Research proves that tea has a number of health benefits. Many of these benefits are related to tea's antioxidant properties, which are created by its high concentrations of plant-based chemicals known as polyphenols. Although the composition of various teas is quite different, both black and white tea have antioxidant properties.
Antioxidants in Tea
Tea contains substances known as polyphenols, which are responsible for its antioxidant properties. Polyphenols are plant chemicals that help the body fight excessive buildup of free radicals, which can contribute to the development of chronic disease. Of the polyphenols found in tea, epigallocatechin-3-gallate, or EGCG, epigallocatechin, or EGC, epicatechin-3-gallate, or ECG, and epicatechin, or EC, are the most important. EGCG in particular has been recognized for its ability to protect cells from free radical damage. According to the National Cancer Institute, these substances may also help prevent cancer cell proliferation.
Tea Production
White, black, oolong and green teas all come from the same plant -- the camellia sinensis. They are distinguished by the stage of leaf development, as well as how long the leaves are allowed to ferment. When tea leaves are exposed to the air they oxidize, which results in a stronger flavor. The caffeine content also increases as the leaves are exposed to the air. The amount of polyphenols in the tea leaves also decreases during the oxidation process.
Black Tea vs. White Tea
White tea differs from black tea in two respects. First, the leaves of white tea are very young and have not yet reached maturity, unlike those that are used to make black tea. Second, white tea leaves go through very little processing, whereas black tea is the most processed form of tea. Because the amount of polyphenols decreases the longer the tea is processed, black tea has less EGCG content than white tea. The fermentation process does increase the number of other polyphenols in black tea, which are known as thearubigins and theaflavins. These polyphenols have been shown to also have potent antioxidant properties, and may be just as effective as EGCG found in white tea.
Considerations
Although tea is considered safe by most doctors, it does contain caffeine, which may result in undesirable side effects if consumed in excess. White tea contains much less caffeine than black tea. White tea contains about 24 to 39 mg per cup, whereas black tea contains 64 to 112 mg per cup. The preparation method may also influence tea's antioxidant properties. According to the National Cancer Institute, brewed hot tea has the highest concentration of polyphenols. Instant tea, iced tea and decaffeinated tea have lower polyphenol levels and less antioxidant activity.
References
- National Cancer Institute: Tea and Cancer Prevention: Strengths and Limits of the Evidence
- MSNBC Today: Drink up: White tea is good for you --- really!; Phil Lempert; 2006
- The Journal of Nutrition; Theaflavins in Black Tea and Catechins in Green Tea Are Equally Effective Antioxidants; Lai Kwok Leung et. al; 2001
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