The association between tea consumption and blood pressure in the adult population in Southwest China

OBJECTIVES

Prior research on the effect of tea consumption on blood pressure (BP) generated inconsistent findings. The objective of this study was to explore the effects of different types of tea consumption on BP.

METHODS

We included 76,673 participants aged 30-79 from the baseline data of the China Multi-Ethnic Cohort (CMEC) study. Binary logistic regression was used to analyze the influences of different types of tea consumption on the risk of hypertensive BP. Moreover, multiple linear regression was used to examine the association between tea drinking and BP.

RESULTS

Tea consumption was associated with a reduced risk of hypertensive BP by 10% (AOR: 0.90, 95%CI: 0.86-0.94). While dark tea was related to a 1.79-5.31 mmHg reduction in systolic blood pressure (SBP) and a 0.47-1.02 mmHg reduction in diastolic blood pressure (DBP), sweet tea, regardless of the duration, frequency, or amount of consumption, significantly was associated with a reduced SBP by 3.19-7.18 mmHg. Green tea also was associated with a reduced SBP by 1.21-2.98 mmHg. Although scented tea was related to reduced SBP by 1.26-2.48 mmHg, the greatest effect came from the long duration (> 40 years:β=-2.17 mmHg, 95%CI=-3.47 mmHg --0.87 mmHg), low frequency (1-2 d/w: β = -2.48 mmHg, 95%CI=-3.76 mmHg--1.20 mmHg), and low amount (≤ 2 g/d: β=-2.21 mmHg, 95%CI=-3.01 mmHg--1.40 mmHg). Additionally, scented tea was correlated to a decrease in DBP at the frequency of 1-2 d/w (β=-0.84 mmHg, 95%CI=-1.65 mmHg--0.02 mmHg). Drinking black tea only was associated with lowered SBP. The protective effect of black tea on SBP was characterized by the long-duration (> 15 years, -2.63--5.76 mmHg), high frequency (6-7 d/w, -2.43 mmHg), and medium amount (2.1-4.0 g/d, -3.06 mmHg).

CONCLUSION

Tea consumption was associated with lower SBP and a reduced risk of hypertensive BP. The antihypertensive effect varies across types of tea consumed.

Exploring the Contribution of (Poly)phenols to the Dietary Exposome Using High Resolution Mass Spectrometry Untargeted Metabolomics

SCOPE

This study presents a workflow to construct a Dietary Exposome Library (DEL) comprised of phytochemicals and their metabolites derived from host and gut microbiome metabolism for use in peak identification/annotation of untargeted metabolomics datasets.

METHODS AND RESULTS

An evidence mapping initiative established target analytes related to the consumption of phytochemical-rich foods. Analytes were confirmed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS(n)) analysis of human biospecimens from dietary intervention studies of (poly)phenol-rich diets. One hundred and sixty six verified compounds were subsequently analyzed on an untargeted metabolomics platform to acquire chromatographic and high-resolution mass spectral data for construction of a DEL. The DEL facilitated identification/annotation of 123 metabolites associate with exposure to (poly)phenol enriched diets, which included aromatic ketones, benzoic acids, ellagic acids, caffeoylquinic acids, catecholamines, coumarins, hippuric acid, hydroxytoluenes, phenylamines, stilbenes, urolithins, valerolactones, and xanthonoids, in untargeted metabolomics datasets acquire from human plasma and urine reference materials.

CONCLUSIONS

The DEL focusing on (poly)phenols and their metabolites of dietary exposure facilitated identification/annotation of ingested food components and their associated pathways in untargeted metabolomics datasets acquired from human biospecimens. The DEL continues to expand with the aim to provide evidence-based data for dietary metabolites in exposome research and inform the development of dietary intervention strategies.

The Role of Gut Microbiota in the Immunopathology of Atherosclerosis: focus on immune cells

Gut microbiota (GM) play important roles in multiple organ function, homeostasis and several diseases. More recently, increasing evidences have suggested that the compositional and functional alterations of GM play a crucial role in the accumulation of foam cells and the formation of atherosclerotic plaque in atherosclerosis. In particular, the effects of bacterial components and metabolites on innate and adaptive immune cells have been explored as the underlying mechanisms. Understanding the effects of GM and metabolites on immunoregulation are important for clinical therapy for atherosclerosis. Herein, we summarize the potential role of the GM (such as bacterial components lipopolysaccharide and peptidoglycan) and GM-derived metabolites (such as short-chain fatty acids, trimethylamine N-oxide and bile acids) in the immunopathology of atherosclerosis. Based on that, we further discuss the anti-atherosclerotic effects of GM-directed dietary bioactive factors such as dietary fibers, dietary polyphenols and probiotics. Because of drug-induced adverse events in anti-inflammatory therapies, personalized dietary interventions would be potential therapies for atherosclerosis, and the interactions between GM-derived products and immune cells should be studied further.

The chemistry, processing, and preclinical anti-hyperuricemia potential of tea: a comprehensive review

Hyperuricemia is an abnormal purine metabolic disease that occurs when there is an excess of uric acid in the blood, associated with cardiovascular diseases, hypertension, gout, and renal disease. Dietary intervention is one of the most promising strategies for preventing hyperuricemia and controlling uric acid concentrations. Tea (Camellia sinensis) is known as one of the most common beverages and the source of dietary polyphenols. However, the effect of tea on hyperuricemia is unclear. Recent evidence shows that a lower risk of hyperuricemia is associated with tea intake. To better understand the anti-hyperuricemia effect of tea, this review first briefly describes the pathogenesis of hyperuricemia and the processing techniques of different types of tea. Next, the epidemiological and experimental studies of tea and its bioactive compounds on hyperuricemia in recent years were reviewed. Particular attention was paid to the anti-hyperuricemia mechanisms targeting the hepatic uric acid synthase, renal uric acid transporters, and intestinal microbiota. Additionally, the desirable intake of tea for preventing hyperuricemia is provided. Understanding the anti-hyperuricemia effect and mechanisms of tea can better utilize it as a preventive dietary strategy.HighlightsHigh purine diet, excessive alcohol/fructose consumption, and less exercise/sleep are the induction factors of hyperuricemia.Tea and tea compounds showed alleviated effects for hyperuricemia, especially polyphenols.Tea (containing caffeine or not) is not associated with a higher risk of hyperuricemia.Xanthine oxidase inhibition (reduce uric acid production), Nrf2 activation, and urate transporters regulation (increase uric acid excretion) are the potential molecular targets of anti-hyperuricemic effect of tea.About 5 g tea intake per day may be beneficial for hyperuricemia prevention.

Bubble tea consumption and its association with mental health symptoms: An observational cross-sectional study on Chinese young adults

BACKGROUND

Bubble tea has become enormously popular in China in recent years. This cross-sectional study investigated the association between bubble tea consumption and symptoms of anxiety and depression in a population-based sample.

METHODS

Self-report questionnaires were used to assess bubble tea consumption and mental status. Symptoms of depression were assessed using the self-rated Patient Health Questionnaire-2 (PHQ-2) and anxiety using the self-rated Generalized Anxiety Disorder Scale-2 (GAD-2). Logistic regressions were performed to evaluate the association between the frequency of bubble tea consumption (cups/week) (FBTC) and psychological symptoms, adjusting for demographic and socioeconomic characteristics. Path analysis was used to investigate the possible meditating effects of confounding factors.

RESULTS

After adjusting for potential confounding factors, high frequency of bubble tea consumption was observed to be significantly associated with high risk for depression in the regression model (p for trend = 0.045); no significant association was found with anxiety (p for trend = 0.332). In path analysis model, education mediated the association between FBTC and depression. Unlike the result in regression model, with education, exercise time and occupation as mediating factors, anxiety was found to be indirectly associated with FBTC.

LIMITATIONS

Symptoms of depression and anxiety were self-reported. And the cross-sectional nature of the study does not allow inferring causality.

CONCLUSIONS

Bubble tea consumption was associated with an increased risk of experiencing symptoms of depression and anxiety in Chinese young adults. Additional longitudinal research is required to elucidate the possible reverse causation from bubble tea consumption on symptoms of depression and anxiety.

Tea consumption and its effects on primary and secondary prevention of coronary artery disease: Qualitative synthesis of evidence from randomized controlled trials

BACKGROUND AND AIMS

There is a general interest in understanding how the consumption of tea impacts cardiovascular function in individuals at risk of developing cardiovascular disease (CVD). The current review focuses on evidence from randomized controlled trials (RCTs) reporting on associations between tea consumption and endothelial function, in the primary and secondary prevention of coronary artery disease (CAD).

METHODS

PubMed, EMBASE, and Google Scholar databases/search engines were used to identify eligible studies. Included studies had to report on the impact of tea supplementation of endothelial function or CAD related markers. In addition to flow-mediated dilation (FMD), makers of oxidative stress and inflammation such as oxidized low-density lipoprotein and C-reactive protein were considered as determinants of endothelial function. A total of 34 RCTs met the inclusion criteria, and these reported on the impact of tea consumption on endothelial function in individuals at risk of CVD or patients with CAD.

RESULTS

The current qualitative synthesis of literature demonstrates that beyond enhancing nitric oxide bioavailability and lowering blood pressure, regular consumption of tea and its active ingredients such as epigallocatechin gallate may be beneficial in reducing markers of oxidative stress and inflammation. Moreover, the reduction of oxidized low-density lipoprotein and C-reactive protein levels, could be a sign of improved endothelial function in individuals at increased risk of developing CVD.

CONCLUSIONS

The cumulative evidence also suggests that the development of epigallocatechin gallate as a nutraceutical or enriching foods with this bioactive compound could be a feasible strategy to improve endothelial function and lower CVD-risk. However, well-designed RCTs are still necessary to confirm long-term benefits of tea consumption on vascular health.

Novel insights in the relationship of gut microbiota and coronary artery diseases

Atherosclerosis is a chronic, progressive, inflammatory disease in the vasculature and is common in both coronary and peripheral arteries. Human beings harbor a complex and dynamic population of microorganisms defined as the microbiota. Importantly, alterations in the bacterial composition (dysbiosis) and the metabolic compounds produced by these bacteria have been associated with the pathogenesis of many inflammatory diseases and infections. There is also a close relationship between intestinal microbiota and cardiovascular diseases. The aim of this review was to analyze how changes in the gut microbiota and their metabolites might affect coronary artery diseases. The most representative groups of bacteria that make up the intestinal microbiota are altered in coronary artery disease patients, resulting in a decrease in Bacteroidetes and an increase in Firmicutes. In relation to metabolites, trimethylamine-N-oxide plays an important role in atherosclerosis and may act as a cardiovascular risk predictor. In addition, the use of probiotics, prebiotics, diet modulation, and fecal transplantation, which may represent alternative treatments for these diseases, is thoroughly discussed. Finally, the role of lipid-lowering treatments is also analyzed as they may affect and alter the gut microbiota and, conversely, gut microbiota diversity could be associated with resistance or sensitivity to these treatments.

Short-Term Tea Consumption Is Not Associated with a Reduction in Blood Lipids or Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

A recent systematic review of epidemiological evidence suggests that higher amounts of tea intake are associated with lower risks of cardiovascular disease (CVD) incidence and mortality.

OBJECTIVES

Our study objective was to assess mechanisms by which tea consumption may influence CVD risks.

METHODS

A systematic review and meta-analysis was conducted to investigate the effects of green and/or black tea consumption (≥4 wk) on systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride (TG) in healthy populations and among at-risk adults (analyzed separately) with metabolic syndrome, prediabetes, and hypercholesterolemia. The Grading of Recommendations Assessment, Development and Evaluation approach was used to rate the strength of evidence (SoE).

RESULTS

A total of 14 unique RCTs which randomly assigned 798 participants to either green tea, black tea, or placebo controls were included in our analyses. Intervention durations ranged from 4 to 24 wk (mean: 7.4 wk). Individual studies were judged as moderate to high quality based on risk of bias assessments. SoE was low to moderate owing to low sample sizes and insufficient power for most included studies to observe changes in the measured CVD biomarkers. Meta-analyses showed no significant effects of tea consumption on SBP, DBP, total cholesterol, LDL cholesterol, HDL cholesterol, and TG in healthy and at-risk adults (i.e., adults with obesity, prediabetes, borderline hypercholesterolemia, and metabolic syndrome).

CONCLUSIONS

Short-term (4-24 wk) tea consumption does not appear to significantly affect blood pressure or lipids in healthy or at-risk adults, although the evidence is limited by insufficient power to detect changes in these CVD biomarkers. High-quality RCTs with longer durations and sufficient sample sizes are needed to fully elucidate the effects of tea. This systematic review was registered at www.crd.york.ac.uk/prospero/ as CRD42020134513.

The effect of black tea supplementation on blood pressure: a systematic review and dose-response meta-analysis of randomized controlled trials

The main goal of this work was to clarify the effects of black tea supplementation on blood pressure (BP) by performing a systematic review according to the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines, followed by a dose-response meta-analysis of randomized controlled trials (RCTs). Electronic search was carried out in PubMed, Embase and the Cochrane Library databases published up to March 2020. To be included, RCTs had to report the effect of black tea supplementation on systolic blood pressure (SBP) or diastolic blood pressure (DBP) in adults. A total of 13 trials, including 22 study arms were eligible for inclusion in the final quantitative analysis. It was observed that black tea supplementation significantly reduced SBP (WMD - 1.04 mmHg; 95% CI - 2.05 to -0.03; and P = 0.04) and DBP (WMD - 0.59 mmHg; 95% CI - 1.05 to -0.13; and P = 0.01) compared to the control. However, nonlinear analysis failed to indicate a significant influence of black tea flavonoid supplementation dose or duration on both SBP and DBP. Sensitivity analysis showed that no individual study had a significant impact on our results. In addition, we found no evidence for the presence of small-study effects among studies for both SBP and DBP. Thus, the favorable effect of black tea supplementation emerging from the current meta-analysis suggests the possible use of this tea as an active compound in order to promote cardiovascular health, mostly when used for longer duration (>7 days) and in men. Furthermore RCTs using different doses of black tea and various durations may contribute to confirming our conclusion.

Coffee and Endothelial Function: A Coffee Paradox?

Coffee is a popular beverage throughout the world. Coffee contains various chemical compounds (e.g., caffeine, chlorogenic acids, hydroxyhydroquinone, kahweol, cafestol, and complex chemical mixtures). Caffeine is also the most widely consumed pharmacological substance in the world and is included in various beverages (e.g., coffee, tea, soft drinks, and energy drinks), products containing chocolate, and drugs. The effects of coffee and caffeine on cardiovascular diseases remain controversial. It is well known that there are J-curve-type or U-curve-type associations of coffee consumption with cardiovascular events including myocardial infarction and stroke. However, there is little information on the direct and indirect effects of coffee consumption on endothelial function in humans. It is likely that the coffee paradox or caffeine paradox exists the association of coffee intake with cardiovascular diseases, cardiovascular outcomes, and endothelial function. This review focusses on the effects of coffee and caffeine on endothelial function from molecular mechanisms to clinical perspectives.

The gut microbiome and cardiovascular disease: current knowledge and clinical potential

Cardiovascular disease (CVD) is the leading cause of death worldwide. The human body is populated by a diverse community of microbes, dominated by bacteria, but also including viruses and fungi. The largest and most complex of these communities is located in the gastrointestinal system and, with its associated genome, is known as the gut microbiome. Gut microbiome perturbations and related dysbiosis have been implicated in the progression and pathogenesis of CVD, including atherosclerosis, hypertension, and heart failure. Although there have been advances in the characterization and analysis of the gut microbiota and associated bacterial metabolites, the exact mechanisms through which they exert their action are not well understood. This review will focus on the role of the gut microbiome and associated functional components in the development and progression of atherosclerosis. Potential treatments to alter the gut microbiome to prevent or treat atherosclerosis and CVD are also discussed.