The effects of catechin on endothelial function: A systematic review and meta-analysis of randomized controlled trials

Brazil nuts potential: effects on lipid peroxidation and heart health in nephrectomized rats

OBJECTIVES

To investigate the effects of a Brazil nut-enriched diet on the wall thickness and the left ventricular chamber diameter of the heart, and lipid peroxidation in a CKD-induced model.

METHODS

Male Wistar rats at 12 weeks of age were divided into two groups (n=16/group): the Nx group, which underwent 5/6 nephrectomy, and the Sham group, as a control. After 5 weeks, the groups were subdivided according to diet (n=8/group): the Nx and Sham groups received a control diet; the Nx5% and Sham5% groups received a diet enriched with 5 % Brazil nuts for 8 weeks. The left ventricular thickening and chamber diameter were determined. Plasma biochemical parameters were evaluated. Analysis of thiobarbituric acid reactive substances (TBARS) and antioxidant enzyme activity was performed in the plasma and the left ventricle (LV). LV mRNA expression of nuclear factor-kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) was evaluated by reverse transcription-polymerase chain reaction.

RESULTS

The Nx5% group showed a remodeled LV wall with decreased thickness compared to the Nx group (p=0.016). Furthermore, LV TBARS concentration was reduced in the Nx5% group (p=0.0064). In addition, the Nx5% group showed an increase in plasma GPx activity (p=0.0431). No significant results were found concerning the LV mRNA expression of NF-κB and Nrf2 genes.

CONCLUSIONS

A Brazil nut-enriched diet decreased LV thickness and LV TBARS concentration and increased GPx activity in a 5/6 nephrectomy experimental model, making it a promising adjuvant therapy to improve antioxidant status and cardiovascular outcomes in chronic kidney disease.

The Interplay between Endogenous and Foodborne Pro-Oxidants and Antioxidants in Shaping Redox Homeostasis

Oxidative stress has been known about in biological sciences for several decades; however, the understanding of this concept has evolved greatly since its foundation. Over the past years, reactive oxygen species, once viewed as solely deleterious, have become recognized as intrinsic components of life. In contrast, antioxidants, initially believed to be cure-all remedies, have failed to prove their efficacy in clinical trials. Fortunately, research on the health-promoting properties of antioxidants has been ongoing. Subsequent years showed that the former assumption that all antioxidants acted similarly was greatly oversimplified. Redox-active compounds differ in their chemical structures, electrochemical properties, mechanisms of action, and bioavailability; therefore, their efficacy in protecting against oxidative stress also varies. In this review, we discuss the changing perception of oxidative stress and its sources, emphasizing everyday-life exposures, particularly those of dietary origin. Finally, we posit that a better understanding of the physicochemical properties and biological outcomes of antioxidants is crucial to fully utilize their beneficial impact on health.

Dietary polyphenols and sleep modulation: Current evidence and perspectives

Polyphenols are plant compounds with several biological activities. This review aims to summarize current knowledge on the potential role of polyphenols in modulating sleep. A total of 28 preclinical studies, 12 intervention studies and four observational studies exploring the role of polyphenol intake on sleep were identified. From animal studies, 26 out of the 28 studies found beneficial effects of polyphenols on sleep architecture. Three out of four human observational studies found a beneficial association between polyphenol intake and sleep parameters. And, among clinical intervention studies, eight from a total of 12 studies found some beneficial effect of polyphenol intake on various sleep parameters, although some discrepancies between studies were found. Overall, emerging evidence suggests a benefit of polyphenol intake on sleep. Several mechanisms of action have been suggested, ranging from effects on neurotransmitters to an action through the gut-brain axis. However, more research in this field is needed, emphasizing the use of nutritional doses in mechanistic studies and interventions targeting participants with sleep problems. This would allow to elucidate whether an additional biological effect of polyphenols is modulation of sleep, a behavior associated with adverse health outcomes.

The effects of folic acid supplementation on endothelial function in adults: a systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND

Endothelial dysfunction serves as an early marker for the risk of cardiovascular disease (CVD); therefore, it is an attractive site of therapeutic interventions to reduce the risk of CVD. This study was conducted to investigate the effect of folic acid supplementation on endothelial function markers in randomized controlled trials (RCTs).

METHODS

PubMed, ISI web of science, and Scopus databases were searched up to July 2022 for detecting eligible studies. A random-effects model was used for meta-analysis, and linear Meta-regression and non-linear dose-response analysis were performed to assess whether the effect of folic acid supplementation was affected by the dose and duration of intervention. Cochrane tools were also used to assess the risk of bias in the included studies.

RESULTS

Twenty-one studies, including 2025 participants (1010 cases and 1015 controls), were included in the present meta-analysis. Folic acid supplementation significantly affected the percentage of flow-mediated dilation (FMD%) (WMD: 2.59%; 95% CI: 1.51, 3.67; P < 0.001) and flow-mediated dilation (FMD) (WMD: 24.38 μm; 95% CI: 3.08, 45.68; P = 0.025), but not end-diastolic diameter (EDD) (WMD: 0.21 mm; 95% CI: - 0.09, 0.52; P = 0.176), and intercellular adhesion molecule (ICAM) (WMD: 0.18 ng/ml; 95% CI: - 10.02, 13.81; P = 0.755).

CONCLUSIONS

These findings suggest that folic acid supplementation may improve endothelial function by increasing FMD and FMD% levels.

TRIAL REGISTRATION

PROSPERO registration cod: CRD42021289744.

Roles of Oxidative Stress and Inflammation in Vascular Endothelial Dysfunction-Related Disease

Oxidative stress and chronic inflammation play an important role in the pathogenesis of atherosclerosis. Atherosclerosis develops as the first step of vascular endothelial dysfunction induced by complex molecular mechanisms. Vascular endothelial dysfunction leads to oxidative stress and inflammation of vessel walls, which in turn enhances vascular endothelial dysfunction. Vascular endothelial dysfunction and vascular wall oxidative stress and chronic inflammation make a vicious cycle that leads to the development of atherosclerosis. Simultaneously capturing and accurately evaluating the association of vascular endothelial function with oxidative stress and inflammation would be useful for elucidating the pathophysiology of atherosclerosis, determining treatment efficacy, and predicting future cardiovascular complications. Intervention in both areas is expected to inhibit the progression of atherosclerosis and prevent cardiovascular complications.

Protective Effects of Polyphenols Present in Mediterranean Diet on Endothelial Dysfunction

Endothelial dysfunction tends to be the initial indicator in proinflammatory state and macro- and microvascular complications, such as atherosclerosis and cardiovascular diseases. It has been shown that certain compounds in diet can generate beneficial effects on cardiovascular disease due to its interactions with endothelial cells. Thus, this review is aimed at investigating whether certain polyphenols present in the Mediterranean diet, specifically catechin, quercetin, resveratrol, and urolithin, could exert positive effects on endothelial dysfunction. After analysis of numerous papers, we found that polyphenols aiding endothelial function is beneficial not only for patients with cardiovascular disease, diabetes, or endothelial dysfunction but for all people as it can improve the effects of aging on the endothelia. The additional benefit of these polyphenols on weight loss further improves health and lowers the risk of several diseases, including those caused by endothelial dysfunction. However, it is important to note that the dosages in the majorities of the studies mentioned in this review were of supplemental rather than nutritionally relevant quantities, and therefore, the recommended dosages are difficult to determine.

The role of nutraceuticals in prevention and treatment of hypertension: An updated review of the literature

Hypertension (HTN) is a worldwide epidemic in both developed and developing countries. It is one of the leading causes of major health problems such as cardiovascular disease, stroke, and heart attack. In recent years, several studies have reported associations between specific dietary ingredients and improving HTN. Nutraceuticals are natural food components with pharmacological properties. Reports suggest that functional foods and nutraceutical ingredients might support patients to obtain the desired therapeutic blood pressure (BP) goals and reduce cardiovascular risks by modulating various risk factors such as oxidative stress, renin-angiotensin system hyperactivity, inflammation, hyperlipidemia, and vascular resistance. We review the recent clinical experiments that have evaluated the biological and pharmacological activities of several types of nutraceuticals, including sour tea, cocoa, common spices, vitamin C, vitamin E, lycopene, flavonoids, coenzyme Q10, milk's tripeptides, calcium, magnesium, polyunsaturated fatty acids, and prebiotics in preventing and treating HTN. This review summarizes recent knowledge about the impact of common nutraceuticals for the regulation of BP.