Clinical studies have revealed that green tea contains antioxidants that can prevent atherosclerosis as well as coronary heart disease. During these studies, the researchers followed a large group of people over a certain period and compared individuals residing in different countries with distinct dietary habits. While they have not confirmed how green tea extract reduces the risk of developing cardiovascular diseases, they found out that it is highly effective in lowering triglyceride and cholesterol levels. Studies also prove that black tea can produce a number of beneficial effects that are similar to green tea.

Those who drank at least three cups of green or black tea every day had smaller chances of having a heart attack by up to 11%. However, the FDA refused to approve the petition of tea makers who wanted to claim that green tea extract could prevent the development heart disease. The FDA also concluded that no solid evidence could support the increasing claims for green tea or its extract when it comes to preventing the development of atherosclerosis and other cardiovascular diseases.

High cholesterol

Research studies also confirmed that green tea could lower bad cholesterol levels while raising HDL cholesterol in humans and animals. Another population-based study discovered that mean who include green tea in their daily diet also have lower cholesterol levels than individuals who do not prefer drinking green tea. An animal study also suggests that the polyphenols found in green tea can prevent the intestines from absorbing cholesterol by allowing the body to excrete it naturally. Researchers also found out that male smokers who drank green tea also experience a significant reduction in harmful cholesterol levels.

Cancer

A series of clinical studies also proved that both black and green teas could offer greater protection against cancer. Certain countries where people drink green tea in a regular basis were found to have lower rates of cancer. However, these population-based studies cannot confirm if green tea extract can actually prevent the formation of cancerous cells. Emerging research studies have suggested that polyphenols in green tea play a huge role in preventing cancer. Researches also noticed that polyphenols are powerful enough to destroy cancerous cells and prevent them from developing further.

• Bladder cancer

Several laboratory studies have already observed the relationship between tea consumption and bladder cancer. A particular study that compared healthy individuals to bladder cancer patients revealed that women who are used to drinking powdered green tea and black tea have fewer chances of developing bladder cancer. The same group of researchers also conducted a follow-up study that discovered how patients suffering from bladder cancer who drank green tea had better survival rates that those who refused to drink any type of tea.

• Breast cancer

Animal studies also suggest that green tea contains polyphenols that can also delay the development of breast cancer cells. A group of researchers studied 472 women who are suffering from different studies of cancer. They concluded that women who drank green tea also experienced slower spread of cancer. This is especially true among pre-menopausal women who are only in the first stages of breast cancer. They were also amazed to find out that women in the early stage of cancer who drank five cups of green tea on a daily basis were also less likely to experience the recurrent growth of cancer cells after their treatment plan has been completed.

However, women who were already in the terminal stages of breast cancer did not experience a lot of improvement when they started consuming green tea. When it comes to preventing breast cancer, these studies are still considered inconclusive. In a large scientific study, researchers also found out that the habit of drinking green tea and other types of tea cannot be associated with the decreased risk of contracting breast cancer. When researchers tried breaking down their sample groups by age, women younger than 50 who drank three cups of green or black tea every day were found to be 37% less likely to have breast cancer as compared to those who refused drinking tea.

• Ovarian cancer

In China, a population-based study was conducted to observe the condition of patients suffering from ovarian cancer. Researchers found out that patients who were accustomed to drinking at least a cup of tea every day were able to survive longer than non-tea drinkers. Researchers also found out that the women who drank more green tea also survived longest. Other clinical studies contradicted these results when they did not find beneficial effects associated with the act of drinking green or black tea.

• Colorectal cancer

Scientific studies that aim to discover how green tea affects those who are suffering from rectal or colon cancer also produced contradictory results. While some population-based studies have proven decreased risk of colon cancer among individuals who drink green tea, other studies showed bigger risks. In a certain study, women drank five or cups of green tea every day and experienced lower risks of colorectal cancer when compared non-tea drinkers. However, tea consumption did not affect male subjects. Other studies reveal that regular consumption of green tea may help women in preventing the development of colorectal cancer. Researchers need further evidence before they can finally recommend green tea for preventing colorectal cancer.

• Pancreatic cancer

In a large-scale study, researchers also attempted to compare tea drinkers with non-tea drinkers. They found out that individuals who drank more green tea were less prone to pancreatic cancer. These figures were also true for female subjects because those who drank the largest amount of green tea were half less prone to suffer from pancreatic cancer than those who drank less tea. Men who drank the most tea were also 37% less susceptible to pancreatic cancer. However, this study has not yet confirmed whether green or black tea is the only one responsible for reducing the risk of developing pancreatic cancer. Additional studies in humans and animals are still needed before scientists can gain the authority to recommend green tea to those who wish to prevent pancreatic cancer.

• Prostate cancer

Clinical studies also discovered that the extract of green tea could inhibit the development of prostate cancer cells. A large-scale clinical study was launched in Southeast China and it found out that the susceptibility to prostate cancer could actually decline with increasing duration, quantity, and frequency of drinking green tea However, both black tea and green tea extracts can stimulate certain genes that may cause cells to become less responsive to chemotherapy and anti-cancer drugs. Considering this potential drug interaction, people are advised to discontinue the use of green and black tea while undergoing chemotherapy.

• Skin cancer

Epigallocatechin gallate (ECG) is considered as the chief polyphenol in green tea. Scientific studies have already suggested that EGCG, along with other polyphenols in green tea, possess anticancer and anti-inflammatory properties that can stop the growth and onset of cancerous tumors.

Inflammatory bowel disease (IBD)

Green tea can also decrease the inflammation related to ulcerative colitis and Crohns disease, two of the most common forms of IBD. Since green tea consumption is also helpful when it comes to preventing colorectal cancer, this effect serves as an added benefit among IBD sufferers who have higher risks of developing colon cancer.

Diabetes

Traditionally, green tea was used to regulate blood sugar levels. Animal studies have suggested that it can put off the progress of Type I Diabetes and slowing down its progression if it has already been developed. People who are suffering from Type I Diabetes produce inadequate amounts of insulin, which is responsible for converting starch, glucose, and other food items into the energy your body needs to function well. Green tea solves this problem by regulating glucose levels. Some studies have concluded that regular supplementation of green tea extract powder can also lower the level of hemoglobin A1c among individuals suffering from borderline diabetes.

Liver disease

A series of clinical studies also revealed that male subjects who have become accustomed of drinking ten cups of black or green tea every day are also less likely to develop liver disorders. In fact, green tea seems to offer great protection from liver damage caused by a number of toxic substances. Animal studies also revealed that green tea could delay the progress of liver tumors in mice.

Results from human and animal studies propose that catechin, one of green teas polyphenols, may help in curing viral hepatitis as well. In these scientific studies, researchers isolated catechin from green tea and utilized them in high concentrations. It is not yet clear whether the extract of green tea can offer the same health benefits to patients suffering from hepatitis because its catechin content is lower than that of other types of tea.

Weight loss

Certain studies also revealed that the extract of green tea could boost metabolism and turn the body into a fat-burning powerhouse. A particular study also supported the assumption that the combination of caffeine and green tea could improve weight loss in moderately obese and overweight people. Some researchers assume that the polyphenols in green tea, particularly catechins, can deliver amazing fat-burning effects.

Other uses

An independent study for tooth decay also found out that green tea is effective in preventing dental caries. However, more studies are still needed before researchers can confirm these results. Green tea is also useful in curing arthritis and other inflammatory diseases. Research states that green tea benefits people who are suffering from arthritis by delaying cartilage breakdown and reducing inflammation. Green tea also contains certain chemicals that are effective in preventing the symptoms of influenza and treating genital warts. Studies also prove that individuals who drink green tea also have lower mortality rates.

Reference: http://www.umm.edu/altmed/articles/green-tea-000255.htm

If you are taking the medications listed below, do not attempt to drink any form of green tea or its extract without consulting your doctor:

• Adenosine – Green tea may contradict the effect of adenosine, a drug that is usually given in hospitals to patients who have un unstable or irregular heart rhythm.
• Antibiotics, Beta-lactam – Green tea can also affect the effects of antibiotics that contain beta-lactam because it can reduce the resistance of bacteria to treatment.
• Benzodiazepines – Caffeine, particularly the ones found in green tea, may also reduce the sedating effect of benzodiazepines and certain medications used for curing anxiety.
• Beta-blockers, Metoprolol, and Propranolol – Caffeine, including the ones found in green tea, can suddenly increase the blood pressure of people who are taking metoprolol or propranolol to remedy heart disease and hypertension.
• Blood-thinning Medications (i.e. aspirin) – Patients who are taking Warfarin, a popular blood-thinning medication, should also forget their decision to use green tea products. Green tea possesses high levels of vitamin K so it can counteract the effect of Warfarin. Patients are also advised to stop drinking green tea along with aspirin because their combination can prevent platelets from clotting. Using them together will significantly increase your chances of bleeding.
• Chemotherapy – The combined effect of green tea and anticancer medications, particularly tamoxifen and doxorubicin, can boost their effectiveness. However, human studies have not yet finalized these results. There are also some studies that have reported how black and green tea extracts can stimulate particular genes in prostate cancer cells and make them less responsive to chemotherapy drugs. This drug interaction suggests that people who are undergoing chemotherapy for drink should not consume green or black tea.
• Clozapine – The antipsychotic effect of clozapine will also be reduced if they are taken 40 minutes after patients drink green tea.
• Ephedrine – When green tea is taken along with ephedrine, it can also cause tremors, insomnia, agitation, and sudden weight fluctuations.
• Lithium – Green tea can also reduce the level of lithium, a medication that intends to cure manic depression.
• Monoamine Oxidase Inhibitors – When taken together with MAOIs, green tea can also cause a hypertensive crisis, which refers to a severe and sudden increase in blood pressure. Examples of MOIs include tranylcypromine and phenelzine, which are both used for curing depression.
• Oral contraceptives – Oral contraceptives were also proven to extend the amount of time that caffeine takes effect in the body, thus boosting is stimulating effects.
• Phenylpropanolamine – The combined effect of caffeine and phenylpropanolamine, an ingredient found in OTC medications for cough and cold as well as weight loss supplements, can lead to severe cases of hypertension and mania. In November 2000, the FDA announced a health advisory that warns people about the possible risk of brain bleeding due to this medication. The FDA also advised every manufacturer of drugs that contain phenylpropanolamine to pull out their products.