Health Benefits of Tea
Its no secret that Green Tea has many health benefits, it is high in anti-oxidants which help cleanse the body
of harmful carcinogens. Other teas loose this property during the fermentation process. It has been said that Green
Tea can help suppress and reverse aging as it refreshes the body. It's high Vitamin B content can help the human
body better deal with stress, and release more energy. Green Tea can also help lower cholesterol and cut the risk
of stroke in men. (American Medical Association). Drinking green tea on a daily basis is also helpfull in weight
loss.
Benefits from green tea
A number of health claims have been made for green tea claiming that its polyphenol content has antioxidant properties
that can help prevent cancer. There is also the suggestion that it can increase endurance in exercise by improving
fat metabolism.
An article in New Scientist magazine (20 March 2004) mentions that numerous studies suggest that green tea protects
against a range of cancers, including lung, prostate and breast cancer. The secret is the antioxidant epigallocatechin
gallate (EGCG), according to Hirofumi Tachibana's team at Kyushu University in Japan. Their research showed that
growth of human lung cancer cells that have a cell receptor called 67 LR is slowed significantly after drinking
just two or three cups of green tea, which contains EGCG. The research also showed that 67 LR is involved in the
propagation of prion diseases such as mad cow disease in humans. So knowledge of EGCG's effect on 67 LR might have
implications in the treatment of these diseases too. (Full report in Nature Structural and Molecular Biology, DOI:10.1038/nsmb743).
According to the U.S. National Cancer Institute, in laboratory studies using animals, catechins scavenged oxidants
before cell damage occurred, reduced the number and size of tumors, and inhibited the growth of cancer cells. White
tea is said to be even more effective. However, human studies have proven more contradictory, perhaps due to such
factors as variances in diet, environments, and populations.
Clinical trials conducted by the University of Geneva, in Switzerland indicate that green tea raises metabolic
rates and speed up fat oxidation. In addition to caffeine, green tea contains catechin polyphenols that raise thermogenesis
(the rate at which calories are burned) and hence increases energy expenditure.
Antioxidant
An antioxidant is a chemical that prevents the oxidation of other chemicals. In biological systems, the normal
processes of oxidation (plus a minor contribution from ionizing radiation) produce highly reactive free radicals.
These can readily react with and damage other molecules: in some cases the body uses this to fight infection. In
other cases, the damage may be to the body's own cells. The presence of extremely easily oxidisable compounds in
the system can "mop up" free radicals before they damage other essential molecules.
The following vitamins have shown positive antioxidant effects:
Retinol (Vitamin A or beta-carotene) has been discovered to protect dark green, yellow and orange vegetables and
fruits from solar radiation damage, and is thought to play a similar role in human body. Carrots, squash, broccoli,
sweet potatoes, tomatoes, kale, collards, cantaloupe, peaches and apricots are particularly rich sources of beta-carotene.
Ascorbic acid (Vitamin C) is a water-soluble compound that fulfills this role, among others, in living systems.
Important sources include citrus fruits (like oranges, sweet lime, etc.), green peppers, broccoli, green leafy
vegetables, strawberries, raw cabbage and tomatoes.
Vitamin E (tocopherol) is fat soluble and protects lipids. Sources include wheat germ, nuts, seeds, whole grains,
green leafy vegetables, vegetable oil and fish-liver oil.
Selenium is best obtained through foods, as large doses of the supplement form can be toxic. Good food sources
include fish, shellfish, red meat, grains, eggs, chicken and garlic. Vegetables can also be a good source if grown
in selenium-rich soils.
Several food additives (including ascorbic acid and tocopherol-derived compounds) are used as antioxidants to help
guard against deterioration of food.
Other antioxidants are enzymes. These include glutathione peroxidase, superoxide dismutase and catalase.
Much damage is done by free radicals in mitochondria as a byproduct of oxidative phosphorylation. Superoxide radicals
are generated which can damage mitochodrial DNA and mitochondrial membranes. Unlike DNA in the cell nucleus, mitochondrial
DNA has only a few DNA-repair enzymes and the DNA is not protected by histones.
Many antioxidants, however (including vitamic C and vitamin E) can't get into mitochondria for various reasons
(e.g. because too hydrophilic to cross mitochondrial membranes or too hydrophobic to cross the cytoplasm). A group
of scientists in Russia (led by V. Skulachev) has created a custom antioxidant (A Skulachev ion forms the point
of the molecule and penetrates the mitochondrial membrane; the antioxidising part is attached behind it) that can
enter the mitochondria and stays there preventing damage to DNA.'
Although there is little doubt that antioxidants are a necessary component for good health, there is considerable
doubt as to the most beneficial antioxidant and as to the optimal amount for results. Due to the complex nature
of the interactions of antioxidants with the body, it is difficult to interpret the results of many experiments
designed to test such things.
For example, recent studies are suggesting that at high levels, antioxidant vitamins may prove to have pro-oxidant
effects: increasing the formation of free radicals.
The benefits of antioxidants were examined during the Age-Related Eye Disease Study. |
