Green tea is made from the leaves from Camellia sinensis that have undergone minimal oxidation during processing. Green tea originated in China, but it has become associated with many cultures throughout Asia. Green tea has recently become relatively widespread in the West where black tea has been the traditionally consumed tea.
Many claims have been made for the beneficial health effects of green tea consumption, but they have generally not been borne out by scientific investigation; excessive consumption is associated with some harmful health effects.
Green tea is considered one of the world’s healthiest drinks and contains one of the highest amount of antioxidants of any tea. The natural chemicals called polyphenols in tea are what are thought to provide its anti-inflammatory and anti-carcinogenic effects.
- Weight Loss. Green tea increases the metabolism. The polyphenol found in green tea works to intensify levels of fat oxidation and the rate at which your body turns food into calories. Evidence is still inconclusive in this area, but it’s thought that the catechins found in tea, specifically green tea, create thermogenesis-the production of heat within the body which is related to burning calories. Thesecompounds may inhibit certainchemicals in the brain, therby prolonging thermogenesis. In one study, participants who drank four cups of tea daily had remarkably higher fat oxidation (by 12 percent) and burned an average of 67 additional calories a day. Drinking at least three cups a day is recommended to raise the body’s metabolic rate.
- Green tea apparently helps regulate glucose levels slowing the rise of blood sugar after eating. This can prevent high insulin spikes and resulting fat storage. Type 2 Diabetes:
Studies concerning the relationship between green tea and diabetes have been inconsistent. Some have shown a lower risk of developing type 2 diabetes for green tea drinkers than for those who consumed no tea, while other studies have found no association between tea consumption and diabetes at all.
- Heart Disease. Scientists think, green tea works on the lining of blood vessels, helping keep them stay relaxed and better able to withstand changes in blood pressure. It may also protect against the formation of clots, which are the primary cause of heart attacks. Tea consumption is also associated with a lower risk of heart disease and stroke.Research published by Harvarddemonstrates that people who drink at least one cup of tea daily have a 44 percent lower risk of heart attack. Some animal studies have demonstrated that tea also lowers cholesterol levels.
- Esophageal Cancer. It can reduce the risk of esophageal cancer, but it is also widely thought to kill cancer cells in general without damaging the healthy tissue around them.
- Green tea reduces bad cholesterol in the blood and improves the ratio of good cholesterol to bad cholesterol.
- Alzheimer’s and Parkinson’s. It is said to delay the deterioration caused by Alzheimer’s and Parkinson’s. Studies carried out on mice showed that green tea protected brain cells from dying and restored damaged brain cells.
- Tooth Decay.Studies suggests that the chemical antioxidant “catechin” in tea can destroy bacteria and viruses that cause throat infections, dental caries and other dental conditions. Along with the natural fluoride found in tea, polyphenols and catechins are associated with killing bacteria that cause tooth decay, bad breath, and gum disease-the number one cause for tooth loss. A study published this year by the European Journal of Nutrition found that consumption of one or more cups of green tea a day was significantly associated with decreasing the risk of tooth loss. Adding sugar, honey, or other sweeteners to tea however, may negate these benefits.
- Blood Pressure.Regular consumption of green tea is thought to reduce the risk of high blood pressure.
- Theanine is an amino acid naturally found in tea leaves. It is this substance that is thought to provide a relaxing and tranquilizing effect and be a great benefit to tea drinkers.
- Anti-viral and Anti-bacterial. Tea catechins are strong antibacterial and antiviral agents which make them effective for treating everything from influenza to cancer. In some studies green tea has been shown to inhibit the spread of many diseases.
- Green tea can apparently also help with wrinkles and the signs of aging, This is because of their antioxidant and anti-inflammatory activities. Both animal and human studies have demonstrated that green tea applied topically can reduce sun damage.
According to the National Cancer Institute, the polyphenols in tea have been shown to decrease tumorgrowth in laboratory and animal studies and may protect against damage caused by ultraviolet UVB radiation.In countries where green tea consumption is high cancer rates tend to be lower, but it is impossible to know for sure whether it is the green tea that prevents cancer in these specific populations or other lifestyle factors.4
One large-scale clinical study compared green tea drinkers with non-drinkers and found that those who drank the most tea were less likely to develop pancreatic cancer, particularly women, who were 50% less likely to develop the disease.Studies have also shown the positive impacts of green tea on breast, bladder, ovarian, colorectal, esophageal, lung, prostate, skin and stomach cancer.Researchers believe that it is the high level of polyphenols in tea that help kill cancerous cells and stop them from growing, however the exact mechanisms by which tea interacts with cancerous cells is unknown.
Other studies have shown a lack of preventative effects of tea on cancer. The amount of tea required for cancer-preventive effects has also varied widely in studies – from 2- 10 cups per day.1
In 2005, the FDA stated that “there is no credible evidence to support qualified health claims for green tea consumption and a reduced risk of gastric, lung, colon/rectal, esophageal, pancreatic, ovarian, and combined cancers.Numerous research has demonstrated that tea is beneficial in preventing cancer including prostate, pancreatic, breast, colorectal, esophageal, bladder, lung, and stomach. The catechins found in tea prevent cell mutation, deactivate certain carcinogens, and reduce the formation and growth of tumors. Drinking as many as four cups a day may be necessary to reap the anti-cancer benefits.
Routine tea consumption, especially for more than 10 years, has been associated with decreasing the risk of osteoporotic fractures. It’s thought that tea helps diminish bone loss through antioxidant and anti-inflammatory activity. Additionally, tea’s health-promoting properties are thought to suppress the breakdown of bone while increasing the amount and activity of bone building cells.
Recent developments on the benefits of green tea from MNT news
Green tea or coffee may reduce stroke risk. Drinking green tea or coffee on a regular basis is associated with a reduced risk of stroke, according to a study published in the journal Stroke: Journal of the American Heart Association.
Green tea may help fight prostate cancer. British researchers have scientifically proven that broccoli, turmeric, green tea and pomegranate help fight the most common cancer in men in the United States and the United Kingdom – prostate cancer.
Green tea may boost our working memory. New research published in the journal Psychopharmacologysuggests green tea can enhance our brain’s cognitive functions, particularly the working memory.
Green tea component upsets cancer cell metabolism. A new study reveals how an active component of green tea disrupts the metabolism of cancer cells in pancreatic cancer, offering an explanation for its effect on reducing risk of cancer and slowing its progression. The researchers believe the discovery signals a new approach to studying cancer prevention.
Reported in the journal Metabolomics, the study explores the effect of epigallocatechin gallate or “EGCG,” an active biological agent of green tea.
Precautions and risks
There are little to no known side effects or contraindications to drinking green tea for adults. Those with severe caffeine sensitivities could experience insomnia, anxiety, irritability, nausea or upset stomach.
Those taking anticoagulant drugs such as Coumadin/warfarin should drink green tea with caution due to itsvitamin K content.
If taken with stimulant drugs, green tea could possibly increase blood pressure and heart rate.
Green tea supplements however, contain high levels of active substances that can trigger side effects and interact with other herbs, supplements, or medications.4 Green tea supplements are unregulated by the FDA and may also contain other substances unsafe for health or with unproven health benefits. Always check with a physician before starting any herb or supplement regimen.
In particular, pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should not take green tea supplements or extracts
These are some of the many benefits but the reality is one cup of tea a day will not give you all the abundant gains. The jury is out on how many cups are necessary; some say as little as two cups a day while others five cups — and more still say you can drink up to ten cups a day. If you are thinking of going down this route, you may want to consider taking a green tea supplement instead (it would keep you out of the bathroom).
Another thing to point out is that there is caffeine in green tea — so if you are sensitive to caffeine then one cup should be your limit. Green tea also contains tannins (which can decrease the absorption of iron and folic acid), so if you are pregnant or trying to conceive then green tea may not be ideal for you. You can try mixing green tea with other healthy ingredients such as ginger.
For the rest of us with all these abundant benefits…it’s a wonder we drink anything else