Camellia sinensis

Related Terms

Alpha-tocopherol, aluminum, anthocyanins, antioxidants, beta-carotene, caffeine, calcium, camellia, Camellia assamica, Camellia sinensis, Camellia sinensis (L.) Kuntze, camellia tea, camellia thea, Camellia theifera, catechin, Chinese tea, copper, flavonoids, fluoride, folic acid, green tea, iron, Japanese tea, kaempferol, manganese, mercury, myricetin, oolong tea, oxalate, phenolic acids, phylloquinone, polyphenols, quercetin, riboflavin, rutin, tannic acid, t? negro (Spanish), tea for America, Thea bohea, Thea sinensis, Thea viridis, theaflavin, theanine, thearubigins, theifers, total phosphate, trace elements, vitamins, white tea, zinc.

Background

Black tea is made from the dried leaves of Camellia sinensis, a shrub native to southeastern Asia. Green tea, black tea, and oolong tea all come from the same plant. Black tea is a traditional beverage in Britain. The quality of tea depends on the age of the tea leaves.
Black tea is a source of caffeine, which stimulates the heart and central nervous system, relaxes smooth muscle in the lungs, and promotes urination. One cup of tea contains about 50 milligrams of caffeine, depending on the strength and size of the cup, while coffee contains 65-175 milligrams of caffeine per cup. Tea also contains vitamins, a compound called tannin, and antioxidants called polyphenols.
There is conflicting evidence for the use of black tea in preventing heart disease and cancer. Regular tea consumption may lower the risk of heart attacks and all-cause mortality, regardless of age, sex, smoking status, obesity, and medical history. There is preliminary evidence for the use of black tea in increasing bone marrow density (BMD), preventing osteoporosis in older women, and enhancing brain and muscle function. The evidence is also preliminary for the use of black tea as a mouthwash in the prevention of dental cavities.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *


Preliminary evidence suggests that adult asthma sufferers may benefit from drinking black tea or coffee. However, there is not enough evidence, and more research is needed before conclusions can be made.

 C


Preliminary evidence suggests that adult asthma sufferers may benefit from drinking black tea or coffee. However, there is not enough evidence, and more research is needed before conclusions can be made.

 C


Overall, there is conflicting evidence for the use of black tea in cancer prevention. Preliminary evidence suggests that there may be a link between tea consumption and cancer, although other results found that countries with significantly higher tea consumption did not have lower rates of death from cancer. Black tea has been studied for use in mouth, throat, stomach, pancreatic, and colorectal cancer, but results have been mixed. More research is needed before any conclusions can be made.

 C


Overall, there is conflicting evidence for the use of black tea in cancer prevention. Preliminary evidence suggests that there may be a link between tea consumption and cancer, although other results found that countries with significantly higher tea consumption did not have lower rates of death from cancer. Black tea has been studied for use in mouth, throat, stomach, pancreatic, and colorectal cancer, but results have been mixed. More research is needed before any conclusions can be made.

 C


There is preliminary evidence to support the use of black tea as a mouthwash in the prevention of dental cavities. More studies are required to confirm this potential benefit.

 C


There is preliminary evidence to support the use of black tea as a mouthwash in the prevention of dental cavities. More studies are required to confirm this potential benefit.

 C


Some studies suggested that instant black tea may lower blood sugar and increase insulin levels, compared to water and caffeine. However, results are conflicting, and further research is required.

 C


Some studies suggested that instant black tea may lower blood sugar and increase insulin levels, compared to water and caffeine. However, results are conflicting, and further research is required.

 C


There is conflicting evidence for the use of black tea for heart health problems. Some studies suggest that black tea may help prevent hardened arteries and heart disease, but the results are unclear. The effect on blood pressure is also not clear. Future studies may reveal more about black tea's effects on heart health.

 C


There is conflicting evidence for the use of black tea for heart health problems. Some studies suggest that black tea may help prevent hardened arteries and heart disease, but the results are unclear. The effect on blood pressure is also not clear. Future studies may reveal more about black tea's effects on heart health.

 C


There is preliminary evidence supporting the use of black tea in improving brain function and memory. Future trials are needed to compare the potential benefits of coffee, black tea, green tea, and caffeine supplements to determine safety and effectiveness.

 C


There is preliminary evidence supporting the use of black tea in improving brain function and memory. Future trials are needed to compare the potential benefits of coffee, black tea, green tea, and caffeine supplements to determine safety and effectiveness.

 C


Preliminary studies have examined the effects of caffeine, tea, or coffee use on short- and long-term memory and alertness. There is evidence to support the use of black tea in increasing mental alertness, but results are still unclear and more research is needed.

 C


Preliminary studies have examined the effects of caffeine, tea, or coffee use on short- and long-term memory and alertness. There is evidence to support the use of black tea in increasing mental alertness, but results are still unclear and more research is needed.

 C


Preliminary research showed that inhaled catechin, an antioxidant found in tea, may be temporarily effective in treating a bacterial infection, MRSA, and may shorten length of hospital stay in elderly patients with this condition. However, results are unclear, and additional research is needed before conclusions can be made.

 C


Preliminary research showed that inhaled catechin, an antioxidant found in tea, may be temporarily effective in treating a bacterial infection, MRSA, and may shorten length of hospital stay in elderly patients with this condition. However, results are unclear, and additional research is needed before conclusions can be made.

 C


Early studies report that "mixed" tea smeared on leukoplakia patches may improve the condition and reduce DNA damage, thereby preventing mouth cancer. Further research is needed to confirm these results.

 C


Early studies report that "mixed" tea smeared on leukoplakia patches may improve the condition and reduce DNA damage, thereby preventing mouth cancer. Further research is needed to confirm these results.

 C


Preliminary evidence suggests that black tea may increase bone mineral density and help prevent osteoporosis in older women. More research is needed to confirm these findings.

 C


Preliminary evidence suggests that black tea may increase bone mineral density and help prevent osteoporosis in older women. More research is needed to confirm these findings.

 C


Preliminary evidence suggests that tea consumption may improve feelings of relaxation and decrease levels of cortisol, a stress hormone. More well-designed studies are required before conclusions can be made in this field.

 C


Preliminary evidence suggests that tea consumption may improve feelings of relaxation and decrease levels of cortisol, a stress hormone. More well-designed studies are required before conclusions can be made in this field.

 C


Black tea has been studied as an ingredient in many combination weight loss products. More well-designed studies are needed to understand the potential benefits of black tea for this purpose.

 C


Black tea has been studied as an ingredient in many combination weight loss products. More well-designed studies are needed to understand the potential benefits of black tea for this purpose.

 C
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Dosing

Adults (18 years and older)
Note: Many studies have looked at the use of black tea for many different conditions. Dosing for studies that showed positive effects are presented below.
To prevent dental cavities, 20 milliliters has been gargled in the mouth for 60 seconds.
To treat diarrhea, 2-3 cups of black tea (240-320 milligrams of antioxidant content) have been taken by mouth daily.
To prevent heart attack, five servings of black tea have been taken by mouth daily for three weeks. An unspecified dose of black tea has been taken by mouth for up to six weeks. Six grams of tea has been taken by mouth as a single dose. Four standard cups of black tea have been taken by mouth over 30 minutes. Five cups of black tea (250 milliliters each) have been taken by mouth daily for four weeks.
To enhance memory, 400 milliliters of black tea has been taken by mouth three times daily.
To prevent mouth cancer and/or leukoplakia (white patches in the mouth), black tea has been taken by mouth over one year.
To stimulate and provide energy, seven or more cups of black tea have been taken by mouth daily (the effects may depend on the caffeine content).
To manage stress, black tea has been taken by mouth for six weeks.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Interactions

Interactions with Drugs
General: Drug interactions linked to black tea are mostly based on theory. They are generally based on the side effects profile of caffeine.
Black tea may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin?) or heparin, antiplatelet drugs such as clopidogrel (Plavix?), and nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin?, Advil?) or naproxen (Naprosyn?, Aleve?).
Black tea may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. People taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
Black tea may cause low blood pressure. Caution is advised in people taking drugs that lower blood pressure.
Black tea may interfere with the way the body processes certain drugs using the liver's cytochrome P450 enzyme system. As a result, the levels of these drugs may be increased in the blood and may cause increased effects or potentially serious adverse reactions. People using any medications should check the package insert and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.
Black tea may also interact with acetaminophen, adenosine, agents that may affect blood vessel width, agents that may affect the immune system, agents that may increase the risk of seizure, agents that may promote urination, agents that may treat osteoporosis, agents that may treat skin disorders, alcohol, amphetamine, antibiotics, anticancer agents, antidepressants, anti-inflammatories, antipsychotics, antiulcer agents, aspirin, benzodiazepines, beta-agonists, beta-blockers, birth control, caffeine, calcium salts, carbamazepine, central nervous system depressants, cholesterol-lowering agents, clozapine, dexamethasone, dipyridamole, disulfiram, ephedrine, ergot derivatives, estrogens, flubendiamide, fluconazole, fluoride, fluvoxamine, furafylline, hydrocortisone, inotropes, iron salts, lithium, methoxsalen, methylenedioxymethamphetamine (MDMA, or "Ecstasy"), methylphenidate, mexiletine, monoamine oxidase inhibitors (MAOIs), nicotine, opiates, oseltamivir, pain relievers, perazine, phenytoin, potassium dichromate, proton pump inhibitors (PPIs), quinolones, riluzole, sedatives, teeth-whitening agents, terbinafine, tetracyclines, theophylline, and verapamil.

Attribution

This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

Banko LT, Haq SA, Rainaldi DA, et al. Incidence of caffeine in serum of patients undergoing dipyridamole myocardial perfusion stress test by an intensive versus routine caffeine history screening. Am.J Cardiol. 5-15-2010;105(10):1474-1479.
Buscemi S, Verga S, Batsis JA, et al. Acute effects of coffee on endothelial function in healthy subjects. Eur.J Clin Nutr. 2010;64(5):483-489.
Chen Y, Kang Z, Yan J, et al. Liu wei di huang wan, a well-known traditional Chinese medicine, induces CYP1A2 while suppressing CYP2A6 and N-acetyltransferase 2 activities in man. J Ethnopharmacol. 10-28-2010;132(1):213-218.
Chien CF, Wu YT, Lee WC, et al. Herb-drug interaction of Andrographis paniculata extract and andrographolide on the pharmacokinetics of theophylline in rats. Chem Biol.Interact. 3-30-2010;184(3):458-465.
Goh BC, Reddy NJ, Dandamudi UB, et al. An evaluation of the drug interaction potential of pazopanib, an oral vascular endothelial growth factor receptor tyrosine kinase inhibitor, using a modified Cooperstown 5+1 cocktail in patients with advanced solid tumors. Clin Pharmacol Ther 2010;88(5):652-659.
Greenberg JA, Owen DR, and Geliebter A. Decaffeinated coffee and glucose metabolism in young men. Diabetes Care 2010;33(2):278-280.
Jenkins J, Williams D, Deng Y, et al. Eltrombopag, an oral thrombopoietin receptor agonist, has no impact on the pharmacokinetic profile of probe drugs for cytochrome P450 isoenzymes CYP3A4, CYP1A2, CYP2C9 and CYP2C19 in healthy men: a cocktail analysis. Eur.J Clin Pharmacol 2010;66(1):67-76.
Kjaerstad MB, Nielsen F, Nohr-Jensen L, et al. Systemic uptake of miconazole during vaginal suppository use and effect on CYP1A2 and CYP3A4 associated enzyme activities in women. Eur.J Clin Pharmacol 2010;66(12):1189-1197.
Machado M, Koch AJ, Willardson JM, et al. Caffeine does not augment markers of muscle damage or leukocytosis following resistance exercise. Int.J Sports Physiol Perform. 2010;5(1):18-26.
Moisey LL, Robinson LE, and Graham TE. Consumption of caffeinated coffee and a high carbohydrate meal affects postprandial metabolism of a subsequent oral glucose tolerance test in young, healthy males. Br.J Nutr. 2010;103(6):833-841.
Perera V, Gross AS, and McLachlan AJ. Caffeine and paraxanthine HPLC assay for CYP1A2 phenotype assessment using saliva and plasma. Biomed.Chromatogr. 2010;24(10):1136-1144.
Schmidt RJ, Romitti PA, Burns TL, et al. Caffeine, selected metabolic gene variants, and risk for neural tube defects. Birth Defects Res.A Clin Mol.Teratol. 2010;88(7):560-569.
Suzuki S, Murayama Y, Sugiyama E, et al. Estimating pediatric doses of drugs metabolized by cytochrome P450 (CYP) isozymes, based on physiological liver development and serum protein levels. Yakugaku Zasshi 2010;130(4):613-620.
Tomalik-Scharte D, Maiter D, Kirchheiner J, et al. Impaired hepatic drug and steroid metabolism in congenital adrenal hyperplasia due to P450 oxidoreductase deficiency. Eur.J Endocrinol. 2010;163(6):919-924.
Wang X and Yeung JH. Effects of the aqueous extract from Salvia miltiorrhiza Bunge on caffeine pharmacokinetics and liver microsomal CYP1A2 activity in humans and rats. J Pharm.Pharmacol 2010;62(8):1077-1083.