Tea, Camellia sinensis and especially green tea have become known in recent years as a healthy drink, mainly because of their antioxidant effect. What is an antioxidant and how does Camellia sinensis work? Antioxidants are, as the name suggests, substances that can inhibit the harmful, but normal, effects of the physiological oxidation process in animal tissue. This process is a result of aerobic respiration and metabolism.
The oxidative process
Oxygen (O2) is a very aggressive substance that can cause major damage to our cells. After all, it is easily converted into various reactive forms that act as oxidants, or substances that create oxygen compounds.
Several of these oxidants are free radicals containing an oxygen atom such as OH· and NO·. These reactive oxygen species, ROS for short, are chemical compounds that contain an unpaired electron. A free radical is very reactive
because it tries to withdraw an electron from another compound as quickly as possible. When that electron is removed from DNA, lipids or proteins, it can trigger a series of degenerative reactions,
resulting in irreversible damage to the cells or tissues in our body.
Antioxidants or oxygen scavengers
Free radicals not only arise in the body, but can also be caused by exogenous environmental factors such as air pollution, smoking or sunlight.
The human body has various defense mechanisms to curb the uncontrolled chain reactions resulting from radical formation. These mechanisms function via the body’s own enzymatic substances and via antioxidants provided by the diet. The most important nutrients in this category are:
- vitamin C
- vitamin E
- carotenoids
- flavonoids
Antioxidants block the oxidative process by neutralizing free radicals. In doing so, they donate an electron to the free radical, which actually causes the antioxidant itself to be oxidized. When the body’s defense mechanisms against oxidation processes fail, the body comes under oxidative stress, which can damage DNA, proteins or lipids. This is believed to be an important factor in the pathogenesis of many conditions such as coronary heart disease, Alzheimer’s disease, certain cancers or autoimmune disorders.
Tea as an antioxidant
The flavanols, commonly known as catechins, comprise the most active components of green tea leaves and are present among a number of different chemical molecules. The most important of these are:
- Epicatechin (EC)
- Epicatechin-3-gallate (ECG)
- Epigallocatechin (EGC)
- Epigallocatechin-3-gallate (EGCG)
ECGC is present in the highest concentration and is also said to be responsible for the main medicinal properties of green tea. Many studies show that flavonoids are very powerful antioxidants. They are mainly found in fruits, vegetables, grains and drinks such as red wine and tea. One cup of tea is said to have relatively as much antioxidant activity as four apples or seven glasses of orange juice. Due to its easy use as a daily drink, Chinese tea and especially green tea can make a good contribution to the health of every person.
