Tea
Written by Tommy Li and Jerry Lau
Tea was and still is one of the most highly sought after commodities in the world. From its origins in a small province in ancient China, to its massive rise as a huge motivator in world conflicts, tea has been anything but a drink. But why tea? Tea has been used around the world for its perceived medicinal qualities, its rich taste, its ability to bring people together, etc. Here we will focus on tea’s perceived medicinal qualities and weigh out how the health claims on tea hold out versus the scientific community.
Teas’ health claims range from the relatively benign claim of improving blood pressure and circulation to eye-raising claims of being able to fight various forms of cancer (3). However most studies state that these health benefits come from drinking tea over long periods of time and do not paint tea as a “miracle substance” that many from the tea industry characterize it to be. How does tea have these benefits? There are substances in tea called polyphenols, more specifically catechins and epicatechins. Lab and animal studies find that these molecules have anti-inflammatory and antioxidant properties (1). This is corroborated by multiple studies in the field; one such study stating that patients with elevated blood pressure or hypertension would benefit from regular tea intake which was shown to have positive effects on the patients’ blood pressure (2).
There are many different types of tea available to purchase; some popular ones being black tea, green tea, oolong tea, and Kombucha. Although all teas contain polyphenols, not all teas are made equal. For example, Kombucha, a probiotic-rich fermented drink made with tea (green or black), sugar, bacteria, and yeast, is very interesting. Kombucha has a yeast component that usually includes Saccharomyces and other species; the bacterial component almost always includes Gluconacetobacter xylinus. It can be a fermented slightly effervescent, sweetened (slightly sour) drink used as a functional beverage to provide health benefits (0.5-3% alcohol). Microbes break sugars down to alcohol and CO2. Then bacteria converts alcohol to acids (e.g. acetic). It has been traditionally used primarily in Manchuria, Russia, eastern Europe and Japan. Kombucha claims to have benefits to asthma, cataracts, diabetes, diarrhea, gout, herpes, insomnia and rheumatism; to shrink the prostate, raise the libido, reverse grey hair, remove wrinkles, relieve hemorrhoids, lower hypertension, prevent cancer, to promote general well-being, help to lose weight, treat constipation, and to stimulate the immune system (4). But because of its microbial sourcing and possible non-sterile packaging, it is not recommended for people with poor immune function (HIV), women who are pregnant or nursing, and children under 4 years old. Furthermore, matcha, a type of green tea, is very effective in reducing stress. Beside caffeine, it also contains theanine, a major amino acid in green tea that exhibits a stress-reducing effect in mice and humans (5).
The potentials of tea have been analyzed in many experiments. Further research will be needed to investigate more benefits and side effects. Given the tremendous amount of time in history, people have learned to appreciate tea - a taste of age.
References:
Zhang Z, Feng X, Wang Y, et al. Advances in research on functional genes of tea plants. Gene. 2019;711:143940.
Mahdavi-Roshan M, Salari A, Ghorbani Z, Ashouri A. The effects of regular consumption of green or black tea beverages on blood pressure in those with elevated blood pressure or hypertension: A systematic review and meta-analysis. Complement Ther Med. 2020;51:102430.
“The Hidden Health Benefits of Tea”. Health and Wellness. PennMedicine. https://www.pennmedicine.org/updates/blogs/health-and-wellness/2019/december/health-benefits-of-tea. Accessed 2021 Aug 26.
Beaufort, S, Bouajila, J, Taillandier, P. “Understanding Kombucha Tea Fermentation: A Review”. https://pubmed-ncbi-nlm-nih-gov.jerome.stjohns.edu/29508944/ 2018 Mar;83(3):580-588.
Unno K, Furushima D, Hamamoto S, Iguchi K, Yamada H, Morita A, et al. . Stress-reducing function of matcha green tea in animal experiments and clinical trials. Nutrients. (2018) 10:1468. 10.3390/nu10101468
Green tea, extracted from Camellia sinensis leaves, has been revered for centuries for its refreshing taste and presumed health advantages. Traditional Chinese and Indian medicines acknowledge its therapeutic properties, and contemporary studies continue to unveil its potential in pharmacology. A prominent constituent of green tea is catechins, antioxidants that may safeguard cells against harm. Among these, epigallocatechin gallate (EGCG) stands out for its potent antioxidant properties. Antioxidants neutralize harmful free radicals, thereby reducing oxidative stress and inflammation, both of which are linked to various chronic ailments.
The medicinal benefits of green tea are manifold, including potential protection against cardiovascular disease. Research suggests that green tea consumption may decrease LDL cholesterol levels and diminish the risk of heart disease. Catechins in green tea may also enhance endothelial function, which helps regulate blood pressure and clotting, further supporting heart health. Green tea has been linked to a reduced risk of certain cancers. Studies indicate that EGCG may impede tumor growth and prevent cancer cell proliferation, particularly in breast, prostate, and colorectal cancers. Although further research is needed to fully comprehend the mechanisms, green tea's anti-cancer properties show promise. Green tea is also associated with weight management and metabolic health benefits. Some studies suggest that catechins can boost energy expenditure and fat oxidation, leading to weight and body fat reduction. Green tea extract supplements are sometimes used as a natural weight loss aid. Another area of interest is green tea's potential to protect the brain. Some studies suggest that catechins may shield brain cells from damage and reduce the risk of neurodegenerative diseases like Alzheimer's and Parkinson's. Green tea consumption has also been linked to improved cognitive function and reduced cognitive decline in older adults. Green tea catechins can interact with various enzymes and signaling pathways in the body. For example, EGCG can inhibit the activity of catechol-O-methyltransferase (COMT), an enzyme that breaks down neurotransmitters like dopamine, potentially affecting mood and cognition.
Green tea also contains caffeine, albeit in smaller amounts than coffee. Caffeine is a stimulant that can enhance alertness, concentration, and mood. The combination of caffeine and catechins in green tea may synergistically boost brain function, contributing to its reputation as a "brain-boosting" beverage.
In conclusion, green tea offers a wide range of potential health benefits, supported by both traditional knowledge and modern research. Its abundant antioxidants, particularly EGCG, contribute to its medicinal properties, which include cardiovascular protection, cancer prevention, weight management, and neuroprotection. While more research is needed to fully understand the mechanisms and optimize its therapeutic use, incorporating green tea into a balanced diet may offer numerous health advantages.
References:
https://www.nccih.nih.gov/health/green-tea#:~:text=Tea%20has%20been%20used%20for,headaches%2C%20and%20promoting%20weight%20loss.
https://www.mskcc.org/cancer-care/integrative-medicine/herbs/green-tea