Dietary minerals and modification of cardiovascular risk factors

High serum cholesterol, hypertension and obesity are major risk factors for cardiovascular diseases, and together with insulin resistance form a deadly disorder referred to as the metabolic syndrome. All the aspects of this syndrome are strongly related to dietary and lifestyle factors; therefore, it would be reasonable to look for dietary approaches to their modification. Mineral nutrients, such as calcium, potassium and magnesium, lower blood pressure, and especially calcium has beneficial effects also on serum lipids. Recent evidence suggests that increased intake of calcium may help in weight control as well. This review summarizes previous literature on the effects and use of dietary minerals on serum lipids, blood pressure and obesity, with specific focus on the effects of calcium. Calcium and magnesium as divalent cations can form insoluble soaps with fatty acids in the intestine and thus prevent the absorption of part of the dietary fat. Decreased absorption of saturated fat leads to reduction in serum cholesterol level via decreased production of VLDL and increased intake of LDL in the liver. Dietary calcium may also bind bile acids, which increases the conversion of cholesterol to bile acids in the liver. Furthermore, calcium appears to enhance the cholesterol-lowering effect of plant sterols. Thus, dietary combination of the mineral nutrients and plant sterols provides a promising novel approach to the modification of cardiovascular risk factors.     

Endpiece: Hospital league tables 1830

ObjectiveTo assess the long term effects of advice to restrict dietary sodium in adults with and without hypertension.DesignSystematic review and meta-analysis of randomised controlled trials.OutcomesMortality, cardiovascular events, blood pressure, urinary sodium excretion, quality of life, and use of antihypertensive drugs.ResultsThree trials in normotensive people (n=2326), five trials in those with untreated hypertension (n=387), and three trials in people being treated for hypertension (n=801) were included, with follow up from six months to seven years. The large high quality (and therefore most informative) studies used intensive behavioural interventions. Deaths and cardiovascular events were inconsistently defined and reported. There were 17 deaths, equally distributed between intervention and control groups. Systolic and diastolic blood pressures were reduced (systolic by 1.1 mm Hg, 95% confidence interval 1.8 to 0.4 mm Hg; diastolic by 0.6 mm Hg, 1.5 to −0.3 mm Hg) at 13 to 60 months, as was urinary 24 hour sodium excretion (by 35.5 mmol/24 hours, 47.2 to 23.9). Degree of reduction in sodium intake and change in blood pressure were not related.ConclusionsIntensive interventions, unsuited to primary care or population prevention programmes, provide only small reductions in blood pressure and sodium excretion, and effects on deaths and cardiovascular events are unclear. Advice to reduce sodium intake may help people on antihypertensive drugs to stop their medication while maintaining good blood pressure control.

What is already known on this topic

Restricting sodium intake in people with hypertension reduces blood pressureLong term effects (on blood pressure, mortality, and morbidity) of reduced salt intake in people with and without hypertension are unclear

What this study adds

Few deaths and cardiovascular events have been reported in salt reduction trialsMeta-analysis shows that blood pressure was reduced (systolic by 1.1 mm Hg, diastolic by 0.6 mm Hg) at 13 to 60 months, with a reduction in sodium excretion of almost a quarter (35.5 mmol/24 hours)The interventions used were highly intensive and unsuited to primary care or population prevention programmesLower salt intake may help people on antihypertensive drugs to stop their medication while maintaining good control of blood pressure, but there are doubts about effects of sodium reduction on overall health     

Lifestyle modifications to prevent and control hypertension. 5. Recommendations on dietary salt. Canadian Hypertension Society,Canadian Coalition for High Blood Pressure Prevention and Control,Laboratory Centre for Disease Control at Health Canada,Heart and Stroke Foundation of Canada

OBJECTIVE: To provide updated, evidence-based recommendations concerning the effects of dietary salt intake on the prevention and control of hypertension in adults (except pregnant women). The guidelines are intended for use in clinical practice and public education campaigns. OPTIONS: Restriction of dietary salt intake may be an alternative to antihypertensive medications or may supplement such medications. Other options include other nonpharmacologic treatments for hypertension and no treatment. OUTCOMES: The health outcomes considered were changes in blood pressure and in morbidity and mortality rates. Because of insufficient evidence, no economic outcomes were considered. EVIDENCE: A MEDLINE search was conducted for the period 1966-1996 using the terms hypertension, blood pressure, vascular resistance, sodium chloride, sodium, diet, sodium or sodium chloride dietary, sodium restricted/reducing diet, clinical trials, controlled clinical trial, randomized controlled trial and random allocation. Both trials and review articles were obtained, and other relevant evidence was obtained from the reference lists of the articles identified, from the personal files of the authors and through contacts with experts. The articles were reviewed, classified according to study design and graded according to level of evidence. In addition, a systematic review of all published randomized controlled trials relating to dietary salt intake and hypertension was conducted. VALUES: A high value was placed on the avoidance of cardiovascular morbidity and premature death caused by untreated hypertension. BENEFITS, HARMS AND COSTS: For normotensive people, a marked change in sodium intake is required to achieve a modest reduction in blood pressure (there is a decrease of 1 mm Hg in systolic blood pressure for every 100 mmol decrease in daily sodium intake). For hypertensive patients, the effects of dietary salt restriction are most pronounced if age is greater than 44 years. A decrease of 6.3 mm Hg in systolic blood pressure and 2.2 mm Hg in diastolic blood pressure per 100 mmol decrease in daily sodium intake was observed in people of this age group. For hypertensive patients 44 years of age and younger, the decreases were 2.4 mm Hg for systolic blood pressure and negligible for diastolic blood pressure. A diet in which salt is moderately restricted appears not to be associated with health risks. RECOMMENDATIONS: (1) Restriction of salt intake for the normotensive population is not recommended at present, because of insufficient evidence demonstrating that this would lead to a reduced incidence of hypertension. (2) To avoid excessive intake of salt, people should be counselled to choose foods low in salt (e.g., fresh fruits and vegetables), to avoid foods high in salt (e.g., pre-prepared foods), to refrain from adding salt at the table and minimize the amount of salt used in cooking, and to increase awareness of the salt content of food choices in restaurants. (3) For hypertensive patients, particularly those over the age of 44 years, it is recommended that the intake of dietary sodium be moderately restricted, to a target range of 90-130 mmol per day (which corresponds to 3-7 g of salt per day). (4) The salt consumption of hypertensive patients should be determined by interview. VALIDATION: These recommendations were reviewed by all of the sponsoring organizations and by participants in a satellite symposium of the fourth International Conference on Preventive Cardiology. They have not been clinically tested. SPONSORS: The Canadian Hypertension Society, the Canadian Coalition for High Blood Pressure Prevention and Control, the Laboratory Centre for Disease Control at Health Canada, and the Heart and Stroke Foundation of Canada.     

The effects of protein intake on blood pressure and cardiovascular disease

PURPOSE OF REVIEW: Investigators, especially those from western countries, have commonly assumed that there is either no association or a direct association of protein intake with elevated blood pressure and atherosclerosis. In contrast, recent observational studies and clinical trials have suggested that increased protein intake, particularly protein from plant sources, might actually reduce blood pressure and prevent cardiovascular disease. RECENT FINDINGS: In epidemiological studies, an increased intake of protein has been associated with lower blood pressure and an attenuated increase in blood pressure over time. Furthermore, such studies also suggest that the beneficial effects of increased protein intake result from an increased consumption of protein from plant rather than animal sources. In several predominantly small trials, an increased intake of soy protein lowered blood pressure. With respect to clinical outcomes, reports from large cohort studies suggest that increased protein intake is associated with a reduced risk of ischemic heart disease and perhaps intraparenchymal hemorrhage. In other reports, a higher protein intake is one characteristic of a dietary pattern associated with a reduced risk of ischemic heart disease. The mechanisms by which protein could exert its beneficial effects include an increased intake of biologically active amino acids, peptides, or highly correlated nutrients. SUMMARY: Recent evidence suggests that an increased intake of protein, particularly plant protein, may lower blood pressure and reduce the risk of cardiovascular disease. However, the data are not sufficiently compelling to advocate an increased consumption of protein.     

Session on sodium and calcium in the management of hypertension summary of remarks of discussant and chairman

The evidence favouring a link between sodium and blood pressure, namely the interpopulation comparisons, the experimental animal models, and clinical trials of high sodium intake and very low sodium diets, appears to outweigh the evidence disputing this relationship. Differences between studies on the effect of sodium restriction on blood pressure may be explained by differences in a large number of factors including the nature of the study population, dietary sodium intake, amount of reduction of sodium, concurrent dietary intake of other ions and alcohol, and blood pressure at entry into the study. Further research is needed in order to answer the questions raised herein and to provide additional information on sodium and calcium management of hypertension.     

Lifestyle modifications to prevent and control hypertension. 6. Recommendations on potassium,magnesium and calcium. Canadian Hypertension Society,Canadian Coalition for High Blood Pressure Prevention and Control,Laboratory Centre for Disease Control at Health Canada,Heart and Stroke Foundation of Canada

OBJECTIVE: To provide updated, evidence-based recommendations on the consumption, through diet, and supplementation of the cations potassium, magnesium and calcium for the prevention and treatment of hypertension in otherwise healthy adults (except pregnant women). OPTIONS: Dietary supplementation with cations has been suggested as an alternative or adjunctive therapy to antihypertensive medications. Other options include other nonpharmacologic treatments for hypertension. OUTCOMES: The health outcomes considered were changes in blood pressure and in morbidity and mortality rates. Because of insufficient evidence, no economic outcomes were considered. EVIDENCE: A MEDLINE search was conducted for the period 1966-1996 with the terms hypertension and potassium, magnesium and calcium. Reports of trials, meta-analyses and review articles were obtained. Other relevant evidence was obtained from the reference lists of articles identified, from the personal files of the authors and through contacts with experts. The articles were reviewed, classified according to study design, and graded according to the level of evidence. VALUES: A high value was placed on the avoidance of cardiovascular morbidity and premature death caused by untreated hypertension. BENEFITS, HARMS AND COSTS: The weight of the evidence from randomized controlled trials indicates that increasing intake of or supplementing the diet with potassium, magnesium or calcium is not associated with prevention of hypertension, nor is it effective in reducing high blood pressure. Potassium supplementation may be effective in reducing blood pressure in patients with hypokalemia during diuretic therapy. RECOMMENDATIONS: For the prevention of hypertension, the following recommendations are made: (1) The daily dietary intake of potassium should be 60 mmol or more, because this level of intake has been associated with a reduced risk of stroke-related mortality. (2) For normotensive people obtaining on average 60 mmol of potassium daily through dietary intake, potassium supplementation is not recommended as a means of preventing an increase in blood pressure. (3) For normotensive people, magnesium supplementation is not recommended as a means of preventing an increase in blood pressure. (4) For normotensive people, calcium supplementation above the recommended daily intake is not recommended as a means of preventing an increase in blood pressure. For the treatment of hypertension, the following recommendations are made. (5) Potassium supplementation above the recommended daily dietary intake of 60 mmol is not recommended as a treatment for hypertension. (6) Magnesium supplementation is not recommended as a treatment for hypertension. (7) Calcium supplementation above the recommended daily dietary intake is not recommended as a treatment for hypertension. VALIDATION: These guidelines are consistent with the results of meta-analyses and recommendations made by other organizations. They have not been clinically tested. SPONSORS: The Canadian Hypertension Society, the Canadian Coalition for High Blood Pressure Prevention and Control, the Laboratory Centre for Disease Control at Health Canada, and the Heart and Stroke Foundation of Canada.     

Hypertension and nutrition in the young: early intervention?

The few studies, carried out on infants, children, and adolescents, relating blood pressure to sodium intake have shown a weak positive correlation in some but not all individuals. The effect of body size on blood pressure confounds the interpretation of the effect of dietary sodium on blood pressure. There appear to be sodium-sensitive and sodium-unsensitive infants, children, and adolescents and is probably genetically transmitted. Most infants, children, and adolescents in industrialized populations have a salt intake far greater than required, and reduction in dietary sodium is safe and may be beneficial to those individuals with a family history of primary hypertension.     

Role of dietary magnesium in cardiovascular disease prevention, insulin sensitivity and diabetes

PURPOSE OF REVIEW: This review summarizes the evidence for benefits of magnesium on metabolic abnormalities, inflammatory parameters, and cardiovascular risk factors and related-potential mechanisms. Controversy due to contrasting results in the literature is also discussed. RECENT FINDINGS: Increased dietary magnesium intake confers protection against the incidence of diabetes, metabolic syndrome, hypertension, and cardiovascular disease. It ameliorates insulin resistance, serum lipid profiles, and lowers inflammation, endothelial dysfunction, oxidative stress, and platelet aggregability. Magnesium acts as a mild calcium antagonist on vascular smooth muscle tone, and on postreceptor insulin signaling; it is critically involved in energy metabolism, fatty acid synthesis, glucose utilization, ATPase functions, release of neurotransmitters, and endothelial cell function and secretion. Prospective studies, however, have found only a modest effect for dietary magnesium on incident pathologies. Furthermore, magnesium supplementation on glucose metabolism, blood lipid levels, and ischemic heart disease has given inconsistent results. SUMMARY: There is strong biological plausibility for the direct impact of magnesium intake on metabolic and cardiovascular risk factors, but in-vivo magnesium deficiency might play only a modest role. Reverse causality, the strong association between magnesium and other beneficial nutrients, or the possibility that people who choose magnesium-rich foods are more health-conscious may be confounding factors.     

Dietary Protein and Blood Pressure: A Systematic Review

Background

Elevated blood pressure (BP), which is a major risk factor for cardiovascular disease, is highly prevalent worldwide. Recently, interest has grown in the role of dietary protein in human BP. We performed a systematic review of all published scientific literature on dietary protein, including protein from various sources, in relation to human BP.

Methodology/Principal Findings

We performed a MEDLINE search and a manual search to identify English language studies on the association between protein and blood pressure, published before June 2010. A total of 46 papers met the inclusion criteria. Most observational studies showed no association or an inverse association between total dietary protein and BP or incident hypertension. Results of biomarker studies and randomized controlled trials indicated a beneficial effect of protein on BP. This beneficial effect may be mainly driven by plant protein, according to results in observational studies. Data on protein from specific sources (e.g. from fish, dairy, grain, soy, and nut) were scarce. There was some evidence that BP in people with elevated BP and/or older age could be more sensitive to dietary protein.

Conclusions/Significance

In conclusion, evidence suggests a small beneficial effect of protein on BP, especially for plant protein. A blood pressure lowering effect of protein may have important public health implications. However, this warrants further investigation in randomized controlled trials. Furthermore, more data are needed on protein from specific sources in relation to BP, and on the protein-BP relation in population subgroups.     

The effect of fat intake and antihypertensive drug therapy on serum lipid profile: a cross-sectional survey of serum lipids in male and female hypertensives

The present study aimed to investigate the effect of betablocker with diuretics therapy on serum cholesterol and high density lipoprotein (HDL-C) lipids in cross-sectional data (age, sex, weight, and body mass index (BMI), smoking/alcoholic consumption) and supplemented vegetarian low-fat diet with daily low fat energy intake, salt intake, duration of drug therapy, and serum protein as effective measures of lowering blood pressure among hypertensives in both males and females. Hypertensive patients on betablocker and/or thiazide therapy were compared in cross-section study with their age, blood pressure, fat intake, serum lipid profile, BMI, and serum albumin in males and females. Dietary fat intake and serum lipid profile were income related. Betablocker and diuretics therapy in combination with dietary fat intervention was beneficial for prolonged dyslipidemia control. Serum cholesterol level was main contributing factor dependent on BMI, duration of drug, and socio-economic factors. Fat intake contributed in hypertension and serum cholesterol levels. A cross-sectional data analysis showed beneficial effects of “low fat-salt-smoking-alcohol consumption and combined polyunsaturated fatty acid with antihypertensive therapy approach” to keep normal dyslipidemia and hypertension. Low fat intake, low salt, smoking, alcohol consumption, and combination of dietary oil supplements with lipid betablockers and diuretic modulators were associated with low hypertension and controlled dyslipidemia in Asian sedentary population.     

Effects of polyunsaturated fatty acid intake and status during pregnancy,lactation, and early childhood on cardiometabolic health: A systematic review

The importance of polyunsaturated fatty acid (PUFA) intake in fetal life and infancy has been widely studied in relation to child cognitive and visual development, but whether early life PUFA exposure is related to cardiometabolic risk factors is unclear. The focus of this systematic review was to evaluate the effects of PUFA dietary intake and blood levels during pregnancy, lactation, or early childhood (⩽5 y) on obesity, blood pressure, blood lipids, and insulin sensitivity. We identified 4302 abstracts in the databases Embase, Medline and Cochrane Central (April 2014), of which 56 articles, reporting on 45 unique studies, met all selection criteria. Many of the included studies focused on obesity as an outcome (33 studies), whereas studies on insulin sensitivity were relatively scarce (6 studies). Overall, results for obesity, blood pressure, and blood lipids were inconsistent, with a few studies reporting effects in opposite directions and other studies that did not observe any effects of PUFAs on these outcomes. Four studies suggested beneficial effects of PUFAs on insulin sensitivity. We conclude that there is insufficient evidence to support a beneficial effect of PUFAs in fetal life or early childhood on obesity, blood pressure, or blood lipids. More research is needed to investigate the potential favorable effects of PUFAs on insulin sensitivity, and to examine the role of specific fatty acids in early life on later cardiometabolic health.     

Programming of adult cardiovascular function after early maternal undernutrition in sheep

The prenatal nutritional environment influences the subsequent risk of hypertension in adulthood. Animal studies have used, generally, the rat as a model species to illustrate the association between maternal nutrient intake and blood pressure in the resulting adult offspring. No study to date has shown programming of adult cardiovascular function in the sheep through maternal dietary intervention. We therefore fed pregnant sheep to either 100% recommended intake from day 0 of gestation to term [ approximately 147 days gestational age (dGA); controls n = 8] or to 50% recommended intake from day 0 to 95 dGA and thereafter to 100% intake (NR; n = 9). Sheep lambed naturally, offspring were weaned at 16 wk, and the male offspring were reared on pasture until 3 yr of age. At this time, cardiovascular catheters were inserted under halothane anesthesia and sheep were allowed 2-4 days recovery. Basal cardiovascular status and pressor responses to infusion of norepinephrine, angiotensin II, and captopril were then assessed alongside basal plasma concentrations of glucose, cortisol, and leptin. NR sheep were of similar birth weight to controls but at 3 yr of age had higher blood pressure before, but not after, feeding. Peripheral sensitivity to vasoconstrictor infusion was similar between dietary groups, although a reflex bradycardia was not apparent in NR sheep during norepinephrine infusion. Circulating leptin correlated well with fat mass and increased more after vasoconstrictor infusion in NR sheep. In conclusion, early NR has been shown to program aspects of cardiovascular control and adipocyte function in adult sheep.     

Nutrition and hypertension

There has been a good deal of interest in the relation of nutrition to cardiovascular diseases and this is likely to continue. We consider recent research developments concerned with the well known examples of the association of high salt intake with hypertension and of saturated fats with atherosclerosis. Some of the difficulties encountered in the investigation of dietary factors in hypertension are similar to those encountered in the investigation of dietary factors in atherosclerosis and coronary heart disease. Much additional research, which takes into account the multifactorial nature of cardiovascular disease, is needed to determine the effects of diet on the development and treatment of these diseases.     

Beneficial effects of Provinols: cardiovascular system and kidney

Red wine polyphenols have been reported to exert beneficial effects in preventing cardiovascular diseases but their molecular mechanisms of hemodynamic effects on functional cardiovascular and renal changes were studied much less. The review is focused on in vitro as well as in vivo effects of red wine extract containing polyphenolic compounds (Provinols) on cardiovascular systems and kidney in relation to the molecular and biochemical mechanisms of these compounds. This review provides the evidence that Provinols is able to produce ex vivo endothelium-dependent relaxation as a result of enhanced NO synthesis. Administration of Provinols partially prevents the development of hypertension during NO deficiency and accelerates the decrease of blood pressure in already established hypertension. The effects of Provinols include prevention and/or attenuation of myocardial fibrosis, reduction of aortic wall thickening and improvement of vascular functions. These functional and structural alterations are associated with significant augmentation of NO production, seen as the increase of NO synthase activity and eNOS protein expression. Moreover, it has been documented that Provinols decreased the oxidative stress within the cardiovascular system and kidney.     

Cardiovascular complications and related risk factors underlying opium consumption

Opium is considered as the second most abused addictive compound in worldwide. It seems that one of the causes for common consumption of opium in many countries is a traditional belief, even among medical personnel, through which opium might have advantageous influences on cardiovascular events and be beneficial in controlling hypertension, dyslipidemia, and diabetes. According to several investigations, it is thought that opium not only has no beneficial effects on cardiovascular events, but it might have deleterious influences on these settings. As a result, people need to be trained with regard to the adverse effects of opium on cardiovascular events. In this review, we try to go through the understanding of the effects of opium cardiovascular disorders and related complications such as blood pressure, blood sugar, lipid circumstances, and finally atherosclerosis.     

Docosahexaenoic acid (DHA) and cardiovascular disease risk factors

Numerous epidemiological and controlled interventional trials have supported the health benefits of long-chain omega-3 fatty acids in the form of docosahexaenoic acid (DHA, 22:6n-3) plus eicosapentaenoic acid (EPA, 20:5n-3) from fish and fish oils as well as from algal sources. The beneficial effects on cardiovascular disease and related mortality including various risk factors for cardiovascular disease (particularly lowering circulating triglyceride levels and the triglyceride:HDL-cholesterol ratio) have been observed in the absence of any concomitant blood cholesterol lowering. With appropriate dosages, consistent reductions in both fasting and postprandial triglyceride levels and moderate increases in fasting HDL-cholesterol levels have been observed with algal DHA in the majority of trials. These results are similar to findings for fish oils containing DHA and EPA. Related to greater fish intake, higher levels of DHA in circulating blood biomarkers (such as serum phospholipid) have been associated with reduced risks for the progression of coronary atherosclerosis and lowered risk from sudden cardiac death. Controlled clinical trials have also indicated the potential for algal DHA supplementation to have moderate beneficial effects on other cardiovascular disease risk factors including blood pressures and resting heart rates. Recommended intakes of DHA+EPA from numerous international groups for the prevention and management of cardiovascular disease have been forthcoming, although most have not offered specific recommendations for the optimal individual intake of DHA and EPA.     

Sodium manipulation in the management of hypertension. The view against its general use

Extreme changes in sodium intake do have an effect on blood pressure of both normotensive and hypertensive individuals. Cross-population correlates of average sodium intake and mean population blood pressure are discordant with the results of studies within single populations and cannot be used as sufficient evidence to justify a reduction of dietary sodium intake in the general population to prevent hypertension. Both explanatory and management trials of sodium restriction have yielded contradictory results, and convincing evidence on the nature and size of subgroups of hypertensives with enhanced sodium sensitivity is lacking. The proportion of patients who will follow a moderately restricted sodium diet is low, unless expensive and time-consuming programs of instruction and monitoring are introduced. In light of this evidence, it is premature to recommend diets that are low in sodium as a public health measure and as initial and sole treatment of hypertension.     

Systematic review of randomised controlled trials of multiple risk factor interventions for preventing coronary heart disease.

OBJECTIVE: To assess the effectiveness of multiple risk factor intervention in reducing cardiovascular risk factors, total mortality, and mortality from coronary heart disease among adults. DESIGN: Systematic review and meta-analysis of randomised controlled trials in workforces and in primary care in which subjects were randomly allocated to more than one of six interventions (stopping smoking, exercise, dietary advice, weight control, antihypertensive drugs, and cholesterol lowering drugs) and followed up for at least six months. SUBJECTS: Adults aged 17-73 years, 903000 person years of observation were included in nine trials with clinical event outcomes and 303000 person years in five trials with risk factor outcomes alone. MAIN OUTCOME MEASURES: Changes in systolic and diastolic blood pressure, smoking rates, blood cholesterol concentrations, total mortality, and mortality from coronary heart disease. RESULTS: Net decreases in systolic and diastolic blood pressure, smoking prevalence, and blood cholesterol were 4.2 mm Hg (SE 0.19 mm Hg), 2.7 mm Hg (0.09 mm Hg), 4.2% (0.3%), and 0.14 mmol/l (0.01 mmol/l) respectively. In the nine trials with clinical event end points the pooled odds ratios for total and coronary heart disease mortality were 0.97 (95% confidence interval 0.92 to 1.02) and 0.96 (0.88 to 1.04) respectively. Statistical heterogeneity between the studies with respect to changes in mortality and risk factors was due to trials focusing on hypertensive participants and those using considerable amounts of drug treatment, with only these trials showing significant reductions in mortality. CONCLUSIONS: The pooled effects of multiple risk factor intervention on mortality were insignificant and a small, but potentially important, benefit of treatment (about a 10% reduction in mortality) may have been missed. Changes in risk factors were modest, were related to the amount of pharmacological treatment used, and in some cases may have been overestimated because of regression to the mean, lack of intention to treat analyses, habituation to blood pressure measurement, and use of self reports of smoking. Interventions using personal or family counselling and education with or without pharmacological treatments seem to be more effective at reducing risk factors and therefore mortality in high risk hypertensive populations. The evidence suggests that such interventions implemented through standard health education methods have limited use in the general population. Health protection through fiscal and legislative measure may be more effective.     

Diet and calcium stones.

OBJECTIVE: To review the current literature on the dietary modification of urinary risk factors as a means of reducing the likelihood of recurrent stone formation and to develop practical dietary recommendations that might be useful to this end. DATA SOURCES: MEDLINE was searched for English-language articles published from 1983 to 1990. Additional references were selected from the bibliographies of identified articles. STUDY SELECTION: Nonrandomized trials and retrospective reviews were included because of a paucity of randomized controlled trials. DATA SYNTHESIS: Information on the dietary intake of calcium, oxalate, protein, sodium and fibre and on alcohol and fluid intake was used to develop practical guidelines on dietary modification. CONCLUSION: Dietary modification plays an important role in the reduction of urinary risk factors in patients with calcium stone disease of the urinary tract. As an initial form of prevention attention should be directed toward moderating the intake of calcium, oxalate, protein, sodium and alcohol and increasing the intake of fibre and water. Future research should include an assessment of the long-term reduction of dietary and urinary risk factors and the rates of recurrence of calcium stones.     

Beneficial effects of potassium on human health

Until recently, humans consumed a diet high in potassium. However, with the increasing consumption of processed food, which has potassium removed, combined with a reduction in the consumption of fruits and vegetables, there has been a large decrease in potassium intake which now, in most developed countries, averages around 70 mmol day⁻¹, i.e. only one third of our evolutionary intake. Much evidence shows that increasing potassium intake has beneficial effects on human health. Epidemiological and clinical studies show that a high-potassium diet lowers blood pressure in individuals with both raised blood pressure and average population blood pressure. Prospective cohort studies and outcome trials show that increasing potassium intake reduces cardiovascular disease mortality. This is mainly attributable to the blood pressure-lowering effect and may also be partially because of the direct effects of potassium on the cardiovascular system. A high-potassium diet may also prevent or at least slow the progression of renal disease. An increased potassium intake lowers urinary calcium excretion and plays an important role in the management of hypercalciuria and kidney stones and is likely to decrease the risk of osteoporosis. Low serum potassium is strongly related to glucose intolerance, and increasing potassium intake may prevent the development of diabetes that occurs with prolonged treatment with thiazide diuretics. Reduced serum potassium increases the risk of lethal ventricular arrhythmias in patients with ischaemic heart disease, heart failure and left ventricular hypertrophy, and increasing potassium intake may prevent this. The best way to increase potassium intake is to increase the consumption of fruits and vegetables.