Acute black tea consumption improves cutaneous vascular function in healthy middle-aged humans

Health-Promoting Effects of Black Tea: A Narrative Review of Clinical Trials

Black tea, a popular beverage, is rich in polyphenols. However, thorough analyses of clinical trial evidence supporting its health benefits are lacking. This narrative review is aimed at addressing this knowledge gap by synthesizing findings across pivotal clinical domains and identifying critical areas for further investigation. A comprehensive search of PubMed/MEDLINE, PubMed Central, Scopus, Web of Science, and Google Scholar was performed for English-language papers from January 1990 to July 2024, focusing on cardiovascular and metabolic health, as well as cognitive function. Findings from clinical trials indicated that consuming black tea regularly enhances endothelial and vascular health, notably by improving flow-mediated vasodilation. These advantages are largely due to the tea's antioxidant, anti-inflammatory, and gut microbiota-modulating effects, including the promotion of beneficial bacterial species such as Flavonifractor plautii. Effects on metabolic health, such as lipid profiles and glucose metabolism, were inconsistent. However, black tea was linked to improved cognitive function, especially attention and alertness, likely due to caffeine and L-theanine. Despite these promising results, further research is needed to overcome limitations like small sample sizes and short study durations. Future studies should be aimed at standardizing black tea preparations to optimize health benefits.

Flavonoids and Other Phenolic Compounds for Physiological Roles, Plant Species Delimitation, and Medical Benefits: A Promising View

Flavonoids and other phenolic constituents are a large group of plant metabolites that have long attracted interest from researchers worldwide due to their functions in plant physiology, as well as their huge number of benefits for human health and well-being. This review attempts to reveal a promising view of the major physiological roles of flavonoids and other phenolic phytochemical molecules, e.g., protection agents against UV damage, pathogen defense agents, detoxifying agents, and agents promoting pollen fertility and successful pollination. Besides, the value of both flavonoids and other phenolic phytochemicals for plant species delimitation was also emphasized for the first time with the determination of their major physiological roles. Furthermore, their medical benefits for mankind were also highlighted in this current work.

From a Cup of Tea to Cardiovascular Care: Vascular Mechanisms of Action

Tea consumption is increasingly recognized for its potential benefits to cardiovascular health. This study reviews the available research, concentrating on the major components of tea and their mechanisms of action in the cardiovascular system. Tea is abundant in bioactive compounds, such as flavonoids and polysaccharides, which possess significant antioxidant and anti-inflammatory properties. These compounds play a crucial role in mitigating oxidative stress and inflammation, thereby supporting cardiovascular health. They enhance endothelial function, leading to improved vascular relaxation and reduced arterial stiffness, and exhibit antithrombotic effects. Additionally, regular tea consumption is potentially associated with better regulation of blood pressure, improved cholesterol profiles, and effective blood sugar control. It has been suggested that incorporating tea into daily dietary habits could be a practical strategy for cardiovascular disease prevention and management. Despite the promising evidence, more rigorous clinical trials are needed to establish standardized consumption recommendations and fully understand long-term effects. This review offers a more comprehensive analysis of the current evidence based on endothelium function and identifies the gaps that future research should address.

Protective effects and molecular mechanisms of tea polyphenols on cardiovascular diseases

Aging is the most important factor contributing to cardiovascular diseases (CVDs), and the incidence and severity of cardiovascular events tend to increase with age. Currently, CVD is the leading cause of death in the global population. In-depth analysis of the mechanisms and interventions of cardiovascular aging and related diseases is an important basis for achieving healthy aging. Tea polyphenols (TPs) are the general term for the polyhydroxy compounds contained in tea leaves, whose main components are catechins, flavonoids, flavonols, anthocyanins, phenolic acids, condensed phenolic acids and polymeric phenols. Among them, catechins are the main components of TPs. In this article, we provide a detailed review of the classification and composition of teas, as well as an overview of the causes of aging-related CVDs. Then, we focus on ten aspects of the effects of TPs, including anti-hypertension, lipid-lowering effects, anti-oxidation, anti-inflammation, anti-proliferation, anti-angiogenesis, anti-atherosclerosis, recovery of endothelial function, anti-thrombosis, myocardial protective effect, to improve CVDs and the detailed molecular mechanisms.

Acute impact of aerobic exercise on local cutaneous thermal hyperaemia

Little is known about the acute changes in cutaneous microvascular function that occur in response to exercise, the accumulation of which may provide the basis for beneficial chronic cutaneous vascular adaptations. Therefore, we examined the effects of acute exercise on cutaneous thermal hyperaemia. Twelve healthy, recreationally active participants (11 male, 1 female) performed 30-minute cycling at 50 % (low-intensity exercise, LOW) or 75 % (high-intensity exercise, HIGH) maximum heart rate. Laser Doppler flowmetry (LDF) and rapid local skin heating were used to quantify cutaneous thermal hyperaemia before (PRE), immediately following (IMM) and 1-h (1HR) after exercise. Baseline, axon reflex peak, axon reflex nadir, plateau, maximum skin blood flow responses to rapid local heating (42 °C for 30-min followed by 44 °C for 15-min) at each stage were assessed and indexed as cutaneous vascular conductance [CVC = flux / mean arterial blood pressure (MAP), PU·mm Hg^-1], and expressed as a percentage of maximum (%CVC_max). Exercise increased heart rate (HR), MAP and skin blood flow (all P < 0.001), and to a greater extent during HIGH (all P < 0.001). The axon reflex peak and nadir were increased immediately and 1-h after exercise (all comparisons P < 0.01 vs. PRE), which did not differ between intensities (peak: P = 0.34, axon reflex nadir: P = 0.91). The endothelium-dependent plateau response was slightly elevated after exercise (P = 0.06), with no effect of intensity (P = 0.58) nor any interaction effect (P = 0.55). CONCLUSION: Exercise increases cutaneous microvascular axonal responses to local heating for up to 1-h, suggesting an augmented sensory afferent function post-exercise. Acute exercise may only modestly affect endothelial function in cutaneous microcirculation.

Research progress on the lipid-lowering and weight loss effects of tea and the mechanism of its functional components

Obesity caused by poor eating habits has become a great challenge faced by public health organizations worldwide. Optimizing dietary intake and ingesting special foods containing biologically active substances (such as polyphenols, alkaloids, and terpenes) is a safe and effective dietary intervention to prevent the occurrence and development of obesity. Tea contains several active dietary factors, and daily tea consumption has been shown to have various health benefits, especially in regulating human metabolic diseases. Here, we reviewed recent advances in research on tea and its functional components in improving obesity-related metabolic dysfunction, and gut microbiota homeostasis and related clinical research. Furthermore, the potential mechanisms by which the functional components of tea could promote lipid-lowering and weight-loss effects by regulating fat synthesis/metabolism, glucose metabolism, gut microbial homeostasis, and liver function were summarized. The research results showing a "positive effect" or "no effect" objectively evaluates the lipid-lowering and weight-loss effects of the functional components of tea. This review provides a new scientific basis for further research on the functional ingredients of tea for lipid lowering and weight loss and the development of lipid-lowering and weight-loss functional foods and beverages derived from tea.

Aging-Induced Impairment of Vascular Function: Mitochondrial Redox Contributions and Physiological/Clinical Implications

Significance: The vasculature responds to the respiratory needs of tissue by modulating luminal diameter through smooth muscle constriction or relaxation. Coronary perfusion, diastolic function, and coronary flow reserve are drastically reduced with aging. This loss of blood flow contributes to and exacerbates pathological processes such as angina pectoris, atherosclerosis, and coronary artery and microvascular disease. Recent Advances: Increased attention has recently been given to defining mechanisms behind aging-mediated loss of vascular function and development of therapeutic strategies to restore youthful vascular responsiveness. The ultimate goal aims at providing new avenues for symptom management, reversal of tissue damage, and preventing or delaying of aging-induced vascular damage and dysfunction in the first place. Critical Issues: Our major objective is to describe how aging-associated mitochondrial dysfunction contributes to endothelial and smooth muscle dysfunction via dysregulated reactive oxygen species production, the clinical impact of this phenomenon, and to discuss emerging therapeutic strategies. Pathological changes in regulation of mitochondrial oxidative and nitrosative balance (Section 1) and mitochondrial dynamics of fission/fusion (Section 2) have widespread effects on the mechanisms underlying the ability of the vasculature to relax, leading to hyperconstriction with aging. We will focus on flow-mediated dilation, endothelial hyperpolarizing factors (Sections 3 and 4), and adrenergic receptors (Section 5), as outlined in Figure 1. The clinical implications of these changes on major adverse cardiac events and mortality are described (Section 6). Future Directions: We discuss antioxidative therapeutic strategies currently in development to restore mitochondrial redox homeostasis and subsequently vascular function and evaluate their potential clinical impact (Section 7). Antioxid. Redox Signal. 35, 974-1015.

Research progress on the potential delaying skin aging effect and mechanism of tea for oral and external use

Skin aging is characterized by the gradual loss of elasticity, the formation of wrinkles and various color spots, the degradation of extracellular matrix proteins, and the structural changes of the dermis. With the increasingly prominent problems of environmental pollution, social pressure, ozone layer thinning and food safety, skin problems have become more and more complex. The skin can reflect the overall health of the body. Skincare products for external use alone cannot fundamentally solve skin problems; it needs to improve the overall health of the body. Based on the literature review in recent 20 years, this paper systematically reviewed the potential delaying effect of tea and its active ingredients on skin aging by oral and external use. Tea is the second-largest health drink after water. It is rich in tea polyphenols, l-theanine, tea pigments, caffeine, tea saponins, tea polysaccharides and other secondary metabolites. Tea and its active substances have whitening, nourishing, anti-wrinkle, removing spots and other skincare effects. Its mechanism of action is ultraviolet absorption, antioxidant, anti-inflammatory, inhibition of extracellular matrix aging, inhibiting the accumulation of melanin and toxic oxidation products, balancing intestinal and skin microorganisms, and improving mood and sleep, among other effects. At present, tea elements skincare products are deeply loved by consumers. This paper provides a scientific theoretical basis for tea-assisted beauty and the high-end application of tea in skincare products.

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.

Higher tea consumption is associated with decreased risk of small vessel stroke

BACKGROUND & AIM

Observational studies have reported that tea consumption is associated with risk of stroke. However, this observed association is inconsistent, and whether this observed association is due to confounding factors or reverse causation remains unclear. Thus, we applied a two-sample mendelian randomization (MR) approach to determine whether genetically predicted tea consumption is causally associated with risk of stroke, ischemic stroke (IS), and IS subtypes.

METHODS

UK Biobank available data (349,376 samples of European ancestry) was used to identify single nucleotide polymorphisms associated with tea consumption (cups/day). The summary statistics for stroke, IS, and IS subtypes were obtained from the MEGASTROKE consortium with 40,585 stroke cases and 406,111 controls.

RESULTS

We found that genetically predicted an extra daily cup of tea consumption was casually associated with a reduced risk of small vessel stroke (odds ratio (OR), 0.79; 95% confidence interval (CI), 0.69-0.91; P = 0.001), but not with cardioembolic stroke (OR, 0.97; 95% CI, 0.86-1.09; P = 0.582), large artery stroke (OR, 0.95; 95% CI, 0.82-1.10; P = 0.506), stroke (OR, 1.00; 95% CI, 0.95-1.06; P = 0.889) or IS (OR, 0.95; 95% CI, 0.89-1.01; P = 0.083).

CONCLUSIONS

Our study provided evidence that genetically predicted an extra daily cup of tea consumption is causally associated with a reduced risk of small vessel stroke.

Health Functions and Related Molecular Mechanisms of Tea Components: An Update Review

Tea is widely consumed all over the world. Generally, tea is divided into six categories: White, green, yellow, oolong, black, and dark teas, based on the fermentation degree. Tea contains abundant phytochemicals, such as polyphenols, pigments, polysaccharides, alkaloids, free amino acids, and saponins. However, the bioavailability of tea phytochemicals is relatively low. Thus, some novel technologies like nanotechnology have been developed to improve the bioavailability of tea bioactive components and consequently enhance the bioactivity. So far, many studies have demonstrated that tea shows various health functions, such as antioxidant, anti-inflammatory, immuno-regulatory, anticancer, cardiovascular-protective, anti-diabetic, anti-obesity, and hepato-protective effects. Moreover, it is also considered that drinking tea is safe to humans, since reports about the severe adverse effects of tea consumption are rare. In order to provide a better understanding of tea and its health potential, this review summarizes and discusses recent literature on the bioactive components, bioavailability, health functions, and safety issues of tea, with special attention paid to the related molecular mechanisms of tea health functions.

Yerba Maté (Ilex paraguariensis) Metabolic, Satiety, and Mood State Effects at Rest and during Prolonged Exercise

Yerba Maté (YM), has become a popular herb ingested for enhancing metabolic health and weight-loss outcomes. No studies have tested the combined metabolic, satiety, and psychomotor effects of YM during exercise. We tested whether YM ingestion affects fatty acid oxidation (FAO), profile of mood state score (POMS), and subjective appetite scale (VAS), during prolonged moderate exercise. Twelve healthy active females were randomized to ingest either 2 g of YM or placebo (PLC) in a repeated-measures design. Participants rested for 120 min before performing a 30-min cycling exercise corresponding to individuals’ crossover point intensity (COP). FAO, determined using indirect calorimetry, was significantly higher during the 30-min exercise in YM vs. PLC (0.21 ± 0.07 vs. 0.17 ± 0.06 g/min, p < 0.05). VAS scores for hunger, prospective eating, and desire to eat were all reduced (p < 0.05). Whereas, POMS measures of focus, energy, and concentration were all increased (p < 0.05). There was no significant time-effect for any of the measured variables, nor was there any interaction effects between YM treatment and time. Combining YM intake with prolonged exercise at targeted ”fat-loss”’ intensities augments FAO and improves measures of satiety and mood state. Such positive combined metabolic, satiety, and psychomotor effects may provide an important role for designing future fat and weight-loss lifestyle interventions.