Dietary protein and soluble fiber reduce ambulatory blood pressure in treated hypertensives

Dietary protein and risk of hypertension in a Dutch older population: the Rotterdam study

BACKGROUND

Several observational studies suggest an inverse association of protein with blood pressure (BP). However, little is known about the role of dietary protein from specific sources in BP.

METHOD

We examined the relation between several types of dietary protein (total, plant, animal, dairy, meat, grain, fish, soy, and nut) and incident hypertension in 2241 participants from the Rotterdam Study, aged at least 55 years, who were free of hypertension at baseline. Hazard ratios, with 95% confidence intervals (CIs), for incident hypertension during 6 years of follow-up were obtained per standard deviation (SD) of energy-adjusted intake of protein. Hazard ratios were adjusted for age, sex, body mass index (BMI), baseline systolic blood pressure (SBP) smoking, educational level, alcohol, intake of carbohydrates, other nutrients, and other types of protein (if applicable). We conducted stratified analyses by age (cut-off 70 years), sex, and BMI (cut-off 25 kg/m).

RESULTS

The risk of hypertension in the total cohort (1113 cases) was not related to intake of total protein or types of protein (all hazard ratios ∼1.00 per SD). Sex and BMI did not significantly modify the associations of dietary protein with hypertension. In 559 participants aged at least 70 years, the intake of animal protein was positively related to risk of hypertension (hazard ratio 1.37 per SD, 95% CI 1.09-1.72). For participants aged below 70 years no association was found (hazard ratio 0.92, 95% CI 0.81-1.06).

CONCLUSION

Total dietary protein or types of protein are not related to incident hypertension in this older population. In the more aged, however, high intake of animal protein may increase the risk of hypertension, which warrants further investigation.

Lifestyle Intervention Strategies for the Prevention and Treatment of Hypertension: A Review

Hypertension (HTN) is an extraordinarily common progressive cardiovascular syndrome in the United States, afflicting approximately one third of the adult population. HTN is a powerful and unequivocal independent risk factor for cardiovascular and renal diseases, including coronary heart disease, stroke, and renal failure. Despite major advances in the understanding and treatment of HTN over the past several decades, the disease remains the most common primary diagnosis in the United States and is a major public health concern. Adoption of healthy lifestyle modifications has proven to be highly effective in both the prevention of new-onset HTN and in the treatment of those diagnosed with HTN. In view of the continuing epidemic of HTN and blood pressure (BP)—related diseases and the invaluable role of applying nonpharmacological therapy in the prevention and management of HTN, a review of current therapeutic lifestyle strategies appears warranted. This review will define 6 well-established nonpharmacological lifestyle modifications for preventing and managing HTN in addition to 3 novel lifestyle interventions that show promise as effective adjunct strategies for lowering BP. A healthy lifestyle prescription ideally comprising a number of these BP-lowering lifestyle intervention strategies should be dispensed by all primary care physicians for both the prevention and treatment of elevated BP, an action that would have major, positive public health ramifications.

The effects of a lupin-enriched diet on oxidative stress and factors influencing vascular function in overweight subjects

A diet enriched in lupin kernel flour can lower blood pressure, but mechanisms responsible are unclear. Lupin is a source of polyphenols, protein, and L-arginine, factors that may influence blood pressure via effects on oxidative stress and vascular function. Therefore, we aimed to determine the effects of a lupin-enriched diet on oxidative stress and factors influencing vascular function as potential mechanisms for demonstrated benefits on blood pressure. Overweight men and women (n = 88) were recruited to a 16-week parallel-design study. Participants were randomly assigned to replace 15%-20% of their usual daily energy intake with white bread (control) or lupin kernel flour-enriched bread (lupin). All measurements were taken at baseline and 16 weeks. At baseline, plasma F₂-isoprostanes and 20-hydroxyeicosatetraenoic acid (20-HETE) were positively associated with blood pressure, and plasma nitrite was negatively associated with blood pressure (p < 0.05). For lupin relative to control, the estimated differences in plasma F₂-isoprostanes (45 pmol/L; 95%CI: -68, 158), urinary F₂-isoprostanes (17 pmol/mmol creatinine; 95%CI: -43, 76), plasma 20-HETE (75 pmol/L; 95%CI: -91, 241), and plasma nitrite (-0.3 μmol/L; 95%CI: -1.1, 0.4) were not significant. Although regular consumption of lupin-enriched bread can lower blood pressure, these results do not support for the hypothesis that this is via effects on oxidative stress or vascular function.

Dietary protein and risk of ischemic heart disease in middle-aged men

BACKGROUND

Prospective studies in US women have suggested an inverse relation between dietary protein and risk of ischemic heart disease (IHD). However, no large-scale prospective studies have been conducted in US men.

OBJECTIVE

The objective was to examine the association between dietary protein and risk of IHD in a prospective study of US men.

DESIGN

Intakes of protein and other nutrients were assessed by using a validated food-frequency questionnaire at 4 time points during follow-up of 43,960 men participating in the Health Professionals Follow-Up Study. Cox proportional hazards models were used to calculate multivariable-adjusted relative risks (RRs) and 95% CIs.

RESULTS

During 18 y of follow-up, we documented 2959 incident cases of IHD. The RR of IHD was 1.08 (95% CI: 0.95, 1.23; P for trend = 0.30) comparing the top with the bottom quintile of percentage of energy from total protein. RRs for animal and vegetable protein were 1.11 (95% CI: 0.97, 1.28; P for trend = 0.18) and 0.93 (95% CI: 0.78, 1.12; P for trend = 0.49), respectively. When the population was restricted to "healthy" men (those free of hypertension, hypercholesterolemia, and diabetes at baseline), the RR of IHD was 1.21 (95% CI: 1.01, 1.44; P for trend = 0.02) for total protein, 1.25 (95% CI: 1.04, 1.51; P for trend = 0.02) for animal protein, and 0.93 (95% CI: 0.72, 1.19; P for trend = 0.65) for vegetable protein.

CONCLUSIONS

We observed no association between dietary protein and risk of total IHD in this group of men aged 40-75 y. However, higher intake of animal protein may be associated with an increased risk of IHD in "healthy" men.

The effect of nutrition on blood pressure

The incidence and severity of hypertension are affected by nutritional status and intake of many nutrients. Excessive energy intake and obesity are major causes of hypertension. Obesity is associated with increased activity of the renin-angiotensin-aldosterone and sympathetic nervous systems, possibly other mineralcorticoid activity, insulin resistance, salt-sensitive hypertension and excess salt intake, and reduced kidney function. High sodium chloride intake strongly predisposes to hypertension. Increased alcohol consumption may acutely elevate blood pressure. High intakes of potassium, polyunsaturated fatty acids, and protein, along with exercise and possibly vitamin D, may reduce blood pressure. Less-conclusive studies suggest that amino acids, tea, green coffee bean extract, dark chocolate, and foods high in nitrates may reduce blood pressure. Short-term studies indicate that specialized diets may prevent or ameliorate mild hypertension; most notable are the Dietary Approaches to Stop Hypertension (DASH) diet, which is high in fruits, vegetables, and low-fat dairy products, and the DASH low-sodium diet. Long-term compliance to these diets remains a major concern.

The right fiber for the right disease: an update on the psyllium seed husk and the metabolic syndrome

The metabolic syndrome (MS) is a clustering of hyperglycemia/insulin resistance, dyslipidemia, overweight and hypertension. MS identifies patients who are at high risk of developing atherosclerotic cardiovascular disease (CVD) and type 2 diabetes (T2D). Based on current data dietary fibre intake from whole foods or supplements may lower blood pressure, may improve serum lipid levels, may reduce indicators of inflammations,may lower serum glucose levels and favour body weight loss. US Food and Drug Administration in 2006 authorized a health claim that psyllium husk, beta glucan in oats and beta glucan in barley can reduce the risk of heart disease. Solubility in water, viscosity, fermentability, and the kind and amounts of protein and tocotrienols have been explored as possible basis for this effect. In particular, many experimental and clinical studies suggest that psyllium does lower serum and liver cholesterol concentrations and may increase HDL-cholesterol levels- Moreover,water soluble fibres, such as psyllium, moderate post prandial glucose and insulin concentrations in non-insulin dependent diabetic patients, if taken with meals and favour the reduction of body weight and hypertension. Therefore, the favourable effect of various fibres and particularly of psyllium, on body weight reduction and satiety, on cholesterol and tryglycerides levels, on fasting glycaemia and on blood pressure suggests a potential role of these fibres in the treatment of MS.

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.

Nitric oxide enhancement and blood pressure decrease in patients with metabolic syndrome using soy protein or fish oil

OBJECTIVE: To verify the effects of fish oil and soy on nitric oxide (NO) and blood pressure in patients with metabolic syndrome (MS). SUBJECTS AND METHODS: Sixty women with MS were investigated in a parallel randomized design study. The first group maintained their usual diet; the second group received 25 g/day of soy; the third group received 3 g/day of n-3 fatty acids, and the fourth group the same amount previously cited of n-3 fatty acids and soy. RESULTS: Serum nitric oxide metabolites showed significant increase after 90 days in the fish oil and soy groups. Systolic pressure reduced after 45 days of treatment with fish oil, whereas diastolic pressure decreased significantly throughout the study in the soy group. CONCLUSIONS: NO increase and blood pressure reduction with fish oil or soy protein reinforce the importance of the influence of NO on blood pressure in patients with MS.

ASH position paper: dietary approaches to lower blood pressure

A substantial body of evidence has implicated several aspects of diet in the pathogenesis of elevated blood pressure (BP). Well-established risk factors for elevated BP include excess salt intake, low potassium intake, excess weight, high alcohol consumption, and suboptimal dietary pattern. African Americans are especially sensitive to the BP-raising effects of excess salt intake, insufficient potassium intake, and suboptimal diet. In this setting, dietary changes have the potential to substantially reduce racial disparities in BP and its consequences. In view of the age-related rise in BP in both children and adults, the direct, progressive relationship of BP with cardiovascular-renal diseases throughout the usual range of BP, and the worldwide epidemic of BP-related disease, efforts to reduce BP in nonhypertensive as well as hypertensive individuals are warranted. In nonhypertensives, dietary changes can lower BP and delay, if not prevent, hypertension. In uncomplicated stage I hypertension, dietary changes serve as initial treatment before drug therapy. In hypertensive individuals already on drug therapy, lifestyle modifications can further lower BP. The current challenge is designing and implementing effective clinical and public health interventions that lead to sustained dietary changes among individuals and more broadly in the general population.

Factors influencing dietary protein sources in the PREMIER trial population

Previous research suggests that protein intake, particularly plant protein, may benefit blood pressure control. However, very little has been published regarding protein sources in diets of US adults and factors influencing these choices. The purpose of this report is to describe specific sources of animal and plant proteins in diets of PREMIER clinical trial participants at baseline and how the PREMIER intervention, along with participant demographics, affected protein sources. Adult participants (n=809) who completed the 18-month PREMIER lifestyle intervention trial and had at least one diet recall at each of three study visits were included. Participants were recruited from four clinical centers in the Eastern, Southern, and Northeastern regions of United States. The PREMIER trial, conducted from 1999 to 2002, compared the impact on blood pressure of two structured behavioral interventions focusing on the traditional lifestyle modifications for blood pressure control with or without the Dietary Approaches to Stop Hypertension dietary pattern. Protein sources were assessed by two unannounced 24-hour recalls at each of three study visits. Differences in protein sources were mainly related to participant demographics, with relatively moderate impact of the intervention. The top four protein sources for all the study participants were poultry, dairy, refined grains and beef, each contributing approximately 10% to 17% in descending order to the total protein intake at baseline. Animal and plant protein each comprised approximately 66% and 34%, respectively, to the total daily protein intake at baseline, and such overall contribution pattern remained relatively constant over time. However, sex, race, age, and body weight status all influenced contribution patterns from different food groups significantly. These influences significantly impact choice and are essential elements to consider when designing intervention programs to alter protein contributions from animal vs plant sources.

Changes in arterial blood pressure of a soluble cocoa fiber product in spontaneously hypertensive rats

The effect produced by long-term intake of a soluble cocoa fiber product (SCFP) on the development of hypertension of spontaneously hypertensive rats (SHR) was evaluated. Twenty male 3-week-old SHR were divided into two groups of 10 animals that drank either tap water (control) or a solution of SCFP (0.75 g/day SCFP) until the 20th week of life. Five 20-week-old rats of each group were sacrificed. Tap water as drinking fluid was given to all the animals from the 20th to 24th week of life. The 24-week-old rats were also sacrificed. Body weight, liquid and dry food intake, and arterial blood pressure (tail cuff) were recorded weekly. Malondialdehyde (MDA), glucose and angiotensin converting enzyme (ACE) activity in the plasma from the sacrificed rats were also obtained, and we evaluated the relaxation caused by acetylcholine in the aorta from these animals. SCFP attenuated the development of hypertension in SHR; however, the withdrawal of SCFP caused an increase in blood pressure in the rats. Body weight gain was slower in the group treated with SCFP. SCFP increased liquid intake but decreased dry food intake in the rats. SCFP decreased plasma MDA concentrations and slightly decreased plasma ACE activity, but no differences were observed in plasma glucose and in the aorta responses to acetylcholine in both groups of 20-week-old SHR. We have demonstrated the antihypertensive and antioxidant properties of SCFP. The control of body weight and the control of increased angiotensin II may be involved in the antihypertensive effect of this product.

Antihypertensive Peptides from Milk Proteins

Dietary proteins possess a wide range of nutritional and functional properties. They are used as a source of energy and amino acids, which are needed for growth and development. Many dietary proteins, especially milk proteins, contain physiologically active peptides encrypted in the protein sequence. These peptides may be released during gastrointestinal digestion or food processing and once liberated, cause different physiological functions. Milk-derived bioactive peptides are shown to have antihypertensive, antimicrobial, immunomodulatory, antioxidative and mineral-binding properties. During the fermentation of milk with certain lactobacilli, two interesting tripeptides Ile-Pro-Pro and Val-Pro-Pro are released from casein to the final product. These lactotripeptides have attenuated the development of hypertension in several animal models and lowered blood pressure in clinical studies. They inhibit ACE in vitro at micromolar concentrations, protect endothelial function in vitro and reduce arterial stiffness in humans. Thus, milk as a traditional food product can after certain processing serve as a functional food and carry specific health-promoting effects, providing an option to control blood pressure.

Dietary fiber supplements: effects in obesity and metabolic syndrome and relationship to gastrointestinal functions

Dietary fiber is a term that reflects a heterogeneous group of natural food sources, processed grains, and commercial supplements. Several forms of dietary fiber have been used as complementary or alternative agents in the management of manifestations of the metabolic syndrome, including obesity. Not surprisingly, there is a great variation in the biological efficacy of dietary fiber in the metabolic syndrome and body weight control. Diverse factors and mechanisms have been reported as mediators of the effects of dietary fiber on the metabolic syndrome and obesity. Among this array of mechanisms, the modulation of gastric sensorimotor influences appears to be crucial for the effects of dietary fiber but also quite variable. This report focuses on the role, mechanism of action, and benefits of different forms of fiber and supplements on obesity and the metabolic syndrome, glycemia, dyslipidemia, and cardiovascular risk and explores the effects of dietary fiber on gastric sensorimotor function and satiety in mediating these actions of dietary fiber.

Lack of association between dietary protein intake and risk of stroke among middle-aged men

BACKGROUND

Prospective cohort studies in Japanese populations have shown an inverse association between dietary protein and stroke risk. However, this association has not been examined among any study populations of US men.

OBJECTIVE

Our objective was to examine the relation between dietary protein and risk of stroke in men who participated in the Health Professionals Follow-Up Study.

DESIGN

A total of 43,960 men who were free of cardiovascular disease and cancer at baseline were included in the analysis. Dietary protein (total, animal, and vegetable) was assessed with the use of a food-frequency questionnaire at 5 time points during the follow-up period of 1986-2004. Cox proportional hazards models were used to calculate multivariate relative risks and 95% CIs, which represented the effect of the substitution of protein for an equal percentage of energy from carbohydrate.

RESULTS

During 18 y of follow-up there were 1057 incident stroke events (638 ischemic, 171 hemorrhagic, and 248 of unknown type). For total stroke, the relative risk for the top quintile of percentage energy from protein compared with the bottom was 1.14 (95% CI: 0.90, 1.43; P for linear trend: 0.43) for total protein, 1.11 (95% CI: 0.87, 1.41; P for linear trend: 0.52) for animal protein, and 0.82 (95% CI: 0.60, 1.12; P for linear trend: 0.17) for vegetable protein. The results were similar when ischemic and hemorrhagic stroke subtypes were considered separately.

CONCLUSION

In contrast to studies in Japanese populations, this study did not show a statistically significant association between total, animal, or vegetable protein and risk of stroke in this population of US men.

Design and methods for testing a simple dietary message to improve weight loss and dietary quality

BACKGROUND

The current food pyramid guidelines have been criticized because of their complexity and the knowledge required for users to understand the recommendations. Simplification of a dietary message to focus on a single key aspect of dietary quality, e.g., fiber intake, may make the message much easier to comprehend and adhere, such that respondents can achieve greater weight loss, better dietary quality and overall metabolic health.

METHODS AND DESIGN

This is a randomized controlled clinical trial with two equal sized arms. In total, 240 obese adults who meet diagnostic criteria for the metabolic syndrome will be randomized to one of the two conditions: 1) a high fiber diet and 2) the American Heart Association (AHA) diet. In the high fiber diet condition, patients will be given instruction only on achieving daily dietary fiber intake of 30 g or more. In the AHA diet condition, patients will be instructed to make the several dietary changes recommended by the AHA 2006 guidelines. The trial examines participant weight loss and dietary quality as well as changes in components of the metabolic syndrome, inflammatory biomarkers, low-density lipoprotein cholesterol levels, insulin levels, and glycosolated hemoglobin. Potential mediators, i.e., diet adherence and perceived ease of the diet, and the intervention effect on weight change will also be examined.

DISCUSSIONS

The purpose of this paper is to outline the study design and methods for testing the simple message of increasing dietary fiber. If the simple dietary approach is found efficacious for weight loss; and, improves dietary quality, metabolic health, and adherence, it might then be used to develop a simple public health message.

TRIAL REGISTRATION

NCT00911885.

ASH Position Paper: Dietary approaches to lower blood pressure

A substantial body of evidence has implicated several aspects of diet in the pathogenesis of elevated blood pressure (BP). Well-established risk factors for elevated BP include excess salt intake, low potassium intake, excess weight, high alcohol consumption, and suboptimal dietary pattern. African Americans are especially sensitive to the BP-raising effects of excess salt intake, insufficient potassium intake, and suboptimal diet. In this setting, dietary changes have the potential to substantially reduce racial disparities in BP and its consequences. In view of the age-related rise in BP in both children and adults, the direct, progressive relationship of BP with cardiovascular-renal diseases throughout the usual range of BP, and the worldwide epidemic of BP-related disease, efforts to reduce BP in nonhypertensive as well as hypertensive individuals are warranted. In nonhypertensives, dietary changes can lower BP and delay, if not prevent, hypertension. In uncomplicated stage I hypertension, dietary changes serve as initial treatment before drug therapy. In hypertensive individuals already on drug therapy, lifestyle modifications can further lower BP. The current challenge is designing and implementing effective clinical and public health interventions that lead to sustained dietary changes among individuals and more broadly in the general population.

Antihypertensive properties of plant-based prebiotics

Hypertension is one of the major risk factors for cardiovascular disease. Although various drugs for its treatment have been synthesized, the occurring side effects have generated the need for natural interventions for the treatment and prevention of hypertension. Dietary intervention such as the administration of prebiotics has been seen as a highly acceptable approach. Prebiotics are indigestible food ingredients that bypass digestion and reach the lower gut as substrates for indigenous microflora. Most of the prebiotics used as food adjuncts, such as inulin, fructooligosaccharides, dietary fiber and gums, are derived from plants. Experimental evidence from recent studies has suggested that prebiotics are capable of reducing and preventing hypertension. This paper will discuss some of the mechanisms involved, the evidence generated from both in-vitro experiments and in-vivo trials and some controversial findings that are raised.

Different Effect of Psyllium and Guar Dietary Supplementation on Blood Pressure Control in Hypertensive Overweight Patients: A Six-Month, Randomized Clinical Trial

In the setting of a six-month, open-label clinical trial, 141 consecutively enrolled, hypertensive, overweight patients were randomized to the oral ingestion of psyllium powder or guar gum 3.5 gr t.i.d., to be taken 20 min before the main two meals, or to standard diet. Both fibers improved significantly BMI, FPG, FPI, HOMA Index, HbA1c, LDL-C, and ApoB. Psyllium supplementation only exerted a significant improvement in plasma TG concentration, in SBP and DBP. In our study, six-month supplementation with psyllium fiber, but not with guar fiber nor standard diet, appears to significantly reduce both SBP and DBP in hypertensive overweight subjects.

Effects of lupin kernel flour-enriched bread on blood pressure: a controlled intervention study

BACKGROUND

Available data suggest that substitution of refined carbohydrate in the diet with protein and fiber may benefit blood pressure. Lupin kernel flour is high in protein and fiber and low in carbohydrate.

OBJECTIVE

Our objective was to determine the effects on blood pressure of a diet moderately higher in dietary protein and fiber achieved by substituting lupin kernel flour for wheat flour in bread.

DESIGN

Overweight and obese men and women (n = 88) were recruited to a 16-wk parallel-design study. Participants were randomly assigned to replace 15-20% of their usual daily energy intake with white bread (control) or lupin kernel flour-enriched bread (lupin). Measurements, including 24-h ambulatory blood pressure, were taken at baseline and 16 wk.

RESULTS

Seventy-four participants (37 per group) completed the intervention. Baseline mean (+/-SD) systolic/diastolic blood pressures were 122.1 +/- 9.6/70.8 +/- 7.2 mm Hg (control) and 120.1 +/- 9.5/71.2 +/- 5.9 mm Hg (lupin). For lupin relative to control, the estimated mean (95% CI) net differences in protein, fiber, and carbohydrate intakes during the intervention were 13.7 g/d (95% CI: 2.3, 25.0 g/d), 12.5 g/d (95% CI: 8.8, 16.2 g/d), and -19.9 g/d (95% CI: -45.2, 5.5 g/d), respectively. Differences in systolic blood pressure, diastolic blood pressure, pulse pressure, and heart rate were -3.0 mm Hg (95% CI: -5.6, -0.3 mm Hg; P = 0.03), 0.6 mm Hg (95% CI: -1.0, 2.2 mm Hg; P = 0.47), -3.5 mm Hg (95% CI: -5.3, -1.8 mm Hg; P < 0.001), and 0.0 beats/min (95% CI: -1.7, 1.7 beats/min; P = 0.99), respectively.

CONCLUSIONS

Increasing protein and fiber in bread with lupin kernel flour may be a simple dietary approach to help reduce blood pressure and cardiovascular risk. This trial was registered at the Australian New Zealand Clinical Trials Registry at http://www.anzctr.org.au/trial_view.aspx?ID=1014 as ACTRN12606000034538 on 25 January 2006.

The relationship between dietary protein intake and blood pressure: results from the PREMIER study

Observational and clinical studies suggest that high protein intake, particularly protein from plant sources, might reduce blood pressure (BP). To examine the association of dietary protein with BP, we analysed data from PREMIER, an 18-month clinical trial (n=810) that examined the effects of two multi-component lifestyle modifications on BP. We examined the association of protein intake with BP, and in particular the independent relationship of plant and animal protein with BP. Multivariable linear regression analyses were performed with both cross-sectional and longitudinal data. Dietary plant protein was inversely associated with both systolic and diastolic BP in cross-sectional analyses at the 6-month follow-up (P=0.0045 and 0.0096, respectively). Fruit and vegetable intake was also inversely associated with both systolic and diastolic BP cross-sectionally at 6 months (P=0.0003 and 0.0157, respectively). In longitudinal analyses, a high intake of plant protein at 6 months was marginally associated with a reduction of both systolic and diastolic BP from baseline to 6 months only (P=0.0797 and 0.0866, respectively), independent of change in body weight and waist circumference. Furthermore, increased intake of plant protein, and fruits and vegetables was significantly associated with a lower risk of hypertension at 6 but not at 18 months. Results of this study indicate that plant protein had a beneficial effect on BP and was associated with a lower risk of hypertension at 6 months. Our data, in conjunction with other research, suggest that an increased intake of plant protein may be useful as a means to prevent and treat hypertension.

Meat intake and the risk of hypertension in middle-aged and older women

BACKGROUND

Although previous studies have suggested that high intake of meat, particularly red meat, may contribute to the development of hypertension, data on the prospective associations between meat intake and risk of hypertension are still limited.

OBJECTIVE

We investigated the association of total red meat, types of red meat and poultry intake at baseline with the incidence of hypertension in a prospective cohort of 28 766 female US health professionals aged > or = 45 years.

PATIENTS AND METHODS

Baseline red meat and poultry intake were assessed from semiquantitative food frequency questionnaires. Incident cases of hypertension (n = 8693) were identified from annual follow-up questionnaires during 10 years of follow-up.

RESULTS

After adjusting for known hypertension risk factors, the relative risk and 95% confidence interval (CI) of incident hypertension were 1.00 (reference), 1.05 (0.97-1.13), 1.05 (0.97-1.13), 1.05 (0.97-1.14) and 1.13 (1.04-1.23), respectively, across increasing quintiles of baseline total red meat intake (P for trend = 0.008). Using functional cutpoints, women who consumed > 0 to < 0.5, 0.5 to < 1.0, 1.0 to < 1.5 and > or = 1.5 servings/day of total red meat had multivariable relative risks (95% CI) of hypertension of 1.24 (1.08-1.43), 1.25 (1.08-1.44), 1.32 (1.13-1.53) and 1.35 (1.14-1.59) compared to those who consumed no red meat (P for trend = 0.008). By contrast, multivariable relative risks of incident hypertension across increasing quintiles of poultry intake were 1.00, 1.03, 1.03, 1.08 and 1.03 (P for trend = 0.37).

CONCLUSIONS

Red meat intake was positively associated, whereas poultry intake was unassociated, with the risk of hypertension in middle-aged and older women.

[Usefulness of phyto-oestrogens in reduction of blood pressure. Systematic review and meta-analysis]

OBJECTIVES

To determine whether treatment with phyto-oestrogens or soya protein succeeds in lowering blood pressure.

DESIGN

A systematic review, evaluating all the observation studies and clinical trials, was conducted, followed by a meta-analysis to evaluate blood pressure variations in patients treated with phyto-oestrogens. SEARCH: The search strategy adopted used the terms "phyto-oestrogens," "soya meals," "hypertension," and "blood pressure."

DATA SOURCES

The data bases MEDLINE, EMBASE, Cochrane, OVID were used, without time or language restrictions. References in the relevant articles were searched for manually.

STUDY SELECTION

Two independent reviewers analysed the studies found in the search.

DATA EXTRACTION

The Jadad scale was used for the clinical trials and the numerical data in the text or referred to in tables were extracted. Evaluation was made of which observational and experimental articles showed a drop in blood pressure with phyto-oestrogens and which did not. In the meta-analysis, data on sample size, difference in blood pressure before and after intervention and standard deviation were extracted from each study. The weighted difference of means was used with the model of randomised effects. The Review Manager v4.2.9 programme was used.

RESULTS

No significant variations in blood pressure were found, whether systolic (-1.20 mm Hg; 95% CI, -2.80 to 0.41 mm Hg) or diastolic (-1.31 mm Hg; 95% CI, -2.73 to 0.11). If there were any variations, they are clinically of little importance. There was also an important degree of both statistical and clinical heterogeneity.

CONCLUSIONS

There are no statistically significant or clinically important differences in blood pressure between patients treated with phyto-oestrogens and those not treated.

Effects of dietary fibers on disturbances clustered in the metabolic syndrome

Because of its growing prevalence in Western countries, the metabolic syndrome, a common metabolic disorder that clusters a constellation of abnormalities, including central obesity, hypertension, dyslipidemia and insulin resistance, is emerging as one of the most important public health problems in the world, taking into account that it is a major risk factor mainly for type 2 diabetes and cardiovascular diseases, and also for many types of cancer. Although the pathogenesis of this syndrome is complex and not fully understood, obesity and insulin resistance, accompanied by an altered profile of number of hormones and cytokines produced by the adipose tissue, seem to be the main causative agents. A prime therapeutic approach to the prevention and treatment of this syndrome involves lifestyle changes. Among dietary modifications, dietary fiber intake could play an interesting role in the management of metabolic syndrome through different mechanisms related to its dietary sources, specific chemical structure and physical properties, or fermentability in the gut. According to all of these variables, the different types of dietary fibers have been reported to take part in the control of body weight, glucose and lipid homeostasis, insulin sensitivity and in the regulation of many inflammation markers involved in the pathogenesis of metabolic syndrome, and which are also considered to be among its features.

Dietary fiber intake and retinal vascular caliber in the Atherosclerosis Risk in Communities Study

BACKGROUND

Dietary fiber appears to decrease the risk of cardiovascular morbidity and mortality. Microvascular abnormalities can be observed by retinal examination and contribute to the pathogenesis of various cardiovascular diseases. The impact of dietary fiber on the retinal microvasculature is not known.

OBJECTIVE

We aimed to examine the association between dietary fiber intake and retinal vascular caliber.

DESIGN

At the third visit (1993-1995) of the Atherosclerosis Risk in Communities (ARIC) Study, a population-based cohort of adults in 4 US communities, the retinal vascular caliber of 10,659 participants was measured and summarized from digital retinal photographs. Usual dietary intake during the same period was assessed with a 66-item food-frequency questionnaire.

RESULTS

After control for potential confounders including hypertension, diabetes, lipids, demographic factors, cigarette smoking, total energy intake, micronutrients intake, and other cardiovascular disease risk factors, higher intake of fiber from all sources and from cereal were significantly associated with wider retinal arteriolar caliber and narrower venular caliber. Participants in the highest quintile of fiber intake from all sources had a 1.05-microm larger arteriolar caliber (P for trend = 0.012) and a 1.11-microm smaller venular caliber (P for trend = 0.029).

CONCLUSIONS

Dietary fiber was related to wider retinal arteriolar caliber and narrower venular caliber, which are associated with a lower risk of cardiovascular disease. These data add to the growing evidence of the benefits of fiber intake on various aspects of cardiovascular pathogenesis.

Effects of moderate variations in the macronutrient content of the diet on cardiovascular disease risk factors in obese patients with the metabolic syndrome

BACKGROUND

The metabolic syndrome is a cluster of abnormalities that is accompanied by a 2-fold increase in the risk of cardiovascular disease. Even if there is full agreement that lifestyle changes to induce weight loss are the first-line approach, the ideal diet for the treatment of the metabolic syndrome remains uncertain.

OBJECTIVE

The objective was to compare the effects of 2 diets on cardiovascular disease risk factors in obese patients with the metabolic syndrome.

DESIGN

The study was carried out in 100 patients randomly assigned to either a diet relatively rich in carbohydrate [65% of energy as carbohydrate, 13% as protein, and 22% as fat (17% as unsaturated fat)] or a diet that was low in carbohydrate and high in protein and in monounsaturated fat [48% of energy as carbohydrate, 19% as protein, and 33% as fat (24% as unsaturated fat)].

RESULTS

All 100 patients completed the 5-mo study. At the end of the study, all the components of the metabolic syndrome (except HDL, which did not change) decreased significantly in both groups. With the high-carbohydrate diet, a significant decrease in LDL-cholesterol concentrations was also observed. Although the extent of the resolution of the metabolic syndrome was not different between groups, the low-carbohydrate diet was associated with a greater decrease in the prevalence of hypertension (P < 0.05) and of hypertriacylglycerolemia (P < 0.001).

CONCLUSION

Tailoring diet interventions to the specific presentation of the metabolic syndrome may be the best way of reducing the risk factors for cardiovascular disease.

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.

Milk peptides and blood pressure

Epidemiological studies suggest that milk consumption and dietary intake of dairy proteins are inversely related to the risk for hypertension. Also, some intervention studies have shown a blood pressure-lowering effect of milk products and dairy proteins. Milk peptides are formed from milk proteins by enzymatic breakdown by digestive enzymes or by the proteinases formed by lactobacilli during the fermentation of milk. Several milk peptides have been shown to have antihypertensive effects in animal and in clinical studies. The most studied mechanism underlying the antihypertensive effects of milk peptides is inhibition of angiotensin-converting enzyme. Milk peptides may also have other additional mechanisms to lower blood pressure such as opioid-like activities and mineral-binding and antithrombotic properties. The future challenge is to identify the antihypertensive components in milk and their mechanisms of action and thus to find more possibilities for using these constituents and products as a dietary treatment of hypertension.

Nutritional effects on blood pressure

PURPOSE OF REVIEW

There has not been a thorough recent evaluation of the nutritional effects on blood pressure. Apart from outstanding clinical trials like Dietary Approaches to Stop Hypertension, there have been controversial papers on a number of factors influencing blood pressure. This paper is a systematic review of the current literature as it relates to hypertension.

RECENT FINDINGS

Results from many meta-analyses and well controlled clinical trials on the effects of a variety of nutritional factors are presented in this review. Evidence suggests that dietary sodium intake needs reduction. There is a seemingly inverse relationship between protein intake and blood pressure, but data are inconclusive. High monounsaturated fat and fish oil appear to be beneficial. Several studies on dietary fiber indicate that the strongest evidence for blood pressure lowering effects is in hypertensive as opposed to normotensive participants. Vegetarians seem to have lower levels of hypertension and cardiovascular disease risk. Low carbohydrate diets show short-term beneficial effects but are not sustained. High levels of potassium, magnesium, calcium and soy seem to have some benefit, but results remain inconclusive. Weight reduction positively impacts blood pressure.

SUMMARY

More compelling research defining specific factors is needed to inform the public as to steps needed to reduce blood pressure and improve cardiovascular risk.

Effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate metabolism and biomarkers of oxidative stress in men and women with elevated blood pressure

OBJECTIVE

To assess the effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate homeostasis and biomarkers of oxidative stress.

DESIGN

A randomized, double-blind, controlled clinical trial.

SETTING

The trial was conducted at two clinics.

SUBJECTS AND INTERVENTIONS

Ninety-seven men and women with resting systolic blood pressure 130-179 mm Hg and/or diastolic blood pressure 85-109 mm Hg were randomly assigned to consume foods containing oat beta-glucan or control foods for 12 weeks. Resting blood pressures, insulin and glucose values before and after standard breakfast meals, and four biomarkers of oxidative stress were measured before and at the end of the treatment period.

RESULTS

Changes from baseline to week 12 in mean peak insulin and incremental area under the insulin curve differed significantly between groups (P=0.037 and 0.034, respectively), with the beta-glucan group showing declines and the control group remaining essentially unchanged. Blood pressure responses were not significantly different between groups overall. However, in subjects with body mass index above the median (31.5 kg/m(2)), both systolic (8.3 mm Hg, P=0.008) and diastolic (3.9 mm Hg, P=0.018) blood pressures were lowered in the beta-glucan group compared to controls. No significant differences in biomarkers of oxidative stress were observed between treatments.

CONCLUSIONS

The results of the present trial suggest beneficial effects of foods containing beta-glucan from oats on carbohydrate metabolism, and on blood pressure in obese subjects.

Vegetable protein and fiber from cereal are inversely associated with the risk of hypertension in a Spanish cohort

BACKGROUND

Some cross-sectional studies suggest that fiber and protein intake can be associated with lower levels of blood pressure, but results from prospective cohorts are scarce and none has been conducted outside the U.S.

METHODS

The SUN cohort followed-up prospectively 5880 Spanish men and women older than 20 years of age, all university graduates. Dietary information was gathered at baseline with a previously validated semiquantitative food frequency questionnaire. New cases of medically diagnosed hypertension (HT) were identified through responses to a mailed questionnaire after at least 2 years from recruitment.

RESULTS

One hundred and eighty new cases of HT were ascertained after a median follow-up of 28 months. After adjustment for potential confounders and several dietary factors, participants in the highest quintile of vegetable protein intake had a lower risk of incident HT compared with those in the lowest quintile [hazard ratio (HR) = 0.5, 95% confidence interval (CI) 0.2-0.9, p for trend = 0.06]. Similarly, fiber from cereals was inversely associated with a lower risk of HT (HR comparing fifth vs. first quintile = 0.6, 95% CI 0.3-1.0, p for trend = 0.05). Risk reduction was more important among men and obese and older individuals. Total or animal protein and total fiber as well as fiber from other sources different from cereal were not associated with the risk of HT.

CONCLUSIONS

In this Mediterranean cohort, dietary intake of vegetable protein and fiber from cereals was associated with a lower risk of HT when other nutrients were also taken into consideration.

Dietary flavonoids: effects on endothelial function and blood pressure

Several population studies have found an inverse association between flavonoid intake and risk of cardiovascular disease. These studies have resulted in the hypothesis that dietary flavonoids protect against cardiovascular disease. Many in vitro studies, studies using animal models and human intervention trials have been carried out to investigate how flavonoids might provide protection. Emerging and largely consistent evidence suggests that flavonoids can improve endothelial function and may reduce blood pressure. In vitro studies show that a variety of flavonoids cause vasorelaxation of isolated arteries from rats. In human intervention trials, flavonoids derived from tea and cocoa or dark chocolate—both rich sources of catechins—have been found to improve endothelial function acutely and with regular ingestion. The evidence for benefits of flavonoids from other dietary sources is less clear. Improvements in endothelial function could contribute to lower blood pressure. Population studies have associated higher intake of tea and chocolate with lower blood pressure. Short‐term intervention studies in humans have shown blood pressure lowering with cocoa or dark chocolate, but short‐term regular ingestion of tea has not been found to lower blood pressure. The long‐term effects of regular ingestion of a flavonoid‐enriched diet on endothelial function and blood pressure have yet to be assessed. In addition, there is evidence that flavonoid metabolism is an important factor influencing the biological activity and effects of dietary flavonoids, but further studies are needed to investigate this area. Copyright © 2006 Society of Chemical Industry

Partial substitution of carbohydrate intake with protein intake from lean red meat lowers blood pressure in hypertensive persons

BACKGROUND

Compared with carbohydrate intake, dietary intake of plant protein can lower blood pressure in humans, but the effects of animal protein intake on blood pressure have yet to be investigated.

OBJECTIVE

We aimed to determine whether partial substitution of carbohydrate intake with animal protein intake from lean red meat changes blood pressure and other markers of cardiovascular disease risk in hypertensive persons.

DESIGN

Hypertensive persons (n = 60) were recruited to an 8-wk parallel-design study. The participants were randomly assigned either to maintain their usual diet (control group) or to partially replace energy intake from carbohydrate-rich foods with protein from lean red meat (protein group). Measurements were performed at baseline and at the end of the intervention.

RESULTS

Compared with the control group, the protein group had a significantly higher protein intake [x (95% CI) percent of energy: 5.3% (3.7%, 6.9%), P < 0.001] and a corresponding lower carbohydrate intake [-5.3% of energy (-7.9%, -2.7%), P < 0.001]. Body weight and intakes of fat, alcohol, and fiber were not significantly different between the groups. Compared with the control group, the clinic, 24-h, awake, and asleep systolic blood pressures were lower [-5.2 (-10.3, -0.1), -4.0 (-7.4, -0.6), -4.7 (-8.9, -0.5), and -4.7 (-10.3, -0.1) mm Hg, respectively, P < 0.05] and fasting plasma glucose concentrations were higher [0.33 mmol/L (0.09, 0.58 mmol/L), P = 0.008] in the protein group. These differences were independent of age, sex, and changes in weight, alcohol intake, or urinary sodium and potassium excretion. Diastolic blood pressure and heart rate, arterial compliance, blood lipids, and serum insulin were not significantly different between the groups.

CONCLUSION

Within the context of other studies, these results suggest that modest substitution of carbohydrate-rich foods with protein-rich foods may lower blood pressure in hypertensive persons.

Antihypertensive effect of green coffee bean extract on mildly hypertensive subjects

A water-soluble green coffee bean extract (GCE) has been shown to be effective against hypertension in both spontaneously hypertensive rats and humans. This multicenter, randomized, double-blind, placebo-controlled, parallel group study evaluated the dose-response relationship of GCE in 117 male volunteers with mild hypertension. Subjects were randomized into four groups: a placebo and three drug groups that received 46 mg, 93 mg, or 185 mg of GCE once a day. After 28 days, systolic blood pressure (SBP) in the placebo, 46 mg, 93 mg, and 185 mg groups was reduced by -1.3+/-3.0 mmHg, -3.2+/-4.6 mmHg, -4.7+/-4.5 mmHg, and -5.6+/-4.2 mmHg from the baseline, respectively. The decreases in SBP in the 93 mg group (p<0.05) and the 185 mg group (p<0.01) were statistically significant compared with the placebo group. Diastolic blood pressure (DBP) in the placebo, 46 mg, 93 mg, and 185 mg groups was reduced by -0.8+/-3.1 mmHg, -2.9+/-2.9 mmHg, -3.2+/-3.2 mmHg, and -3.9+/-2.8 mmHg from the baseline, respectively, and significant effects were observed in the 93 mg group (p<0.05) and the 185 mg group (p<0.01) compared with the placebo group. Both blood pressures were significantly reduced in a dose-related manner by GCE (p<0.001). Adverse effects caused by GCE were not observed. The results suggested that daily use of GCE has a blood pressure-lowering effect in patients with mild hypertension.

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.

A Miso (Japanese Soybean Paste) Diet Conferred Greater Protection against Hypertension than a Sodium Chloride Diet in Dahl Salt-Sensitive Rats

The purpose of this study was to compare the effects of miso and sodium chloride (NaCl) on blood pressure in both sexes of Dahl and SD rats. The systolic and diastolic blood pressures (SBP/DBP) were measured at 2, 4, 8 and 12 weeks of treatment with a miso diet including 2.3% NaCl, a high-sodium diet including 2.3% or 1.9% NaCl, or a normal diet including 0.3% NaCl (MF diet; Oriental Yeast Co., Tokyo, Japan). The rats were autopsied after 12 weeks on a diet. DBP in male Dahl rats was significantly increased by the 2.3% NaCl diet as compared with that in the MF group (p < 0.01) or miso group (p < 0.05) from 4 weeks of treatment. Thereafter, SBP and DBP in both the high NaCl groups were significantly increased when compared with the MF or miso group. SBP in female Dahl rats on 2.3% NaCI was significantly increased from 8 weeks after treatment. Nephropathy was observed in both sexes of Dahl rats but not SD rats. These results show that blood pressure was not increased by the miso diet.

Dietary protein intake and renal function

Recent trends in weight loss diets have led to a substantial increase in protein intake by individuals. As a result, the safety of habitually consuming dietary protein in excess of recommended intakes has been questioned. In particular, there is concern that high protein intake may promote renal damage by chronically increasing glomerular pressure and hyperfiltration. There is, however, a serious question as to whether there is significant evidence to support this relationship in healthy individuals. In fact, some studies suggest that hyperfiltration, the purported mechanism for renal damage, is a normal adaptative mechanism that occurs in response to several physiological conditions. This paper reviews the available evidence that increased dietary protein intake is a health concern in terms of the potential to initiate or promote renal disease. While protein restriction may be appropriate for treatment of existing kidney disease, we find no significant evidence for a detrimental effect of high protein intakes on kidney function in healthy persons after centuries of a high protein Western diet.

Effect of dietary fiber intake on blood pressure: a meta-analysis of randomized, controlled clinical trials

OBJECTIVE

We conducted a meta-analysis of 25 randomized controlled trials published in English-language journals before February 2004, to assess the effect of dietary fiber intake on blood pressure (BP).

DESIGN

Using a standardized protocol, information on study design, sample size, participant characteristics, duration of follow-up and change in mean BP, was abstracted. The data from each study were pooled using a random effects model to provide an overall estimate of dietary fiber intake on BP.

INTERVENTION

Dietary fiber intake was the only significant intervention difference between the active and control groups.

RESULTS

Overall, dietary fiber intake was associated with a significant -1.65 mmHg [95% confidence interval (CI), -2.70 to -0.61] reduction in diastolic BP (DBP) and a non-significant -1.15 mmHg (95% CI, -2.68 to 0.39) reduction in systolic BP (SBP). A significant reduction in both SBP and DBP was observed in trials conducted among patients with hypertension (SBP -5.95 mmHg, 95% CI, -9.50 to -2.40; DBP -4.20 mmHg, 95% CI, -6.55 to -1.85) and in trials with a duration of intervention > or = 8 weeks (SBP -3.12 mmHg, 95% CI, -5.68 to -0.56; DBP -2.57 mmHg, 95% CI, -4.01 to -1.14).

CONCLUSIONS

Our results indicate that increased intake of dietary fiber may reduce BP in patients with hypertension and suggests a smaller, non-conclusive, reduction in normotensives. An intervention period of at least 8 weeks may be necessary to achieve the maximum reduction in BP. Our findings warrant conduct of additional clinical trials with a larger sample size and longer period of intervention to examine the effect of dietary fiber intake on BP.

Longitudinal study of soy food intake and blood pressure among middle-aged and elderly Chinese women

BACKGROUND

Several small-scale clinical trials have suggested a potential beneficial effect of short-term soy consumption on blood pressure (BP). Data are scanty on long-term effects of the usual intake of soy foods on BP in general populations.

OBJECTIVE

Our aim was to examine the association between usual intake of soy foods and BP.

DESIGN

The usual intake of soy foods was assessed at baseline, and BP was measured 2-3 y after the baseline survey among 45 694 participants of the Shanghai Women's Health Study aged 40-70 y who had no history of hypertension, diabetes, or cardiovascular disease at recruitment. Multiple regression models were used to estimate mean differences in BP associated with various intakes of soy foods.

RESULTS

Soy protein intake was inversely associated with both systolic BP (P for trend = 0.01) and diastolic BP (P for trend = 0.009) after adjustment for age, body mass index, and lifestyle and other dietary factors. The adjusted mean systolic BP was 1.9 mm Hg lower (95% CI: -3.0, -0.8 mm Hg) and the diastolic BP was 0.9 mm Hg lower (-1.6, -0.2 mm Hg) in women who consumed > or =25 g soy protein/d than in women consuming <2.5 g/d. The inverse associations became stronger with increasing age (P for interaction < 0.05 for both BPs). Among women >60 y old, the corresponding differences were -4.9 mm Hg (95% CI: -8.0, -1.9 mm Hg) for systolic BP and -2.2 mm Hg (95% CI: -3.8, -0.6 mm Hg) for diastolic BP.

CONCLUSION

Usual intake of soy foods was inversely associated with both systolic and diastolic BPs, particularly among elderly women.

Origins and evolution of the Western diet: health implications for the 21st century

There is growing awareness that the profound changes in the environment (eg, in diet and other lifestyle conditions) that began with the introduction of agriculture and animal husbandry approximately 10000 y ago occurred too recently on an evolutionary time scale for the human genome to adjust. In conjunction with this discordance between our ancient, genetically determined biology and the nutritional, cultural, and activity patterns of contemporary Western populations, many of the so-called diseases of civilization have emerged. In particular, food staples and food-processing procedures introduced during the Neolithic and Industrial Periods have fundamentally altered 7 crucial nutritional characteristics of ancestral hominin diets: 1) glycemic load, 2) fatty acid composition, 3) macronutrient composition, 4) micronutrient density, 5) acid-base balance, 6) sodium-potassium ratio, and 7) fiber content. The evolutionary collision of our ancient genome with the nutritional qualities of recently introduced foods may underlie many of the chronic diseases of Western civilization.

Blood Pressure Regulation and Vegetarian Diets

Hypertension affects approximately 50 million individuals in the United States and approximately 1 billion worldwide. Although heredity plays a role in blood pressure variability, diet and lifestyle exert considerable influence in blood pressure regulation. This report reviews the evidence of the relationship between a vegetarian diet and blood pressure regulation and presents data as to the putative mechanisms of action.

Hypertension research in the 21st century

This paper presents a signpost for hypertension research, emphasizing areas most likely to yield major clinical and public health benefits. Specific questions are posed in the context of fetal and maternal precursors of cardiovascular disease, vascular biology, resistant hypertension, antihypertensive drugs, primary aldosteronism, lifestyle and genetic interactions and translational research. Worldwide increasing rates of obesity and diabetes demonstrate the need for a global approach to cardiovascular risk and the need for more effective use of existing knowledge. Equal emphasis is given to the critical importance of the fundamental research required to defeat hypertensive cardiovascular disease in the long run.

Effect of dietary fiber intake on blood pressure: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To examine the effect of dietary fiber intake on blood pressure (BP).

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING AND PARTICIPANTS

A total of 110 trial participants aged 30 to 65 years who had untreated, but higher than optimal BP or stage-1 hypertension were recruited from the community in New Orleans, Louisiana, USA.

INTERVENTIONS

Study participants were randomly assigned to receive 8 g/day of water-soluble fiber from oat bran or a control intervention.

MAIN OUTCOME MEASURES

Nine BP measurements were obtained by trained observers using random-zero sphygmomanometers, over three clinical visits, at the baseline and termination visits of the trial. An average of the nine measurements was used to determine mean BP at the baseline and termination visits.

RESULTS

The net changes [95% confidence interval, (CI)] in systolic blood pressure were -1.8 mmHg (-4.3 to 0.8, P = 0.17) following 12 weeks, -2.2 mmHg (-5.3 to 1.0, P = 0.18) following 6 weeks, and -2.0 mmHg (-4.4 to 0.3, P = 0.09) for an average of the 6- and 12-week visits. The corresponding net changes (95% CI) in diastolic blood pressure were -1.2 mmHg (-3.0 to 0.5, P = 0.17) following 12 weeks, -0.8 mmHg (-3.1 to 1.4, P = 0.47) following 6 weeks, and -1.0 mmHg (-2.6 to 0.5, P = 0.19) for an average of the 6- and 12-week visits.

CONCLUSIONS

Our findings suggest that a diet rich in fiber may have a moderate BP-lowering effect and indicate the need for further investigation of this important question.