Green tea polyphenols appear to decrease brain oxidative stress and enhance memory processing. A 2021 review found that regular green tea consumption may lower risk of neurological disease.
In some people, supplements containing green tea extract might worsen symptoms of Irritable Bowel Syndrome (IBS). Green tea polyphenols interfere with the absorption of lithium and might cause liver damage in those taking certain medications.
What is Green Tea Extract?
Green tea is one of the world’s most popular beverages. As a supplement, it’s touted for everything from giving you energy to reducing your risk of cancer to improving your skin. But how does it work? And is it safe to take? To find out, we spoke to integrative medicine specialist Irina Todorov, MD.
The main active ingredients in green tea extract are polyphenols called catechins, of which the flavanols epigallocatechin and epicatechin are most notable. These compounds have strong antioxidant properties and are responsible for the tea’s characteristic flavor, color, and smell. They are also believed to play a role in the health benefits of green tea, including protection against heart disease and lowering cholesterol levels.
Other research has found that the combination of EGCG and caffeine improves fat loss by increasing metabolism and boosting energy expenditure. This is known as thermogenesis. However, the effects are only modest and it is important to talk with your doctor before taking any weight loss supplements, especially if you have a condition like high blood pressure or diabetes.
Green tea extract has been shown to lower cholesterol and blood glucose levels, improve cardiovascular health, and reduce the risk of some types of cancer. It is thought to work by inhibiting enzymes that break down cholesterol, and by helping your body flush excess cholesterol from the body.
There is also some evidence that the EGCG in green tea may reduce tumor growth and metastasis, as well as inhibiting the proliferation of cancer cells. However, more research is needed in this area to determine the exact mechanisms of action and identify possible targets for new therapies.
Green tea extract can be taken in capsule, liquid, or powder form and is generally considered safe for most people when used as directed. It’s important to follow the recommended dosage and avoid taking large doses, as this can cause nausea and liver damage. Additionally, it is not recommended for children, pregnant women, or those who are taking certain medications. If you’re interested in adding a green tea extract supplement to your diet, be sure to consult with your healthcare professional to make sure it is safe for you.
Uses
Green tea is an increasingly popular dietary supplement, largely due to its high antioxidant content. This component of the plant is thought to help prevent cancer and promote heart health. It is also believed to lower cholesterol levels and help maintain a healthy weight. It is also reported to have antimicrobial properties, which could aid in the treatment of bacterial infections. In addition, green tea extract is believed to protect against UV-induced oxidative damage and premature aging.
The polyphenols in green tea are thought to provide the antioxidant effects of this dietary supplement. In one clinical trial, green tea polyphenols were shown to contribute to a reduction in body weight and waist circumference when combined with other healthy lifestyle habits such as diet and exercise. Green tea polyphenols have been shown to reduce the inflammation that can lead to clogged arteries, which is an important risk factor for heart disease. In a similar study, researchers found that participants who took green tea supplements had lower blood pressure than those who did not take the supplement.
In vitro research suggests that the EGCG in green tea may help fight cancer cells by blocking an enzyme that breaks down the body’s own antioxidants. Another study found that consuming a combination of green tea and exercise reduced the number of new blood vessels that form in the lungs. Green tea has been found to improve insulin sensitivity, which can help keep blood sugar levels within a normal range. In a small clinical trial, taking green tea extract supplements helped participants maintain their already-healthy glucose levels after ingesting a sweet drink.
A pilot open uncontrolled study found that the GCHQ in green tea may reduce photoaging by decreasing pro-inflammatory eicosanoids and cellular responses to UV radiation. In a randomized double-blind pilot study, Chiu and colleagues administered oral green tea preparation or a 10% cream with green tea extract (containing catechins, including EGCG) twice daily to forty healthy subjects with Fitzpatrick skin phototypes I to III for 12 weeks. The results indicated that green tea preparation was able to increase skin tissue elasticity and decrease photoaging compared to the placebo group.
Side Effects
Green tea extract is a popular ingredient in weight loss products, but it also has many other health benefits. It is a powerful antioxidant and can help fight cancer, prevent cardiovascular disease, lower cholesterol, and reduce inflammation. However, it can have side effects if taken in excess. These side effects are mostly due to the presence of caffeine, which can cause insomnia, irritability, high blood pressure, and heart problems. People who are sensitive to caffeine should avoid drinking green tea or taking green tea supplements in large amounts.
Several studies have shown that green tea extract can significantly lower blood fat levels, especially cholesterol and triglycerides. In addition, it can help reduce cholesterol by inhibiting the absorption of fat in the digestive tract. It has also been shown to improve blood cholesterol levels in patients with coronary artery disease. (5)
Another study showed that green tea can increase the metabolism of fat cells and decrease their size. This process is called thermogenesis. This can aid in weight loss by burning more calories through physical activity. However, if you are already overweight, this effect will not be as significant as it would be in someone who is at a healthy weight.
Green tea can also have mild blood-thinning properties. Therefore, it is important to drink green tea in moderation if you are taking medications that thin the blood. Furthermore, consuming green tea in conjunction with iron or certain antibiotics can interfere with the absorption of these medications.
Lastly, green tea can increase acid production in the stomach, aggravating symptoms of acid reflux in some individuals. This is because it contains tannins, which can irritate the lining of the stomach.
In rare cases, high intake of green tea can cause hepatotoxicity. This may be due to a buildup of caffeine-related compounds in the liver, which can lead to oxidative stress and damage the cells. This is the reason why it is advisable to take only recommended dosages of green tea.
Conclusions
Green tea is a popular beverage that has been linked to improved health. It contains numerous antioxidants that can promote weight loss, lower cholesterol levels, improve skin health and prevent cancer. However, most studies have focused on the potential benefits of a specific catechin known as epigallocatechin gallate, or EGCG. EGCG is believed to boost the body’s natural defenses against free radicals and help decrease the risk of heart disease.
Several studies have found that EGCG is an effective anti-carcinogenic compound that inhibits the growth of human cancer cells in vitro. It has also been shown to have strong antioxidant properties, and is able to scavenge many different free radicals. It has been shown to reduce oxidative DNA damage in human lymphocytes and colon cancer cells, as well as reduce hepatic cell oxidative stress. In addition, a recent study showed that EGCG protects against UVB-induced oxidative damage in human skin by suppressing cyclin D1.
In vivo studies have shown that dietary green tea polyphenols increase plasma antioxidant capacity and suppress markers of oxidative stress. For example, a diet high in green tea polyphenols significantly reduced urinary 8-hydroxydeoxyguanosine (8-OHdG) levels in smokers, suggesting that the compounds may help protect against DNA damage induced by tobacco smoke [62]. In another study, rats fed a dietary supplement containing EGCG experienced decreased oxidative stress in hepatocytes and pancreas compared to controls. It has also been found that EGCG reduces the amount of lipid peroxidation in the liver and stomach of rats [63].
The results of this study suggest that supplemental EGCG can help prevent fat buildup in your bloodstream, which can lead to high cholesterol and high blood pressure. Furthermore, EGCG can help your body metabolize and burn fat, which can aid in weight loss. The authors of the study also suggested that consuming green tea extract can promote healthy blood sugar and cholesterol levels and improve overall cardiovascular health.
Green tea is safe for most adults when consumed in amounts similar to the average consumption of six cups of brewed green tea per day. However, if you are pregnant or breastfeeding, it is important to avoid green tea. Larger doses of green tea and its supplements can increase the chances of miscarriage, and they can be harmful to newborn babies if they are exposed to caffeine before birth.
