable-adjusted means of diastolic BP (mean difference -3.9 mmHg, P = 0.146).

CONCLUSIONS

The findings suggest that greater adherence to the DASH dietary pattern is associated with lower BP in healthy Iranian primary school children. However, future prospective studies of adequate methodological quality are warranted to confirm these findings.

Effect of salt intake and potassium supplementation on brachial-ankle pulse wave velocity in Chinese subjects: an interventional study

Accumulating evidence has suggested that high salt and potassium might be associated with vascular function. The aim of this study was to investigate the effect of salt intake and potassium supplementation on brachial-ankle pulse wave velocity (PWV) in Chinese subjects. Forty-nine subjects (28-65 years of age) were selected from a rural community of northern China. All subjects were sequentially maintained on a low-salt diet for 7 days (3.0 g/day NaCl), a high-salt diet for an additional 7 days (18.0 g/day NaCl), and a high-salt diet with potassium supplementation for a final 7 days (18.0 g/day NaCl+4.5 g/day KCl). Brachial-ankle PWV was measured at baseline and on the last day of each intervention. Blood pressure levels were significantly increased from the low-salt to high-salt diet, and decreased from the high-salt diet to high-salt plus potassium supplementation. Baseline brachial-ankle PWV in salt-sensitive subjects was significantly higher than in salt-resistant subjects. There was no significant change in brachial-ankle PWV among the 3 intervention periods in salt-sensitive, salt-resistant, or total subjects. No significant correlations were found between brachial-ankle PWV and 24-h sodium and potassium excretions. Our study indicates that dietary salt intake and potassium supplementation, at least in the short term, had no significant effect on brachial-ankle PWV in Chinese subjects.

Focus on prevention, diagnosis and treatment of hypertension in children and adolescents

The European Society of Hypertension has recently published its recommendations on prevention, diagnosis and treatment of high blood pressure in children and adolescents. Taking this contribution as a starting point the Study Group of Hypertension of the Italian Society of Pediatrics together with the Italian Society of Hypertension has conducted a reappraisal of the most recent literature on this subject. The present review does not claim to be an exhaustive description of hypertension in the pediatric population but intends to provide Pediatricians with practical and updated indications in order to guide them in this often unappreciated problem.

This document pays particular attention to the primary hypertension which represents a growing problem in children and adolescents. Subjects at elevated risk of hypertension are those overweight, with low birth weight and presenting a family history of hypertension. However, also children who do not present these risk factors may have elevated blood pressure levels. In pediatric age diagnosis of hypertension or high normal blood pressure is made with repeated office blood pressure measurements that show values exceeding the reference values. Blood pressure should be monitored at least once a year with adequate methods and instrumentation and the observed values have to be interpreted according to the most updated nomograms that are adjusted for children’s gender, age and height. Currently other available methods such as ambulatory blood pressure monitoring and home blood pressure measurement are not yet adequately validated for use as diagnostic instruments. To diagnose primary hypertension it is necessary to exclude secondary forms. The probability of facing a secondary form of hypertension is inversely proportional to the child’s age and directly proportional to blood pressure levels. Medical history, clinical data and blood tests may guide the differential diagnosis of primary versus secondary forms. The prevention of high blood pressure is based on correct lifestyle and nutrition, starting from childhood age. The treatment of primary hypertension in children is almost exclusively dietary/behavioral and includes: a) reduction of overweight whenever present b) reduction of dietary sodium intake c) increase in physical activity. Pharmacological therapy will be needed rarely and only in specific cases.

Evolution of blood pressure from adolescents to youth in salt sensitivies: a 18-year follow-up study in Hanzhong children cohort

BACKGROUND

Essential hypertension mostly originates from children. Salt Sensitivity (SS) is regarded as the intermediate phenotype of essential hypertension. The present study investigated the effects of salt-sensitivity on evolution of blood pressure (BP) and development to hypertension from adolescents to youth.

METHODS

A baseline survey was carried out in 4,623 adolescents aged 6-15 years old in Hanzhong rural areas in 1987, 310 of whom (mean 9.2 years) were randomly recruited for determination of salt sensitivity using the tests of oral saline load and furosemide sodium-volume depletion. SS was diagnosed in 101 subjects while 209 were determined as non-salt-sensitive (NSS). We made a 18-year followed-up of the cohort in 2005.

RESULTS

The response rate for surviving baseline adolescents was 71.9%. At follow up, BP in youth with baseline SS was higher than that in NSS (SBP:122.9 ± 13.1 VS 117.3 ± 12.4, P < 0.01; DBP: 78.2 ± 10.4 VS 74.7 ± 10.8, P < 0.05). Longitudinal analysis of 18-year BP evolution, subjects in SS had greater Systolic BP change than subjects in NSS(19.6 ± 12.714.7 ± 12.2, P < 0.01). The incidence of hypertension in salt sensitive group was higher than that in NSS group (15.5% VS 6.3%, RR = 2.34, P < 0.05).

CONCLUSION

Our findings indicate that adolescents with higher BP salt-sensitivity have a higher rate of incident hypertension in youth. Salt sensitivity could be at high risk predisposing to development of hypertension from adolescents to youth.

Blood pressure variability, prehypertension, and hypertension in adolescents

Medical conditions diagnosed during adolescence may have long term impacts on the health of an individual. As a result, identifying cardiovascular risk factors earlier in life such as prehypertension (pre-HTN) and hypertension (HTN) can have significant benefits across an individual’s lifespan. Diagnosing elevated blood pressure (BP) during adolescence can be difficult, partially due to the natural variability that occurs during this period of life. Levels of BP that define adolescent prehypertension/hypertension are provided as well as an abridged review of BP variability across research groups. Strategies for BP management of adolescents are considered, with the primary focus on nonpharmacologic interventions.

Correlation between blood pressure responses to dietary sodium and potassium intervention in a Chinese population

BACKGROUND

Blood pressure (BP) responses to dietary sodium and potassium intake vary among individuals. We examined the correlation between BP responses to dietary low-sodium, high-sodium, and potassium supplementation interventions in a feeding study.

METHODS

A total of 1,906 Chinese aged > or = 16 years participated in the dietary intervention that included a 7-day low-salt intervention (51.3 mmol/day), a 7-day high-salt intervention (307.8 mmol/day), and a 7-day high-salt plus potassium supplementation (60 mmol/day) intervention. BP was measured nine times during the 3-day baseline observation and during the last 3 days of each intervention phase using a random-zero sphygmomanometer.

RESULTS

The correlation coefficients (95% confidence intervals (CIs)) of the BP responses to low-sodium and high-sodium interventions were -0.47 (-0.51 to -0.44), -0.47 (-0.50 to -0.43), and -0.45 (-0.49 to -0.42) for systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP), respectively (all P < 0.0001). The correlation coefficients (95% CI) of the BP responses to high-sodium intervention and potassium supplementation were -0.52 (-0.56 to -0.49), -0.48 (-0.52 to 0.45), and -0.52 (-0.55 to -0.48) for SBP, DBP, and MAP, respectively (all P < 0.0001). The kappa coefficients were moderate, varying from 0.28 to 0.34, between BP responses to low-sodium and high-sodium interventions (all P < 0.0001).

CONCLUSIONS

These results indicate there is a moderate correlation between BP responses to low-sodium and to high-sodium interventions, and BP responses to high-sodium intervention and potassium supplementation. Furthermore, our study suggests that individuals who were more sensitive to high-sodium diet might benefit more from a low-sodium and/or high-potassium intervention aimed at lowering BP levels.

Concepts guiding therapy for hypertension in children

Increasing attention has been focused on identifying children with prehypertension and hypertension (HTN). Obesity and low birthweight are two risk factors that predispose children to develop HTN during their childhood years or later as adults. Early onset of pre-HTN and HTN increases the lifetime risk for cardiovascular sequelae. Lifestyle modification should be part of the initial recommendations for management of all hypertensive children. In those children requiring pharmacologic therapy, the choice of medication should be guided by the etiology of HTN, the needs of the child and the risk and benefit profiles of the various drug classes. The long-term impact of antihypertensive therapy in children is not known. Concerns regarding the effects of HTN and its treatment on cognitive function are of particular importance in the growing child and warrant further study. Ongoing investigations that offer promise for innovative therapeutic approaches in the future are discussed.

Management of Hypertension in Children and Adolescents With the Metabolic Syndrome

Because elevated blood pressure is one of the defining criteria of the metabolic syndrome, treatment of hypertension will be required in many, if not most, children and adolescents diagnosed with the metabolic syndrome. This review highlights several aspects of the approach to treatment of hypertension in young patients with the metabolic syndrome, including the definition of hypertension, use of nonpharmacologic measures, indications for instituting antihypertensive medications, and the potential adjunctive role that insulin-sensitizing agents may play in blood pressure reduction. The choice of antihypertensive agent is also discussed, along with consideration of the diabetogenic effects of various classes of antihypertensive agents. Consideration of all of these issues is important in achieving blood pressure control in children and adolescents with the metabolic syndrome, as appropriate treatment may help to forestall the development not only of type 2 diabetes but also of the cardiovascular disease that is frequently already present at the time of diagnosis of type 2 diabetes in adults.