trà xanh green tea thành phần hóa học và lợi ích của trà xanh đối với cơ thể

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trà xanh  green tea thành phần hóa học và lợi ích của trà xanh đối với cơ thể

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GREEN TEA Green tea comes from a tea plant native to Asia called Camellia sinensis. Black tea also comes from this same plant. What makes green tea different, and green, is not the plant used to make the tea, but how the plant is processed. Green teas are the least processed of commercial teas and the method used preserves more of the nutrients and health benefits.

GREEN TEA 2 GREEN TEA Green tea comes from a tea plant native to Asia called Camellia sinensis. Black tea also comes from this same plant. What makes green tea different, and green, is not the plant used to make the tea, but how the plant is processed. Green teas are the least processed of commercial teas and the method used preserves more of the nutrients and health benefits. Green tea leaves are picked and then immediately fired, a tea processing term which means the leaves are either steamed or heated. The tea leaves are then dried and prepared for either sale or further processing. Other teas are picked, dried by a process commonly called "withering", rolled or broken which induces oxidation, and then dried. Oxidation removes most of the necessary nutritional values from the tea and then the leaves are dried to halt oxidation. Oxidized teas are called black teas and most of the tea we drink in the Western hemisphere is considered black tea. Because of the process used to make black tea, most of the antioxidants that are proven to provide health benefits are removed which is why green tea, still antioxidant rich, is considered healthier. Black teas have the characteristic brown color when brewed that many associate with tea. Green tea, however, has a much lighter hue and flavor due to the minimal processing. Many people believe green tea to have curative effects. Recent studies indicate that the green teas contain powerful antioxidants that do boost health and the immune system. The American Cancer Society has studied the benefits of green tea to both prevent and treat cancer. Other studies indicate that green tea may ward off or slow Alzheimer's disease. Many believe that green teas are an effective aid in weight loss and others believe green teas offer benefits for arthritic patients. Green teas are available in leaf form, in tea bags, in nutritional supplements, and as prepared beverages. Detailed information is available from a variety of sources. Check with a medical professional, an herbalist, or look in bookstores for complete information about the proven and perceived benefits of green tea. What Does A Tea Leaf Contain? – 3 Fresh-cut tealeaves consist of 75-80% water. A variety of green tea flavors are formed through the combination of three main taste components : Catechin– Bitterness & Astringency Caffeine– Bitterness Theanine & Amino Acids– Flavor & Sweetness Catechin – Catechin is a tannin peculiar to green tea because the black tea fermentation process reduces catechins in black tea. Catechin is a powerful, water soluable polyphenol and antioxidant that is easily oxidized. Several thousand types are available in the plant world. As many as two thousand are known to have a flavon structure and are called flavonoids. Catechin is one of them. Research aimed at finding the active compounds in green tea revealed that its protective effects are due chiefly to catechins. Tea contains four main catechin substances: EC, ECg, EGC and EGCg, all of which are inclusively called catechin. Epigallocatechin gallate (EGCG) is the most powerful of these catechins. EGCG as an antioxidant is about 25-100 times more potent than vitamins C and 4 E. One cup of green tea provides 10-40 mg of polyphenols and has antioxidant effects greater than a serving of broccoli, spinach, carrots, or strawberries. The high antioxidant activity of green tea makes it beneficial for protecting the body from oxidative damage due to free radicals. Research shows that green tea may help the arterial wall by reducing lipids. Green tea can protect against experimentally induced DNA damage, and slow or halt the initiation and progression of undesirable cell colonies. Studies show evidence that green tea provides immunoprotective qualities, particularly in the case of patients undergoing radiation or chemotherapy. White blood cell count appear to be maintained more effectively in patients consuming green tea compared to non-supplemented patients. 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. Below is a list of benefits: - Eliminates free radicals preventing cancer development by blocking the growth of substance that causes cancer. This also arrests aging. - Connects with cholesterol, absorbs and blocks it. - Decreases cholesterol level in blood and prevents bad cholesterol caused by oxidation, which prevents narrowing of blood vessel caused by the build-up of bad cholesterol. - Prevents arterial sclerosis, thrombosis, heart attacks and brain strokes. - Effective for high blood pressure. 5 - Blocks a function of enzyme that digests and absorbs sugar and prevents diabetes. - Suppresses aggregation of platelets and prevents thrombosis such as heart attacks and brain strokes. - Fights bacteria and viruses and prevents influenza, food poisoning and cavities including including: O-157, Dysentery, Cholera, Mouth bacteria that can damage teeth, gums, and lead to periodontal disease, Piccoli, which causes gastric ulcers. - Improves conditions of intestines by blocking growth of bad bacteria and enhancing good bacteria like bifid bacteria. This regulates the function of intestines. - Connects with substances (breath, fish, meat, human waste, etc.) and prevents odor. - Detoxifies by connecting with poisonous substance and harmful heavy metals (lead, chrome, mercury, cadmium, etc.) and dissolves it. - Changes harmful ultraviolet rays into non-harmful light in a plant to protect it. - Gargling with green tea is believed to be an effective way to protect oneself from influenza because of tea’s anti-viral functions. Caffeine – A cup of green tea contains about 15 to 30 mg of caffeine, a stimulant affecting the central nervous system. It is an important quality in green tea providing some of its astringency . Japanese people drink green tea to soothe hangovers and this is because the caffeine in green tea encourages metabolization of alcohol. On a side note: it is said that the habit of drinking green tea started in Japanese history from its refreshing effects caused by caffeine. Caffeine is widely know for its awakening property, and the caffeine contained in green tea is no 6 exception. Taking in appropriate amounts of caffeine encourages brain and muscle exercise, and strengthens stamina. A cup of green tea contains about 15-30mg of caffeine, normally enough to produce the stimulant effects typically associated with caffeine. However, because green tea also contains theanine, caffeine effects are counteracted and little if any stimulation actually occurs. The caffeine- counteraction effect of theanine is being further researched. Theanine is a very important relaxing component unique to green tea. Health Benefit: Typically associated as a stimulant effecting central nervous system and mental alertness. Prevents sleepiness and speeds recovery from fatigue. Caffeine also enhances athletic ability and endurance. When caffeine is taken together with exercise, subcutaneous fat (paniculus adiposus) is metabolized as an energy source rather than depleting glycogen stores, leading to increased stamina. In addition, caffeine is considered a good remedy for hangovers because caffeine blocks absorption of alcohol and enhances its metabolization. Has a diuretic function (enhances urination), which encourages detoxification and the discharge of body wastes and natrium (Na) that raises blood pressure. Activates blood circulation. Amino Acid (L-Theanine: Caffeine Counteraction) – Theanine is an amino acid found in tea that produces a calming effect on the brain (Yokogoshi et al. 1998b). There are about 20 different types of amino acids in tea. More than 60% of these amino acids consist of theanine, which is unique to green tea because the steaming process does not eliminate it. Theanine has a similar structure to glutamine providing an elegant taste and sweetness in green tea. L-theanine is a healthy amino acid that is only found in tea plants and certain mushrooms. 7 Health Benefit: Theanine also helps to protect nerve cells in the brain, lengthening the life of these cells. It is linked to increased alpha brain wave production and is considered a natural antidepressant and stress reliever. Japanese studies link consumption of L-theanine with strengthening the immune system. L-theanine is often added to energy drinks and is known to give a 6-hour sustainable energy boost. Theanine easily crosses the blood-brain barrier and exerts subtle changes in biochemistry that cause a tranquilizing effect. The production of GABA, the brain chemical known for its calming effect, is increased after taking theanine. Increased GABA can also put you in a better mood and create a sense of well-being. Dopamine, another brain chemical with mood-enhancing properties is also increased by theanine. Green tea contains a much higher concentration of theanine than other teas. Theanine has been proven to lower blood pressure. It works through its GABA enhancing effects. Along with its calming effect on the brain, GABA also lowers blood pressure. Amino Acid (Butyric Acid) - Amino Butyric Acid (GABA) is produced if tealeaves are left without oxygen. Regular crude tea processing produces a tea with GABA. 8 Health Benefit: Suppresses high blood pressure. Vitamin A (Carotene) – Several types of carotene exist in tea leaves. ß-carotene is the most prevalent (22mg%). ß-Carotene converts to Vitamin A once absorbed in the body. Carotene content is high in quality teas. Health Benefit: Promotes better vision. Among the carotene types, ß-carotene particularly has strong antioxidant effects, eliminating free radicals. Antioxidant effects help prevent aging and cancer. Vitamin B1 - Thiamine – 9 This vitamin is necessary for proper metabolism of sugar, particularly essential for Asians, whose primary nutrition comes from rice. Amount per 100 g of tea: 600 µg in Matcha Health Benefit: Known to speed recovery from fatigue. Vitamin B2 - Riboflavin Necessary for red blood cell formation, antibody production, and cell respiration and growth. This vitamin also helps tissues of the skin, hair, nails, and hair utilize oxygen more efficiently. Health Benefit: Maintains proper skin condition (Prevents rough skin) and enhances growth. Promotes cell growth and the production of antibodies. Vitamin B3 - Niacin Important for the release of energy from carbohydrates and fats, the metabolism of proteins, making certain hormones, and assisting in the formation of red blood cells. It also imrpoves the blood cholesterol profile Health Benefit: Maintains proper skin condition, lowers cholesterol. Currently being researched for helping to prevent and control diabetes. Vitamin C 10 Necessary for collagen growth, the substance that connects cells. Sencha contains significant amounts of Vitamin C (250mg per 100g of tea). Fermented teas (black, oolong tea) contain far less because vitamin C dissolves in the fermentation process. Health Benefit: Antioxidant vitamin that eliminates free radicals preventing cancer and aging. Antiviral/antibacterial function assists in preventing colds. Collagen growth factor cleanses skin. Vitamin E - Tocopherol This vitamin is an antioxidant known as a tocopherol. Green teas grown in non-shaded environments contain more Vitamin E than teas grown in shaded environments. Health Benefit: Antioxidant through fat eliminating free radicals. Combats infertility. Prevents aging. Important in the prevention of cardiovascular disease and cancer pressure. Vitamin F – Fluorin [...]... cause Parkinson's People drinking green tea also are less likely to progress with Parkinson's 13 Green Tea and Liver Disease Green tea helps prevent transplant failure in people with liver failure Researches showed that green tea destroys harmful free radicals in fatty livers 14 Green Tea and High Blood Pressure Green tea helps prevent high blood pressure Drinking green tea helps keep your blood pressure... stronger in fighting against infections 18 Green Tea and Cold and Flu Green tea prevents you from getting a cold or flu Vitamin C in green tea helps you treat the flu and the common cold 19 Green Tea and Asthma Theophylline in green tea relaxes the muscles which support the bronchial tubes, reducing the severity of asthma 20 Green Tea and Ear Infection 18 Green tea helps with ear infection problem For... leads to bad breath 23 Green Tea and Stress L-theanine, which is a kind of amino acids in green tea, can help relieve stress and anxiety 24 Green Tea and Allergies EGCG found in green tea relieves allergies So, if you have allergies, you should really consider drinking green tea 25 Green Tea and HIV Scientists in Japan have found that EGCG (Epigallocatechin Gallate) in green tea can stop HIV from binding... 8 Green Tea and Cholesterol Green tea can help lower cholesterol level It also improves the ratio of good cholesterol to bad cholesterol, by reducing bad cholesterol level 9 Green Tea and Obesity Green tea prevents obesity by stopping the movement of glucose in fat cells If you are on a healthy diet, exercise regularly and drink green tea, it is unlikely you'll be obese 10 Green Tea and Diabetes Green. .. blood pressure 15 Green Tea and Food Poisoning Catechin found in green tea can kill bacteria which causes food poisoning and kills the toxins produced by those bacteria 16 Green Tea and Blood Sugar Blood sugar tends to increase with age, but polyphenols and polysaccharides in green tea help lower your blood sugar level 17 Green Tea and Immunity Polyphenols and flavenoids found in green tea help boost... health benefits It is extraordinarily amazing what green tea can do for your health And if you're not drinking 3 to 4 cups of green tea today, you're definitely NOT doing your health a big favor Here Are The 25 Reasons Why You Should Start Drinking Green Tea Right Now: 1 Green Tea and Cancer Green tea helps reduce the risk of cancer The antioxidant in green tea is 100 times more effective than vitamin C... infection problem For natural ear cleaning, soak a cotton ball in green tea and clean the infected ear 21 Green Tea and Herpes Green tea increases the effectiveness of topical interferon treatment of herpes First green tea compress is applied, and then let the skin dry before the interferon treatment 22 Green Tea and Tooth Decay Green tea destroys bacteria and viruses that cause many dental diseases... fight against skin cancer 6 Green Tea and Arthritis Green tea can help prevent and reduce the risk of rheumatoid arthritis Green tea has benefit for your health as it protects the cartilage by blocking the enzyme that destroys cartilage 7 Green Tea and Bones The very key to this is high fluoride content found in green tea It helps keep your bones strong If you drink green tea every day, this will help... longevity 4 Green Tea and Weight Loss Green tea helps with your body weight loss Green tea burns fat and boosts your metabolism rate 16 naturally It can help you burn up to 70 calories in just one day That translates to 7 pounds in one year 5 Green Tea and Skin Antioxidant in green tea protects the skin from the harmful effects of free radicals, which cause wrinkling and skin aging Green tea also helps... Diabetes Green tea improves lipid and glucose metabolisms, prevents sharp increases in blood sugar level, and balances your metabolism rate 11 Green Tea and Alzheimer's Green tea helps boost your memory And although there's no cure for Alzheimer's, it helps slow the process of reduced acetylcholine in 17 the brain, which leads to Alzheimer's 12 Green Tea and Parkinson's Antioxidants in green tea helps prevent

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