Blood pressure and nutrition in adults. The National Health and Nutrition Examination Survey

Relationship between blood pressure index and cognition in older adults

OBJECTIVE

We aimed to examine the contributions of blood pressure index (BPI) and other measurements to cognitive function in older adults.

METHOD

Four hundred sixty-six subjects aged over 65 who applied to the outpatient Geriatric Clinics of Gulhane Training and Research Hospital were enrolled in the study. Demographics and clinical conditions were collected from their files. Pulse pressure index (PP) (SBP - DBP), mean arterial pressure index (MAP) [(SBP + DBP x 2)/3] and BPI (SBP/DBP) were recorded. We used the Mini-mental state examination (MMSE) test for evaluating global cognition. We classified participants into two groups based on MMSE score: normal with a score of 27 or more and lower cognitive function with a 26 or lower cognitive function.

RESULTS

31% of subjects (n = 143) had lower and 69% (n = 323) had normal cognitive function. When compared blood pressure measurements between groups, BPI and PP were higher in the subjects with lower cognitive function [BPI: 1.78 ± 0.25 vs. 1.71 ± 0.23, p = .007 and PP: 58.97 ± 17.59 vs. 54.05 ± 15.38, p = .009]. After adjustment for confounders, a 2.545 fold increased risk of cognitive decline was observed among subjects with higher BPI when compared to those with normal (OR: 2.545, 95%CI: 1.024-6.325, p = .044).

CONCLUSION

The findings suggest that BPI is an associated with cognition in older adults and may a novel alternative marker for identifying the subjects at the risk of dementia.

Associations between height and blood pressure in the United States population

The mechanisms linking short stature with an increase in cardiovascular and cerebrovascular disease risk remain elusive. This study tested the hypothesis that significant associations are present between height and blood pressure in a representative sample of the US adult population.Participants were 12,988 men and women from a multiethnic sample (age ≥ 18 years) evaluated in the 1999 to 2006 National Health and Nutrition Examination Survey who were not taking antihypertensive medications and who had complete height, weight, % body fat, and systolic and diastolic arterial blood pressure (SBP and DBP) measurements; mean arterial blood pressure and pulse pressure (MBP and PP) were calculated. Multiple regression models for men and women were developed with each blood pressure as dependent variable and height, age, race/ethnicity, body mass index, % body fat, socioeconomic status, activity level, and smoking history as potential independent variables.Greater height was associated with significantly lower SBP and PP, and higher DBP (all P < .001) in combined race/ethnic-sex group models beginning in the 4th decade. Predicted blood pressure differences between people who are short and tall increased thereafter with greater age except for MBP. Socioeconomic status, activity level, and smoking history did not consistently contribute to blood pressure prediction models.Height-associated blood pressure effects were present in US adults who appeared in the 4th decade and increased in magnitude with greater age thereafter. These observations, in the largest and most diverse population sample evaluated to date, provide support for postulated mechanisms linking adult stature with cardiovascular and cerebrovascular disease risk.

The relationship between dietary intake and other cardiovascular risk factors with blood pressure in individuals without a history of a cardiovascular event: Evidence based study with 5670 subjects

BACKGROUND AND AIM

Raised blood pressure is a leading cause of morbidity and mortality worldwide; improved nutritional approaches to population-wide prevention are required.We aimed to investigate the relationship between dietary intake and other cardiovascular risk factors with blood pressure in individuals without a history of a cardiovascular event in an Iranian cohort.

MATERIAL AND METHOD

A cross-sectional study of 5670 healthy subjects [approximately 40% (n=2179) males and 60% (n=3491) females] was undertaken in a sample from northeastern Iran. Subjects were recruited from an urban population, using a stratified-cluster method and derived from the Mashhad Stroke Heart Atherosclerosis Disorder (MASHAD) study, Mashhad, Iran. The age of the subjects was between 35 and 64 years. None of the subjects had a past history of major disease.

RESULTS

The mean ages for the male and female subgroups were 50.1± 8.1years and 48.2 ±7.8 y respectively. Not unexpectedly, subjects without hypertension (HTN) were younger than those with established HTN. Individuals with HTN were significantly more adipose than those without (p<0.01). We found no significant differences in crude or total energy adjusted intake of nutrients between the three groups (p>0.05), except for crude and energy adjusted phosphorus intake (p<0.05) and crude intake of the cholesterol (p<0.05). There was a significant correlation between the dietary intake of total fatty acids, phosphorus and vitamin E with both systolic blood pressure (SBP) and diastolic blood pressure (DBP). PUFA (odds ratio [OR] [95% confidence interval (CI)], 1.56 [1.05-1.06]; P<0.01), sodium (OR [95% CI], 1.00 [(1.00-1.01)]; P<0.01) and phosphorus (OR [95% CI], 1.00 [(1.00-1.01)]; P<0.01)were significant independent predictors of HTN after adjustment for energy intake.

CONCLUSION

In our representative population from North-Eastern Iran, it appears that in adults without a history of cardiovascular disease, crude or energy adjusted intake of phosphorus and total fatty acid intake were significant determinants of BP, however we found no association between sodium and potassium intake with BP.

Refeeding and metabolic syndromes: two sides of the same coin

Refeeding syndrome describes the metabolic and clinical changes attributed to aggressive rehabilitation of malnourished subjects. The metabolic changes of refeeding are related to hypophosphatemia, hypokalemia, hypomagnesemia, sodium retention and hyperglycemia, and these are believed to be mainly the result of increased insulin secretion following high carbohydrate intake. In the past few decades, increased consumption of processed food (refined cereals, oils, sugar and sweeteners, and so on) lowered the intake of several macrominerals (mainly phosphorus, potassium and magnesium). This seems to have compromised the postprandial status of these macrominerals, in a manner that mimics low grade refeeding syndrome status. At the pathophysiological level, this condition favored the development of the different components of the metabolic syndrome. Thus, it is reasonable to postulate that metabolic syndrome is the result of long term exposure to a mild refeeding syndrome.

Dietary sodium and potassium intake is not associated with elevated blood pressure in US adults with no prior history of hypertension

The relationship between dietary sodium and potassium intake with elevated blood pressure (BP) levels is unclear. The authors examined the association between dietary sodium and potassium intake and BP levels in 6985 adults aged 18 years and older with no prior history of hypertension who participated in the National Health and Nutrition Examination Survey (2001-2006). After adjustment for age, sex, race, body mass index, diabetes, and estimated glomerular filtration rate, there was no association between higher quartiles of sodium or potassium intake with the risk of a BP >140/90 mm Hg or >130/80 mm Hg. There was also no relationship between dietary sodium and potassium intake with BP when systolic and diastolic BP were measured as continuous outcomes (P=.68 and P=.74, respectively). Furthermore, no association was found between combinations of sodium and potassium intake with elevated BP. In the US adult population without hypertension, increased dietary sodium or low potassium intake was not associated with elevated BP levels.

A review of nutritional factors in hypertension management

Hypertension is a major health problem worldwide. Its attendant morbidity and mortality complications have a great impact on patient's quality of life and survival. Optimizing blood pressure control has been shown to improve overall health outcomes. In addition to pharmacological therapies, nonpharmacological approach such as dietary modification plays an important role in controlling blood pressure. Many dietary components such as sodium, potassium, calcium, and magnesium have been studied substantially in the past decades. While some of these nutrients have clear evidence for their recommendation, some remain controversial and are still of ongoing study. Dietary modification is often discussed with patients and can provide a great benefit in blood pressure regulation. As such, reviewing the current evidence will be very useful in guiding patients and their physician and/or dietician in decision making. In this review article of nutritional factors in hypertension management, we aim to examine the role of nutritional factors individually and as components of whole dietary patterns.

Dietary phosphorus, blood pressure, and incidence of hypertension in the atherosclerosis risk in communities study and the multi-ethnic study of atherosclerosis

Greater phosphorus intake has been associated with lower levels of blood pressure in cross-sectional studies. This association, however, has not been assessed prospectively. We studied 13 444 participants from the Atherosclerosis Risk in Communities cohort and the Multi-Ethnic Study of Atherosclerosis, with diet assessed at baseline using validated food frequency questionnaires. Blood pressure and use of antihypertensive medication were determined at baseline and during follow-up visits. Compared with individuals in the lowest quintile of phosphorus intake at baseline, those in the highest quintile had lower baseline systolic and diastolic blood pressures after adjustment for dietary and nondietary confounders (-2.0 mm Hg [95% CI: -3.6 to -0.5], P for trend=0.01; and -0.6 [95% CI: -1.6 to +0.3], P for trend=0.20, respectively). During an average 6.2 years of follow-up, 3345 cases of hypertension were identified. Phosphorus intake was associated with the risk of hypertension (hazard ratio: 0.80 [95% CI: 0.80 to 1.00], comparing extreme quintiles; P for trend=0.02) after adjustment for nondietary factors but not after additional adjustment for dietary variables (hazard ratio: 1.01 [95% CI: 0.82 to 1.23], P for trend=0.88). Phosphorus from dairy products but not from other sources was associated with lower baseline blood pressure and reduced risk of incident hypertension. Hazard ratios (95% CIs) comparing extreme quintiles were 0.86 (0.76 to 0.97; P for trend=0.01) for phosphorus from dairy foods and 1.04 (0.93 to 1.17; P for trend=0.48) for phosphorus from other foods. These findings could indicate an effect of phosphorus in conjunction with other dairy constituents or of dairy itself without involvement of phosphorus.

The long-term effects of low-dose 17β-estradiol and dydrogesterone hormone replacement therapy on 24-h ambulatory blood pressure in hypertensive postmenopausal women: a 1-year randomized, prospective study

OBJECTIVE

The aim of this study was to assess the long-term effects of low-dose oral hormone replacement therapy (HRT) on 24-h blood pressure in hypertensive postmenopausal women.

STUDY DESIGN

In this 12-month, prospective study, 66 postmenopausal women with mild or moderate hypertension were randomly assigned to receive either HRT with 1 mg/day micronized 17beta-estradiol sequentially combined with 10 mg/day dydrogesterone for 14 days of each 28-day cycle, or no therapy. Ambulatory blood pressure measurements were recorded for a 24-h period at baseline and after 12 months of treatment or follow-up.

RESULTS

Blood pressure did not differ significantly between the groups at baseline. After 12 months, there were falls in 24-h systolic, diastolic and mean arterial blood pressure in both the HRT and control groups; only the fall in mean arterial blood pressure in the HRT group achieved statistical significance (-2.0 +/- 0.8 mmHg, p < 0.01). While there was no significant decrease in daytime systolic or mean arterial blood pressure in either group, a significant decrease in diastolic blood pressure (-1.8 +/- 10 mmHg, p < 0.001) was observed in the HRT group. Night-time systolic and mean arterial blood pressure also decreased significantly (p < 0.001) in the HRT group (-3.0 +/- 1.5 mmHg and -2.2 +/- 0.6 mmHg, respectively), but no significant change was observed in the control group.

CONCLUSION

Low-dose oral HRT caused significant falls in both daytime and night-time ambulatory blood pressure in postmenopausal women with mild or moderate hypertension.

Dietary phosphorus and blood pressure: international study of macro- and micro-nutrients and blood pressure

Raised blood pressure is a leading cause of morbidity and mortality worldwide; improved nutritional approaches to population-wide prevention are required. Few data are available on dietary phosphorus and blood pressure and none are available on possible combined effects of phosphorus, magnesium, and calcium on blood pressure. The International Study of Macro- and Micro-Nutrients and Blood Pressure is a cross-sectional epidemiologic study of 4680 men and women ages 40 to 59 from 17 population samples in Japan, China, United Kingdom, and United States. Blood pressure was measured 8 times at 4 visits. Dietary intakes were obtained from four 24-hour recalls plus data on supplement use. Dietary phosphorus was inversely associated with blood pressure in a series of predefined multiple regression models, with the successive addition of potential confounders, both nondietary and dietary. Estimated blood pressure differences per 232 mg/1000 kcal (2 SD) of higher dietary phosphorus were -1.1 to -2.3 mm Hg systolic/-0.6 to -1.5 mm Hg diastolic (n=4680) and -1.6 to -3.5 mm Hg systolic/-0.8 to -1.8 mm Hg diastolic for 2238 "nonintervened" individuals, ie, those without special diet/nutritional supplements or diagnosis/treatment for cardiovascular disease or diabetes. Dietary calcium and magnesium, correlated with phosphorus (partial r=0.71 and r=0.68), were inversely associated with blood pressure. Blood pressures were lower by 1.9 to 4.2 mm Hg systolic/1.2 to 2.4 mm Hg diastolic for people with intakes above versus below country-specific medians for all 3 of the minerals. These results indicate the potential for increased phosphorus/mineral intake to lower blood pressure as part of the recommendations for healthier eating patterns for the prevention and control of prehypertension and hypertension.

Protein intake and blood pressure in cardiovascular disease

Raised blood pressure (BP) is a major cause of CHD and the leading cause of stroke. Although BP rises with age in most populations, there are remote populations around the world where BP does not rise with age and where the high prevalence of high BP and frank hypertension seen in the UK and other Western countries in the older age-groups is not found. However, when such populations migrate to urban settings, their BPs rise, indicating that the population-wide BP problem is largely environmental in origin. Thus, a substantial body of evidence has accumulated on the importance of dietary factors in BP (Na and alcohol intakes (direct relationship) and K intake (inverse relationship)) as well as body weight (direct relationship). More recently, attention has shifted to other dietary factors that might affect BP. Data from studies of vegetarians (who tend to have lower BP than meat-eating populations) as well as clinical data on the adverse effects of protein intake in patients with renal insufficiency led to the view in Western countries that dietary (animal or total) protein had an adverse effect on BP. By contrast, studies in Japan and China suggested that dietary protein might be protective of high BP and stroke. Recent epidemiological studies have found inverse associations between dietary protein intake and BP, consistent with this view, and supported by some evidence from animal studies. Recent controlled clinical trials of soyabean supplementation have also suggested a BP-lowering effect of protein intake. Results of further large-scale epidemiological studies of protein and BP are awaited.

Association between protein intake and blood pressure: the INTERMAP Study

BACKGROUND

Findings from epidemiological studies suggest an inverse relationship between individuals' protein intake and their blood pressure.

METHODS

Cross-sectional epidemiological study of 4680 persons, aged 40 to 59 years, from 4 countries. Systolic and diastolic blood pressure was measured 8 times at 4 visits. Dietary intake based on 24-hour dietary recalls was recorded 4 times. Information on dietary supplements was noted. Two 24-hour urine samples were obtained per person.

RESULTS

There was a significant inverse relationship between vegetable protein intake and blood pressure. After adjusting for confounders, blood pressure differences associated with higher vegetable protein intake of 2.8% kilocalories were -2.14 mm Hg systolic and -1.35 mm Hg diastolic (P<.001 for both); after further adjustment for height and weight, these differences were -1.11 mm Hg systolic (P<.01) and -0.71 mm Hg diastolic (P<.05). For animal protein intake, significant positive blood pressure differences did not persist after adjusting for height and weight. For total protein intake (which had a significant interaction with sex), there was no significant association with blood pressure in women, nor in men after adjusting for dietary confounders. There were significant differences in the amino acid content of the diets of persons with high vegetable and low animal protein intake vs the diets of persons with low vegetable and high animal protein intake.

CONCLUSIONS

Vegetable protein intake was inversely related to blood pressure. This finding is consistent with recommendations that a diet high in vegetable products be part of healthy lifestyle for prevention of high blood pressure and related diseases.

Information subsystem of the Ca/Mg ratio as a database for studying its influence on human health

Dalmatia is situated in the Dinaric karst in Southern Croatia. It is characterized by insufficient quantities of water during the summer months and a relatively excessive amount of rainfall during the winter and spring months. Other hydrographic characteristics of Dinaric carst include scarce and long surface streamflows with a few tributaries with changeable capacities, a small number of springs, and a relatively great number of submarine springs along the coast. The water supply and health-care institutions are especially interested in observing and monitoring water quality. A relational database has been developed for carrying out chemical analyses expressed by the Ca/Mg ratio since it is necessary to organize and integrate a large number of analytical and ecological health data. The database can serve as a methodological platform for the study of environmental factors influencing human health. The prototype database consists of data obtained by investigations which have been conducted by the water Examination Department of the Public Health Institute of the Split Dalmatian county (Croatia) University of Split Medical School. The database currently contains more than 2500 data.

Menopause induced by oophorectomy reveals a role of ovarian estrogen on the maintenance of pressure homeostasis

OBJECTIVES

Following spontaneous menopause women show a greater increase in systolic and diastolic blood pressure than men of the same age. The aim of the present study was to assess the effect of acute ovarian hormone withdrawal and replacement on blood pressure and forearm blood flow.

METHODS

We studied 18 fertile middle-aged normotensive women (48 +/- 1.5 years, range 46-51 years) 1 week prior and 1 month subsequent to bilateral oophorectomy by means of 24-h blood pressure monitoring and strain-gauge venous occlusion plethysmography. Eighteen subjects who had undergone hysterectomy with ovarian sparing, matched for age and biophysical characteristics, were used as a control group. All women were free from cardiovascular risk factors or disease.

RESULTS

Oophorectomy increased the mean values of 24 h (P < 0.001), daytime (P < 0.05), and nighttime (P < 0.01) diastolic blood pressure and nighttime systolic blood pressure (P < 0.01). Blood pressure increase was associated with a rise in forearm vascular resistance (P < 0.01). No significant changes in either blood pressure or forearm vascular resistance values were observed in hysterectomized women. In 16 oophorectomized women a 3-month estrogen replacement therapy (ERT) (17beta-estradiol, 100 mcg/day by transdermal patches) brought blood pressure and forearm vascular resistance values to a level comparable to that recorded before intervention.

CONCLUSIONS

Surgically-induced menopause causes an increase in peripheral vascular resistance and blood pressure suggesting a role of ovarian hormones in the homeostatic pressure modulation. Recovery of the baseline condition after ERT suggests that the accelerated increase in blood pressure after menopause is due to ovarian and above all estrogen insufficiency.

Functional status of patients with primary biliary cirrhosis

OBJECTIVES

Although autoimmune diseases can have a significant impact on the quality of life, there has been a relative paucity of data with respect to the functional status of patients with primary biliary cirrhosis (PBC).

METHODS

We conducted a case-control study of 182 patients ("cases") with PBC as well as 225 age- and sex-matched friend control subjects using a standardized instrument obtained from the National Health and Nutrition Examination Survey.

RESULTS

In all, 126 of 182 cases (69%) and 141 of 225 friend controls (62.6%) responded to this survey, a response rate comparable to or better than in similar previous studies of such instruments. Patients with PBC had a significantly reduced functional status score compared to their controls (p < 0.001). Interestingly, a lower level of education and the presence of arthritis and hypertension were significantly associated with these lower levels of functional capabilities. These data were subjected to multivariate analysis and confirmed. Age was not associated with impaired functional status in either the patients or controls.

CONCLUSIONS

Studies of this nature have potential implications for the well-being and management of patients with PBC, and focus on issues that can be addressed to help maintain functional status in this chronic disease.

The association between gravidity and primary biliary cirrhosis

PURPOSE

Primary biliary cirrhosis is an autoimmune disease with female predominance that leads to liver failure. The goal of this study was to identify reproductive risk factors associated with this disease.

METHODS

We compared 182 cases of PBC with 225 age- and sex-matched friend controls to examine the role of reproductive factors. The survey instrument was developed using standardized questions obtained from the National Health and Nutrition Examination Survey (NHANES) III.

RESULTS

A total of 126/182 cases (69%) and 141/225 (62.6%) friend controls responded to the survey. More cases than controls reported ever having genitourinary infection [adjusted odds ratio (OR) = 2.12, 95% confidence interval (CI) 1.01, 4.42] among those without a personal or family history of autoimmune disease. The most notable finding was that cases reported significantly more pregnancies than controls (p = 0.008). The adjusted OR for each additional pregnancy among those without a personal or family history of autoimmune disease was 1.40 (95% CI 1.14, 1.7). More controls (24.4%) than cases (16.0%) were nulliparous. Cases reported having five or more children (16.0%) with double the frequency of controls (8.2%).

CONCLUSIONS

The association reported herein, between primary biliary cirrhosis and gravidity, is particularly significant because of the overwhelming female predominance.

Hypertension and obesity

Obesity, as defined by bodily weight (body weight) and by bodily conformation-derived variables, accompanies hypertension in many patients. Both conditions are independent cardiovascular risk factors. In a formal survey carried out in the adult general population of Uruguay (LATIR Study, 575 adult and elderly subjects of whom 41.6% were males), we found the prevalence of hypertension to be 28.5% (95% CI: 24.9-32.4%) and that 74.4% of hypertensive individuals had a body mass index (BMI) higher than 25 kg/m(2) (95% CI: 67.0-80.8%). This association between obesity and hypertension forms part of a broader relationship between body weight and blood pressure (BP). In the general population, BP bears a positive linear correlation with BMI and waist-to-hip ratio over the continuous ranges of normal and unfavourable values of these three variables (r = 0.42, P < 0.001 for the correlation between BMI and mean BP, LATIR Study). Patients who present hypertension and obesity usually present other unfavourable conditions for cardiovascular prognosis, including changes in carbohydrate and lipid metabolism, hyperuricaemia, left ventricular hypertrophy, and/or the obstructive sleep apnoea syndrome. On average, hypertension is salt-sensitive in obese patients, and plasma volume and cardiac index are increased. Adequate control of body weight results in substantial reductions in total blood volume, cardiac output, BP and left ventricular mass, and in an amelioration or the disappearance of sleep apnoea. Adequate sodium intake restriction must form part of any diet prescribed to obese hypertensive patients. Various drug classes may be used to treat hypertension efficaciously in patients who also present obesity.

Hypertension in menopausal women--a special case, for special treatment?

After the menopause the consequences of hypertension in women change. Their risks of myocardial infarction and stroke rise steeply, a rise that has been blamed in part on the loss of estrogen and the onset of menopausal metabolic syndrome, with endothelial dysfunction, hyperlipidemia, insulin resistance and derangement in coagulation. Hypertensive menopausal women have not had optimum treatment. They have poorer prognoses than men of the same age. Their antihypertensive management therefore merits special attention. Hormone replacement, aspirin prophylaxis and lipid-lowering drugs have their place. The antihypertensive drug chosen should not worsen the metabolic syndrome: angiotensin-II converting enzyme (ACE) inhibitors are therefore among the first-line drugs. Few drugs have been specifically aimed at menopausal hypertension and these are reviewed here.

Effect of alcohol abstinence on blood pressure: assessment by 24-hour ambulatory blood pressure monitoring

Several studies have shown that cessation of alcohol drinking reduces blood pressure (BP). However, attempts to reproduce these findings by ambulatory BP monitoring (ABPM) have shown inconsistent results. The aim of the present study was to assess the effect of 1 month of proven abstinence from alcohol on the 24-hour BP profile in heavy alcohol drinkers. Forty-two men who were heavy drinkers (>100 g of pure ethanol per day) were consecutively admitted to a general ward for voluntary alcohol detoxification. On the day of admission, they received a total dose of 2 g/kg of ethanol diluted in orange juice in 5 divided doses, and a 24-hour ABPM was performed. A new 24-hour BP monitoring in the same environmental conditions was performed after 1 month of proven alcohol abstinence while the subjects were receiving the same amount of fluid but without the addition of alcohol. After 1 month of proven alcohol abstinence, BP and heart rate (HR) significantly decreased. The reduction was 7.2 mm Hg for 24-hour systolic BP (SBP) (95% CI, 4.5 to 9.9), 6.6 mm Hg for 24-hour diastolic BP (DBP) (95% CI, 4.2 to 9.0), and 7.9 bpm for HR (95% CI, 5.1 to 10.7). The proportion of alcoholic patients considered hypertensive on the basis of 24-hour BP criteria (daytime SBP >/=135 mm Hg or daytime DBP >/=85 mm Hg) fell from 42% during alcohol drinking to 12% after 1 month of complete abstinence. Abstinence did not modify either the long-term BP variability, assessed by SD of 24-hour BP, or its circadian profile. We conclude that abstinence in heavy alcohol drinkers significantly reduces BP assessed by 24-hour ABPM and that this reduction is clinically relevant. These results show that heavy alcohol consumption has an important effect on BP, and thus cessation of alcohol consumption must be recommended as a priority for hypertensive alcohol drinkers.

Blood pressure, serum cholesterol and nutritional state in Tanzania and in the Amazon: comparison with an Italian population

OBJECTIVE

To confirm that westernization of dietary habits represents a stimulus for the expression of cardiovascular risk.

DESIGN

Three representative age- and sex-matched samples of general populations of three continents were compared cross-sectionally by analysis of variance.

PARTICIPANTS

In total 1110 subjects aged 22-89 years, divided into three groups (370 from Tanzania and Uganda, 370 from the Amazonian region of Brazil, and 370 from northern Italy; 111 men and 259 women in each group).

RESULTS

The blood pressure of Africans eating a low-salt fish and vegetable' diet was lower than those of Brazilians, whose diet was based on cereals and meat, and highly urbanized Italians. The systolic blood pressure was correlated to the body mass index for all three populations, but with age only for the Brazilians and Italians. The total cholesterol level and body mass index, both of which are low among Africans, increased progressively with increasing economic level.

CONCLUSIONS

Transition from a rural to an urbanized lifestyle is accompanied by a rise in the main cardiovascular risk factors; the present data also show that environmental rather than racial factors have a crucial impact on the risk pattern of populations.

Regulation of blood pressure with calcium-dependent dopamine synthesizing system in the brain and its related phenomena

The effects of calcium on blood pressure regulation remain controversial. Although the mechanism by which calcium increases blood pressure when it is given intravenously and acutely has been elucidated, that by which calcium reduces blood pressure when it is supplemented chronically and slightly through daily diet is unclear. From a number of animal experiments concerning the effects of calcium on blood pressure, we believe that calcium ions have two separate roles in the regulation of blood pressure through both central and peripheral systems: (1) calcium ions reduce blood pressure through a central, calcium/calmodulin-dependent dopamine-synthesizing system and (2) calcium ions increase blood pressure through an intracellular, calcium-dependent mechanism in the peripheral vasculature. These concepts were applied to elucidate the mechanisms underlying hypertension in spontaneously hypertensive rats (SHR) and changes in blood pressure in other experimental animals, and the following conclusions were reached. The decrease of the serum calcium level in spontaneously hypertensive rats (SHR) causes a decrease in calcium/calmodulin-dependent dopamine synthesis in the brain. The subsequent low level of brain dopamine induces hypertension. The increase in susceptibility to epileptic convulsions and the occurrence of hypertension in epileptic mice (El mice) may be linked through a lowering of calcium-dependent dopamine synthesis in the brain, and epilepsy and hypertension may be associated. Exercise leads to increases in calcium-dependent dopamine synthesis in the brain, and the increased dopamine levels induce physiological changes, including a decrease in blood pressure. Cadmium which is not distinguished from calcium by calmodulin, activates calmodulin-dependent functions in the brain, and increased dopamine levels may decrease blood pressure. In this report, our studies are considered in light of reports from many other laboratories.

A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group

BACKGROUND

It is known that obesity, sodium intake, and alcohol consumption factors influence blood pressure. In this clinical trial, Dietary Approaches to Stop Hypertension, we assessed the effects of dietary patterns on blood pressure.

METHODS

We enrolled 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic blood pressures of 80 to 95 mm Hg. For three weeks, the subjects were fed a control diet that was low in fruits, vegetables, and dairy products, with a fat content typical of the average diet in the United States. They were then randomly assigned to receive for eight weeks the control diet, a diet rich in fruits and vegetables, or a "combination" diet rich in fruits, vegetables, and low-fat dairy products and with reduced saturated and total fat. Sodium intake and body weight were maintained at constant levels.

RESULTS

At base line, the mean (+/-SD) systolic and diastolic blood pressures were 131.3+/-10.8 mm Hg and 84.7+/-4.7 mm Hg, respectively. The combination diet reduced systolic and diastolic blood pressure by 5.5 and 3.0 mm Hg more, respectively, than the control diet (P<0.001 for each); the fruits-and-vegetables diet reduced systolic blood pressure by 2.8 mm Hg more (P<0.001) and diastolic blood pressure by 1.1 mm Hg more than the control diet (P=0.07). Among the 133 subjects with hypertension (systolic pressure, > or =140 mm Hg; diastolic pressure, > or =90 mm Hg; or both), the combination diet reduced systolic and diastolic blood pressure by 11.4 and 5.5 mm Hg more, respectively, than the control diet (P<0.001 for each); among the 326 subjects without hypertension, the corresponding reductions were 3.5 mm Hg (P<0.001) and 2.1 mm Hg (P=0.003).

CONCLUSIONS

A diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure. This diet offers an additional nutritional approach to preventing and treating hypertension.

Mean red cell volume as a correlate of blood pressure

BACKGROUND

Clinical studies suggest that hypertensives have lower mean corpuscular volume (MCVs) than do normotensives. Epidemiological studies show no relation or higher MCVs. In the present study of elderly men (71 to 93 years of age) of the Honolulu Heart Program, elements of both findings are confirmed.

METHODS AND RESULTS

Three groups are identified: (1) those receiving no hypertension treatment, (2) those receiving treatment with any diuretic, and (3) those receiving treatment with nondiuretics only. MCV is lower in group 3 than in group 1 (-0.85 fL, P<.001) but the same in groups 1 and 2. Within groups 1 and 3, inverse relations of -0.22 and -0.09 mm Hg/fL (P<.05) are noted for systolic (SBP) and diastolic (DBP) blood pressures. No relations are observed in group 2. MCV and red blood cell count (RBC) are inversely correlated (r=-.45). In group 2, adjustment for RBC unmasks a direct relation between MCV and SBP (0.5 mm Hg/fL, P=.02) and DBP (0.3 mm Hg/fL, P=.02). In groups 1 and 3, relations between SBP and MCV are lost after adjustment for RBC (0.005 mm Hg/fL). For DBP, adding RBC plus an MCV x RBC interaction is significant (P<.001). DBP is 5 mm Hg greater in the highest RBC quartile than in the lowest. A +3 mm Hg difference between extreme MCV quartiles is noted only at high RBC levels.

CONCLUSIONS

The relation between blood pressure and red cell measures is probably mediated by whole blood viscosity. Hematocrit is a determinant of whole blood viscosity. Viscosity affects peripheral resistance to blood flow, and peripheral resistance affects DBP. At high RBC levels, MCV may be "downregulated." This may lower whole blood viscosity and partially reduce DBP without compromising flow.

Epidemiology of hypertension in African American women

To describe the epidemiology of hypertension in U.S. African American women and to highlight priority areas for future research, data from the nationwide surveys of the U.S. National Center for Health Statistics, from selected multicenter studies of the U.S. National Heart, Lung, and Blood Institute, as well as from selected other population-based studies, were reviewed. In 1988 through 1991, an estimated 3 million African American women aged 18 and older had hypertension. Compared with that in U.S. whites, hypertension in black women is characterized by higher incidence, earlier onset, longer duration, higher prevalence, and higher rates of hypertension-related mortality and morbidity. Risk factors for hypertension incidence in black women include obesity and weight gain. The effectiveness of drug therapy of hypertension has been established in black women, and important gains in rates of treatment and control have been accomplished. Nevertheless, rates of hypertension-related mortality for black women remain among the highest in the industrialized nations. Further research on causes and prevention of hypertension in black women is needed. Goals related to prevention and control of hypertension in African Americans for the year 2000 have been established and must be vigorously pursued.

The importance of calcium in the control of salt intake

There is no doubt that the renin-angiotensin-aldosterone system (RAAS) can have a major influence on salt intake but the conditions used to demonstrate this are rare outside the laboratory. Changes in RAAS activity do not explain the voluntary intake of NaCl solution shown by non-deprived rats or the preference for salty foods shown by humans. As a first attempt to investigate an alternative mechanism, my colleagues and I are studying the effects of dietary calcium on salt appetite. Even though calcium-deprived rats have normal RAAS activity, they show a striking increase in NaCl intake, which can surpass the effects of the most severe manipulations of the RAAS. The physiological mechanism underlying this behavior is unknown but it probably involves an adrenal factor, perhaps corticosterone. Whatever the mechanism, the calcium-deprived rat and other low-renin models of salt intake provide a promising approach to help understand the physiological basis of excess salt consumption by humans.

Blood pressure responses of white men with hypertension to two low-sodium metabolic diets with different levels of dietary calcium

OBJECTIVE

To compare the blood pressure responses of men with hypertension consuming low-sodium (Na) metabolic diets differing in dietary calcium (Ca) for two 6-week periods.

SUBJECTS

White men who had hypertension, were nonsmokers, and were sedentary.

INTERVENTION

This study consisted of two separate 6-week metabolic feeding periods. In the first period, a high-Ca group (n = 6) was fed 1,400 mg Ca per day. In the second period, a low-Ca group (n = 5) was fed 400 mg Ca per day. Both groups were fed 1,500 mg Na per day.

MAIN OUTCOME MEASURES

Blood pressure; urine and blood measured for electrolyte, calcitriol, renin, and parathyroid hormone (PTH) levels. To measure typical nutrient intakes, 3-day dietary records were collected before the beginning of each treatment period.

STATISTICAL ANALYSES PERFORMED

Repeated-measures analysis of variance and split-plot analysis of variance were used to analyze, respectively, blood pressure responses and response variables over time.

RESULTS

In both groups, serum Na level decreased (P < .05) over the 6-week period; urine Na decreased (P < .05) only in the low-Ca group. Serum PTH level decreased (P < .05) in the high-Ca group and increased (P < .05) in the low-Ca group; no change occurred in serum calcitriol level. Diastolic blood pressure decreased (8 mm Hg) in the low-Ca group (P < .05). The low-Ca group showed an 8% to 9% decrease in both systolic and diastolic blood pressure vs a 2% to 3% decrease in the high-Ca group. We also examined how the metabolic diet differed from subjects' typical diet. Results showed a positive correlation between the change in Na intake (usual to metabolic diet) and the change in systolic and diastolic blood pressure in both groups (P < .04). Results also showed a negative correlation between the change in the ratio of Na to Ca (usual to metabolic diet) and the change in diastolic blood pressure in the low-Ca group (P < .03). Directional change in blood pressure (either increase or decrease) could be predicted on the basis of how much the Na and Ca in the metabolic diet differed from subject's typical diet.

APPLICATIONS

Results of this study suggest that in the dietary management of hypertension it may be more important to focus on specific changes in a person's diet (eg, decreasing Na intake by 1,000 mg/day and increasing Ca intake by 400 mg/day) rather than setting specific levels of Na and Ca to be consumed.

Hypertension in epileptic mice: a phenomenon related to reduction of Ca(2+)-dependent catecholamine synthesis in the brain

The possible complication of hypertension and epilepsy was investigated through the response in epileptic El mice. The systolic blood pressure in El mice (male, 8 weeks of age) and that in normal ddY mice (the parent strain of El mice) were compared by a tail-cuff method, using a programmed sphygmomanometer. The systolic blood pressure in El mice (120.5 +/- 5.6 mm Hg) was 28% (P < 0.01) higher than that in ddY mice (93.9 +/- 5.3 mm Hg). The higher systolic blood pressure in El mice was lowered by the acute intracerebroventricular administration of CaCl2 (10 mumol/kg, 30 min before measurement) or dopamine (30 nmol/mouse, 15 min before measurement), and was also improved by the chronic oral supplementation with 1.2% calcium (Ca2+) solution. Combining these results with those in our previous reports, where it is stated that lowering of Ca(2+)-calmodulin-dependent catecholamine synthesis increases the susceptibility to epileptic convulsions, we suggest that the increase in susceptibility to epileptic convulsion and occurrence of hypertension in El mice may be linked and that the two diseases may be associated.

A study of pattern of body mass index (BMI) and prevalence of obesity in a Saudi population

The present study was conducted to assess the pattern of body mass index (BMI) prevalence of obesity, and the association between obesity and other health-related problems in a Saudi population. The study was conducted in Queza district of Jeddah, Saudi Arabia. A systematic random sample of Saudi nationals aged 16 years and above were selected (total number 1037; 611 males and 426 females). The study population was clinically examined and a specially-designed questionnaire was administered to obtain the information. Anthropometric measurements, blood pressure and urine analysis were carried out. The collected data were analyzed using simple as well as multivariate statistical methods. It was observed that BMI significantly increased with age. The crude mean BMI was significantly greater in females compared to males. Prevalence of Grade I obesity among different age groups in males ranged from 15.7% to 43.0%, while in females the range was from 22.8% to 45.7%. Similar patterns for both genders were found for Grade II obesity (5.2%-18.9%; and 11.1%-47.8% respectively). Obesity was significantly associated with an increase in both systolic and diastolic blood pressure, where increase in BMI by one unit increased systolic blood pressure by 0.617 mm Hg, and diastolic blood pressure by 0.484 mm Hg. This relationship held true even after allowing for other confounding factors. The present study concluded that obesity is a problem prevalent in the community of Queza district. It is recommended that health education programs be implemented through primary health care services in the community to prevent this problem.

Potassium inhibits free radical formation

We conducted this study to determine whether physiological changes in potassium concentration affect free radical formation by vascular cells. We assessed the effects of potassium on reactive oxygen species formed by cultured endothelial and monocyte/macrophage cells or freshly isolated human white blood cells by cytochrome c reduction or luminol chemiluminescence, respectively. Reducing potassium concentration of endothelial cell media (normally 5.1 to 6.1 mmol/L) to 3.0 mmol/L exponentially increased the rate of cytochrome c reduction, up to 8.4-fold at 2 hours; raising potassium concentration to 5.5 or 7.0 mmol/L at 1 hour reduced the maximal rate of cytochrome c reduction by 86% or 93%. Subsequent studies were done 30 to 75 minutes after media change. Potassium reduced the rate of cytochrome c reduction by 49% (endothelial cells) to 55% (monocytes/macrophages) between 3.0 and 7.0 mmol/L; the greatest decrement (20% to 26%) occurred between 3.0 and 4.0 mmol/L. Superoxide dismutase reduced the rate of cytochrome c reduction by 62% or 50% in endothelial or monocyte/macrophage cells. Potassium had no effect on the rate of cytochrome c reduction in the presence of superoxide dismutase. Increasing potassium concentration from 1.48 to 4.77 or 7.94 mmol/L also reduced luminol chemiluminescence in human white blood cells challenged by 1 to 10 mg/mL zymosan. We conclude that physiological increases in potassium concentration inhibit the rate of superoxide anion formation by cell lines derived from endothelium and from monocytes/macrophages and reactive oxygen species formation by human white blood cells.

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.

Cardiovascular risk in adult Melbourne Chinese

Chinese migrants have low cardiovascular mortality, particularly in their first 10 years of residence in Australia. The apparent increase in cardiovascular deaths among Asian migrants who have lived in Australia for more than 10 years suggests that cardiovascular risk transition may occur soon after migration. In this descriptive study, we found that Melbourne Chinese were not low in cardiovascular risk factors as usually defined. The prevalence of hyperlipidaemia (7.7 per cent for men and 5.2 per cent for women) was similar to the prevalence for other Australians (6.8 per cent for men and 4.4 per cent for women). In spite of low mean blood pressure (systolic blood pressure 114 +/- 23 mmHg (mean +/- standard deviation) and diastolic blood pressure 67.3 +/- 10.6 mmHg), Melbourne Chinese women were hypertensive as often as their Australian counterparts. The prevalence of cigarette smoking in men (26.9 per cent) was also comparable to prevalence for Australian males (24.1 per cent). Being slim is the only recognised cardiovascular protection that Melbourne Chinese may have. A high waist-to-hip ratio (0.91 +/- 0.054 for men and 0.88 +/- 0.077 for women), however, may outweigh the potential benefit of lower prevalence of overweight (17.7 per cent for men and 14.1 per cent for women). Melbourne Chinese men had a multiple risk-factor profile similar to their Australian counterparts. Differences in multiple risk factors in women were attributable to fewer Chinese women having a single risk factor (15.4 per cent versus 30.1 per cent).(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between hemoglobin and cardiovascular risk factors in young adults

To understand mechanisms of association between hemoglobin and cardiovascular disease (CVD), the relationships between hemoglobin and CVD risk factors were examined in 5115 black and white men and women who participated in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Hemoglobin was higher in men than women, whites than blacks, and smokers than non-smokers (p < 0.001). After adjusting for age, body mass index, current smoking status, and clinical center, hemoglobin correlated with diastolic blood pressure (0.11 < or = r < or = 0.22, p < 0.001) and plasma total cholesterol (0.08 < or = r < or = 0.11, p < 0.01) in all four race-sex groups and with systolic blood pressure in all but black women (0.07 < or = r < or = 0.13, p < 0.05). Among other factors possibly related to CVD risk, only serum albumin and white blood cell count showed significant correlations with hemoglobin in all groups (0.19 < or = r < or = 0.27, 0.07 < or = r < or = 0.18, respectively). These findings suggest that an association of hemoglobin with CVD risk factors may explain the association of hemoglobin with CVD.

Central neural mechanism contributing to attenuation of angiotensin II-induced hypertension in rats on dietary calcium supplementation

The effect of dietary calcium (Ca) supplementation on blood pressure (BP) and the central nervous system (CNS) mechanism underlying this effect were studied in angiotensin II (Ang II)-induced hypertensive rats. The effects of dietary Ca (0.5, 2, 4%) on systolic blood pressure (SBP), ionized Ca concentration (Ca++) in cerebrospinal fluid (CSF) and central norepinephrine (NE) turnover were investigated in male Wistar rats receiving subcutaneous infusion of Ang II (100 ng/min). Central NE turnover was studied by measuring 3-methoxy-4-hydroxyphenylglycol (MHPG) concentration in CSF with multiple electrode liquid chromatography. Ang II significantly increased SBP, and dietary Ca dose-dependently attenuated the increase. SBP inversely correlated with Ca++ and MHPG in CSF. Intracerebroventricular injection of CaCl2 more markedly reduced BP in Ang II-treated rats than that in control rats. These results suggest that modulation of central NE turnover possibly caused by the increase in CNS Ca++ is involved in the anti-hypertensive mechanism of dietary Ca supplementation in Ang II-induced hypertensive rats.

Alterations in cellular calcium handling as a result of systemic calcium deficiency in the developing chick embryo: II. Ventricular myocytes

We have previously shown that cardiovascular anomalies, such as hypertension and tachycardia, develop in Ca(2+)-deficient, shell-less (SL) chick embryos cultured ex ovo, accompanied by elevated circulating catecholamines and higher alpha-adrenergic sensitivity of cardiovascular functions. Results described in the preceding work, using erythrocytes as an experimental system, show that cellular Ca2+ handling properties are also altered as a result of long-term calcium deficiency. To examine the relevance of these findings to cells of the cardiovasculature, we have analyzed and compared the Ca2+ handling characteristics of the heart cells of SL and normal (NL) embryos. For this study, isolated and cultured ventricular myocytes of SL and NL embryos were loaded with Fura-2 via transient membrane damage with glass beads. Compared to Fura-2/AM, bead loading yielded similar values and kinetic profiles of [Ca2+]i-dependent differential fluorescence and, in addition, did not affect cell viability and beating activity. The Fura-2 loaded ventricular myocytes were washed in Ca(2+)-free buffer and then analyzed by ratiometric fluorescence (350 nm/380 nm) microscopy for kinetic changes in [Ca2+]i (R350/380 values) as a function of [Ca2+]o and adrenergic modifiers. At 0.5 and 1.0 mM [Ca2+]o, SL cells showed significantly higher [Ca2+]i, higher beating rates, and faster rate of increase in [Ca2+]i compared to NL cells. At higher [Ca2+]o (3.5 mM), there was no significant difference in [Ca2+]i and beating rate between NL and SL cells. Treatment with norepinephrine (NE; 0.01-1 microM) at 1 mM [Ca2+]o substantially increased [Ca2+]i in both NL and SL cells. In the former, the NE effect was completely inhibited by beta-blockade (1 microM propranolol). In contrast, in SL cells, NE remained effective after beta-blockade, and combined alpha-blockade (1 microM prazosin) and beta-blockade was needed to inhibit completely the NE effect. In both NL and SL cells, treatment with NE substantially increased beating rates in a similar manner. Taken together, these findings suggest that Ca2+ handling and adrenergic regulation of the heart cells are significantly altered in the SL embryos, and that these alterations may be related to the development of impaired cardiovascular functions resulting from systemic Ca2+ deficiency.

Alterations in cellular calcium handling as a result of systemic calcium deficiency in the developing chick embryo: I. Erythrocytes

Chick embryos rendered calcium (Ca) deficient by shell-less (SL) culture develop hypertension and tachycardia. Since hypocalcemia is accompanied by hypernatremia systemically but not by lower cellular Ca (Koide and Tuan, 1989), we speculate that cellular Ca handling may be altered in the SL embryo, perhaps involving Na transport. Using erythrocytes (RBC) from day-14 SL and normal (NL) embryos as the experimental cell, cellular Ca handling was studied under varying extracellular osmotic and ionic conditions by analyzing 45Ca uptake and cell volume regulation. Two agents, p-chloromercuriphenylsulfonate (PCM), and inosine/iodoacetamide (INI) were used to treat the RBCs to modify plasma membrane ion permeability and to deplete cellular ATP, respectively. Other cellular functions and activities related to Ca homeostasis, including ATP content and Ca(2+)-ATPase activity, were also analyzed. These analyses showed: (1) in NaCl, Ca uptake was similar in NL and SL cells, except after INI treatment, which resulted in slower Ca uptake by the SL cells, (2) in choline and sucrose, Ca uptake by SL RBCs was higher, (3) Ca uptake by RBCs of both embryos changed depending on the osmotic agent (Na < K < or = choline < sucrose), (4) Ca(2+)-ATPase activity was higher in SL RBC, although there was no change in the size or charge of the enzyme, and (5) in any osmotic agent, cellular Na was significantly lower, whereas cellular K was higher, in SL RBC. Based on these results, three features of RBC Ca handling were apparent: (1) Na-Ca exchange was functional and was more active in SL RBCs, (2) Ca uptake was dependent on the total ionic electrochemical gradient but not on bulk H2O movement, and (3) Ca pumping out capacity was directly correlated with Ca(2+)-ATPase activity. Elevated Ca uptake in sucrose-treated SL RBC is therefore indicative of its greater ion permeability. Taken together, these findings indicate that cellular Ca handling of the RBCs of SL chick embryos is characterized by a more active Na-Ca exchange system, greater ion permeability, and higher Ca pumping out capacity, thereby suggesting an up-regulated Ca handling function in the SL RBCs. The abnormal cellular Ca handling may be a direct result of the systemic Ca deficiency of the SL chick embryo and may be functionally related to its hypertension and tachycardia.

A prospective study of nutritional factors and hypertension among US men

BACKGROUND

An effect of diet in determining blood pressure is suggested by epidemiological studies, but the role of specific nutrients is still unsettled.

METHODS AND RESULTS

The relation of various nutritional factors with hypertension was examined prospectively among 30,681 predominantly white US male health professionals, 40-75 years old, without diagnosed hypertension. During 4 years of follow-up, 1,248 men reported a diagnosis of hypertension. Age, relative weight, and alcohol consumption were the strongest predictors for the development of hypertension. Dietary fiber, potassium, and magnesium were each significantly associated with lower risk of hypertension when considered individually and after adjustment for age, relative weight, alcohol consumption, and energy intake. When these nutrients were considered simultaneously, only dietary fiber had an independent inverse association with hypertension. For men with a fiber intake of < 12 g/day, the relative risk of hypertension was 1.57 (95% confidence interval, 1.20-2.05) compared with an intake of > 24 g/day. Calcium was significantly associated with lower risk of hypertension only in lean men. Dietary fiber, potassium, and magnesium were also inversely related to baseline systolic and diastolic blood pressure and to change in blood pressure during the follow-up among men who did not develop hypertension. Calcium was inversely associated with baseline blood pressure but not with change in blood pressure. No significant associations with hypertension were observed for sodium, total fat, or saturated, transunsaturated, and polyunsaturated fatty acids. Fruit fiber but not vegetable or cereal fiber was inversely associated with incidence of hypertension.

CONCLUSIONS

These results support hypotheses that an increased intake of fiber and magnesium may contribute to the prevention of hypertension.

[Evaluation of dietary intake of calcium in adult subjects with idiopathic arterial hypertension]

The calcium-intake relationship with other alimentary and anthropometric variables was investigates in a group of 60 adult (19-75 year-old) subjects, 50 females and 10 males, with essential arterial hypertension (DAP > 90 mmHg). The calcium intake was assessed by three different protocols: 24-hour food intake recall, food-frequency questionnaire and 3 day self-food intake register, repeated along with anthropometric measurements on three different occasions (2-15 month-intervals). The calcium intake assessed by the three methods, as well as the anthropometric data, were statistically similar on all three occasions. The mean data were then compared with those form the control, composed of 75 healthy subjects matched with the hypertensive group by age and sex. The patients ingested less calcium (mean +/- SD) than the controls on the daily (517 +/- 271 x 740 +/- 353 mg/d) and body-weight (8.1 +/- 5.0 x 11.4 +/- 5.9 mg/kg/d) basis. Among the males the calcium intake was the only difference found between groups and could be attributed to the lower intake of calcium-rich foods. The hypertensive females showed also higher lean-body mass (Body-mass index and arm muscle circumference). Thus the calcium intake discriminated both groups being associated with changes in other nutritional parameters only in females.

Socioeconomic status and electrolyte intake in black adults: the Pitt County Study

BACKGROUND

Although the inverse association between socioeconomic status (SES) and blood pressure has often been observed, little is known about the relationship between SES and dietary risk factors for elevated blood pressure. Therefore, this study described the distribution of dietary intakes of sodium, potassium, and calcium and examined the association between electrolyte intake and SES among 1784 Black men and women aged 25 to 50 residing in eastern North Carolina.

METHODS

Household interviews were conducted in 1988 to obtain information on psychosocial and dietary correlates of blood pressure. Electrolyte intake (mg/day) was assessed using a food frequency questionnaire adapted to reflect regional and ethnic food preferences. SES was categorized into three levels defined by the participant's educational level and occupation.

RESULTS

After adjustment for age and energy intake, potassium and calcium intake increased with increasing SES for both sexes. Sodium intake was high for all groups and did not vary markedly with SES, but sodium to potassium and sodium to calcium ratios decreased with increasing SES. In addition, high SES individuals were more likely to believe that diet affects risk for disease and to report less salt use at the table and less current sodium consumption than in the past.

CONCLUSION

These data indicate that nutritional beliefs as well as the consumption of electrolytes are associated with SES in Black adults.

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.

Epidemiologic studies utilizing surveys: accounting for the sampling design

BACKGROUND

Since large-scale health surveys usually have complicated sampling schemes, there is often a question as to whether the sampling design must be considered in the analysis of the data. A recent disagreement concerning the analysis of a body iron stores-cancer association found in the first National Health and Nutrition Examination Survey and its follow-up is used to highlight the issues.

METHODS

We explain and illustrate the importance of two aspects of the sampling design: clustering and weighting of observations. The body iron stores-cancer data are reanalyzed by utilizing or ignoring various aspects of the sampling design. Simple formulas are given to describe how using the sampling design of a survey in the analysis will affect the conclusions of that analysis.

RESULTS

The different analyses of the body iron stores-cancer data lead to very different conclusions. Application of the simple formulas suggests that utilization of the sample clustering in the analysis is appropriate, but that a standard utilization of the sample weights leads to an uninformative analysis. The recommended analysis incorporates the sampling weights in a nonstandard way and the sample clustering in the standard way.

CONCLUSIONS

Which particular aspects of the sampling design to use in the analysis of complex survey data and how to use them depend on certain features of the design. We give some guidelines for when to use the sample clustering and sample weights in the analysis.