In a recent article published in Heliyon, researchers summarized the content of active ingredients in different types of tea, the second most consumed beverage in the world. They also explored the possibility of using tea extracts for coronavirus disease 2019 (COVID-19) prevention and treatment.
COVID-19 primarily affects the upper respiratory tract, causing symptoms like fever, fatigue, and cough. As of January 2023, COVID-19 has impacted the lives of over 662 million people worldwide. Moreover, the currently available drugs, mainly antiviral, antibacterial, and immune drugs, are not specific to COVID-19 and ineffective in preventing and treating its persistent symptoms.
Previous studies have extensively studied chemical constituents in tea, but their effects on COVID-19 and its sequelae still need to be clarified. The active ingredients in tea include polyphenols, alkaloids, polysaccharides, triterpenoids, and organic acids. The chemical constituents in tea have antibacterial, antioxidant, hypoglycemic, and other effects.
However, excessive tea could cause nausea, diarrhea, and adverse reactions. Accordingly, the Food and Drug Administration (FDA) approved a green tea polyphenol preparation with epigallocatechin gallate (EGCG), a type of catechin.
About the study
In the present study, researchers explored different types of teas, their effect (s) on COVID-19, and their short- and long-term symptoms to propose a scientific way of consuming tea.
Furthermore, they used network pharmacology technology to analyze tea targets, chemical components, and related action pathways. The researchers also verified the effects of tea on new coronary pneumonia and complications.
The authors classified tea leaves broadly into six types based on their production methods, oxidation speed, and the number of flavanols in them. Accordingly, they described green, yellow, dark, black, oolong, and white teas varying in their medicinal characteristics. For instance, dark and green teas are the warmest and the coldest, respectively, and yellow and oolong teas are relatively mild. These revelations indicate which tea types are more suitable for people inhabiting different geographical regions worldwide. Thus, people inhabiting perennially hot areas should consume green tea, whereas those inhabiting colder regions should preferably consume fermented teas.
Like a previous review, the study analysis found that catechin, including catechin gallate and EGCG, are upstream active tea components. More importantly, it identified TERT as the core target of tea that could treat COVID-19 and its six long-term sequelae. These were atherosclerosis, hypertension, arrhythmia, pulmonary fibrosis, and motor and cognitive deficits. Furthermore, the study analysis implicated Ras-proximate-1 (Rap1) signaling pathway in the respiratory, cardiovascular, and nervous systems-related COVID-19 sequelae.
Most importantly, the researchers emphasized the scientific tea consumption and timing its consumption to prevent the adverse effects of caffeine in the tea leaves on the gastric mucosa.
Notably, consuming tea immediately after a meal releases tannin from the tea leaves, which with protein from a meal, increases the burden on the stomach. However, its scientific consumption could inhibit proinflammatory factors released in response to infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It reduces the damage caused to the body by a cytokine storm through tumor growth factor beta (TGF-β) and other signaling pathways. In addition, it reduces pulmonary fibrosis by regulating several immune signaling pathways.
Active tea ingredients, such as alkaloids, amino acids (AAs), and catechins, had many beneficial roles. For instance, AAs and alkaloids freshen up the mind, and polyphenols promote lipid metabolism. Likewise, catechins and alkaloids regulate blood pressure and heart rate and help recover from atherosclerosis by regulating vasoconstriction. Concerning new onset coronary pneumonia, which leads to COVID-19-related neurological sequelae in over 50% of patients, the tea component, L-theanine, promotes neuron differentiation and proliferation. Similarly, polyphenols in tea potentially repair injured neurons and improve depression and anxiety.
To summarize, the study analysis uncovered that different types of teas could prevent and treat COVID-19 and its sequelae. With more extensive clinical evaluations, some of the active ingredients in tea are effective drugs for the prevention and treatment of COVID-19.
Some of the active ingredients in tea could hinder SARS-CoV-2 from invading and replicating in the human body. Even if it does invade, the active ingredients might minimize COVID-19 severity by reducing cytokine levels and responding to SARS-CoV-2 reinfection by manipulating the immune system. According to the authors, for tea and its active ingredients to work synergistically to prevent and treat COVID-19 and its sequelae, it is of utmost importance to consume tea scientifically.
- Jiaming Ge, Tianbao Song, Mengyuan Li, Weisan Chen, Jiarong Li, Sihan Gong, Ying Zhao, Lin Ma, Hongjian Yu, Xiankuan Li, Kun Fu. (2023. The medicinal value of tea drinking in the management of COVID-19. HELIYON. doi: https://doi.org/10.1016/j.heliyon.2023.e12968 https://www.sciencedirect.com/science/article/pii/S2405844023001755