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Black tea

Black tea is made from the leaves of a bush called Camellia sinensis. A process called oxidation changes the color of the leaves from green to black-brown. Oxidation in this context means that the leaves are exposed to moist, oxygen-rich air. Tea manufacturers can control the degree of oxidation. Black tea is completely oxidized. Green tea comes from the same plant, but is not oxidized

Why do people use black tea?

Many people drink black tea to wake them up and give them more energy. There is sufficient scientific research to show that this works. Black tea contains a lot of caffeine. It also contains a small amount of the stimulating substance theophylline. Both caffeine and theophylline can speed up the heart rate and improve alertness, and black tea also contains healthy substances called polyphenols. Polyphenols are antioxidants that can help protect the body's cells from DNA damage.

Some scientists believe that specific antioxidants found in black tea, including polyphenols and catechins, may help prevent some types of cancer. For example, some studies show that women who regularly drink black tea have a lower risk of ovarian cancer. However, more research is needed on the protective effects against cancer. So far, studies have shown that black tea does not reduce the risk of breast, stomach and colon cancer. There is increasing evidence that antioxidants contained in black tea may reduce arteriosclerosis (a clogging of the arteries), particularly in women. They may also help to reduce the risk of heart attack. Regular consumption of black tea could also reduce the risk of diabetes, high cholesterol, kidney stones and Parkinson's disease. However, further research is needed to be able to make a definite statement about the effect of black tea on these conditions. Early research also suggests that long-term use of black tea may help protect against osteoporosis and lung cancer. However, further, larger-scale studies are needed to confirm these applications. Black tea extract, like green tea extract, is sold as a supplement. Sometimes such supplements contain other plant extracts, vitamins and minerals. Consuming moderate amounts of black tea in the range of one to four cups per day can slightly increase blood pressure, but this effect does not last long. Consumption of these amounts of black tea is not associated with a long-term increase in blood pressure. Preliminary studies have shown that supplements containing black tea extracts can increase metabolic rate and blood pressure. While changes in blood pressure may be a cause for concern, a small increase may be helpful for people who suffer from dizziness when standing up due to low blood pressure

Recommended dosage

Optimal dosages for black tea extracts have not yet been determined. As the ingredients of supplements and their quality can vary greatly, it is difficult to establish a standard dosage.

Risks and side effects?

Consuming moderate amounts of black tea is generally considered safe and harmless for most people. However, consuming large amounts of black tea above 4 to 5 cups per day can cause potential health problems. These are mainly caffeine-related side effects. Side effects of black tea can include restlessness, sleep problems, faster breathing, headaches, increased urination, irregular heartbeat, nausea and vomiting, nervousness and restlessness, ringing in the ears and tremors. The combination of black tea with other types of caffeine or with ephedra can be dangerous. Problems that such a combination can cause include hypertension, an increase in blood pressure, changes in heart rate, seizures and fainting.

Interactions

Black tea or supplements containing black tea extracts may interact with other medications or supplements. Some medications can cause caffeine to remain active in the body longer than usual. For this reason, the use of black tea supplements should be discussed with your doctor if you are taking medication. The caffeine contained in black tea can also affect the results of certain blood tests. Therefore, you should inform your doctor before blood tests if you drink a lot of black tea.

References

  1. National Cancer Institute web site: "Tea and Cancer Prevention Fact Sheet. "Roberts, A. Alternative Medicine Review, 2005.
  2. The Leaf web site: "Oxidation and Fermentation in Tea Manufacture." National Cancer Institute web site: "Tea and Cancer Prevention Fact Sheet."
  3. Natural Medicines Comprehensive Database: "Black Tea." Baker, J.A. International Journal of Gynecological Cancer, January-February 2007.
  4. Gardner, E.J. European Journal of Clinical Nutrition. January 2007.Hodgson, J.M. Food and Function, January 19, 2013.
  5. Hodgson, J.M. Molecular Aspects of Medicine, December 2010.Bersniak, A. BMJ Open, Nov. 8, 2012.