Dietary fats, antioxidants and blood pressure

Although obesity and alcohol intake as well as dietary sodium, potassium and magnesium are the major non-genetic determinants of blood pressure levels, interest has recently been stimulated in the function of fatty acids and antioxidants in the aetiology of hypertension. In the Kuopio Ischaemic Heart Disease Risk Factor Study both plasma ascorbic acid and serum selenium concentrations had a moderate, independent inverse association, estimated dietary intake of saturated fatty acids had a positive association and estimated dietary intake of linolenic acid had an inverse association with the mean resting blood pressure in 722 Eastern Finnish men with neither self reported hypertension nor cerebrovascular disease. Even though these cross sectional observations do not prove causality, they warrant clinical trials to verify or disprove that dietary fats and antioxidants are factors in the development of hypertension.     

Dietary Fats,Antioxidants and Blood Pressure

Although obesity and alcohol intake as well as dietary sodium, potassium and magnesium are the major non-genetic determinants of blood pressure levels, interest has recently been stimulated in the function of fatty acids and antioxidants in the aetiology of hypertension. In the Kuopio Ischaemic Heart Disease Risk Factor Study both plasma ascorbic acid and serum selenium concentrations had a moderate, independent inverse association, estimated dietary intake of saturated fatty acids had a positive association and estimated dietary intake of linolenic acid had an inverse association with the mean resting blood pressure in 722 Eastern Finnish men with neither self reported hypertension nor cerebrovascular disease. Even though these cross sectional observations do not prove causality, they warrant clinical trials to verify or disprove that dietary fats and antioxidants are factors in the development of hypertension.     

Salt and hypertension: recent advances and perspectives

Dietary sodium intake has long been considered important in the genesis and maintenance of hypertension. This view is predicated on the results of epidemiologic observations, experiments in animals, investigations at the cellular level, and the results from dietary intervention trials. In the past decade a considerable body of new evidence has been gathered. A comprehensive, world-wide epidemiologic investigation involving over 10,000 subjects found significant relationships between sodium excretion and blood pressure levels and between sodium excretion and the slope of increase in blood pressure with age. The relationships, however, are not as straight-forward as previously proposed. Investigations in animals and in human subjects emphasize the genetic nature of salt sensitivity of blood pressure. A putative genetic marker has been suggested in human studies. At the cellular level, increases in sodium-lithium countertransport, sodium-hydrogen exchange, and cytosolic calcium level have been identified. Cytosolic calcium level was found to increase in lymphocytes in response to a high-salt diet in salt-sensitive individuals with hypertension, yet the identification of a circulating inhibitor of sodium-potassium--dependent adenosine triphosphatase remains elusive. Dietary intervention trials of salt restriction in patients with hypertension are generally disappointing. Active research is elucidating the role of sodium intake and hypertension at all levels. The data to date, however, still do not allow sweeping conclusions or generalizations.     

Induction of arterial hypertension in normal and adrenalectomized rats given cortisone acetate

1. Marked hypertension was induced in adrenalectomized rats on a sodium-restricted intake by the administration of cortisone acetate; on a similar regimen, adrenalectomized rats receiving DCA failed to become hypertensive. 2. The incorporation of a liberal amount of sodium in the diet of adrenalectomized rats receiving cortisone acetate resulted in a lesser degree of hypertension; whereas on a similar regimen, DCA-injected animals became strikingly hypertensive, as has been previously reported. 3. The presence of hypertension in the cortisone acetate-treated rats was not associated with histological evidence of renal damage or serum electrolyte disturbance, such as was observed in hypertensive animals receiving DCA. 4. The hypertension in sodium-restricted normal rats receiving cortisone acetate was less striking than in similarly treated adrenalectomized animals. On a liberal sodium intake similar degrees of hypertension were noted in both intact and adrenalectomized groups. 5. To approximate the loss of weight which occurred in cortisone acetate-injected rats, it was necessary to curtail the food intake of partially fasted control groups to 50 to 75 per cent of the amount consumed by the animals receiving the steroid. 6. The serum cholesterol levels of the cortisone acetate-injected rats were consistently and strikingly elevated as contrasted with normal, partially fasted, or DCA-treated animals.     

Role of uric acid in hypertension, renal disease, and metabolic syndrome

Hyperuricemia has long been known to be associated with cardiovascular disease, and it is particularly common in people with hypertension, metabolic syndrome, or kidney disease. Most authorities have viewed elevated uric acid as a secondary phenomenon that is either innocuous or perhaps even beneficial, since uric acid can be an antioxidant. However, recent experiments have challenged this viewpoint. In this paper we argue that uric acid is a true risk factor for cardiovascular disease. Furthermore, we suggest that the recent increased intake in the American diet of fructose, which is a known cause of hyperuricemia, may be contributing to the current epidemic of obesity and diabetes.     

Implications of nutritional status on human biochemistry, physiology, and health

Optimum nutrition is the level of intake that should promote the highest level of health. Although excess caloric intake will lead to obesity, a deficit in nutrition may result in a tissue depletion of essential nutrients that can lead to biochemical changes and eventually to clinical signs and symptoms. Nutrition requirements may differ according to sex, age, activity, or physiological state and can be influenced by drugs, smoking, alcohol, and other factors. With ever-increasing sedentary life styles and less physically demanding jobs, the resulting reduced caloric requirements have made it more difficult to make nutritionally sound food choices. Nutrition is the single most important component of preventive health care. Diet has been associated with cancer, heart disease, diabetes, stroke and hypertension, arteriosclerosis, and cirrhosis of the liver. The ability of the human to respond to stresses, such as altitude, heat, trauma, surgery, and infection can be influenced by nutritional status. Nutritional status is reflected in a variety of metabolic processes that provide the basis for a number of methods for its assessment.     

Prevalence of and risk factors for isolated systolic hypertension in the rural adult population of Liaoning Province, China

The prevalence of and associated risk factors for isolated systolic hypertension, as defined by the Joint National Committee (JNC)-6 classification, were investigated in the rural population of Liaoning Province, China. A total of 45,925 people aged 35 years or older were examined in a cross-sectional study. Overall, the prevalence of isolated systolic hypertension was 10.6% (males 10.1%; females 11.2%). The prevalence of isolated systolic hypertension was positively correlated with age, gender, smoking status, alcohol intake, body mass index, salt intake and Mongolian race. This study showed that isolated systolic hypertension was very common in rural Chinese people and that many risk factors are linked with isolated systolic hypertension.     

Therapeutic implications of sodium abnormalities in hypertension

Abnormalities in cellular sodium transport have been demonstrated in leukocytes and erythrocytes of some patients with essential hypertension. Some patients with essential hypertension retain more sodium on a high-salt diet, despite an accompanying increase in pressure. Some epidemiological studies suggest a relationship between dietary sodium intake and essential hypertension. The biological significance of these findings remains uncertain. There is too little evidence to support dietary sodium restriction as a primary preventive measure in essential hypertension. Restriction of dietary intake of sodium to 80 mmol/day results in a reduction in blood pressure in a minority of patients with essential hypertension.     

Calcium and hypertension

A possible relationship between dietary calcium intake and blood pressure has been the focus of considerable recent observational and experimental research. To provide a current perspective, we have reviewed and summarized the epidemiologic data, evidence suggesting abnormalities in calcium metabolism in human hypertension, studies evaluating calcium supplementation in various hypertension populations, and data that may help elucidate possible blood pressure-lowering mechanisms of calcium supplementation. An important relationship between "calcium metabolism" and "salt-sensitivity" is emerging and appears to be providing insights into potential mechanisms that account for the antihypertensive properties of dietary calcium in certain individuals. More experimental work needs to be performed to further define the individuals with hypertension who demonstrate a blood pressure-lowering response to dietary calcium supplementation.     

Electrolytes in the epidemiology, pathophysiology, and treatment of hypertension

The data regarding the value of manipulating electrolytes in hypertension are controversial. It appears there are subsets of hypertensive patients who respond with lowering of blood pressure in conjunction with changes in intake of sodium, potassium, and calcium. The information regarding phosphorus and magnesium is less convincing. This paper examines current reports regarding these electrolytes and their role in the pathophysiology and treatment of essential hypertension.     

Japanese dietary intake of salt and protein--relating to the strategy of salt restriction

The high level of Japanese salt intake, which has been the major risk factor for cerebrovascular disease and hypertension, has decreased since World War II, and reached a steady level. In the present study, the dietary salt intake in Tohoku (once the district of highest sodium intake) and that in Kyushu (once the district of median or low sodium intake) were studied in relation to nutritional status by the analysis of sodium and urea-nitrogen excretion in 24-hr urine samples collected from 305 healthy Japanese. When the amount of urinary creatinine and urea-nitrogen were adjusted, the mean value of urinary sodium in females was significantly larger in Tohoku than in Kyushu, but not significantly in males. The regional difference of salt intake still remains, although it seems to be disappearing. Traditionally, Japanese high intake of salt was accompanied by poor nutritional status. In the present study, however, a significant positive correlation was observed between sodium and urea-nitrogen. The excess of protein intake would cause the excess of salt intake. Therefore, the strategy of further salt restriction should be directed to not only traditional salty foods but also nutritional status such as protein intake.     

The effect of n-3 polyunsaturated fatty acids on lipids, platelet function, coagulation, fibrinolysis and monocyte chemotaxis in patients with hypertension

We have studied the effect of dietary supplementation with 4 g of n-3 polyunsaturated fatty acids (n-3 PUFA) daily for 6 wk on plasma lipids, haemostasis and monocyte chemotaxis in 10 patients with untreated hypertension. Total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides did not change, but the ratio of total to HDL-cholesterol was significantly reduced after the fish oil supplement. Platelet function was unaltered by intake of n-3. Plasma fibrinogen and fibronectin decreased after supplementation with n-3 PUFA, while the effects on fibrinolysis were equivocal. Monocyte chemotaxis was reduced by the supplement. These data lend support to a role for an increased intake of n-3 PUFA in the management of patients with hypertension.     

A prospective study of patients with radiological pyelonephritis, papillary necrosis and obstructive atrophy

Twenty-six patients with radiological unilateral chronic pyelonephritis,36 patients with bilateral chronic pyelonephritis, 14 patientswith papillary necrosis and nine patients with obstructive atrophyhave been followed from five to 135 months for a total of 374patient years. Serial changes in renal function and pyelographicappearances have been correlated with bacteriuria, analgesicingestion, blood pressure and reflux. The calculated survival rate at five years was 95 per cent forpatients with bilateral pyelonephritis and 92 per cent for patientswith papillary necrosis. The ten-year survival rate was 86 percent and 56 per cent respectively. The survival rate for patientswith unilateral pyelonephritis and obstructive atrophy was 100per cent at five and ten years. Bacteriuria was not associated with deteriorating renal functiondetermined by serial plasma creatinine estimations. Althoughall patients in whom there was some radiographic change hadbacteriuria on later review, other factors, including excessanalgesic intake, reflux and stones were recognized in most. There was a high incidence of analgesic ingestion among patientswhose renal function declined and in whom there was some changein serial radiographs. The prevalence of hypertension among patients with normal renalfunction was 12 and 28 per cent for patients with unilateralpyelonephritis and bilateral pyelonephritis respectively. Therewas a significant increase in both blood urea and plasma creatininein all patients with hypertension (diastolic pressure >90mmHg) and a much higher prevalence of hypertension in patientswhose plasma creatinine exceeded 1.3 mg/100 ml. Thirty per centof patients with unilateral pyelonephritis and 50 per cent withbilateral pyelonephritis had vesicoureteric reflux of varyingdegrees. There was no evidence to suggest that major degreesof reflux (grade 3) was associated with further renal damage. These observations indicate the benign course of the majorityof patients with radiological pyelonephritis. Control of bloodpressure, and analgesic intake will help to preserve renal functionwhilst prevention of symptomatic urinary infection by long termlow dose therapy will reduce morbidity.     

Diabetic nephropathy: early detection, prevention and management.

Diabetic nephropathy typically presents more than a decade after diagnosis of diabetes and correlates with the duration of poorly controlled disease. Diabetic nephropathy begins as glomerular hypertension and hyperfiltration, followed by microalbuminuria and the development of hypertension, overt proteinuria, nephrotic syndrome, and a progressive decline in the glomerular filtration rate. Increasing expansion of the glomerular mesangium correlates with loss of function, resulting in uremia. This process eventually leads to the need for dialysis or renal transplantation in 30 percent of patients with insulin-dependent diabetes. By lowering intraglomerular pressure through enhanced glycemic control, inhibition of angiotensin and limitation of protein intake, severe nephropathy may be prevented, delayed or even partially reversed. Treatment must stress control of hypertension.     

Pharmacokinetic and bioavailability of diltiazem sustained-release: influence of food and time of administration

Summary— Diltiazem is a calcium channel blocking agent known to be effective in the treatment of angina pectoris, hypertension and supraventricular arrhythmias. To improve the conditions of diltiazem administration in the treatment of hypertensive patients, a sustained-release formulation (Mono-Tildiem® LP 300 mg) allowing a single daily oral administration has been developed. The aim of the present study was to first evaluate the influence of food intake and second to evaluate those of the time of administration on the pharmacokinetic parameters and the bioavailability of this sustained-release formulation. The influence of these factors was investigated over two different open, randomized, cross-over studies in 12 healthy volunteers. Although a significant decrease in Tmax and an increase in Cmax occurred when diltiazem sustained-release was administered with food intake, AUC_0–48, and therefore the fraction absorbed, were not modified either by concurrent food intake or by different times of administration. The minor modifications of pharmacokinetic parameters of diltiazem sustained release observed were unlikely to induce any clinical consequence.     

Change in women's dietary fat intake following an acute cardiac event: Extent, predictors and comparison with non-cardiac Australian women and older adults.

BACKGROUND: Cardiac patients are encouraged to reduce their dietary fat intake, yet few studies have assessed fat intake in female cardiac patients. AIM: We assessed changes in fat intake for female cardiac patients at four occasions during the first year following their event, and compared it with fat intake for a non-cardiac sample. METHODS: The Short Fat Questionnaire (SFQ) was administered to 239 women aged 36 to 84 years consecutively admitted to four hospitals at the time of an acute event. Mplus was used to analyse change over time in SFQ scores and to identify predictors of change. Mean SFQ scores were compared with those for a sample of randomly selected Australian women and older adults. RESULTS: Mean SFQ scores decreased substantially during the first two months (t(139) = 8.374, p < 0.001), then increased over the subsequent 10 months (t(146) = 4.656, p < 0.001). By 12 months, SFQ scores remained significantly lower than at baseline. Older women and those with hypertension showed less reduction in fat intake. At all four time-points, mean SFQ scores were significantly lower than those reported for other Australian women and older adults. CONCLUSION: Even prior to their event, female cardiac patients reported lower fat intake than other Australian women and older adults, but showed partial deterioration in adherence following convalescence. Future studies could investigate options for assisting patients to sustain dietary changes, with attention to older patients and those with hypertension.     

Hypertension: endothelial dysfunction, the prothrombotic state and antithrombotic therapy

The pathophysiology of essential hypertension and its complications has been a focus of much research and clinical interest. More recent attention has been directed towards inflammation and endothelial dysfunction, especially since inflammation can promote endothelial dysfunction and the latter has been intimately related to thrombogenesis and atherogenesis. Hypertension is also associated with a prothrombotic or hypercoagulable state, and this may contribute to the observation that despite the blood vessels being exposed to high pressures in hypertension the common complications of the latter are paradoxically thrombotic rather than hemorrhagic--the so-called 'thrombotic paradox of hypertension' (or 'Birmingham paradox'). Despite these thrombotic complications, the role of antithrombotic therapy for primary prevention in hypertension is less defined, unless the patient is at significant risk of cardiovascular events or has renal impairment. Antithrombotic therapy for secondary prevention in hypertension is recommended, but unanswered questions regarding the interactions between aspirin and angiotensin-converting enzyme inhibitors remain.     

The role of obesity, salt and exercise on blood pressure in children and adolescents

The increasing trends of blood pressure (BP) in children and adolescents pose great concern for the burden of hypertension-related cardiovascular disease. Although primary hypertension in childhood is commonly associated with obesity, it seems that other factors, such as dietary sodium and exercise, also influence BP levels in children and adolescents. Several studies support that sympathetic nervous system imbalance, impairment of the physiological mechanism of pressure natriuresis, hyperinsulinemia and early vascular changes are involved in the mechanisms causing elevated BP in obese children and adolescents. Under the current evidence on the association of salt intake and BP, dietary sodium restriction appears to be a rational step in the prevention of hypertension in genetically predisposed children and adolescents. Finally, interventional studies show that regular aerobic exercise can significantly reduce BP and restore vascular changes in obese with hypertensive pediatric patients. This article aims to summarize previous studies on the role of obesity, salt intake and exercise on BP in children and adolescents.     

The role of obesity,salt and exercise on blood pressure in children and adolescents

The increasing trends of blood pressure (BP) in children and adolescents pose great concern for the burden of hypertension-related cardiovascular disease. Although primary hypertension in childhood is commonly associated with obesity, it seems that other factors, such as dietary sodium and exercise, also influence BP levels in children and adolescents. Several studies support that sympathetic nervous system imbalance, impairment of the physiological mechanism of pressure natriuresis, hyperinsulinemia and early vascular changes are involved in the mechanisms causing elevated BP in obese children and adolescents. Under the current evidence on the association of salt intake and BP, dietary sodium restriction appears to be a rational step in the prevention of hypertension in genetically predisposed children and adolescents. Finally, interventional studies show that regular aerobic exercise can significantly reduce BP and restore vascular changes in obese with hypertensive pediatric patients. This article aims to summarize previous studies on the role of obesity, salt intake and exercise on BP in children and adolescents.     

Minerals and Blood Pressure

The mineral elements sodium, potassium, calcium and magnesium play a central role in the normal regulation of blood pressure. In particular, these mineral elements have important interrelationships in the control of arterial resistance.

These elements, especially sodium and potassium, also regulate the fluid balance of the body and, hence, influence the cardiac output. Evidence shows that the present levels of intake of mineral elements are not optimum for maintaining normal blood pressure but predispose to the development of arterial hypertension.

Research results suggest that without sodium chloride (common salt) and other sodium compounds being added to the diet arterial hypertension would be virtually non existent. Moreover, blood pressure would not rise with age. In communities with a high consumption of added sodium, a high intake of potassium and, possibly, magnesium seem to protect against the development of arterial hypertension and the rise of blood pressure with age.

A marked reduction of sodium intake is effective in treating even severe hypertension. A moderate restriction of sodium intake or an increase in potassium intake exert remarkable antihypertensive effects, at least in some hypertensive patients. Magnesium and possibly also calcium supplements may be effective in reducing blood pressure in some hypertensives.

In hypertensive patients treated with drugs sodium restriction and potassium and magnesium supplementation enhance the therapeutic effect, reduce the number and dosage, and lessen the adverse effects of prescribed antihypertensive drugs. Hence, a fall in sodium consumption and increases in potassium and magnesium consumption are useful in preventing and treating arterial hypertension.