Effects of vitamin E, vitamin C and polyphenols on the rate of blood pressure variation: results of two randomised controlled trials

Comprehensive Strategies for Metabolic Syndrome: How Nutrition, Dietary Polyphenols, Physical Activity, and Lifestyle Modifications Address Diabesity, Cardiovascular Diseases, and Neurodegenerative Conditions

Several hallmarks of metabolic syndrome, such as dysregulation in the glucose and lipid metabolism, endothelial dysfunction, insulin resistance, low-to-medium systemic inflammation, and intestinal microbiota dysbiosis, represent a pathological bridge between metabolic syndrome and diabesity, cardiovascular, and neurodegenerative disorders. This review aims to highlight some therapeutic strategies against metabolic syndrome involving integrative approaches to improve lifestyle and daily diet. The beneficial effects of foods containing antioxidant polyphenols, intestinal microbiota control, and physical activity were also considered. We comprehensively examined a large body of published articles involving basic, animal, and human studie, as well as recent guidelines. As a result, dietary polyphenols from natural plant-based antioxidants and adherence to the Mediterranean diet, along with physical exercise, are promising complementary therapies to delay or prevent the onset of metabolic syndrome and counteract diabesity and cardiovascular diseases, as well as to protect against neurodegenerative disorders and cognitive decline. Modulation of the intestinal microbiota reduces the risks associated with MS, improves diabetes and cardiovascular diseases (CVD), and exerts neuroprotective action. Despite several studies, the estimation of dietary polyphenol intake is inconclusive and requires further evidence. Lifestyle interventions involving physical activity and reduced calorie intake can improve metabolic outcomes.

Differential influences of serum vitamin C on blood pressure based on age and sex in normotensive individuals

Aim

Hypertension is among the most prevalent chronic diseases with diverse etiology, affecting over 1 billion people globally. In numerous studies, vitamin C inversely correlated with blood pressure and was suspected to have antihypertensive properties. Currently, there is conflicting evidence regarding the relationship between vitamin C and blood pressure, with most studies being conducted on hypertensive subjects. The principal objective of this project was to investigate the relationship between vitamin C and blood pressure in normotensive adult subjects.

Methods

A total of 2,533 individuals aged 20 years and above were enrolled in the present study from the National Health and Nutrition Examination Survey (NHANES) 2017-2018. Outcome variables were systolic blood pressure (SBP) and diastolic blood pressure (DBP). Serum vitamin C was regarded as an independent variable. EmpowerStats software and R (version 3.4.3) were used to examine the association between vitamin C and SBP or DBP.

Results

Vitamin C was reversely correlated with both SBP (β = −0.02, 95% CI: −0.03 to −0.00, p = 0.0306) and DBP (β = −0.02, 95% CI: −0.04 to −0.01, p = <0.0011) after adjusting all covariates. This reverse relationship may be affected by a number of factors, including a person’s gender, age, race, and ethnicity. A U-shaped association between vitamin C and SBP in females and an inverted one between vitamin C and DBP in males were detected, respectively. We further calculated the inflection points at 90.3 μmol/L for females and 40 μmol/L for males. It is somewhat surprising that a reverse U-shaped distribution between vitamin C and SBP and DBP in people over 50 was detected, and the point of inflection of vitamin C were all located at 40 μmol/L.

Conclusion

Vitamin C was negatively correlated with both SBP and DBP in this cross-sectional analysis. However, a U-shaped relationship and an inverted one were also observed in certain people, which implied that, though vitamin C is considered a vital antioxidant, maintaining vitamin C at appropriate levels may be beneficial according to different populations.

The effect of grape (Vitis vinifera) seed extract supplementation on flow-mediated dilation, blood pressure, and heart rate: A systematic review and meta-analysis of controlled trials with duration- and dose-response analysis

The objective of this systematic review and meta-analysis of controlled trials was to assess the long-term effect of grape seed extract (GSE) supplementation on flow-mediated dilation (FMD), systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) in adults. Web of Science, Scopus, Medline, Cochrane Library, and Google Scholar were searched up to May 24, 2021. Nineteen trials were included in this study. Weighted mean difference (WMD) and 95% confidence interval (CI) were calculated using a random-effects model. GSE supplementation significantly reduced DBP (WMD: -2.20 mmHg, 95% CI: -3.79 to -0.60, I² = 88.8%) and HR (WMD: -1.25 bpm, 95% CI: -2.32 to -0.19, I² = 59.5%) but had no significant effects on FMD (WMD: 1.02%, 95% CI: -0.62 to 2.66, I² = 92.0%) and SBP (WMD: -3.55 mmHg, 95% CI: -7.59 to 0.49, I² = 97.4%). Subgroup analysis revealed that the dose and duration of GSE administration and the characteristics of study participants could be sources of between-study heterogeneity. Significant non-linear relationships were found between DBP and the duration of GSE supplementation (P = 0.044) and its dose (P = 0.007). In conclusion, GSE may be beneficial for individuals with or at risk of cardiovascular disease because it may have hypotensive and HR-lowering properties.

A Systematic Review of Effects of Vitamin E on the Cardiovascular System

Vitamin E is a fat-soluble vitamin and an antioxidant that prevents the peroxidation of lipid in vitro. The antioxidant role of vitamin E in preventing adverse cardiovascular outcomes is controversial as some studies support it, while others reject it. Therefore, this review aims to determine whether there is an association between vitamin E and cardiovascular diseases (CVDs). An electronic search was done to find out relevant articles. Papers were shortlisted after the initial title and abstract screen. A full-text study was done, and inclusion and exclusion criteria were applied before the quality assessment of each paper was done. Only high-quality papers were selected for analysis. Full-text articles of the last ten years were included, while non-English articles, gray literature, and animal studies were excluded. The majority of the papers, including 75% of the total population in this review, suggested no role of vitamin E in preventing CVD and CVD mortality. Some studies also suggested that a high level of vitamin E can be associated with adverse cardiovascular outcomes. Thus, one should be prudent about taking vitamin E supplementation for cardiovascular risk prevention.

Cardiovascular and Metabolic Protection by Vitamin E: A Matter of Treatment Strategy?

Cardiovascular diseases (CVD) cause about 1/3 of global deaths. Therefore, new strategies for the prevention and treatment of cardiovascular events are highly sought-after. Vitamin E is known for significant antioxidative and anti-inflammatory properties, and has been studied in the prevention of CVD, supported by findings that vitamin E deficiency is associated with increased risk of cardiovascular events. However, randomized controlled trials in humans reveal conflicting and ultimately disappointing results regarding the reduction of cardiovascular events with vitamin E supplementation. As we discuss in detail, this outcome is strongly affected by study design, cohort selection, co-morbidities, genetic variations, age, and gender. For effective chronic primary and secondary prevention by vitamin E, oxidative and inflammatory status might not have been sufficiently antagonized. In contrast, acute administration of vitamin E may be more translatable into positive clinical outcomes. In patients with myocardial infarction (MI), which is associated with severe oxidative and inflammatory reactions, decreased plasma levels of vitamin E have been found. The offsetting of this acute vitamin E deficiency via short-term treatment in MI has shown promising results, and, thus, acute medication, rather than chronic supplementation, with vitamin E might revitalize vitamin E therapy and even provide positive clinical outcomes.

Nuts

Nuts are fruits composed of two parts: an inedible hard shell and an edible seed. Nuts are known as an energy-dense and nutrient-rich food source. In general, nuts are recognized as a good source of fat, fiber, and protein. Nuts are extremely beneficial parts of any diet since their consumption may lower risk for some diseases, such as cardiovascular diseases and cancer. They are acknowledged for their low glycemic index owning to high unsaturated fat and protein content and relatively low carbohydrate content. They have been shown to increase cognitive function as well.

Sex, Oxidative Stress, and Hypertension: Insights From Animal Models

One of the mechanisms responsible for blood pressure (BP) regulation is thought to be oxidative stress. In this review, we highlight preclinical studies that strongly support a role for oxidative stress in development and maintenance of hypertension in male animals, based on depressor responses to antioxidants, particularly tempol and apocynin. In females, oxidative stress seems to be important in the initial development of hypertension. However, whether maintenance of hypertension in females is mediated by oxidative stress is not clear. In clinical studies, pharmacological intervention to reduce BP with antioxidants has conflicting results, mostly negative. This review will discuss the uncertainties regarding blood pressure control and oxidative stress and potential reasons for these outcomes.

Oxidative stress and vascular stiffness in hypertension: A renewed interest for antioxidant therapies?

Since the first successful launch of the Veterans Administration(VA) cooperative studies in the late 1960s, the increasing access to blood pressure lowering medications has significantly contributed to improving longevity and quality of life in hypertensive patients. Since then, insights into the pathogenesis of hypertension have shown a mechanistic role for reactive oxygen species (ROS) in all phases of disease progression, suggesting the potential utility of antioxidant therapies to counteract symptoms and, at the same time, treat a fundamental mechanism of the disease. Despite these progresses, hypertension still remains the main contributor to the global incidence of cardiovascular disease and the leading cause of morbidity and mortality worldwide. We here briefly review and update the role of ROS and ROS-dependent metalloproteinase activation in the maladaptive remodeling of the vascular wall in hypertension. Such understanding should provide new Potential sites of action for antioxidant therapies as an integrated therapeutic approach to hypertension and its consequences.

Genetic polymorphisms associated with reactive oxygen species and blood pressure regulation

Hypertension is the most prevalent cause of cardiovascular disease and kidney failure, but only about 50% of patients achieve adequate blood pressure control, in part, due to inter-individual genetic variations in the response to antihypertensive medication. Significant strides have been made toward the understanding of the role of reactive oxygen species (ROS) in the regulation of the cardiovascular system. However, the role of ROS in human hypertension is still unclear. Polymorphisms of some genes involved in the regulation of ROS production are associated with hypertension, suggesting their potential influence on blood pressure control and response to antihypertensive medication. This review provides an update on the genes associated with the regulation of ROS production in hypertension and discusses the controversies on the use of antioxidants in the treatment of hypertension, including the antioxidant effects of antihypertensive drugs.

Potato consumption and risk of all cause, cancer and cardiovascular mortality: a systematic review and dose-response meta-analysis of prospective cohort studies

A systematic review and meta-analysis of prospective cohort studies was conducted to examine the association of potato consumption and risk of all-cause, cancer and cardiovascular mortality in adults. We searched PubMed, Scopus databases up to September 2018 for all relevant published papers. All analyses were performed on HRs or RRs and 95% CIs. In twenty prospective studies, 25,208 cases were reported for all-cause mortality, 4877 for cancer mortality and 2366 for CVD mortality. No significant association was found between potato consumption and risk of all-cause (0.90; 95% CI: 0.8, 1.02, p = 0.096) and cancer (1.09; 95% CI: 0.96, 1.24, P = 0.204) mortality. In addition, no significant linear association was found between each 100 g/d increments in potato consumption and risk of all-cause (P = 0.7) and cancer (P = 0.09) mortality. Moreover, nonlinear association between potato consumption and risk of cancer mortality was non-significant (P-nonlinearity = 0.99). In addition, two of three studies which examined the association of potato consumption with CVD mortality did not find any significant relationship. There was no evidence for publication bias in this study. We failed to find significant association between potato consumption and risk of mortality. Further studies are required to confirm this issue.

Effects of pomegranate juice consumption on blood pressure and lipid profile in patients with type 2 diabetes: A single-blind randomized clinical trial

Pomegranate juice (PJ) has abundant anti-oxidative polyphenolic compounds which are assumed to have cardioprotective effects such as hypotensive properties. This study aimed to investigate the effects of PJ consumption on blood pressure and lipid profile F variables in patients with type 2 diabetes. Sixty subjects (30 in intervention group and 30 in control group) were recruited in this single-blind placebo-controlled randomized clinical trial. The volunteers were randomly assigned to one of two groups. Treatment group consumed 200 ml/day PJ for 6 weeks, while control group received no intervention. Systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) concentrations were measured following 12-14 h of fasting at baseline and at the end of the study. After 6 weeks of intervention, SBP (13.5 ± 1.5 mmHg vs. 12.3 ± 2.5, P < 0.001) and DBP (7.7 ± 1.6 vs. 7.2 ± 1.6 mmHg, P < 0.05) significantly decreased in the intervention group. Similarly, SBP and DBP in the intervention group were significantly lower than the control group after intervention (P < 0.02 and P < 0.03, respectively). At the end of the intervention, TC, TG, LDL-C and HDL-C did not significantly differ between the intervention group and the control group however, TC and LDL-C decreased significantly compared to pre-trial values within the intervention group. It is concluded that PJ consumption could decrease systolic and diastolic blood pressure in patients with diabetes while having no effect on lipid profile. A more definitive result will be obtained if future studies could conducted in hyperlipidemic individuals who might be more prone to respond to the lipid-lowering effects.

Autophagy and oxidative stress in non-communicable diseases: A matter of the inflammatory state?

Non-communicable diseases (NCDs), also known as chronic diseases, are long-lasting conditions that affect millions of people around the world. Different factors contribute to their genesis and progression; however they share common features, which are critical for the development of novel therapeutic strategies. A persistently altered inflammatory response is typically observed in many NCDs together with redox imbalance. Additionally, dysregulated proteostasis, mainly derived as a consequence of compromised autophagy, is a common feature of several chronic diseases. In this review, we discuss the crosstalk among inflammation, autophagy and oxidative stress, and how they participate in the progression of chronic diseases such as cancer, cardiovascular diseases, obesity and type II diabetes mellitus.

Biogenic Aldehydes as Therapeutic Targets for Cardiovascular Disease

Aldehydes are continuously formed in biological systems through enzyme-dependent and spontaneous oxidation of lipids, glucose, and primary amines. These highly reactive, biogenic electrophiles can become toxic via covalent modification of proteins, lipids and DNA. Thus, agents that scavenge aldehydes through conjugation have therapeutic value for a number of major cardiovascular diseases. Several commonly-prescribed drugs (e.g., hydralazine) have been shown to have potent aldehyde-conjugating properties which may contribute to their beneficial effects. Herein, we briefly describe the major sources and toxicities of biogenic aldehydes in cardiovascular system, and provide an overview of drugs that are known to have aldehyde-conjugating effects. Some compounds of phytochemical origin, and histidyl-dipeptides with emerging therapeutic value in this area are also discussed.

The role of nutraceuticals in the prevention of cardiovascular disease

Cardiovascular disease (CVD) ranks among the most common health-related and economic issues worldwide. Dietary factors are important contributors to cardiovascular risk, either directly, or through their effects on other cardiovascular risk factors including hypertension, dyslipidemia and diabetes mellitus. Nutraceuticals are natural nutritional compounds, which have been shown to be efficacious in preventative medicine or in the treatment of disease. Several foods and dietary supplements have been shown to protect against the development of CVD. The aim of this review is to present an update on the most recent evidence relating to the use of nutraceuticals in the context of the prevention and treatment of CVD.

Polyphenol-based nutraceuticals for the prevention and treatment of cardiovascular disease: Review of human evidence

BACKGROUND

In addition to prescription drugs, nutraceuticals/functional foods/medical foods are being increasingly added as adjunct treatment of cardiovascular disease (CVD), even though most of them have been exclusively studied in vitro.

HYPOTHESIS/PURPOSE

We review the available evidence (focusing on when the amount of polyphenols' intake was measured) coming from randomized controlled trials (RCTs) of (poly)phenol-based supplements.

CONCLUSION

We conclude that (poly)phenol-based nutraceuticals and functional foods might be indeed used as adjunct therapy of CVD, but additional long-term RCTs with adequate numerosity and with clinically relevant end points are needed to provide unequivocal evidence of their clinical usefulness.

Nrf2 signaling and redox homeostasis in the aging heart: A potential target to prevent cardiovascular diseases?

Aging process is often accompanied with a high incidence of cardiovascular diseases (CVD) due to the synergistic effects of age-related changes in heart morphology/function and prolonged exposure to injurious effects of CVD risk factors. Oxidative stress, considered a hallmark of aging, is also an important feature in pathologies that predispose to CVD development, like hypertension, diabetes and obesity. Approaches directed to prevent the occurrence of CVD during aging have been explored both in experimental models and in controlled clinical trials, in order to improve health span, reduce hospitalizations and increase life quality during elderly. In this review we discuss oxidative stress role as a main risk factor that relates CVD with aging. As well as interventions that aim to reduce oxidative stress by supplementing with exogenous antioxidants. In particular, strategies of improving the endogenous antioxidant defenses through activating the nuclear factor related-2 factor (Nrf2) pathway; one of the best studied molecules in cellular redox homeostasis and a master regulator of the antioxidant and phase II detoxification response.

Effect of Grape Polyphenols on Blood Pressure: A Meta-Analysis of Randomized Controlled Trials

Background

The effect of grape polyphenols on blood pressure remains unclear, which we aimed to address via a meta-analysis study.

Methods

We conducted study trial searches in PubMed, Embase, and the Cochrane Library databases. Summary estimates of weighted mean differences and 95% confidence intervals were obtained by using fixed-effects models. Subgroup analyses were performed to identify the source of heterogeneity. The protocol details of our meta-analysis have been submitted to the international database of prospectively registered systematic reviews (registration number CRD42015019196).

Results

Ten studies were included in the present meta-analysis. Our results showed daily grape polyphenol intake could significantly reduce systolic blood pressure by 1.48 mmHg when compared to control subjects (12 comparisons; -1.48 [-2.79 to -0.16] mmHg; P = 0.03). Subgroup analyses indicated larger reduction was identified in the intake of low-dose of grape polyphenols (< 733 mg/day, median level of the included studies) or patients with metabolic syndrome. Contrarily, diastolic blood pressure was not significantly decreased in the grape polyphenols group as compared to controls. No significant heterogeneity or publication bias was detected in the meta-analysis of either systolic or diastolic blood pressure.

Conclusions

Daily grape polyphenol intake can significantly reduce the systolic blood pressure in humans, although the reduction is modest when compared with anti-hypertensive medications. Larger, better designed trials, that specifically include hypertensive subjects, are required to verify our results in the future.

Polyphenol-rich juices reduce blood pressure measures in a randomised controlled trial in high normal and hypertensive volunteers

Intake of fruits and berries may lower blood pressure (BP), most probably due to the high content of polyphenols. In the present study, we tested whether consumption of two polyphenol-rich juices could lower BP. In a randomised, double-blinded, placebo-controlled trial of 12 weeks, 134 healthy individuals, aged 50–70 years, with high normal range BP (130/85–139/89 mmHg, seventy-two subjects) or stage 1-2 hypertension (140/90–179/109 mmHg, sixty-two subjects), were included. They consumed 500 ml/d of one of either (1) a commercially available polyphenol-rich juice based on red grapes, cherries, chokeberries and bilberries; (2) a juice similar to (1) but enriched with polyphenol-rich extracts from blackcurrant press-residue or (3) a placebo juice (polyphenol contents 245·5, 305·2 and 76 mg/100 g, respectively). Resting BP was measured three times, with a 1 min interval, at baseline and after 6 and 12 weeks of intervention. Systolic BP significantly reduced over time (6 and 12 weeks, respectively) in the pooled juice group compared with the placebo group in the first of the three measurements, both for the whole study group (6·9 and 3·4 mmHg; P= 0·01) and even more pronounced in the hypertensive subjects when analysed separately (7·3 and 6·8 mmHg; P= 0·04). The variation in the BP measurements was significantly reduced in the pooled juice group compared with the placebo group (1·4 and 1·7 mmHg; P= 0·03). In conclusion, the present findings suggest that polyphenol-rich berry juice may contribute to a BP- and BP variability lowering effect, being more pronounced in hypertensive than in normotensive subjects.