Factors related to blood pressure in a biracial adolescent female population

Effects of vitamin D and/or calcium intervention on sleep quality in individuals with prediabetes: a post hoc analysis of a randomized controlled trial

PURPOSE

The aim of this study was to evaluate the effects of vitamin D and/or calcium supplementation on sleep quality in individuals with prediabetes.

METHODS

A 24-week randomized controlled trial (RCT) was conducted in a 212 Chinese population with prediabetes. Participants were randomly assigned to four groups: vitamin D + calcium group (1600 IU/day + 500 mg/day, n = 53), vitamin D group (1600 IU/day, n = 54), calcium group (500 mg/day, n = 51), and control group (placebo, n = 54). The Pittsburgh Sleep Quality Index (PSQI) was used as the primary outcome to assess sleep quality. Questionnaires and fasting blood samples were collected at baseline and post-intervention for demographic assessment and correlation index analysis.

RESULTS

After a 24-week intervention, a significant difference was observed in serum 25(OH)D concentration among the four groups (P < 0.05), and the total PSQI score in vitamin D + calcium group was lower compared to the preintervention levels. Subgroup analyses revealed improved sleep quality with calcium supplementation (P < 0.05) for specific groups, including women, individuals with a low baseline 25(OH)D level (< 30 ng/mL), and individuals in menopause. Moreover, correlation analysis revealed a negative correlation between the extent of change in sleep efficiency scores before and after the calcium intervention and the degree of change in insulin efficiency scores (r = - 0.264, P = 0.007), as well as the magnitude of change in islet beta cell function (r = - 0.304, P = 0.002).

CONCLUSIONS

The combined intervention of vitamin D and calcium, as well as calcium interventions alone, exhibits substantial potential for improving sleep quality in individuals with prediabetes.

CLINICAL TRIAL REGISTRATION

The trial was registered in August 2019 as ChiCTR190002487.

Higher intakes of nutrients and regular drinking are associated with habitual sleep duration in pre- and postmenopausal women with comorbidities

OBJECTIVES

We aimed to assess the association between nutrient intake, health-related behaviors, and habitual sleep duration in pre- and postmenopausal women.

DESIGN

A cross-sectional study.

PARTICIPANTS

2084 pre- and postmenopausal women aged 18-80 years old.

MEASUREMENTS

Nutrient intake and sleep duration were measured by a 24-hour recall approach and self-reports, respectively. We examined the association and interaction between comorbidities, nutrient intake, and sleep duration groups among 2084 women using data from KNHASES (2016-2018) and multinomial logistic regression.

RESULTS

In premenopausal women, we observed negative associations between very short (<5 hours)/short (5-6 hours)/long (≥9 hours) sleep duration and 12 nutrients (vitamin B1, B3, vitamin C, PUFA, n-6 fatty acid, iron, potassium, phosphorus, calcium, fiber, carbohydrate) and a positive association between retinol and short sleep duration (prevalence ratio (PR), 1.08; 95% CI, 1.01-1.15). In premenopausal women, interactions were found between comorbidities and PUFA (PR, 3.83; 95% CI, 1.56-9.41), n-3 fatty acid (PR, 2.43; 95% CI, 1.17-5.05), n-6 fatty acid (PR, 3.45; 95% CI, 1.46-8.13), fat (PR, 2.77; 95% CI, 1.15-6.64), and retinol (PR, 1.28; 95% CI, 1.06-1.53) for very short and short sleep duration, respectively. Interactions between comorbidities, vitamin C (PR, 0.41; 95% CI, 0.24-0.72), and carbohydrates (PR, 1.67; 95% CI, 1.05-2.70) for very short and short sleep duration in postmenopausal women, respectively. Regular drinking was positively associated with a risk of short sleep duration in postmenopausal women (PR, 2.74, 95% CI: 1.11-6.74).

CONCLUSIONS

Dietary intake and alcohol use were found to be involved in sleep duration, so healthcare staff should encourage women to maintain a healthy diet and reduce alcohol use to improve sleep duration.

The association between modified Nordic diet with sleep quality and circadian rhythm in overweight and obese woman: a cross-sectional study

OBJECTIVE

Previous studies have shown an association between diet quality and sleep quality. The objective of this study was to investigate the association between modified Nordic diet with sleep quality and circadian rhythm in overweight and obese woman.

METHODS

We enrolled 399 overweight and obese women (body mass index (BMI): 25-40 kg/m²), aged 18-48 years, in this cross-sectional study. For each participant, anthropometric measurements, biochemical tests, and food intake were evaluated. Sleep quality and circadian rhythm was measured by Pittsburgh Sleep Quality Index (PSQI) and morning-evening questionnaire (MEQ) questionnaire. Modified Nordic diet score was measured using a validated 147-item food frequency questionnaire (FFQ).

RESULTS

Overall, 51.7% of the subjects were good sleepers (the Pittsburgh Sleep Quality Index (PSQI) < 5) while 48.3% were poor sleepers (PSQI ≥ 5). Moreover, participants were divided into five groups of MEQ, namely, completely morning 8 (2.4%), rarely morning 82 (24.8%), normal 196 (59.2%), rarely evening 43 (13%), and completely evening 2 (0.6%). After controlling for confounders, there was a significant association between poor sleep quality and the modified Nordic diet (OR = 0.80, %95 CI = 0.66-0.98, P = 0.01). Moreover, a significant positive association was observed between the completely morning and modified Nordic diet (OR = 1.80, %95 CI = 0.54-6.00, P = 0.03), in addition to a significant inverse association between the completely evening type and modified Nordic diet (OR = 0.16, %95 CI = 0.002-5.41, P = 0.02).

CONCLUSIONS

The present study indicated that higher adherence to a modified Nordic diet reduces poor sleep quality. Also, the completely morning type was associated with higher adherence to a modified Nordic diet, and completely evening type was associated with lower adherence to a modified Nordic diet.

LEVELS OF EVIDENCE

Level IV, evidence obtained from multiple time series analysis.

Lower calcium levels in hair of Parkinson's disease patients are associated with presence of sleeping disturbances

Objectives: To investigate the correlation between sleep disorders and the concentrations of three metals analyzed from hair samples of PD patients.The hypothesis of an involvement of an imbalance of metals in the development of Parkinson's Disease (PD) has been strengthened by several clinical chemistry studies. Interestingly, while sparse, some studies have correlated the imbalance of metals in PD patients with comorbidities present in this disease. Although not all PD sufferers present sleep disturbances, significant disorders of sleep are common in this population. Methods: Sleep evaluation was divided into three parameters: sleep quality, excessive daytime sleepiness and clinically probable REM Sleep Behavior Disorder. Flame atomic absorption spectrometry (F AAS) was used to assess the concentrations of calcium, iron and zinc in hair samples collected from a population of PD patients registered in a Brazilian city and from controls (a total of 53 subjects). All subjects lived within a restricted geographical region and were exposed to similar environmental conditions. Results: PD patients with poor sleep quality and excessive daytime sleepiness exhibited significant differences in concentrations of calcium, but not iron or zinc when compared to levels found in controls and PD patients who do not report these sleeping problems. Discussion: Our data suggest that different subgroups of PD patients exist, and clinical chemistry could be useful as a biomarker for these subgroups, which needs to be confirmed in a larger patient population. Further, our data raise the question regarding whether normalization of calcium levels could improve the sleep quality and somnolence in PD patients.

Micronutrient Inadequacy in Short Sleep: Analysis of the NHANES 2005-2016

One third of U.S. adults report short sleep (<7 h), which has been linked to negative health outcomes. Inadequate intake of micronutrients across the U.S. adult population has been reported, and a relationship between sleep conditions and micronutrient intake is emerging. This cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES 2005–2016) (n = 26,211) showed that participants with short sleep duration had a lower usual intake (Food + Supplements) of calcium, magnesium, and vitamin D in all adults aged 19+ years, and vitamin K in adults aged 19–50 years, even after adjusting for covariates. In addition, participants reporting short sleep had a higher percentage of individuals with intake lower than the estimated average requirement (EAR) across multiple nutrients. Age and gender differences were observed in the prevalence of inadequate intake across multiple nutrients. Adults aged 51–99 years with short sleep duration had inadequate intake with respect to more nutrients. In females there was an association between short sleep and a higher prevalence of inadequate intake (Food + Spp) for calcium, magnesium, and vitamins A, C, D, E, and K (above adequate intake). Conversely, males reporting short sleep only had an inadequate intake of vitamin D. Overall, we demonstrate that short sleep is associated with increased nutrient inadequacy, emphasizing the possible need for dietary supplementation.

Sodium intake and blood pressure in children and adolescents: a systematic review and meta-analysis of experimental and observational studies

Background

High sodium intake is a cause of elevated blood pressure in adults. In children and adolescents, less evidence is available and findings are equivocal. We systematically reviewed the evidence from experimental and observational studies on the association between sodium intake and blood pressure in children and adolescents.

Methods

A systematic search of the Medline, Embase, CINAHL and CENTRAL databases up to March 2017 was conducted and supplemented by a manual search of bibliographies and unpublished studies. Experimental and observational studies involving children or adolescents between 0 and 18 years of age were included. Random-effects meta-analyses were performed by pooling data across all studies, separately for experimental and observational studies, and restricting to studies with sodium intake and blood pressure measurement methods of high quality. Subgroup meta-analyses, sensitivity analyses and meta-regressions were conducted to investigate sources of heterogeneity and confounding. The dose-response relationship was also investigated.

Results

Of the 6572 publications identified, 85 studies (14 experimental; 71 observational, including 60 cross-sectional, 6 cohort and 5 case-control studies) with 58 531 participants were included. In experimental studies, sodium reduction interventions decreased systolic blood pressure by 0.6 mm Hg [95% confidence interval (CI): 0.5, 0.8] and diastolic blood pressure by 1.2 mm Hg (95% CI: 0.4, 1.9). The meta-analysis of 18 experimental and observational studies (including 3406 participants) with sodium intake and blood pressure measurement methods of high quality showed that, for every additional gram of sodium intake per day, systolic blood pressure increased by 0.8 mm Hg (95% CI: 0.4, 1.3) and diastolic blood pressure by 0.7 mm Hg (95% CI: 0.0, 1.4). The association was stronger among children with overweight and with low potassium intake. A quasi-linear relationship was found between sodium intake and blood pressure.

Conclusions

Sodium intake is positively associated with blood pressure in children and adolescents, with consistent findings in experimental and observational studies. Since blood pressure tracks across the life course, our findings support the reduction of sodium intake during childhood and adolescence to lower blood pressure and prevent the development of hypertension.

What Is the Relationship Between Dairy Intake and Blood Pressure in Black and White Children and Adolescents Enrolled in a Weight Management Program?

BACKGROUND

The DASH (Dietary Approaches to Stop Hypertension) clinical trials and other studies have demonstrated a relationship between diet and cardiovascular outcomes in adults, yet little is known of this relationship in children. Childhood obesity has reached epidemic proportions in the United States, with similar increases in hypertension among this population. The purpose of our study was to examine the association between dairy intake and blood pressure (BP) in a cohort of children and adolescents (aged 4-17 years) enrolled in a weight management program.

METHODS AND RESULTS

Dietary intake was assessed using the Block Kids 2004 food frequency questionnaire in a cross-sectional sample of participants enrolled in the Pediatric Metabolic Syndrome Study at the Children's Hospital (Charleston, SC). BP and other anthropometrics were obtained at baseline. Only children with complete baseline data and food frequency questionnaires were included in this analysis (n=117). Associations between food group/nutrient intake and BP were examined across race and sex using ANOVA and Pearson correlations. Linear regression models were controlled for body mass index and age. In the total sample, a significant inverse relationship was found between the intake of dairy and systolic BP (r=-0.24, P=0.009). The effect of dairy on systolic BP, however, differed by race. We observed a decrease of 11.2 mm Hg for each serving of dairy consumed by white children, and no decrease in systolic BP in black children (P=0.001 for the race-dairy serving interaction).

CONCLUSIONS

Nutrition professionals must consider nonnutrition factors contributing to childhood hypertension, as current dietary recommendations appear to have differential outcomes across races.

Sleep symptoms associated with intake of specific dietary nutrients

Sleep symptoms are associated with weight gain and cardiometabolic disease. The potential role of diet has been largely unexplored. Data from the 2007-2008 National Health and Nutrition Examination Survey (NHANES) were used (n = 4552) to determine which nutrients were associated with sleep symptoms in a nationally representative sample. Survey items assessed difficulty falling asleep, sleep maintenance difficulties, non-restorative sleep and daytime sleepiness. Analyses were adjusted for energy intake, other dietary factors, exercise, body mass index (BMI) and sociodemographics. Population-weighted, logistic regression, with backwards-stepwise selection, examined which nutrients were associated with sleep symptoms. Odds ratios (ORs) reflect the difference in odds of sleep symptoms associated with a doubling in nutrient. Nutrients that were associated independently with difficulty falling asleep included (in order): alpha-carotene (OR = 0.96), selenium (OR = 0.80), dodecanoic acid (OR = 0.91), calcium (OR = 0.83) and hexadecanoic acid (OR = 1.10). Nutrients that were associated independently with sleep maintenance difficulties included: salt (OR = 1.19), butanoic acid (0.81), carbohydrate (OR = 0.71), dodecanoic acid (OR = 0.90), vitamin D (OR = 0.84), lycopene (OR = 0.98), hexanoic acid (OR = 1.25) and moisture (OR = 1.27). Nutrients that were associated independently with non-restorative sleep included butanoic acid (OR = 1.09), calcium (OR = 0.81), vitamin C (OR = 0.92), water (OR = 0.98), moisture (OR = 1.41) and cholesterol (OR = 1.10). Nutrients that were associated independently with sleepiness included: moisture (OR = 1.20), theobromine (OR = 1.04), potassium (OR = 0.70) and water (OR = 0.97). These results suggest novel associations between sleep symptoms and diet/metabolism, potentially explaining associations between sleep and cardiometabolic diseases.

High blood pressure in school children: prevalence and risk factors

Background

The purpose of this study was to determine the prevalence of high blood pressure (HBP) and associated risk factors in school children 8 to 13 years of age.

Methods

Elementary school children (n = 1,066) were examined. Associations between HBP, body mass index (BMI), gender, ethnicity, and acanthosis nigricans (AN) were investigated using a school based cross-sectional study. Blood pressure was measured and the 95^th percentile was used to determine HBP. Comparisons between children with and without HBP were utilized. The crude and multiple logistic regression adjusted odds ratios were used as measures of association.

Results

Females, Hispanics, overweight children, and children with AN had an increased likelihood of HBP. Overweight children (BMI ≥ 85^th percentile) and those with AN were at least twice as likely to present with HBP after controlling for confounding factors.

Conclusion

Twenty one percent of school children had HBP, especially the prevalence was higher among the overweight and Hispanic group. The association identified here can be used as independent markers for increased likelihood of HBP in children.

Diet and blood pressure in children

PURPOSE OF REVIEW

The prevalence of hypertension among children in the US is increasing in concert with rising obesity rates. Leading health organizations agree that elevated blood pressure should be managed in children; however, data on the relation between diet and lifestyle and blood pressure in this age group are sparse and controversial. The purpose of this review is to summarize the current evidence regarding nutrients, foods, and dietary patterns and their role in blood pressure elevation and in the treatment of pediatric hypertension.

RECENT FINDINGS

There is clear evidence that avoidance of excess weight gain in early life is important for the prevention of future hypertension and that weight reduction is an important therapeutic intervention for the prevention and treatment of hypertension in overweight children. Similarly, reduction in dietary sodium may be beneficial for children who are salt sensitive, but this trait cannot be easily measured. Children who were breast-fed or consume a diet rich in fruits, vegetables, and dairy foods tend to have lower blood pressure in adolescence. How these foods lower blood pressure is unclear.

SUMMARY

Data supporting the efficacy of dietary interventions for preventing or treating high blood pressure are limited. Future studies should emphasize adequate sample size, adjustment for confounding factors, use of standardized blood pressure techniques, and random assignment of children in intervention trials. Additionally, because adherence to dietary interventions may be particularly problematic among children, innovative nutrition intervention approaches are needed that address the unique needs and circumstances of this age group.

Blood pressure and sexual maturity in adolescents: the Heartfelt Study

This study investigates sexual maturity as a predictor of resting blood pressures independent of other known predictors, in 179 boys and 204 girls 11-16 years of age from the Heartfelt Study. The sample included youth of African (n = 140), Mexican (n = 117), and European and "other" (n = 126) backgrounds. Sexual maturity was assessed during clinical examination of three standard indicators for each sex. Systolic and diastolic blood pressures were higher in children of maturity stages IV and V, compared to stages I-III, in each gender/ethnic group (P < 0.01 in almost all groups). Boys and girls advanced in sexual maturity for their age group, had significantly higher systolic blood pressures (but not diastolic) than the less advanced in linear models that included height, body mass index (BMI), ethnicity, and age as co-predictors. Diastolic blood pressures were predicted by height in boys and by age and the BMI in girls. This analysis, using a very conservative approach, suggests that sexual maturity provides important and independent information on systolic blood pressure in adolescents. Further investigation of its role in 24-hr blood pressures and in blood pressures taken during physical and emotional stress, is recommended.

Benefits of dairy product consumption on blood pressure in humans: a summary of the biomedical literature

The inverse relationship between intake of dairy products and blood pressure levels was first suggested by several epidemiologic surveys in the early 1980's that revealed low calcium intake in populations with increased prevalence of hypertension. Subsequent laboratory and clinical investigations provided further evidence of the association between calcium and blood pressure, but the results of these studies were often inconsistent due to variations in study design and methods, study participants and calcium sources. The recently published results of the large and carefully executed Dietary Approaches to Stop Hypertension Study, "DASH," which demonstrated a dramatic blood-pressure lowering effect of diets rich in dairy products, fruits and vegetables, addressed many of the issues contributing to the inconsistencies in the blood pressure-calcium data. In the following review, we discuss the evolution of the scientific evidence of the association between dietary calcium intake and blood pressure, the findings and significance of the DASH trial and the consensus that now exists among health professionals regarding the importance of adequate dairy product intake for optimal blood pressure regulation.

Effect of calcium supplementation on blood pressure in children

OBJECTIVE

To evaluate the effect of calcium supplementation on blood pressure in children.

DESIGN

Randomized, double-masked, placebo-controlled trial.

SETTING AND PARTICIPANTS

One hundred one fifth-grade students in one inner-city school.

INTERVENTION

Each child consumed 480 ml of juice beverages, containing either no calcium or 600 mg calcium (as calcium citrate malate) daily for 12 weeks.

MEASUREMENTS

At baseline we obtained nutrient data from three sets of 2-day food records on each subject. We measured blood pressure four times on each of three weekly sittings at baseline and at follow-up. Using multiple linear regression analysis, we compared mean blood pressure change in the intervention group with that in the placebo group.

RESULTS

There were 50 girls and 51 boys; 61 subjects were black. At baseline, mean age was 11.0 years, systolic and diastolic blood pressures were 101.7 and 57.7 mm Hg, daily total energy intake was 1966 kcal, and calcium intake was 827 mg. With control for age, height, hours of television watched, and baseline blood pressure, systolic blood pressure increased 1.0 mm Hg in the intervention group and 2.8 mm Hg in the placebo group (effect estimate = -1.8 mm Hg; 95% confidence interval -4.0, 0.3). In black subjects the intervention effect estimate was -2.0 mm Hg (95% confidence interval -4.4, 0.4). From lowest to highest quartile of baseline calcium intake (per 1000 kcal), the intervention effect estimates were -3.5, -2.8, -1.3, and 0.0 mm Hg (p for trend = 0.009). There was little effect on diastolic blood pressure.

CONCLUSION

These data suggest a blood pressure-lowering effect of calcium supplementation in children, especially in subjects with low baseline calcium intake.

Dietary calcium and blood pressure in experimental models of hypertension. A review

More than 80 studies have reported lowered blood pressure after dietary calcium enrichment in experimental models of hypertension. The evidence presented here suggests that dietary calcium may act concurrently through a number of physiological mechanisms to influence blood pressure. The importance of any given mechanism may vary depending on the experimental model under consideration. Supplemental dietary calcium is associated with reduced membrane permeability, increased Ca(2+)-ATPase and Na,K-ATPase, and reduced intracellular calcium. These results suggest that supplemental calcium may limit calcium influx into the cell and improve the ability of the VSMC to extrude calcium. This could be a direct effect of calcium on the VSMC or an indirect effect mediated hormonally. The calcium-regulating hormones have all been found to have vasoactive properties and therefore may influence blood pressure. Furthermore, CGRP and the proposed parathyroid hypertensive factor are both vasoactive substances that are responsive to dietary calcium. Therefore, diet-induced variations in calcium-regulating hormones may influence blood pressure. Modulation of the sympathetic nervous system is another important way that dietary calcium can influence blood pressure. There is evidence of altered norepinephrine levels in the hypothalamus as a consequence of manipulations of dietary calcium as well as changes in central sympathetic nervous system outflow. Dietary calcium has also been shown to specifically modify alpha 1-adrenergic receptor activity in the periphery. In some experimental models of hypertension, dietary calcium may alter blood pressure by changing the metabolism of other electrolytes. For example, the ability of calcium to prevent sodium chloride-induced elevations in blood pressure may be attributed to natriuresis. However, natriuresis does not account for all of the interactive effects of calcium and sodium chloride on blood pressure. Sodium chloride-induced hypertension may be due in part to calcium wasting and subsequent elevation of calcium-regulating hormones. Chloride is an important mediator of this effect because it appears that sodium does not cause calcium wasting when it is not combined with chloride. More attention to the central nervous system effects of dietary calcium is needed. Not only can calcium itself influence neural function, but many of the calcium-regulating hormones appear to affect the central nervous system. The influence of calcium and calcium-regulating hormones on central nervous system activity may have important implications for blood pressure regulation and also may extend to other aspects of physiology and behavior.

Racial aspects of blood pressure in children and adolescents

The incidence, prevalence, and severity of essential hypertension are higher in minority adult populations, especially black Americans. Studies have not uniformly shown that black children and adolescents have higher blood pressure values than whites of the same age. The goal of this article is to review data available comparing minority and white populations. A section discussing studies addressing racial differences in related topics is included to demonstrate the existing fields of research that may not be familiar to the general pediatrician.

Calcium intake in youth: sex, age, and racial differences in NHANES II

METHODS

Data from the NHANES II survey were used to determine whether the calcium intake of children ages 3-18 met the minimum recommended daily allowance. In addition, the impact of age, race, sex, and socioeconomic status on calcium intake and the density of calcium intake was explored.

RESULTS

The results indicated significant differences between groups of children based on age, sex, and race (P less than 0.05). Males across all age groups (3-5, 6-7, 8-10, 11-12, 13-18) had a higher calcium intake than females. In addition, calcium intake levels among males always met or exceeded the minimum RDA. Levels among all blacks started below the minimum RDA in the age group 3-5. During the adolescent years, calcium intake again fell below the RDA for black males and for females of both races, with the calcium intake of the adolescent females resembling that of the group ages 3-5. In a multiple regression model sex, age, race, and total energy intake predicted 49% (P less than 0.0001) of the variance in calcium intake. Socioeconomic status (using parents' reported income) was not a significant predictor. Another regression model was used to examine the relationship among age, race, sex, and socioeconomic status and its effect on the density of calcium intake (mg/kcal). While the overall model was significant (P less than 0.0001) it accounted for only 3.5% of the variance.

CONCLUSION

Age, sex, and race of the child significantly predicted the density of calcium (P less than 0.05); however, parents' gross income did not (P less than 0.81), indicating that income level does not contribute to explaining these differences.

Risk factors for hypertension in a national cohort study

Hypertension continues to be a major public health problem in the United States. We used data from the National Health and Nutrition Examination Survey Epidemiologic Followup Study (1971-1984) to examine predictors of hypertension for the 7,073 participants free from hypertension at the baseline examination. The follow-up period averaged 10 years. Body mass index was positively related to the probability of hypertension developing among white men (n = 2,370), white women (n = 3,949), black men (n = 231), and black women (n = 523). Education was inversely associated with the probability of hypertension developing among white women and was of borderline significance among white men and black women. In a subanalysis of white men (n = 1,790) and white women (n = 3,063) who completed the 24-hour recall dietary questionnaire, dietary consumption of sodium, calcium, and potassium did not predict the development of hypertension. The failure of our study to support findings relating intake of dietary cations to the development of hypertension may be attributable to imprecision in the measurement of dietary data and misclassification of hypertension status. These data reinforce the importance of weight control in the primary prevention of hypertension.

Relation of serum and erythrocyte magnesium levels to blood pressure and a family history of hypertension. A follow-up study in Japanese children, 12-14 years old

Serum and erythrocyte magnesium concentrations (S-Mg, E-Mg) were measured in 122 junior high school students followed up for two years from 12 to 14 years of age, and the relationship to blood pressure and a family history of hypertension were investigated. The subjects who had high S-Mg and E-Mg levels at the first examination two years prior tended to show high levels after this follow-up. There were significant positive correlations between two intraindividual values of S-Mg and E-Mg. A similar tendency was found for blood pressure. Tracking phenomena were observed with these measures. The subjects who had high E-Mg levels at the first examination showed no blood pressure elevation during the two-year period. The subjects with a family history of hypertension [FH(+)] showed a higher degree of blood pressure rise during two years than those with no family history [FH(-)], with a significant difference in systolic blood pressure at the age of 14. E-Mg tended to be lower in the FH(+) group than in the FH(-) group with a significant difference in 14-year-old girls. These results suggest that a hereditary predisposition to hypertension is related to magnesium metabolism and that intracellular magnesium deficiency may influence blood pressure elevation in the FH(+) children.

The role of dietary electrolytes in hypertension

The possible contribution of dietary electrolyte intake as a cause of or contributor to the development of hypertension has been intensively investigated for over 50 years. Evidence from various sources suggests a role for sodium-salt, chloride, calcium, and magnesium. In this article, we will review the evidence supporting a role for each of these electrolytes in human hypertension.

Calcium metabolism and hypertension

Returning to the patient presented today, perhaps we can now understand some of his findings. As I noted, men are more likely to demonstrate alterations in calcium metabolism associated with elevations in blood pressure. Furthermore, blacks are more likely than whites to develop hyperparathyroidism, particularly in the third and fourth decades of life. It is unlikely, however, that parathyroid hormone was responsible for the increase in this patient's arterial pressure because PTH has a vasodilating action. Moreover, the long-term response to parathyroidectomy is more likely to be an increase rather than a decrease in blood pressure. It is also unlikely that the mild elevations in the serum total calcium observed in this patient were responsible for his hypertension. Correction of hypercalcemia by surgical intervention failed to improve the blood pressure. There is little evidence that mild, protracted hypercalcemia can account for increases in arterial pressure. Finally, the patient's alcohol abuse might have contributed to his elevated blood pressure; it is possible that his hypertension was in part a reflection of the abnormal calcium metabolism he developed as a consequence of the alcohol abuse. Answers to some questions we faced when we first studied this patient more than a decade ago can be provided by the wealth of basic research and clinical investigation that has occurred since. We now know that calcium metabolism is a factor in blood pressure regulation in some humans and in some experimental models. Epidemiologic studies document a consistent association between lower dietary calcium intake and higher blood pressures in humans. An additional non-pharmacologic approach has been identified that can produce a modest but important lowering of blood pressure in a subset of hypertensive individuals. Much data show that calcium-regulating hormones have important cardiovascular actions that might account for some of the mechanisms by which increased dietary calcium lowers blood pressure. Research in this area also has set the stage for exploring another theoretical mechanism for sodium-chloride-sensitive hypertension. Finally, a theoretical mechanism(s) has emerged that could provide a pathophysiologic link between hypertension and certain high-risk populations such as blacks, the elderly, type-II diabetics, and pregnant women. The principal clinical implication derived from this work to date is the following: In patients with mild to moderate hypertension, the level of dietary calcium intake should be assessed. Patients whose intake is deficient should be encouraged simply to maintain calcium intake at 800 to 1000 mg/day.(ABSTRACT TRUNCATED AT 400 WORDS)