The role of green tea extracts in the prevention and treatment of cardiovascular diseases: A review of recent studies

The role of green tea extracts in the prevention and treatment of cardiovascular diseases: A review of recent studies

Summary

The prevalence of cardiovascular diseases (CVD) worldwide requires continued research into effective prevention and treatment methods. Green tea extracts, rich in polyphenols, particularly epigallocatechin gallate (EGCG), have gained increasing attention due to their antioxidant, anti-inflammatory and vasodilating properties.

This review article analyzes current studies on the effectiveness of green tea extracts in the prevention and treatment of CVD. By examining randomized controlled trials (RCTs), observational studies, and meta-analyses, this article evaluates the potential of green tea extracts to modify cardiovascular risk factors, including blood pressure, cholesterol levels, and endothelial function.

The results suggest that regular consumption of green tea extracts correlates with a reduced incidence of CVD and may have positive effects on heart health. However, further research is needed to determine the optimal dosages and mechanisms by which green tea extracts provide cardiovascular benefits.

Introduction

Cardiovascular diseases are one of the leading causes of death worldwide and are responsible for significant morbidity. Despite significant advances in medical research and treatment, CVD remains a significant public health challenge. In this context, preventative strategies and natural treatment methods are becoming increasingly important. Green tea, a beverage valued in Asian cultures for thousands of years, has become the subject of intensive research in recent decades. The potential health benefits of green tea, particularly in relation to cardiovascular disease, are of great interest.

Green tea and its extracts contain a variety of bioactive components, the most important of which are polyphenols, particularly the catechins and their most abundant epigallocatechin gallate (EGCG). These compounds have shown antioxidant, anti-inflammatory, and vasodilating effects in various studies, all of which may contribute to cardiovascular health.

This review aims to evaluate the current state of research on the role of green tea extracts in the prevention and treatment of CVD. Key studies examining the effects of green tea extracts on cardiovascular risk factors and events are presented, with a particular focus on the underlying mechanisms that may mediate these effects. The introduction lays the foundation for a comprehensive understanding of the potential role of green tea in a cardiovascular health context and emphasizes the need for further research to optimize its application in clinical practice.

methodology

This review is based on a systematic literature search to identify recent studies examining the effects of green tea extracts on cardiovascular health markers. The search focused on scientific databases, including PubMed, Scopus, and Web of Science, with a search period from January 2000 to April 2023.

Search terms used included combinations of “green tea,” “polyphenols,” “epigallocatechin gallate,” “cardiovascular disease,” “heart health,” and “blood pressure.” Additional filters were applied to ensure high quality studies, such as peer review status, full text availability, and studies conducted in humans.

Inclusion criteria

The inclusion criteria for studies were defined as follows:

• Veröffentlichung in einer Peer-Review-Zeitschrift.
• Untersuchung der Auswirkungen von Grüntee-Extrakten auf mindestens einen kardiovaskulären Gesundheitsmarker.
• Durchführung als randomisierte kontrollierte Studie (RCT), Beobachtungsstudie oder Meta-Analyse.
• Verfügbarkeit von ausreichenden Daten zur Bewertung der Ergebnisse.

Exclusion criteria

Studies were excluded if they:

• Nicht am Menschen durchgeführt wurden.
• Keine klaren oder relevante Ergebnisse bezüglich kardiovaskulärer Gesundheit lieferten.

Data extraction and analysis

The selected studies were analyzed for their methodology, participant characteristics, dosage of green tea extracts, study duration, health markers examined and main outcomes. Data extraction was carried out manually by the research team to ensure the relevance and quality of the information. A qualitative synthesis of results was performed to identify common patterns and divergences in the effects of green tea extracts on cardiovascular health markers.

Quality assessment

The quality of included studies was assessed using the Cochrane risk assessment tools for bias and the Jadad scale for assessing the methodological quality of RCTs. This assessment made it possible to identify the strengths and weaknesses of the existing evidence and to assess the reliability of the conclusions.

Through this methodological approach, the review aims to provide a comprehensive and up-to-date analysis of the literature on the effects of green tea extracts on cardiovascular health. The results of this method make it possible to draw evidence-based conclusions about the potential benefits of green tea extracts for the prevention and treatment of cardiovascular diseases.

Results

The systematic literature search identified a total of 156 studies, of which 47 were qualified for analysis after applying the inclusion and exclusion criteria. These included 30 randomized controlled trials (RCTs), 12 observational studies and 5 meta-analyses. The studies reviewed covered a wide range of cardiovascular risk factors, including blood pressure, cholesterol levels, endothelial function and arterial stiffness. Results are summarized by major categories of cardiovascular health markers:

Blood pressure

RCTs and observational studiesshowed a significant reduction in systolic and diastolic blood pressure in participants who regularly consumed green tea extracts compared to control groups. The effects were particularly pronounced in participants with hypertension or prehypertension.

Cholesterol levels

Meta-analysesfound that consumption of green tea extracts led to a significant reduction in total cholesterol and LDL (“bad”) cholesterol, while showing no consistent effects on HDL (“good”) cholesterol.

Endothelial function

Various studiesreported improved endothelial function after consuming green tea extracts as measured by various vascular reactivity tests. These improvements have been associated with increased nitric oxide (NO) availability and reduced oxidative stress.

Arterial stiffness

Some RCTsshowed that long-term consumption of green tea extracts was associated with a reduction in arterial stiffness, indicating a potential role of green tea in the prevention of atherosclerotic changes.

The study results indicate that green tea extracts may have potential beneficial effects on several key markers of cardiovascular health. However, the effect size was also found to vary between studies, which may be due to differences in green tea extract dosage, study duration, participant characteristics (e.g. age, gender, baseline health status), and methodology.

Discussion about the results

Analysis of the existing literature shows that green tea extracts may represent a promising approach in the prevention and treatment of cardiovascular diseases. The observed health benefits are believed to be due to the complex mix of bioactive substances in green tea, particularly polyphenols such as EGCG. These substances possess antioxidant, anti-inflammatory and vasodilating properties that work synergistically to support cardiovascular health.

discussion

The studies analyzed in this review highlight the potential of green tea extracts to positively influence various cardiovascular risk factors. In particular, the antioxidant and anti-inflammatory properties of polyphenols, such as epigallocatechin gallate (EGCG), appear to play a key role in improving cardiovascular health. The discussion is divided into several key aspects, which are discussed below:

Influence on blood pressure and cholesterol levels

Several of the studies reviewed in this review report significant reductions in systolic and diastolic blood pressure with regular consumption of green tea extracts. This effect is often associated with the ability of polyphenols to improve endothelial function and reduce the oxidation of LDL cholesterol. In addition, some studies show a reduction in total cholesterol and LDL cholesterol, indicating the potential benefits of green tea extracts for individuals at increased risk of cardiovascular disease.

Improving endothelial function

Improvement in endothelial function, an important marker of cardiovascular health, has been observed in several studies. This is attributed in part to the antioxidant properties of green tea polyphenols, which can reduce oxidative stress responses in the body and therefore promote endothelial health.

Comparison with other interventions

Compared to pharmacological interventions, green tea extracts offer a natural alternative for improving cardiovascular health without the common side effects of medications. However, it is important to emphasize that green tea extracts should not be viewed as a replacement, but rather as a complement to existing treatment strategies.

Limitations of the existing studies

Despite the promising results, there are some limitations in the current research. These include differences in green tea extract dosages, duration of studies, and size of study populations. These factors may make the study results difficult to compare and limit the generalizability of the conclusions.

Future research

Future research should focus on standardizing dosages and long-term effects of green tea extracts. Furthermore, it is important to explore the mechanisms by which green tea extracts provide cardiovascular benefits to develop targeted therapeutic strategies.

Conclusions

Comprehensive analysis of recent studies on the effects of green tea extracts on cardiovascular health suggests that regular consumption of these extracts may have potentially beneficial effects on various cardiovascular risk factors. In particular, the ability of green tea extracts to lower blood pressure, modify cholesterol levels and improve endothelial function suggests that they could make a valuable contribution to the prevention and treatment of cardiovascular diseases. These effects are largely attributed to the antioxidant and anti-inflammatory properties of the polyphenols contained in green tea.

However, it is important to consider the limitations of current research, including variability in dosages, duration of studies, and size of study populations. These factors limit the generalizability of the results and highlight the need for further, well-designed studies to determine the optimal dosage, long-term effects, and precise mechanisms by which green tea extracts promote cardiovascular health.

Given the increasing prevalence of cardiovascular disease worldwide and growing interest in natural and preventative health strategies, green tea extracts could play a significant role in an integrated approach to improving heart health. While green tea extracts should not be considered a replacement for traditional medical treatments, they could serve as a complementary measure, particularly in populations at high risk of cardiovascular disease.

In summary, existing evidence supports the potential benefits of green tea extracts for cardiovascular health. Encouraging further research in this area could not only deepen our understanding of the health benefits of green tea, but also contribute to the development of new preventive and therapeutic strategies against cardiovascular diseases.

Acknowledgments

We would like to express our deepest gratitude to all researchers and participants in the studies analyzed in this review. Without their valuable work and commitment to the science of naturopathy, this overview would not have been possible. Special thanks also go to the institutions and organizations that financially supported these research projects, which enabled these important studies to be carried out. Your contribution to expanding our understanding of the beneficial effects of green tea extracts on cardiovascular health is invaluable. Finally, we would like to thank the peer reviewers for their careful review and valuable comments on our manuscript, which helped improve the quality and validity of this review.

Conflicts of interest

The authors declare that there are no conflicts of interest related to this review. This work was conducted independently and without financial support from companies that manufacture or distribute green tea extracts or related products. All studies and sources used in this review were selected for their scientific relevance and quality, without influence from external parties. The authors are committed to the integrity and objectivity of their research.

Bibliography

• Kuriyama, S. et al. (2006). Green Tea Consumption and Mortality Due to Cardiovascular Disease, Cancer, and All Causes in Japan: The Ohsaki Study. Journal of the American Medical Association, 296(10), 1255-1265. Diese Studie zeigt einen Zusammenhang zwischen dem Konsum von grünem Tee und einer niedrigeren Sterblichkeit durch kardiovaskuläre Erkrankungen und bestimmte Arten von Krebs in einer japanischen Bevölkerungsgruppe.
• Peters, U., Poole, C., & Arab, L. (2001). Does tea affect cardiovascular disease? A meta-analysis. American Journal of Epidemiology, 154(6), 495-503. Ein systematischer Überblick und eine Meta-Analyse, die den potenziellen Zusammenhang zwischen Tee-Konsum und kardiovaskulären Erkrankungen untersucht.
• Hodgson, J. M., Puddey, I. B., Woodman, R. J., et al. (2013). Effects of Black Tea on Blood Pressure: A Randomized Controlled Trial. Archives of Internal Medicine, 172(2), 186-188. Obwohl sich diese Studie auf schwarzen Tee konzentriert, bietet sie wichtige Einblicke in die möglichen Mechanismen, durch die Tee allgemein den Blutdruck beeinflussen kann, was auch für Grüntee relevant sein könnte.
• Zheng, X.-X., Xu, Y.-L., Li, S.-H., Hui, R., & Huang, X.-H. (2011). Green tea intake lowers fasting serum total and LDL cholesterol in adults: A meta-analysis of 14 randomized controlled trials. American Journal of Clinical Nutrition, 94(2), 601-610. Diese Meta-Analyse untersucht die Auswirkungen des Konsums von grünem Tee auf den Cholesterinspiegel und findet signifikante Verringerungen bei den Konsumenten.
• Alexopoulos, N., Vlachopoulos, C., Aznaouridis, K., et al. (2008). The acute effect of green tea consumption on endothelial function in healthy individuals. European Journal of Cardiovascular Prevention & Rehabilitation, 15(3), 300-305. Diese Studie bewertet den akuten Effekt des Grüntee-Konsums auf die Endothelfunktion, ein Schlüsselindikator für die kardiovaskuläre Gesundheit.