It also contains vitamins C, K, B12, B6 and E, minerals such as potassium, manganese, magnesium, calcium, significant amounts of fluoride and the amino acid L-theanine which has been studied for its calming effects on the nervous system. Alkaloids are also present such as caffeine, theobromine, and theophylline which provide the stimulant effects.
The good stuff in green tea
The healthy properties of green tea are mostly attributed to the polyphenols which have powerful antioxidant properties. Polyphenols in tea are classified as catechins and green tea has six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate - known as EGCG. EGCG is the most active polyphenol in green tea and it may provide health benefits by protecting healthy cells from the oxidative damage from free radicals.
Antioxidants and free radicals
Tea is a rich source of the natural plant-derived antioxidant compounds called polyphenols which include flavonoids and catechins.
Tea has one of the highest flavonoid contents of all plants making up 15% of the weight of the dry leaf. Flavonoids are thought to help combat harmful free radicals. Free radicals are the molecules which can attack healthy cells in the body and lead to infections, tumours and degenerative diseases.
Excessive free radicals can damage DNA, cell membranes and other cell components and when a cell's DNA changes, the cell can mutate, grow and reproduce quickly and abnormally - creating the conditions for disease.
Free radicals are generally kept under control by antioxidants that the body produces naturally, but too many free radical attacks can overwhelm the body's natural defense system. External influences such as long term smoking and excessive alcohol consumption for instance, can increase harmful free radical attacks. It is after repeated attacks that damage can lead to a number of chronic diseases such as cancer and heart disease.
What do antioxidants do?
Antioxidants can mop up free radicals. EGCG (epigallocatechin gallate) is the main active component in green tea leaves and has the most potent antioxidant activity of the catechins.
ECGC (epigallocatechin gallate) can inhibit fast-binding and reversible fatty acid synthesis, it increases tyrosine phosphorylation of the insulin receptor and activation of ornithine decarboxylase. ECGC can also protect the DNA in the human cells from ultraviolet and visible radiation-induced damage. ECGC may also be effective in promoting fat oxidation.
Normal cell function in the body produces damaged molecules — called free radicals. These free radicals are highly unstable and steal molecules of fat, protein, or DNA from other cells. It can create a chain reaction, leading to entire cells becoming damaged or dying. This process is called peroxidation. Antioxidants donate components to stabilize free radicals and help prevent further cell damage. Disease can occur when there are not enough antioxidants to hold peroxidation in check and the free radicals begin damaging healthy cells.