Black tea as preventive medicine
Black tea, a popular beverage derived from the leaves of the Camellia sinensis plant, is gaining attention for its potential health benefits, particularly in the realm of preventive medicine. While commonly overshadowed by green tea in health discussions, black tea is recognized for its unique composition, including theaflavins, theanine, and thearubigins. Research suggests that regular consumption of black tea may be linked to reduced risks of heart disease and related conditions, although evidence remains inconclusive due to the limitations of observational studies and the need for more rigorous clinical trials.
Emerging studies, including those conducted by the National Cancer Institute, indicate that higher black tea consumption may correlate with lower mortality rates from cardiovascular diseases and improved vascular health. Additionally, potential benefits have been noted for stress reduction, cognitive function, and gut health, alongside its anti-inflammatory and antioxidant properties. However, like any beverage containing caffeine, black tea may have side effects, including heartburn and insomnia, and can interact with various medications. Overall, while black tea shows promise as a preventive health measure, further research is necessary to confirm its efficacy and establish optimal consumption guidelines.
Black tea as preventive medicine
DEFINITION: Natural plant product consumed for specific health benefits.
PRINCIPAL PROPOSED USE: Heart disease prevention
OTHER PROPOSED USES: Cancer prevention, diabetes, high blood pressure, high cholesterol, osteoporosis prevention, sports and fitness, stress reduction, neurodegenerative diseases, gut health
Overview
Black and green tea are made from the same plant, but black tea has been allowed to oxidize in processing, which alters its constituents. Although green tea is high in catechins (especially epigallocatechin gallate), black tea contains relatively high levels of theaflavins, theanine, and thearubigins. Although green tea is more commonly presented as a healthful beverage, traditional black tea, too, might have health-promoting properties. However, there is limited evidence of the health benefits of black tea.
Uses and Applications
According to some observational studies, the high consumption of black tea is associated with a reduced risk of heart disease and death from heart disease. However, observational studies are notoriously unreliable for proving the efficacy of a treatment. Some additional support for black tea comes from animal studies that hint black tea may help prevent atherosclerosis, the primary cause of heart disease. However, only double-blind, placebo-controlled studies can prove a treatment effective, and few have been conducted on black tea.
One double-blind, placebo-controlled study found that black tea modestly improves cholesterol profile but enrolled too few participants (fifteen) to provide trustworthy results. Another study, about twice as large, failed to find benefit. A much larger study (more than two hundred participants) evaluated a form of green tea enriched with black tea theaflavin. In this substantial three-month study, using the tea product resulted in significant reductions in LDL (bad) cholesterol compared with placebo. However, these results might not apply to black tea itself.
Theanine, a component of black tea, has been advocated as a sports supplement. Physical activity causes elevation of the stress hormone cortisol, which could, in theory, interfere with the benefits of exercise by slowing muscle growth. One study widely reported by tea advocates tested a mixture of theanine and several other herbs and supplements (Magnolia officinalis, Epimedium koreanum, beta-sitosterol, and phosphatidylserine). The results appeared to indicate that using this combination could decrease the cortisol response to exercise. On this basis, theanine and the combination supplement are widely marketed as a bodybuilding aid. However, this study has several limitations. Perhaps the most important of these limitations is that, presumably, the body releases cortisol during exercise for a reason; preventing this response may not produce health benefits. In addition, the study was not designed to look for particular benefits, such as improved muscle development. Other preliminary evidence from small trials suggests that consuming theanine in black tea may reduce the body’s response to stress in general (physical or psychological), lead to a more relaxed mental state, and help reduce blood pressure.
Black tea might also help prevent cancer, though evidence from observational studies is thoroughly inconsistent. Weak observational study evidence additionally hints at benefits for osteoporosis. Though black tea has shown blood-sugar-lowering effects in healthy people, one study failed to find that a combined extract of black and green tea could help control blood sugar levels in people with type 2 diabetes.
Still, in the twenty-first century, continued studies of the health benefits of black tea have proved to show positive results. A study by the National Cancer Institute in 2022 found that black tea, even at higher consumption levels, can be part of a healthy diet. According to the study, higher tea consumption was associated with a lower risk of death from cardiovascular disease, ischemic heart disease, and stroke. Another study published in 2022 in the Journal of the American Heart Association found that daily consumption of black tea improved the ability of blood vessels to relax and contract in people with coronary artery disease, reducing their risk of heart attack or stroke. Studies showing the positive effects of black tea on cardiovascular health, cognitive function, and gut health and confirming the anti-inflammatory and antioxidant qualities of black tea have been published throughout the early 2020s.
Dosage
The optimal doses of black tea or its constituents are not known.
Safety Issues
As a widely consumed beverage, black tea is presumed to have a high safety factor. Its side effects would be similar to those of coffee: heartburn, gastritis, insomnia, anxiety, and heart arrhythmia (benign palpitations or more serious disturbances of heart rhythm). All drug interactions with caffeine would be expected to occur with black tea.
Important Interactions
The caffeine in black tea could cause dangerous drug interactions in people who are taking monoamine oxidase inhibitors. Also, the stimulant effects of black tea might be amplified in people taking stimulant drugs such as Adderall and other medications for attention-deficit hyperactivity disorder (ADHD). Black tea might interfere with the action of drugs taken to prevent heart arrhythmias or to treat insomnia, heartburn, ulcers, or anxiety. Finally, black tea may decrease the absorption of folic acid into the bloodstream.
Bibliography
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Inoue-Choi, Maki. "NCI Study of Tea Drinkers in the UK Suggests Health Benefits for Black Tea." National Cancer Institute, 29 Aug. 2022, www.cancer.gov/news-events/press-releases/2022/health-benefits-black-tea. Accessed 12 Dec. 2022.
Mackenzie, T., L. Leary, and W. B. Brooks. "The Effect of an Extract of Green and Black Tea on Glucose Control in Adults with Type 2 Diabetes Mellitus." Metabolism, vol. 56, 2007, pp. 1340-1344.
Mukamal, K. J., et al. "A Six-Month Randomized Pilot Study of Black Tea and Cardiovascular Risk Factors." American Heart Journal, vol. 154, 2007, p. 724.
Nobre, A. C., A. Rao, and G. N. Owen. "L-Theanine, a Natural Constituent in Tea, and Its Effect on Mental State." Asia Pacific Journal of Clinical Nutrition, vol. 17, suppl. 1, 2008, pp. 167-168.
Rogers, P. J., et al. "Time for Tea: Mood, Blood Pressure, and Cognitive Performance Effects of Caffeine and Theanine Administered Alone and Together." Psychopharmacology, vol. 195, 2008, pp. 569-577.
"Study Suggests Health Benefits from Black Tea." National Cancer Institute, 29 Aug. 2022, www.cancer.gov/news-events/press-releases/2022/health-benefits-black-tea. Accessed 6 Sept. 2024.
"3 Benefits of Black Tea." Cleveland Clinic Health Essentials, 10 July 2023, health.clevelandclinic.org/black-tea-benefits. Accessed 6 Sept. 2024.
Vinson, J. A., et al. "Green and Black Teas Inhibit Atherosclerosis by Lipid, Antioxidant, and Fibrinolytic Mechanisms." Journal of Agricultural and Food Chemistry, vol. 52, 2004, pp. 3661-3665.